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Effects of Whole Grain Intake, Compared with Refined Grain, on Appetite and Energy Intake: A Systematic Review and Meta-Analysis

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Results from observational studies indicate that whole grain (WG) intake is inversely associated with BMI and risk of weight gain. WG intake may influence energy balance and body composition through effects on appetite and energy intake. To evaluate the impact of WG food consumption on appetite and energy intake, a systematic review and meta-analysis was performed of results from randomized controlled trials (RCTs) assessing WG food consumption, appetite, and energy intake in adults. A search of PubMed, Scopus, and Food Science and Technology Abstracts yielded 36 RCTs measuring subjective appetite ratings after consuming WG foods compared with refined grain (RG) controls. Thirty-two of these studies reported AUCs for subjective appetite (hunger, fullness, satiety, desire to eat, or prospective consumption) and/or energy intake and were included in the meta-analysis. Pooled estimates from meta-analyses are expressed as standardized mean differences (SMDs). Compared with RG foods, intake of WG foods resulted in significant differences in AUCs for subjective hunger (SMD: −0.34; 95% CI: −0.46, −0.22; P < 0.001), fullness (SMD: 0.49; 95% CI: 0.31, 0.66; P < 0.001), satiety (SMD: 0.33; 95% CI: 0.18, 0.47; P < 0.001), and desire to eat (SMD: −0.33; 95% CI: −0.46, −0.20; P < 0.001). There were small, nonsignificant reductions in prospective consumption ratings (P = 0.08) and energy intake (P = 0.07) with WG intake compared with RG. These results support the view that consumption of WG foods, compared with RG foods, significantly impacts subjective appetite, and might partly explain the inverse associations between WG food intake and risk of overweight, obesity, and weight gain over time. PROSPERO registration: CRD42020148217.
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REVIEW
Eects of Whole Grain Intake, Compared with
Rened Grain, on Appetite and Energy Intake:
A Systematic Review and Meta-Analysis
Lisa M Sanders,1Yong Zhu,2Meredith L Wilcox,1Katie Koecher,2and Kevin C Maki1,3
1Midwest Biomedical Research, Addison, IL, USA; 2Bell Institute of Nutrition, General Mills, Inc., Minneapolis, MN, USA; and 3Indiana University, Department
of Applied Health Science, School of Public Health, Bloomington, IN, USA
ABSTRACT
Results from observational studies indicate that whole grain (WG) intake is inversely associated with BMI and risk of weight gain. WG intake may
influence energy balance and body composition through effects on appetite and energy intake. To evaluate the impact of WG food consumption
on appetite and energy intake, a systematic review and meta-analysis was performed of results from randomized controlled trials (RCTs) assessing
WG food consumption, appetite, and energy intake in adults. A search of PubMed, Scopus, and Food Science and Technology Abstracts yielded
36 RCTs measuring subjective appetite ratings after consuming WG foods compared with refined grain (RG) controls. Thirty-two of these studies
reported AUCs for subjective appetite (hunger, fullness, satiety, desire to eat, or prospective consumption) and/or energy intake and were included
in the meta-analysis. Pooled estimates from meta-analyses are expressed as standardized mean differences (SMDs). Compared with RG foods, intake
of WG foods resulted in significant differences in AUCs for subjective hunger (SMD: 0.34; 95% CI: 0.46, 0.22; P<0.001), fullness (SMD: 0.49; 95%
CI: 0.31, 0.66; P<0.001), satiety (SMD: 0.33; 95% CI: 0.18, 0.47; P<0.001), and desire to eat (SMD: 0.33; 95% CI: 0.46, 0.20; P<0.001). There
were small, nonsignificant reductions in prospective consumption ratings (P=0.08) and energy intake (P=0.07) with WG intake compared with
RG. These results support the view that consumption of WG foods, compared with RG foods, significantly impacts subjective appetite, and might
partly explain the inverse associations between WG food intake and risk of overweight, obesity, and weight gain over time. PROSPERO registration:
CRD42020148217. Adv Nutr 2021;00:1–19.
Keywords: whole grain, appetite, satiety, hunger, fullness, desire to eat, prospective food consumption, energy intake, meta-analysis, randomized
controlled trials
Introduction
Whole grains (WGs) are intact, ground, cracked, or aked
grain kernels that contain all 3 anatomical components
endosperm, bran, and germ—in the same relative propor-
tions as they exist in the intact kernel (1,2). WG foods tend
This research was funded by Bell Institute of Nutrition, General Mills, Inc.
Author disclosures: KCM, MLW, and LMS are employees of Midwest Biomedical Research, which
has received research funding from General Mills, Inc., Kellogg Company,and the Quaker
division of PepsiCo. KK and YZ are employees of General Mills, Inc. The funding sponsor
provided comments on early aspects of the study design. Interim analyses and the nal data
were shared with the sponsor prior to publication, but the nal decision for all aspects of study
conduct and manuscript content is that of the authors alone.
Supplemental Tables 1–3 and Supplemental Figures1–6 are available from the
“Supplementary data” link in the online posting of the article and from the same link in the
online table of contents at https://academic.oup.com/advances/.
Address correspondence to KCM (e-mail: kcmaki@iu.edu).
Abbreviations used: GRADE, Grading of Recommendations Assessment, Development and
Evaluation; RCT, randomized controlled trial; RG, rened grain; SMD, standardized mean
dierence; VAS, visual analog scale; WG, whole grain.
to be higher in ber, B vitamins, iron, zinc, magnesium,
and selenium compared with foods made predominantly
with rened grains (RGs) (3). Accordingly, the 2015 Dietary
Guidelines for Americans recommends at least half of daily
grainintaketobefromWGsandincludesWGfoodsinevery
healthyeatingpattern.However,mostAmericanscontinueto
consume more RG foods (e.g., white bread, white rice) than
WG foods (e.g., wholewheat bread, brown rice, oatmeal) (3).
Results from observational studies suggest that higher
intake of WGs is associated with lower risk of weight gain and
incident overweight or obesity (4–6), although, ndings from
short-term (16 wk), randomized controlled trials (RCTs)
evaluating the eect of higher WG intake on body weight
have been equivocal (4,7). One of the potential mechanisms
bywhichWGscouldimpactbodyweightoverthelong
term is by suppressing appetite and, consequently, reducing
energy intake. Many WG foods contain quantities of dietary
C
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ber that have the potential to inuence glucose metabolism
(8–10), gastrointestinal transit (11), and gastrointestinal
hormone secretions (12), all of which have the potential
to impact appetite. Furthermore, fermentation of ber and
other phenolic compounds in WGs by gut microbes can
create secondary metabolites, such as SCFAs, that could
inuence appetite and energy intake (13).
Appetite is typically measured with a series of questions
relating to subjective sensations, such as hunger, fullness,
satiety or satisfaction, desire to eat, and prospective con-
sumption (14,15). Visual analog scales (VAS) with an anchor
termateachendofthescalehavebeenvalidatedasa
method for assessing changes in appetite over time after
food consumption (16). Satiety (How satised are you?) and
fullness (“How full are you?”) are related concepts and often
used interchangeably, depending on the preference of the
investigator, but both questions have been validated (14,
16). Postprandial VAS scores often correlate with subsequent
meal energy intake (15,16). However, VAS scores alone
canbeunreliableasaproxymeasureforsubsequentenergy
intake, so, ideally, both subjective appetite sensations and
energy intake should be measured (17).
Although many clinical trials have investigated the eect
of WG consumption on subjective appetite or energy intake,
due to mixed results and mostly small studies, the totality
of evidence remains unclear. Therefore, the objective of
this systematic review and meta-analysis was to evaluate
the impact of consuming WGs, compared with RGs, on
outcomes related to subjective appetite and energy intake in
RCTs in adults. The primary outcome was hunger AUC and
secondary outcomes were fullness AUC, desire to eat AUC,
satiety AUC, prospective consumption AUC, and energy
intake.
Methods
Literature searches
The Preferred Reporting Items for Systematic Reviews
and Meta-Analyses (PRISMA) guidelines were followed for
performingthesystematicreviewandmeta-analyses(18).
A comprehensive literature search was conducted using the
PubMed database, Scopus, and Food Science & Technology
Abstracts, which covered studies published from 1946
through September 2019. The search was designed to identify
publications of RCTs that examined WG intake from intact
WGs (e.g., rye, oats, quinoa, brown rice, etc.) or foods made
with WGs (e.g., breads, ready-to-eat breakfast cereals, etc.)
and outcomes related to subjective appetite (hunger, fullness,
satiety, desire to eat, prospective consumption), energy
intake, gastric emptying, and appetite-related hormones (e.g.,
ghrelin, leptin). Full search term details are provided in
Supplemental Table 1. Prior to the data analysis, in April
2020, the literature search was performed again in PubMed
only to identify relevant studies published between the
initial search and data analysis. No additional studies were
identied.
Inclusion and exclusion criteria
Inclusion criteria consisted of RCTs conducted in adult
humans (18 y of age), English language publications, WG
foods (51% of grains being WG) (19,20) as the main inter-
vention compared with RG foods as a control, documented
(or the ability to determine) quantitative intake of WG,
and a measurement of subjective appetite, energy intake,
appetite-related hormones, and/or gastric emptying time.
Exclusion criteria included observational studies (cross-
sectional, retrospective or prospective cohorts), case-control
or single-arm studies with no control condition, studies in
animals or in vitro, multicomponent interventions where the
eect of WGs cannot be determined (e.g., intervention with
WGs and additional ber compared with RGs without added
ber), studies comparing dierent types of WGs without an
RG control, studies on individual grain components (e.g.,
bran) or dietary supplements, interventions administered
via tube feeding or enteral nutrition, studies in children
(<18 y of age) or pregnant/lactating women, trials using
medications or supplements known to inuence appetite
or gastric emptying, and studies in subjects with a chronic
disease, with the exception of type 2 diabetes mellitus,
obesity, or metabolic syndrome.
Screening and data extraction
Publications identied in each database using the search
terms were combined and duplicates were removed. First-
level screening of titles and abstracts was completed inde-
pendently by a member of the research team (LMS) using
Abstrackr (http://abstrackr.cebm.brown.edu/). Full texts of
all publications identied as potentially eligible were ob-
tained for further review. Publications that were unclear
with respect to eligibility were resolved by discussion with
the research team. Reference lists from eligible publications
were reviewed to determine any additional studies for
inclusion. Following the full-text review, PICO (population,
intervention, comparator, and outcome) data were extracted
from the eligible studies into a database independently by
1 reviewer (LMS) and veried for accuracy independently
by a second reviewer (MLW). All discrepancies were re-
solved by discussion among the reviewers and referencing
the original publication. Outcomes extracted from eligible
studies included subjective appetite measures, energy intake
(subsequentmealinacutestudiesanddailyintakeforchronic
studies), appetite-related hormones, and gastric emptying.
In studies where outcomes were reported in bar
graphs, Engauge Digitizer software version 4.1 (http:
//markummitchell.github.io/engauge-digitizer/)wasused
to estimate the means and SD or SEM in the graphs for
inclusion in the database. If studies reported measuring
subjective appetite or energy intake but did not report the
data or variability, the corresponding author was contacted
by e-mail to request the quantitative data. One author
responded with additional data which was included in the
data extraction. Two publications (21,22)didnotreport
SDsorSEMsandtheauthorsdidnotrespondtoe-mail
requests, therefore, the SDs for the outcomes were estimated
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as the maximum SD reported by other studies of the same
duration.
For studies where the amount of WG in the nal food
was not documented, the recipes for test foods, or the label
information for commercial products, was reviewed. For
low-moisture foods (e.g., pasta, akes) the percentage WG
in the dry ingredients of the recipe was estimated as the
percentage WG of the nal food. For higher moisture foods
(e.g., bread), the percentage WG in the dry ingredients of the
recipe was estimated as the percentage WG of the nal food
after adjustment for the moisture content. If the moisture
content of the nal food was not provided in the publication,
moisture content was estimated using Food Data Central
from the USDA Agriculture Research Service (23).
Assessment of study quality
Risk of bias for each relevant outcome within a study was
assessed independently by a member of the research team
(LMS) with the Cochrane risk-of-bias tool for randomized
trials (24). The quality of the evidence for each outcome was
assessed through discussion among members of the research
team using the Grading of Recommendations Assessment,
Development and Evaluation (GRADE) method (25).
Statistical analysis
Meta-analyses were completed using MedCalc Statistical
Software version 19.0.5 (MedCalc Software BVBA; https:
//medcalc.org; 2019). Subjective appetite measures were
prespecied as the primary outcome, but because hunger
was the most frequently measured outcome for subjective
appetite, it was selected after the data extraction, but prior to
completion of the meta-analysis, to be the primary outcome
ofthesubjectiveappetitemeasures.Theprimaryanalysisfor
allsubjectiveappetitemeasuresusedpooledSMDestimates
(WG compared with RG control) and 95% CIs for AUCs
of hunger, fullness, satiety, desire to eat, and prospective
consumption. Although all studies used a VAS to measure
appetite and calculate AUCs, some VAS scales diered in
anchoring statements and length (i.e., not all used a 100-mm
line). The use of SMDs allowed pooling of the results from
studies with these dierent approaches. The primary analysis
forenergyintakemeasuresusedpooledSMDestimates(WG
compared with RG control) and 95% CIs for caloric intake.
Statistical signicance for individual study and pooled SMDs
wasdeclaredwhenthe95%CIdidnotincludethenullvalue
of 0 (i.e., Pvalue <0.05). Studies were weighted according
to the inverse of the variance of each study’s eect using
random eects models. Random eects models were chosen
for the primary analyses due to dierences across studies
in key design elements such as subject characteristics and
length of test period. Fixed eects models were completed for
hunger and other appetite measures in the main analysis (i.e.,
not for subgroups) as sensitivity analyses. Because results
did not dier materially between random and xed eects
models, only results from the former are presented. The
magnitude of eect sizes were interpreted as <0.40 =small,
0.40–0.70 =moderate, and >0.70 =large (26). Analyses were
notcompletedforgastricemptyingbecauseonly3studies
with data were available and dierent methodologies were
used for measuring gastric emptying rate and/or time (MRI,
paracetamol, and ultrasound). Analyses for appetite-related
hormones were not completed due to budgetary and time
constraints.
Sensitivity analyses were completed for subjective appetite
measurements to assess the degree to which varying time
frames for determination of AUCs could have impacted the
results. This was achieved by analyzing AUC measurements
<180 min and 180 min separately. An additional sensitivity
analysis on the subset of studies requiring calculation of the
WG content was also completed.
Subgroup analyses were performed on subjective appetite
measuresfortypeofWG,amountofWGconsumed(less
than or equal to the median, or greater than the median),
feeding approach (matching available carbohydrates, match-
ing calories and volume), and measurement timing (immedi-
ately after meal, subsequent meal). Similar subgroup analyses
were performed for energy intake with the 1 dierence
of measurement timing (subsequent meal, third meal, or
daily intake). Subgroup analyses were not possible for health
status (e.g., type 2 diabetes), age, gender, or BMI due to an
insucient number of studies or combined reporting within
studies (e.g., overweight and normal weight data combined)
that did not allow for distinct subgroups.
Statistical heterogeneity was assessed using Cochran
QandtheI2statistic. An I2value 40% was used to
designate moderate or higher heterogeneity, in accordance
with the recommendations in the Cochrane Handbook (27).
The presence of publication bias was assessed visually by
examining funnel plots measuring the SEM as a function of
the SMD.
Results
A ow diagram summarizing the literature search process
is shown in Figure 1.Thescopeofthisreviewislimited
to subjective appetite and energy intake. Therefore, of the
51 eligible articles included in the data extraction, 36 were
included in the systematic review (13,21,22,28–60)and
32 were included in the meta-analysis of subjective appetite
and/or energy intake. The 4 studies excluded from the meta-
analysis (57–60) reported measuring subjective appetite
AUCs and/or energy intake, but did not show the data and
authors did not respond to e-mail requests for the data.
Study characteristics are presented in Table 1.Thirtyve
(13,21,22,28–47,49–60) of the 36 studies were crossover in
design, with only 1 parallel trial (48), and included data from
794 participants. Four studies included daily consumption
of WGs or RGs for 3 to 8 wk (13,48,51,60), whereas the
remaining studies tested the response to acute intake of WGs
and RGs. WG intake in longer-term feeding studies ranged
from 48 to 145 g/d, and acute studies ranged from 40 g
to 254 g. Subjective appetite was measured only in acute
studies.ThemostcommontypeofWGtestedwasryein
15 publications (21,30,31,34,37,38,40–42,44,48,49,51,55,
57), followed by wheat in 12 publications (22,29,32,33,36,
Whole grain intake and appetite 3
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FIGURE 1 Flow diagram of literature search process for the effect of WGs on subjective appetite and energy intake in adults. FSTA, Food
Science & Technology Abstracts; WG, whole grain.
43,48,54,55,57,58,60). Other WGs tested included barley
(39,46,54,59), oats (28,35,45,52), corn (50,53), rice (47),
buckwheat (56), and quinoa (56).
WG intake and hunger
Overall, 35 comparisons reported in 18 dierent studies (21,
22,28–43) were included in the analysis of the impact of WG
on hunger AUC. Intake of WG foods resulted in signicantly
lowerhungerAUCcomparedwithRGfoods(Figure 2,SMD:
0.34; 95% CI: 0.46, 0.22; P<0.001) with no signicant
heterogeneity between studies (Q =40.08, P=0.22,
I2=15.17%). A sensitivity analysis showed the timing of
AUC measurement did not substantially impact the results,
with the eect size diering slightly in studies <180 min
or 180 min (Supplemental Table 2). A sensitivity analysis
including the subset of studies requiring WG amounts to
be calculated showed a slightly larger eect size than the
analysis including all studies (SMD: 0.45); however, studies
requiring calculation of WG content estimated slightly higher
mean levels of WG intake (92.7 ±5.3 g compared with 88.9 ±
4.4 g), which might contribute to this larger eect. Similar
results were found for all other outcomes.
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TABLE 1 Summary of studies included in the systematic review and meta-analysis of WG intake and subjective appetite AUC and/or energy intake in adults1
Study Population Health status Study design WG exposure2
RG control
exposure
Outcomes
measured
Length of
appetite
testing Effect of WG
Wolever e t al. (28)n=40 Healthy Crossover 40 g WG oats Cream of rice in skim
milk
Hunger 180 min NS hunger
60% male Acute appetite test Fullness NS fullness
39.2 ±13.1 y Matched available CHO Desire to eat NS desire to eat
BMI: 26.5 ±3.1 Breakfast meal Prospec tive
consumption
NS prospective consumption
Costabile et al. (29)n=14 Healthy Crossover 117 g WG wheat in pasta Wheat pasta Hunger 240 min Hunger
50% male Acute appetite test Satiety NS satiety
30 ±2 y Matched available CHO Desire to eat Desire toeat
BMI: 22 ±1 Breakfast meal Energy intake NS energy intake
Energy intake at lunch
Lee et al. (30)n=21 Healthy Crossover 40gWGryeinporridge Wheatbread(55g
portion)
Hunger 240 min Hunger (55 g)
52% male Acute appetite test 55 g WG rye in porri dge Fullness Fullness (55 g)
38.6 ±11.8 y Matched calories Desire to eat NS desire to eat
BMI: 24.9 ±3.3 Breakfast meal
Sandberg et al. (31)n=21
48% male
25.3 ±3.9 y
BMI: 22.7 ±2.3
Healthy Crossover
Subsequent meal appetite test
Matched available CHO
Dinner meal
Energy intake at lunch
134.5 g WG rye from rye flour bread
133.5 g WG rye from flour/kernel blend
bread
Wheat bread Hunger
Satiety
Desire to eat
Energy intake
210 min Hunger
Satiety (rye flour bread)
Desire to eat (rye flo ur bread)
NS energy intake
Cioffi et al. (32)n=16 Healthy, overweight to
obese
Crossover 100 g WG wheat in pasta Wheat pasta Hunger 240 min NS hunger
44% male Acute appetite test Fullness Fullness
44 ±10 y
BMI: 30.1 ±2.8
Matched calories and volume
Lunch meal
Satiety
Prospec tive
consumption
Energy intake
Satiety
Prospective consumption
NS energy intake
Cioffi et al. (33)n=8 Healthy, normal weight
to overweight
Crossover 100 g WG wheat in pasta Wheat pasta Hunger 240 min NS hunger
50% male Acute appetite test Fullness NS fullness
39 ±14 y
BMI: 24.7 ±2.7
Matched calories and volume
Lunch meal
Satiety
Prospec tive
consumption
NS satiety
NS prospective consumption
Sandberg et al. (34)n=19 Healthy Crossover 88.8 g WG rye from bread Wheat bread Hunger 180 min Hunger
45% male Subsequent meal appetite test Satiety Satiety
25.6 ±3.5 y Matched availableCHO Desire to eat Desire to eat
BMI: 21.9 ±1.9 Dinner meal
Geliebter et al. (35)n=36 Healthy Crossover 93.6 g WG from oatmeal Corn flakes Hunger 180 min Hunger
50% male 50% normal weight Acute appetite test Fullness Fullness
26–31 y350% overweight Matched calories and volume
Breakfast mealBMI normal weight:
23 ±2males;
22 ±2 females
BMI overweight:
33 ±3males;
36 ±7 females
Gonzalez-Anton
et al. (36)
n=23 Healthy Crossover 90.1 g WG from wheat bread Wheat bread Hunger 180 min NS hunger
55% male Normal weight to
overweight
Acute appetite test Fullness NS fullness
26 ±1 y Matched available CHO Satiety NS satiety
BMI: 23.8 ±0.5 Breakfast meal
Energy intake at lunch
Prospec tive
consumption
NS prospective consumption
NS energy intake
Energy intake
(Continued)
Whole grain intake and appetite 5
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TABLE 1 (Continued)
Study Population Health status Study design WG exposure2
RG control
exposure
Outcomes
measured
Length of
appetite
testing Effect of WG
Johansson et al. (37)n=23 Healthy Crossover 60 g WG from rye crisp bread Wheat crisp bread Hunger 240 min Hunger
30% male Normal weight to
overweight
Acute appetite test Fullness Fullness
60.1 ±12.1 y Matched calories Desire to eat NS desire to eat
BMI: 23.8 ±3.4 Breakfast meal
Forsb erg et al. (21)n=21 Healthy Crossover 76 g WG from rye kernel crisp bread
60.8 g WG from rye kernel crisp bread
Wheat bread (soft) Hunger 240 min Hunger
47% male Normal weight to
overweight
Acute appetite test Satiety Satiety(60.8 g)
39 ±14 y Matched calories Desire to eat Desire to eat
BMI: 23.3 ±3 Breakfastmeal Energy intake Energy intake (60.8 g)
Energy intake at lunch
Hartvigsen et al. (38)n=15 Metabolic syndrome Crossover 90 g WG from rye kernel bread Wheat bread Hunger 270 min Hunger
47% male Acute appetite test Fullness Fullness
62.8 ±4.2 y Matched availableCHO Satiet y Satiety
BMI: 31.1 ±3.2 Breakfast meal
Energy intake at lunch
Prospec tive
consumption
Prospective consumption
Energy intake NS energy intake
Johansson et al. (39)n=19 Healthy Crossover 96.8 g WG from boiled barley kernels Wheat bread Hunger 120 min NS hunger
32% male
24.2 ±1.9 y
Subsequent meal appetite test
Matched available CHO
Satiety
Desire to eat
NS satiety
NS desire to eat
BMI: 22.3 ±2 Dinner meal Energy intake Energy intake
Energy intake at lunch
Rosen et al. (40)n=10 Healthy Crossover 98.5 g WG from rye bread Endosperm rye
bread
Wheat bread
Hunger 120 min4Hunger (porridge)
50% male Acute appetite test 106.6 g WG from rye kernel por ridge Fullness Fullness (porridge)
26 ±1.1 y Matched available CHO 97.1 g WG from wheat kernel porridge Desire to eat Desire to eat (porridge)
BMI: 22.6 ±0.4 Breakfast meal Energy intake Energy intake (rye porridge)
Energy intake at lunch
Rosen et al. (41)n=20 Healthy Crossover 84.7 g WG from commercial rye bread Wheat bread Hunger 180 min Hunger (Evolo)
50% male Acute appetite test 83.2 g WG from Amilo rye bread Fullness NS fullness
26.7 ±0.9 y Matchedavailable CHO 82 g W G fromEvolo r yebread Desire to eat NS desire to eat
BMI: 22.2 ±0.39 Breakfast meal 82.7 g WG from Picasso rye bread
80.1gWGfromVicelloryebread
82.8 g WG from Kaskelott rye bread
Rosen et al. (42)n=14 Healthy Crossover 118.2 g WG from D. Zlote rye bread Wheat bread Hunger 180 min Hunger (Nikita, Rekrut)
50% male Acute appetite test 125.7 g WG from H. Loire rye bread Fullness Fullness
23.6 ±0.5 y Matchedavailable CHO 120.7 g W Gfrom N ikita rye bread Desire to eat NS desire to eat
BMI: 22 ±0.5 Breakfastmeal 122.2 g WG from Rekrut r ye bread
122.9 g WG from Amilo rye bread
(Continued)
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TABLE 1 (Continued)
Study Population Health status Study design WG exposure2
RG control
exposure
Outcomes
measured
Length of
appetite
testing Effect of WG
Kristensen et al. (43)n=16 Healthy Crossover 83.6 g WG from wheat pasta Wheat bread Hunger 180 min NS hunger
38% male Acute appetite test Wheat pasta Fullness NS fullness
24.1 ±3.8 y
BMI: 21.7 ±2.2
Matched available CHO and
calories
Breakfast meal
Energy intake at lunch
Satiety
Prospec tive
consumption
Energy intake
NS satiety
NS prospective consumption
NS energy intake
Solah et al. (22)n=22 Healthy Crossover 53.1 g WG from boiled bulgur kernels HA rice Hunger 240 min NS hunger
Gender, age, BMI not
reported
Acute appetite test 53.1 g WG from steamed bulgur kernels Fullness NR fullness
Matched calories and volume 53.1 g WG from boiled Turkish bulgur
kernels
Desire to eat NR desire to eat
Breakfast meal Prospec tive
consumption
NR prospective consumption
Rosen et al. (44)n=12 Healthy Crossover 66.1 g WG from rye bread Endosperm rye
bread
Wheat bread
Endosperm rye
porridge
Wheat porridge
Satiety 180 min NS satiety
75% male Acute appetite test 51.1 g WG from rye porridge
25.3 ±0.8 y Matched availableCHO
BMI: 23.1 ±0.6 Breakfast meal
Hlebowiczet al. (45)n=12 Healthy Crossover 42.5 g WG from oat flakes Corn flakes Satiety 120 min NS satiet y
50% male Acute appetite test
28 ±4 y Matched calories and volume
BMI: 22 ±2 Breakfast meal
Granfeldtetal.(46)n=10 Healthy Crossover 89 g WG from hull-less barley kernel
porridge
76.2 g WG from hulled barley kernel
porridge
90.6 g WG from hull-less HA barley kernel
porridge
87.7 g WG from hulled HA barley kernel
porridge
Wheat bread Satiety 180 min Satiety (hull-less porridge,
hull-less HA porridge, hulled
HA porridge)
50% male Acute appetite test
34 ±8 y Matched available CHO
BMI: 21.2 ±2 Breakfastmeal
79.1 g WG from hulled barley flour
porridge
90.3 g WG from hull-less HA barley flour
porridge
Hamad et al. (47)n=20 Healthy and type 2
diabetes
Crossover 70 g WG from long-grain brown rice Long-grain white
rice
Hunger 120 min NS all outcomes (for type 2
diabetes)
NR hunger
NR fullness
NR desire to eat
NS prospective consumption
40% male Acute appetite test Fullness
25.4 ±2 y male Matched available CHO Desire to eat
24.7 ±1.9 y female Breakfast meal Pros pectiv e
consumptionBMI: 23.02 ±1.62
male; 22.39 ±1.32
female
(Continued)
Whole grain intake and appetite 7
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TABLE 1 (Continued)
Study Population Health status Study design WG exposure2
RG control
exposure
Outcomes
measured
Length of
appetite
testing Effect of WG
Roager et al. (13)n=50 Overweight or obese, 1
of: impaired fasting
glucose, dyslipidemia,
hypertension
Crossover Target 75gWG/dfromvarietyofWG
foods
Targ et <10 g WG/d
from variety of RG
foods
Energy intake NA NS energy intake
36% male Daily consumption for 8 wk
48.6 ±11.1 y Ad libitum intake
BMI: 28.9 ±3.6 Energy intake over the day
Suhr et al. (48)n=24/arm Overweight to
moderately obese
Parallel No target intake No target intake Energy intake NA NS energy intake
WG rye: 46% male Daily consumption for 6 wk Mean intake WG rye: 124 ±11.8 g/d Mean intake WG:
5.4 ±12.6 g/d53 ±8.9 y Ad libitum intake Mean intake WG wheat: 145 ±12.1 g/d
BMI: 28 ±1.9 Energy intake over the day
WG wheat: 42%
male; 48.2 ±9.9 y;
BMI: 27.7 ±1.9
RG control: 50%
male; 51.8 ±9y;
BMI: 27.8 ±2
Ibrugger et al. (49)n=12 Healthy Crossover 90 g WG from rye kernel porridge Wheat bread Energy intake NA Energy intake
100% male
25.6 ±3.9 y
Matched available CHO and
calories
BMI: 23.1 ±1.2 Dinner meal
Energy intake at lunch
Luhovyy et al. (50)n=30 Healthy Crossover 50g WG from HA corn cook ie Wheat cookie Energy intake NA NS energy intake
100% male Matched calories
22.9 ±0.6 y Preload to lunch
BMI: 22.6 ±0.3 Energy intake at lunch
Isaksson et al. (51)n=24 Healthy Crossover 55 g WG from rye porridge Wheat bread Energy intake NA NS energy intake
21% male Normal weight to
moderately
overweight
Daily consumption for 3 wk—
breakfast meal only
Breakfast meals
Matched calories
33 ±13 y
BMI: 23.4 ±2.2
Energy intake over the day
Zafar et al. (52)n=12 Healthy Crossover 87 g WG from oatmeal Wheat bread Energy intake NA Energy intake
0% males Matched available CHO
Age, BMI not
reported
Breakfast meal
Energy intake at lunch
Anderson et al. (53) Study 1: Healthy Crossover 50 g WG from HA corn in soup HA corn starch in
soup
Energy intake NA NS energy intake (30 min)
n=17 Matched calories and volume Energy intake (120 min)
100% males Preload to lunch
20.2 ±0.1 y Energy intake at lunch (Study 1 =
30 min; Study 2 =120 min)BMI: 22.5 ±0.3
Study 2: n=16
100% males
20.9 ±0.3 y
BMI: 22.5 ±0.4
(Continued)
8 Sanders et al.
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TABLE 1 (Continued)
Study Population Health status Study design WG exposure2
RG control
exposure
Outcomes
measured
Length of
appetite
testing Effect of WG
Schroeder et al. (54)n=50 Healthy Crossover 84 g WG from barley hot cereal and snack
mix78.5 g WG from wheat hot cereal
and snack mix
Rice hot cereal Hunger 240 min NS hunger
26% male Normal weight to obe se Acute appetite test Fullness NS fullness
31 ±11 y Matched calories and volume Desire to eat NS desire to eat
BMI: 23 ±3 Breakfast meal and mid-morning
snack
Prospec tive
consumption
NS prospective consumption
NS energy intake
Energy intake at lunch Energy intake
Isaksson et al. (55)n=22 Healthy Crossover 162 g WG from rye porr idge (breakfast)
and wheat pasta (lunch)
62 g WG from rye porr idge (breakfast
only)
Wheat bread
(breakfast) and
wheat pasta
(lunch)
Energy intake NS energy intake
36% male Normal weight to
moderately
overweight
Matched calories
40.7 ±14.7 y Breakfast and lunch meal
BMI: 23.2 ±2.4 Energy intake at dinner
Berti et al. (56) Study 1: buckwheat Healthy Crossover Study 1: 111.3 g WG from buckwheat
pasta (large portion)
55.7 g WG from buckwheat pasta (small
portion)
Study 2: 419.8 g WG from quinoa risotto
(large portion)
211.6 g WG from quinoa risotto (small
portion)
Study 1: wheat pasta
(large and small
portions)
Study 2: White rice
(large and small
portions)
Energy intake NA NS energy intake
n=14 Matched volume
100% males Mid-morning snack
24 ±2.6 y Energy intake at lunch
BMI: 22.3 ±2.7
Study 2: quinoa
n=12
100% males
25.4 ±2.2 y
BMI: 23 ±1.9
Breen et al. (57)5n=10 Type 2 diabetes Crossover 54.1 g WG from buttermilk wheat bread Wheat bread Hunger 270 min NS hunger
60% male Acute appetite test 135.4 g WG from pumpernickel r yebread Fullness NS fullness
53.9 ±5.5 y Matched available CHO Satiety NS satiety
BMI: 35.1 ±7.5 Breakfast meal Prospec tive
consumption
NS prospective consumption
Holt et al. (58)5n=10 Healthy Crossover 79.8 g WG from wheat bread Wheat bread Hunger 120 min NR hunger
30% males Acute appetite test Fullness NR fullness
23.5 ±6.2 y Matched calories
BMI: 22.1 ±1.3 Breakfast Meal
Nilsson et al. (59)5n=17 Healthy Crossover 105.3 g WG from barley kernel bread Wheat bread Satiety 180 min Satiety (high β-glucan barley
bread)65% males Subsequent meal appetite test 124.4 g WG from cut barley kernel bread
25.9 ±3.2 y Matched available CHO 139.3 g WG from HA barley bread
BMI: 22.5 ±2.1 Dinner meal 253.9 g WG from high β-glucan barley
bread
52.6 g WG from barley kernel bread
Bodinham et al. (60)5n=14 Healthy Crossover 48 g WG from wheat bread Wheat bread Energy intake NA NS energy intak e
36% male Daily consumption for 3 wk
26 ±1.4 y Energy intake over the day
BMI: 21. 8 ±0.8
1CHO, carbohydrate; HA, high-amylose; NA, not applicable; NR, not reported; NS, not significant (P>0.05); RG, refined grain; WG, whole grain.
2Reported or calculated values.
3Range of means provided because age reported by gender and weight status.
4120 min measurement =AUC0–60min +AUC60–120min
5Included in systematic review but data not available to include in meta-analysis.
Whole grain intake and appetite 9
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FIGURE 2 Forest plot of the meta-analysis on the effect of WG intake on hunger in adults. Values are the standardized mean differences
(SMDs) for hunger AUC between WG intake and RG intake (21,22,28–43). Comm., commercial; Ctrl., control; RG, refined grain; var., variety;
WG, whole grain.
Findings from the subgroup analyses for hunger AUC are
shown in Table 2.HungerwaslowerintheWGgrouprelative
to the control when the test and control conditions were
matched by available carbohydrate (P<0.001). However,
studies matched by calories or matched by calories and
volume did not show a signicant dierence in hunger AUC
between WG and RG controls.
Three studies not included in the meta-analysis measured
hunger AUC but did not report the data. All of these studies
(47,54,57) did not show a signicant eect of WG on hunger
AUCcomparedwithRG.
WG intake and fullness
Twe lve stud i e s ( 28,30,32,33,35–38,40–43)with25com-
parisons were included in the analysis of the eect of WG on
fullness.IntakeofWGfoodsresultedinsignicantlygreater
fullness AUC compared with RG foods (Figure 3; SMD: 0.49;
95% CI: 0.31, 0.66; P<0.001) with moderate heterogeneity
between studies (Q =37.95, P=0.035, I2=36.76%). A
sensitivity analysis showed the timing of AUC measurement
impacted the eect size, with studies measuring fullness at
<180 min having a greater eect size than studies measuring
at 180 min (Supplemental Table 2).
Subgroup analyses’ results for fullness AUC are shown
in Table 2. There was a signicant positive eect of WG
on fullness in studies matched by available carbohydrate (P
<0.001), but not in studies that matched calories. There
were insucient studies matched by calories and volume to
include as a subgroup. Subgroup analyses were not possible
for acute compared with subsequent meal studies because all
studies were acute.
Five studies (22,47,54,57,58) not included in the meta-
analysis measured fullness AUC but did not report the data.
Three studies (47,54,57) did not nd a signicant eect of
WG on fullness AUC compared with RG. One of the studies
only calculated fullness AUC to use in a satiety index (58)and
thus did not statistically compare the AUC values between
treatments. Solah et al. (22)didnotreportthestatistical
results for fullness AUC.
WG intake and satiety
Thirteen studies (21,29,31–34,36,38,39,43–46)with
24 comparisons were included in the analysis of the eect of
WG on satiety. There was a signicant positive eect of WG
on satiety AUC (Figure 4, SMD: 0.33; 95% CI: 0.18, 0.47; P
<0.001) with no signicant heterogeneity between studies
(Q =15.40, P=0.88, I2=0.00%). A sensitivity analysis
showed the timing of AUC measurement did not impact the
eect size although there were only 2 studies that measured
satiety AUC for <180 min (Supplemental Table 2).
10 Sanders et al.
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TABLE 2 Subgroup analyses for the eect of WGs on subjective appetite in adults1
Outcome and subgroups
Number of
compar-
isons/studies
Subjects
(WG/control)
Effect estimate SMD
(95% CI)2I2(%) Pvalue2
Hunger AUC
Type of WG
Rye 22/9 759 (378/381) 0.42 (0.57, 0.26) 12.04 <0.001
Wheat 10/7 330 (165/165) 0.27 (0.52, 0.02) 22.14 <0.031
Amount of WG (median split)
88.8 g 18/8 748 (374/374) 0.20 (0.34, 0.06) 0.00 0.006
>88.6 g 17/10 531 (267/264) 0.53 (0.72, 0.35) 16.07 <0.001
Feeding approach
Matched available CHO 24/11 821 (409/412) 0.44 (0.59, 0.30) 10.65 <0.001
Matched calories 7/4 276 (138/138) 0.10 (0.33, 0.14) 0.00 0.421
Matched calories and volume 6/4 246 (123/123) 0.22 (0.47, 0.03) 0.00 0.078
Measurement timing
Acute appetite test 31/15 1096 (548/548) 0.35 (0.49, 0.21) 24.80 <0.001
Subsequent meal appetite test 4/3 183 (90/93) 0.35 (0.64, 0.06) 0.00 0.019
Fullness AUC
Type of WG
Rye 17/6 531 (265/266) 0.54 (0.32, 0.75) 35.77 <0.001
Wheat 6/5 170 (85/85) 0.53 (0.12, 0.94) 42.56 0.012
Amount of WG (median split)
90.0 g 13/6 496 (248/248) 0.33 (0.12, 0.54) 28.12 0.002
>90.0 g 12/6 357 (178/179) 0.69 (0.43, 0.94) 28.72 <0.001
Feeding approach
Matched available CHO 19/7 609 (304/305) 0.57 (0.37, 0.77) 34.09 <0.001
Matched calories 5/3 194 (97/97) 0.19 (0.18, 0.57) 43.81 0.315
Satiety AUC
Type of WG
Rye 10/5 351 (173/178) 0.31 (0.07, 0.55) 22.38 0.011
Wheat 6.5 178 (89/89) 0.22 (0.07, 0.51) 0.00 0.141
Barley 7/2 156 (77/79) 0.46 (0.15, 0.76) 0.00 0.004
Amount of WG (median split)
88.3 g 12/5 323 (160/163) 0.21 (0.004, 0.42) 0.00 0.055
>88.3 g 12/9 386 (191/195) 0.42 (0.23, 0.63) 0.00 <0.001
Feeding approach
Matched available CHO 19/9 561 (277/284) 0.37 (0.21, 0.53) 0.00 <0.001
Matched calories 4/2 146 (73/73) 0.08 (0.24, 0.40) 0.00 0.631
Matched calories and volume 3//3 66 (33/33) 0.36 (0.11, 0.84) 0.00 0.132
Measurement timing
Acute appetite test 20/10 526 (265/261) 0.31 (0.14, 0.48) 0.00 <0.001
Subsequent meal appetite test 4/3 183 (90/93) 0.38 (0.09, 0.67) 0.00 0.011
Desire to eat AUC
Type of WG
Rye 21/8 727 (363/364) 0.36 (0.50, 0.21) 0.00 <0.001
Amount of WG (median split)
88.8 g 13/6 552 (276/276) 0.23 (0.40, 0.07) 0.00 0.006
>88.8 g 13/5 341 (170/171) 0.50 (0.72, 0.28) 6.56 <0.001
Feeding approach
Matched available CHO 20/8 681 (340/341) 0.42 (0.57, 0.27) 0.00 <0.001
Matched calories 5/3 212 (106/106) 0.07 (0.33, 0.20) 0.00 0.623
Measurement timing
Acute appetite test 21/8 711 (355/356) 0.34 (0.50, 0.19) 14.12 <0.001
Subsequent meal appetite test 4/3 182 (91/91) 0.35 (0.64, 0.06) 0.00 0.018
Prospective consumption AUC
Type of WG
Wheat 5/4 150 (75/75) 0.15 (0.51, 0.21) 19.32 0.406
Amount of WG (median split)
86.8 g 4/3 184 (92/92) 0.17 (0.46, 0.12) 0.00 0.240
>86.8 g 4/4 116 (58/58) 0.40 (1.02, 0.23) 62.96 0.213
Feeding approach
Matched avail CHO 6/5 258 (129/129) 0.21 (0.53, 0.11) 38.83 0.202
1CHO, carbohydrate; RG, refined grain; SMD, standardized mean difference; WG, whole grain.
2Effect estimates and Pvalues from random effects models.
Whole grain intake and appetite 11
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FIGURE 3 Forest plot of the meta-analysis on the effect of WG intake on fullness in adults. Values are the standardized mean differences
(SMDs) for fullness AUC between WG intake and RG intake (28,30,32,33,35,36,38–43). Comm., commercial; Ctrl., control; RG, refined
grain; var., variety; WG, whole grain.
Findings of the subgroup analyses for satiety AUC are
shown in Table 2. There was a positive eect on satiety AUC
with WG rye (P=0.011) and WG barley (P=0.004), but not
WG wheat. There was also a signicant positive eect of WG
when tested at amounts greater than the median (88.25 g), but
not less than or equal to the median. A signicant positive
eect of WG on satiety was determined in studies with test
and control conditions matched by available carbohydrate (P
<0.001), but not when matched by calories or calories and
volume.
Two studies (57,59) not included in the meta-analysis
measured satiety AUC but did not report the data. Breen et
FIGURE 4 Forest plot of the meta-analysis on the effect of WG intake on satiety in adults. Values are the standardized mean differences
(SMDs) for satiety AUC between WG intake and RG intake (21,29,31–34,36,38,39,43–46). Ctrl., control; HAWG, high-amylose whole grain;
RG, refined grain; var., variety; WG, whole grain.
12 Sanders et al.
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FIGURE 5 Forest plot of the meta-analysis on the effect of WG intake on desire to eat in adults. Values are the standardized mean
differences (SMDs) for desire to eat AUC between WG intake and RG intake (21,28–31,34,37,39–42). Comm., commercial; Ctrl., control;
RG, refined grain; var., variety; WG, whole grain.
al. (57)didnotndasignicanteectofWGwheatbread
or WG rye bread on satiety AUC compared with RG wheat
breadinastudyofsubjectswithtype2diabetes.Nilsson
et al. (59)foundahighβ-glucan WG barley variety had a
signicantly positive eect on satiety AUC compared with
RG wheat; however, other WG barley treatments were not
signicantly dierent from RG wheat.
WG intake and desire to eat
Twenty-ve comparisons reported in 11 dierent studies (21,
28–31,34,37,39–42) were included in the analysis of the
impact of WGs on desire to eat AUC. Intake of WG foods
resulted in a signicantly lower desire to eat AUC compared
with RG foods (Figure 5;SMD:0.33; 95% CI: 0.47,
0.20; P<0.001) with no signicant heterogeneity between
studies (Q =23.97, P=0.46, I2=0.00%). A sensitivity
analysis showed the timing of AUC measurement did not
substantially impact the results, with the eect size diering
slightly in studies <180 min or 180 min (Supplemental
Table 2).
Results of subgroup analyses for desire to eat AUC are
shown in Table 2. Desire to eat was lower in the WG group
relative to the control when the test and control conditions
matched by available carbohydrate (P<0.001), but not when
matched by calories.
Three studies (22,47,54) not included in the meta-
analysis measured desire to eat AUC but did not report the
data. Two studies (47,54) did not nd a signicant eect of
WGs on desire to eat AUC compared with RGs. The other
study (22) did not report the statistical results for desire to
eat AUC.
WG intake and prospective consumption
Eight comparisons reported in 7 dierent studies (28,32,33,
36,38,43,47) were included in the analysis of the impact of
WG on prospective consumption AUC. There was no eect
of WG on prospective consumption AUC (Figure 6;SMD:
0.25; 95% CI: 0.52, 0.03) with no signicant heterogeneity
between studies (Q =9.91, P=0.19, I2=29.37%).
Sensitivity analyses could not be performed because all
studies measured prospective consumption at a time frame
180 min. There were no signicant eects of WGs on
prospective consumption AUC in any of the subgroups
(Table 2).
Two studies (54,57) not included in the meta-analysis
measured prospective consumption AUC but did not report
the data. One study (57) in subjects with type 2 diabetes
FIGURE 6 Forest plot of the meta-analysis on the effect of WG
intake on prospective consumption in adults. Values are the
standardized mean differences (SMDs) for prospective
consumption AUC between WG intake and RG intake (32,33,36,
38,43,47,61). Ctrl., control; RG, refined grain; var. variety; WG,
whole grain.
Whole grain intake and appetite 13
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FIGURE 7 Forest plot of the meta-analysis on the effect of WG intake on energy intake in adults. Values are the standardized mean
differences (SMDs) for caloric intake between WG intake and RG intake (13,29,31,32,36,38–40,43,48–56). Ctrl., control; RG, refined grain;
WG, whole grain.
did not nd a signicant eect of WG wheat bread or WG
rye bread on prospective consumption AUC compared with
RG wheat bread. The other study (54) found no signicant
dierence in prospective consumption between WG barley
or WG wheat and RG rice.
WG intake and energy intake
The impact of WGs on energy intake included 29 compar-
isons from 17 dierent studies (13,29,31,32,36,38–40,
43,48–56). There was a small, nonsignicant reduction in
energy intake following WG consumption (Figure 7;SMD:
0.11; 95% CI: 0.23, 0.01; P=0.070) and no signicant
heterogeneity between studies (Q =30.25, P=0.35,
I2=7.44%). There was a signicant eect of WGs on energy
intake when the amount of WGs fed was >90.1 g (P=0.006),
the median amount among all studies, but this eect was not
observed with amounts 90.1 g. No other subgroup analyses
showed a signicant eect on energy intake (Ta b le 3 ).
Two studies (21,60) not included in the meta-analysis
measured energy intake but did not report the data. One
study reported no signicant eect of WGs compared with
RGs on energy intake at a subsequent meal (60). Forsberg
et al. (21) also reported no signicant dierence between
WGs and RGs in energy intake at a subsequent meal with a
large breakfast (600 kcal), but a signicant eect of WGs on
energy intake with a smaller breakfast (375 kcal).
Quality of evidence
The quality of evidence as assessed by GRADE criteria is
summarized in Tab le 4 . Overall, the evidence for subjective
measuresofappetiteandenergyintakewasratedasmoderate
(low for prospective consumption). The evidence rating
was downgraded due to concerns about risk of bias in
the studies and possible publication bias. Sources of bias
in the studies were typically inadequate description of
randomization procedures or allocation concealment and
inability to blind the treatments. There was also an indication
of possible publication bias suggesting that smaller studies
with results that did not conrm the main study hypothesis
were not as likely to be published. Risk-of-bias assessment
on the outcomes of individual studies and funnel plots for
the main outcomes are shown in Supplemental Table 3 and
Supplemental Figures 1–6.
Discussion
The results of this meta-analysis of RCTs suggest that
intake of WG foods reduces hunger and desire to eat and
increases fullness and satiety compared with RG foods.
There was no signicant eect of WGs on energy intake
at subsequent meals or across the day compared with RG
foods from the subgroup analyses, although there was a
small, nonsignicant reduction in energy intake in the
main analysis when data were pooled (P=0.07). To our
knowledge, this is the rst systematic review and meta-
analysis to evaluate the eect of WG intake compared with
RG intake on subjective appetite measures and energy intake.
Several meta-analyses have evaluated the relation of WG
intake to body weight, and observational data tend to support
an inverse relation (4–6). However, RCTs with intervention
periods of a few weeks up to a few months have shown
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TABLE 3 Subgroup analyses for the eect of WGs on energy intake in adults1
Outcome and subgroups
Number of
compar-
isons/studies
Subjects
(WG/control)
Effect estimate
SMD (95% CI)2I2(%) Pvalue2
Energy intake
Type of WG
Rye 9/7 311 (156/155) 0.09 (0.30, 0.13) 0.00 0.440
Wheat 8/7 326 (162/162) 0.09 (0.30, 0.12) 0.00 0.407
Other312/8 518 (259/259) 0.17 (0.45, 0.11) 57.00 0.227
Amount of WG (median split)
90.1 g 15/11 660 (330/330) 0.01 (0.18, 0.16) 16.94 0.928
>90.1 g 12/7 411 (207/204) 0.27 (0.46, 0.08) 0.00 0.006
Feeding approach
Matched available CHO 13/9 395 (197/198) 0.13 (0.32, 0.07) 0.00 0.196
Matched calories 9/6 372 (188/184) 0.08 (0.28, 0.12) 0.00 0.435
Measurement timing
Daily intake 4/3 236 (120/116) 0.17 (0.42, 0.09) 0.00 0.191
Subsequent meal intake 21/14 811 (405/406) 0.10 (0.26, 0.06) 25.32 0.228
Third meal intake43/2 108 (54/54) 0.13 (0.51, 0.24) 0.00 0.478
1CHO, carbohydrate; SMD, standardized mean difference; WG, whole grain.
2Effect estimates and Pvalues from random effects models.
3Other category includes barley, buckwheat, corn, oat, and quinoa. There were not enough studies in individual grains to run a separate subgroup analysis.
4Third meal refers to the next meal consumed after the subsequent meal (e.g., breakfast =test meal, lunch =subsequent meal, dinner =third meal).
mixedeectsofWGintakeonbodyweightchange(4,7,13,
62,63).
WG intake was associated with signicant reductions in
appetite ratings, with eects that were small to moderate in
magnitude. There was also a small, nonsignicant reduction
in energy intake that only became signicant at high levels of
WG intake (above the median level of 90.1 g). Taken together,
these results suggest that WGs are able to reduce subjective
appetite following a meal, but not enough to signicantly
impact acute energy intake at a subsequent meal or across the
day. Also, considering the possible publication bias favoring
studies that show benecial eects of WGs on energy intake,
it is likely that WGs have little impact on short-term energy
intake, except perhaps at high levels of WG intake. Studies
that assessed chronic consumption of WGs on energy intake
werefewandonly3to8wkinduration(13,48,51). The
longest RCT (13) did not nd a signicant impact of WGs on
dailyenergyintakecomparedwithanRGdiet,buttherewas
asignicantchangeinbodyweightandbodycompositionin
the WG diet that correlated with a change in energy intake.
Longer-term studies (>16 wk) might be able to determine
whethersmallchangesinenergyintakeassociatedwithWG
consumption can have cumulative long-term eects that
explain dierences in body weight reported in observational
studies.
The diversity in studies allowed for several subgroup
analyses. Firstly, the type of WG tested in the studies
often varied, with WG r ye and WG wheat being the most
TABLE 4 Quality of evidence included in the systematic review and meta-analysis of WGs on subjective appetite measures and energy
intake in adults, based on GRADE approach1
Outcome Risk of bias2Inconsistency3Indirectness Imprecision Publication bias4Decision5
Hunger Some concerns Consistent No serious
indirectness
No serious
imprecision
Possible ⊕⊕⊕Moderate
Fullness Some concerns Moderate No serious
indirectness
No serious
imprecision
Possible ⊕⊕⊕Moderate
Satiety Some concerns Consistent No serious
indirectness
No serious
imprecision
Undetected ⊕⊕⊕Moderate
Desire to eat Some concerns Consistent No serious
indirectness
No serious
imprecision
Possible ⊕⊕⊕Moderate
Prospective
consumption
Some concerns Moderate No serious
indirectness
Moderate
imprecision
Unable to
determine6
⊕⊕∅∅ Low
Energy intake Low Consistent No serious
indirectness
Moderate
imprecision
Possible ⊕⊕⊕Moderate
1GRADE, Grading of Recommendations Assessment, Development and Evaluation; WG, whole grain.
2Ranked down primarily for inadequate description of allocation concealment and lack of blinding.
3Based on I2using thresholds in Cochrane Handbook for Systematic Reviews of Interventions, Version 6. The Cochrane Collaboration, 2019. Available at:
https://training.cochrane.org/handbook/current.
4Based on visual analysis of funnel plots.
5Symbols are suggested representations of quality of evidence from GRADE Handbook (https://gdt.gradepro.org/app/handbook/handbook.html).
6Only 8 studies and a minimum of 10 studies are generally needed to evaluate a funnel plot.
Whole grain intake and appetite 15
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frequently tested and both signicantly reducing hunger and
desire to eat and increasing fullness compared with RGs.
Interestingly, there were fewer studies on WGs such as oat
and barley, which are rich in the viscous, fermentable ber β-
glucan and may impact appetite and energy intake dierently
from wheat and rye with primarily nonviscous and poorly
fermentable bers. Fermentation of ber and other phenolic
compounds in WGs by gut microbes can produce metabo-
lites, such as SCFAs, that could inuence appetite and energy
intake beyond the subsequent meal (13). Furthermore,
viscous bers have been shown to slow gastric emptying
and prolong the release of cholecystokinin in response to
a fat-containing meal, possibly contributing to enhanced
feelings of satiety (35,64). The studies on oat and barley
in this meta-analysis had mixed results regarding subjective
appetite and energy intake so more studies in these WGs are
needed.
Using a median split to create a dichotomy of “higher”
and “lower” WG intake, the results suggest small eect sizes
with lower levels of WGs and moderate eect sizes with
higher levels of WGs. Of note, the quantities of WGs fed
in most studies were relatively high, with medians in the
range of 85 to 90 g. This is higher than typical consumption
and recommendations for intake. Daily WG consumption in
the United States is typically 16 g, and recommendations
suggest 48 g/d (3,65). Intake is somewhat higher in Europe,
ranging from 23 to 36 g/d, but even populations in northern
Europe with the highest intake (37–58 g/d) are still on the
lowendofthelevelstestedinthesestudies(65). Several
studies included these high levels to achieve 50 g of available
carbohydrate from the test food. One study fed >200 g WGs
in a test food and noted it was necessary to achieve 50 g of
available carbohydrate, but also acknowledged that >25% of
thesubjectswereunabletonishconsumingtheentiretest
product (59). Thus, more studies are needed at lower, realistic
levels of WGs recommended for a healthy diet.
The subgroup analyses also showed dierences in appetite
responses based on the feeding design. When interventions
were matched for available carbohydrate, WGs were signif-
icantly dierent from RGs for hunger, fullness, and desire
to eat. However, when studies were matched for calories or
caloriesandvolume(nonewerematchedforvolumealone),
there was not a signicant dierence between WG and RG
conditions. Because calories and volume both impact subjec-
tive appetite (66), this shows the importance of considering
both factors in studies on food ingredients and appetite. WG
foods have less available carbohydrates than RG foods due
to their ber content; therefore, studies that match available
carbohydrates often fed a greater volume of food in the WG
condition than the RG condition, which could contribute to
greaterfeelingsoffullnessorlowerfeelingsofhunger.Indeed,
several of the investigators commented on the dierence
in portion size and calories potentially contributing to the
ndings (29,36,38,42,56). Although matching available
carbohydrate might yield a more mechanistic understanding
of the inuence of glycemic response on appetite, it does not
reect typical consumption patterns or recommendations,
which suggest substitutions, such as exchanging a slice of
white bread for a slice of whole wheat bread. Substitution of
foods containing WGs for similar foods made with RGs often
results in increased dietary ber intake and reduced energy
density, both of which have been associated with lower
daily energy consumption and less weight gain over time
(66). Almost half (14 of 32) of studies in the current meta-
analysis matched available carbohydrates and did not match
conditions for calories or volume. Accordingly, there is a
need for more studies matching calories and volume between
WG and RG conditions to provide greater clarity regarding
drivers of dierences in indicators of appetite associated with
WG food consumption.
Interestingly, studies that measured appetite at a sub-
sequent meal fed 11 h after WG consumption showed
signicant eects on hunger, satiety, and desire to eat,
similar in magnitude to dierences observed in acute meal
studies. The levels of WGs fed were also similar to acute
meal studies, suggesting a potential long-term eect of WGs
on appetite that could be mediated by slowing digestion
or the fermentation of bers from WGs in the colon.
Nilsson et al. (59) showed that an evening meal with
WGs signicantly reduced the gastric emptying rate at a
subsequent standardized breakfast meal, which could have
contributed to the greater feelings of satiety after breakfast.
Fermentation metabolites, such as SCFAs, have been shown
to stimulate the production of appetite-related hormones,
such as glucagon-like peptide-1 and peptide YY (67,61,
68). A meta-analysis has shown glucagon-like peptide-1 to
increase feelings of fullness and reduce energy intake in
humans (69). These potential mechanisms by which WGs
might impact long-term appetite and energy intake should
be further investigated.
The strengths of the current systematic review and meta-
analysis include a comprehensive search of 3 databases to
ensure broad coverage of the literature and the inclusion of a
number of subgroup and sensitivity analyses that have helped
identify hypotheses for additional research and gaps in the
available evidence. However, the systematic review and meta-
analysis was also limited by poor reporting of the amount
of WGs in the studies, which resulted in the exclusion of
several studies and 17 of 36 studies requiring calculations
to estimate WG content based on recipes. Additional studies
were excluded that measured subjective appetite but did not
calculate the AUC. The present analysis also only included
studiesthatprovidedWGfoodswhere51% of the grain
was WG. There was also an indication of possible publication
bias suggesting that smaller studies with results that did not
conrm the main study hypothesis were not as likely to
be published. Finally, there were no studies in participants
with type 2 diabetes that met the inclusion criteria and
provided data for the meta-analysis. Furthermore, only
1 study in the meta-analysis was completed in participants
with metabolic syndrome (38). Thus, more investigation is
needed in these populations to determine whether eects of
WG consumption on appetite diers between groups with
and without metabolic dysregulation.
16 Sanders et al.
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In summary, the results from this systematic review
and meta-analysis show that consumption of WG foods,
compared with RG foods, modestly but signicantly reduced
hunger and desire to eat and increased fullness and satiety,
but showed only a small, nonsignicant reduction in energy
intake at the next meal or across the day. Thus, although
it is plausible that eects of WG consumption on appetite
and subsequent energy intake contribute to the associations
of greater WG intake with lower risks for weight gain and
overweight or obesity reported in observational studies,
additional research, especially with longer feeding periods,
will be needed before rm conclusions can be drawn in this
regard. More studies are warranted to further clarify the
eects of dierent WG types and of consumption in amounts
consistent with current recommendations. Particular atten-
tion should be paid to the research design to ensure calories
and volume are matched because these factors can greatly
inuence appetite and subsequent energy intake.
Acknowledgments
Theauthors’responsibilitieswereasfollowsLMS,YZ,KK,
andKCM:contributedtotheconceptionanddesignof
the systematic review and meta-analysis; LMS: reviewed the
publications, extracted the data, and conducted the risk of
bias assessment; MLW: veried the accuracy of the extraction
andanalyzedthedata;LMSandKCM:interpretedthe
data, performed the GRADE assessment, and prepared the
manuscript; and all authors: read and approved the nal
manuscript.
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Whole grain intake and appetite 19
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... In this regard, some studies have found that adolescents who consume whole grain have a lower tendency to consume fast food 21 . On the other hand, a meta-analysis study found that consumption of whole grains versus refined grains significantly affected subjective appetite and, consequently, consumption of whole grains reduced the risk of overweight and obesity 40 . It seems that more research is needed in this area. ...
... While the results of a study conducted in United States were similar to ours and they showed that consumption of whole grains was not associated with BMI 20 , other studies suggest otherwise. In this regard, other investigations have shown that whole grains can significantly prevent overweight and obesity, especially in students 40,48 . A study also conducted in the United States determined that consumption of more than 3 servings of whole grains in children 6 to 12 years old was not associated with control of overweight and obesity in this age group, whereas consumption of 1.5 to 3 servings www.nature.com/scientificreports/ of whole grains per day was positively and significantly associated with weight measures. ...
... It should be noted that in addition to the appetite questionnaire, visual analog scales (VAS) were also evaluated in the present study. VAS is an anchor term that is recognized as a method for assessing changes in appetite over time 40 . This questionnaire is graded on a scale from zero to ten, with zero indicating no appetite www.nature.com/scientificreports/ ...
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Studies show that regularly consuming whole grains reduce the risk of obesity and a wide range of chronic diseases. Despite this, studies reveal that students are consuming fewer whole grains. In the present study, we aimed to investigate the barriers to the consumption of whole grains among Iranian students. This cross-sectional study examined students at Fasa, Iran in 2020–2021. The online questionnaires were completed by students after receiving informed consent. Statistical analysis was performed using SPSS 26 and Chi-square, t-test, and logistic regression ( P > 0.05). The current study involved 1890 students (1287 (68.1%) girls and 603 (31.9%) boys). Despite the preference for white flour bread among 53.8% of all students, 77.4% ate other whole-grain products, and 75.2% consumed all products at least once a week. Additionally, barriers such as access issues (70.5%), family supply issues (91.8%), lack appeal (72.8%), non-consumption by classmates (96.2%), and high prices in recent years (43.9%) were identified as obstacles to whole grain consumption. Furthermore, white bread eating students had significantly lower appetite levels and tended to eat fast food more often than those who ate whole grains ( P < 0.05). We found that slightly more than half of the participants preferred to eat bread prepared with refined flour. Several other factors, including lack of access, lack of attractiveness, product price, parents not purchasing whole-grain products, students not paying attention to nutrition labels, peers’ effect, and eating with friends instead of family, also contribute to students avoiding whole-grain products.
... In addition to dietary programs, there are 100 s of RCTs on single nutrients, natural health products, food and food categories. For instance, some foods or food groups such as walnuts and whole grains including rye and wheat kernels have satiating [14] and thermogenic [15] properties and thus, may have weight-reducing effects. Weight loss effects of other foods or food groups including dairy products (rich in calcium) [16], legumes (rich in dietary fibers) [17], and fruits and vegetables (rich in dietary fibers and phytochemicals) [18] have also been evaluated in previously published meta-analyses. ...
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Purpose This study aimed at quantifying and ranking the effects of different foods or food groups on weight loss. Methods We searched PubMed, Scopus, Cochrane Central Register of Controlled Trials, and Embase to April 2021. We included randomized trials evaluating the comparative effects of two or more food groups, or compared a food group against a control group (usual diet, no intervention) for weight loss in adults. We conducted random-effects network meta-analysis with Bayesian framework to estimate mean difference [MD] and 95% credible interval [CrI] of the effect of food groups on weight loss. Results 152 RCTs with 9669 participants were eligible. Increased consumption of fish (MD − 0.85 kg, 95% CrI − 1.66, − 0.02; GRADE = low), whole grains (MD − 0.44 kg, 95% CrI − 0.88, 0.0; GRADE = very low), and nuts (MD − 0.37 kg, 95% CrI − 0.72, − 0.01; GRADE = low) demonstrated trivial weight loss, well below minimal clinically important threshold (3.9 kg), when compared with the control group. Interventions with other food groups led to no weight loss when compared with either the control group or other food groups. The certainty of the evidence was rated low to very low with the point estimates for all comparisons less than 1 kg. None of the food groups showed an important reduction in body weight when restricted to studies conducted in participants with overweight or obesity. Conclusions Interventions with a single food or food group resulted in no or trivial weight loss, especially in individuals with overweight or obesity. Further trials on single foods or food groups for weight loss should be highly discouraged.
... 87 Whole-grain foods contain dietary fibre that is capable to influence glucose metabolism, gastrointestinal transit, and gastrointestinal hormone secretions, all of which can influence appetite by preventing hunger and stimulating lower food intake. 88,89 It has been revealed in a study that higher consumption of whole-grain food is associated with a lower risk of weight gain and incident overweight or obesity. 90 Therefore, it is relevant to suggest that FB2 is not only safe to consume but can reduce appetite and food intake which can lower the risk of obesity. ...
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Background: Ficus deltoidea (Ficus: Moraceae) has great potential as a functional food. Administration of F. deltoidea has been reported to reduce hyperglycemia, oxidative stress and increase insulin secretion in diabetic rats and humans. However, the poor bioavailability and intestinal absorption of F. deltoidea impede its therapeutic effectiveness at a lower dosage, thus integrating F. deltoidea into brown rice will provide additional advantages. This study aimed to examine the phyto-physicochemical profile, antioxidant properties, consumer acceptance, and safety of beverages formulated from fine powder mixtures of F. deltoidea leaves and brown rice. Methods: The new beverage formulations were prepared by mixing the fine powders of F. deltoidea leaves with brown rice at ratios of 1:6 and 1:13, respectively. Physicochemical, phytochemical, and antioxidant analyses were performed to characterize the prepared beverages. Consumer acceptance was assessed utilising a 9-point hedonic scale and an acute toxicity study was employed to determine the safety of F. deltoidea-added formulations. Results: F. deltoidea decreased the pH and increased the moisture content, ash, and viscosity of a brown rice beverage. The total phenolic, flavonoid, and tannin content as well as antioxidant activities increased significantly in both F. deltoidea-added formulations. The oral LD50 of the F. deltoidea-added formulation was higher than 2000 mg/kg body weight. Conclusions: These results suggest that adding F. deltoidea leaves to brown rice beverages is safe to consume and improves the phyto-physicochemical profile, antioxidant activities, and consumers’ acceptance of the formulation.
... However, it cannot be excluded that a dietary pattern including these factors together could result in a combined beneficial effect on body weight. The impact of similar dietary patterns on satiation, satiety, and digestibility (26,78) may explain these effects, and they all affect energy intake or access of energy in different ways (79,80). ...
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Background: The aim of this article (scoping review) is to elucidate the current knowledge for the potential role of body weight for setting and updating Dietary Reference Values (DRVs) and Food-Based Dietary Guidelines (FBDGs). The following research questions were formulated:What is known about the association between intakes of specific nutrient and/or foods (exposure/intervention) and body weight (outcome) in the general population?What is known about the association between body weight (exposure) and intakes of specific nutrient and/or foods (outcomes)?Is there any evidence suggesting specific effects of foods or nutrients on body weight independent of caloric content? Methods: To identify potentially relevant articles, PubMed was searched from January 1, 2011 to June 9, 2021. The search strategy was drafted by the NNR2022 Committee. The final results were exported into EndNote. Systematic reviews (SRs), scoping reviews (ScRs), reviews, and meta-analyses (MAs) on the topic 'Body weight' published between January 1, 2011 and June 9, 2021, including human participants from the general population, in English or Scandinavian language (Norwegian, Swedish, or Danish), were considered eligible. Main findings: First, the overall body of evidence based on findings from SRs and MAs of observational and clinical studies indicates that changes in intakes of specific nutrients (sugar, fiber, and fat) and/or foods (sugar sweetened beverages, fiber rich food, and vegetables) are associated with modest or small short-term changes (0.3-1.3 kg) in body weight in the general population (with or without obesity/overweight), while long-term studies are generally lacking. Second, no study in our search assessed any association between body weight (exposure) and intakes of specific nutrients or foods (outcomes). Third, limited evidence suggests, but does not prove, that some foods or nutrients may have specific effects on body weight or body weight measures independent of caloric content (e.g. nuts and dairy). These findings may inform the setting and updating of DRVs and FBDGs in NNR2022.
... In postpartum women, a 1 g/d increase in fibre was associated with a 0.06 kg/m 2 lower BMI and 0.15 kg lower postpartum weight gain [51]; and fibre intake below the recommendation (<29 g/day) increased the risk of PPWR by 24% [52]. These findings may be related to the effects of whole grains [53] and fibre [54] on satiety and fullness and the subsequent inhibitory effect on energy intake. Given the mean wholegrains and fibre intakes were~1.2 ...
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Pre-pregnancy, pregnancy and postpartum are critical life stages associated with higher weight gain and obesity risk. Among these women, the sociodemographic groups at highest risk for suboptimal lifestyle behaviours and core lifestyle components associated with excess adiposity are unclear. This study sought to identify subgroups of women meeting diet/physical activity (PA) recommendations in relation to sociodemographics and assess diet/PA components associated with body mass index (BMI) across these life stages. Cross-sectional data (Australian National Nutrition and Physical Activity Survey 2011-2012) were analysed for pre-pregnancy, pregnant and postpartum women. The majority (63-95%) of women did not meet dietary or PA recommendations at all life stages. Core and discretionary food intake differed by sociodemographic factors. In pre-pregnant women, BMI was inversely associated with higher whole grain intake (β = -1.58, 95% CI -2.96, -0.21; p = 0.025) and energy from alcohol (β = -0.08, -0.14, -0.005; p = 0.035). In postpartum women, BMI was inversely associated with increased fibre (β = -0.06, 95% CI -0.11, -0.004; p = 0.034) and PA (β = -0.002, 95% CI -0.004, -0.001; p = 0.013). This highlights the need for targeting whole grains, fibre and PA to prevent obesity across life stages, addressing those most socioeconomically disadvantaged.
... Results from studies that compared high-protein, ketogenic diets to high-protein, non-ketogenic diets demonstrated greater appetite suppression with the high-protein, ketogenic diet, supporting an independent effect of ketosis on appetite [2•, 18]. Although a higher intake of carbohydrate, especially foods and beverages containing refined starches and added sugars, may result in increased appetite, a moderate carbohydrate intake with an emphasis on fiber-rich foods can be helpful for appetite control [25][26][27]. ...
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Purpose of Review Very-low-carbohydrate (VLC) and ketogenic diets (KDs) have been used for weight loss and more recently in patients with insulin resistance and type 2 diabetes. The impact of VLC and KDs on lipids/lipoproteins is a concern. The purpose of this review is to discuss the impact of KDs on body weight and lipids/lipoproteins. Recent Findings VLC/KDs contribute to greater weight loss in the short term (< 6 months) compared to higher carbohydrate diets, but there is typically no difference between the diets by 12 months. Triglyceride and high-density lipoprotein cholesterol levels generally improve, but there is a variable response in low-density lipoprotein cholesterol levels, with some individuals experiencing a dramatic increase, particularly those with latent genetic dyslipidemias. Summary Healthcare professionals should educate patients on the risks and benefits of following VLC/KDs and encourage the consumption of carbohydrate-rich foods associated with positive health outcomes.
... In postpartum women, a 1 g/d increase in fibre was associated with a 0.06 kg/m 2 lower BMI and 0.15 kg lower postpartum weight gain [51]; and fibre intake below the recommendation (<29 g/day) increased the risk of PPWR by 24% [52]. These findings may be related to the effects of whole grains [53] and fibre [54] on satiety and fullness and the subsequent inhibitory effect on energy intake. Given the mean wholegrains and fibre intakes were~1.2 ...
Chapter
This chapter describes the constituents and health benefits of the major foods and food groups in the Med diet. It also describes possible ways in which these foods may benefit health and implications for how best to implement a Med diet. Extra virgin olive oil (EVOO) is produced by crushing olives, and since olives are the fruit of the tree, EVOO is essentially a fruit juice. Olive oil is the food that most differentiates the Med diet from other healthy eating patterns. Suboptimal intake of fruit and vegetables ranks amongst the top dietary contributors to the global burden of disease and premature death. Pulses are legumes that are usually dried, whereas ‘legume’ is a broader term that also includes green peas and green beans. Mediterranean tree nuts include walnuts, almonds, hazelnuts, pine nuts and pistachios. Sunflower and pumpkin seeds are popular aperitif foods in many Mediterranean countries.
Article
Context Whole grain intake may control help glycemia and reduce food intake by affecting the secretion of glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). Objective This systematic review and meta-analysis aimed to assess the postprandial and long-term effects of whole grains on GLP-1 and GIP levels. Data Sources PubMed, Web of Science, and Scopus online databases were searched systematically to identify relevant randomized clinical trials (RCTs) published up to April 2021. Study Selection RCTs that evaluated the effects of whole grains, compared with refined grains, on the postprandial area under the curve (AUC) value, the postprandial serum concentration of incretins from 0 to 180 minutes, or the fasting level of incretins after at least 14 days of intervention were included. Results Nineteen studies were included in the meta-analysis. The results showed that acute intake of whole grains could not significantly change the AUC value of GLP-1 or GIP. However, the AUC value of GIP was reduced more significantly in (1) unhealthy participants (standard mean difference [SMD] −1.08; 95%CI, −2.07 to −0.10; I2 = 75.9%) compared with healthy participants, and (2) those with a baseline fasting blood glucose of ≥99 mg/dL (SMD −0.71; 95%CI, −1.30 to −0.11; I2 = 74.4%) compared with those with a baseline value of < 99 mg/dL. On the other hand, the results of time-response evaluation during 0 to 180 minutes after the intake of test meals showed that serum concentrations of GIP decreased significantly from 0 to 30 minutes (coefficient = −44.72; P = 0.005), but increased from 60 to 180 minutes (coefficient = 27.03; P = 0.005). However, long-term studies found no significant effects of whole grains on fasting concentrations of GLP-1 or GIP. Conclusion Whole grain intake did not affect postprandial levels of GLP-1 but enhanced postprandial levels of GIP from 60 to 180 minutes. Further high-quality trials are required to assess the long-term effects of whole grain intake on serum levels of incretins. Systematic Review Registration PROSPERO registration no. CRD42021256695.
Article
Introduction: Due to their composition, whole grain cereals allow to achieve the recommended intakes of numerous nutrients that are usually ingested in insufficient amounts according to various studies. On the other hand, scientific evidence indicates that the consumption of whole grain cereals is associated with positive effects on health against the suffering of some chronic non-communicable diseases such as obesity, cardiovascular disease, diabetes or cancer. These effects may be due to their high content of vitamins, minerals, fiber and bioactive compounds. The consumption of whole grain cereals is low, which could be due to the lack of knowledge of its beneficial effects by the population. The consumption of 3 or more servings a day of whole grain cereals contributes to achieve a better nutritional and health status of individuals from early ages.
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Since the release of a previous meta-analysis on the effect of whole-grain intake on obesity measures, several clinical trials have been published. Therefore, we aimed to update the previous meta-analysis on the effect of whole-grain intake on obesity measures by including recently published studies, as well as considering the main limitations in that analysis. We searched the online databases of PubMed, Scopus, Clarivate Web of Science, EmBase, and Google Scholar for relevant studies published up to February 2019, using relevant keywords. Randomized clinical trials investigating the effect of whole-grain products or diets high in whole-grain foods, compared with a control diet, on anthropometric measures [including body weight, BMI, waist circumference, and fat mass (FM)] were included. In total, 21 studies with a total sample of 1798 participants, aged ≥18 years, were considered. Based on 22 effect sizes from 19 studies on body weight, with a total sample of 1698 adults, we found no significant effect of whole-grain consumption on body weight. The same findings were obtained for BMIs, such that using 10 effect sizes from 10 clinical trials with a total sample of 769 individuals we did not find any significant effect. With regards to body fat percentage [weighted mean difference (WMD): 0.27; 95% CI: -0.05 to 0.58%; P = 0.09], FM (WMD: 0.45; 95% CI: -0.12 to 1.02 kg; P = 0.12), fat-free mass (WMD: 0.31; 95% CI: -0.67 to 0.06 kg; P = 0.10), and waist circumference (WMD: 0.06; 95% CI: -0.50 to 0.63 cm; P = 0.82), we failed to find any significant effect of whole-grain consumption. In conclusion, our findings did not support current recommendations of whole-grain intake in attempts to control obesity measures. Given the beneficial effects of whole-grain intake on other measures of human health, additional well-designed studies are required to further investigate the effect on obesity. The protocol has been registered with PROSPERO (registration number CRD42018089176).
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Results from some observational studies suggest that higher whole grain (WG) intake is associated with lower risk of weight gain. Ovid Medline was used to conduct a literature search for observational studies and randomized controlled trials (RCTs) assessing WG food intake and weight status in adults. A meta-regression analysis of cross-sectional data from 12 observational studies (136,834 subjects) and a meta-analysis of nine RCTs (973 subjects) was conducted; six prospective cohort publications were qualitatively reviewed. Cross-sectional data meta-regression results indicate a significant, inverse correlation between WG intake and body mass index (BMI): weighted slope, −0.0141 kg/m2 per g/day of WG intake (95% confidence interval (CI): −0.0207, −0.0077; r = −0.526, p = 0.0001). Prospective cohort results generally showed inverse associations between WG intake and weight change with typical follow-up periods of five to 20 years. RCT meta-analysis results show a nonsignificant pooled standardized effect size of −0.049 kg (95% CI −0.297, 0.199, p = 0.698) for mean difference in weight change (WG versus control interventions). Higher WG intake is significantly inversely associated with BMI in observational studies but not RCTs up to 16 weeks in length; RCTs with longer intervention periods are warranted.
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This meta-analysis summarizes the evidence of a prospective association between the intake of foods [whole grains, refined grains, vegetables, fruit, nuts, legumes, eggs, dairy, fish, red meat, processed meat, and sugar-sweetened beverages (SSBs)] and risk of general overweight/obesity, abdominal obesity, and weight gain. PubMed and Web of Science were searched for prospective observational studies until August 2018. Summary RRs and 95% CIs were estimated from 43 reports for the highest compared with the lowest intake categories, as well as for linear and nonlinear relations focusing on each outcome separately: overweight/obesity, abdominal obesity, and weight gain. The quality of evidence was evaluated with use of the NutriGrade tool. In the dose-response meta-analysis, inverse associations were found for whole-grain (RRoverweight/obesity: 0.93; 95% CI: 0.89, 0.96), fruit (RRoverweight/obesity: 0.93; 95% CI: 0.86, 1.00; RRweight gain: 0.91; 95% CI: 0.86, 0.97), nut (RRabdominal obesity: 0.42; 95% CI: 0.31, 0.57), legume (RRoverweight/obesity: 0.88; 95% CI: 0.84, 0.93), and fish (RRabdominal obesity: 0.83; 95% CI: 0.71, 0.97) consumption and positive associations were found for refined grains (RRoverweight/obesity: 1.05; 95% CI: 1.00, 1.10), red meat (RRabdominal obesity: 1.10; 95% CI: 1.04, 1.16; RRweight gain: 1.14; 95% CI: 1.03, 1.26), and SSBs (RRoverweight/obesity: 1.05; 95% CI: 1.00, 1.11; RRabdominal obesity: 1.12; 95% CI: 1.04, 1.20). The dose-response meta-analytical findings provided very low to low quality of evidence that certain food groups have an impact on different measurements of adiposity risk. To improve the quality of evidence, better-designed observational studies, inclusion of intervention trials, and use of novel statistical methods (e.g., substitution analyses or network meta-analyses) are needed.
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Background/Objectives Soaking oats overnight in milk renders them ready to eat the next morning, however, it is unknown whether oats prepared this way will retain its relatively low glycaemic and insulinaemic impact. Therefore, we compared the glycaemic, insulinaemic and subjective hunger responses elicited by oats soaked overnight in 110 g skim-milk (ONO) vs. cooked cream of rice cereal (CR), both with and without inclusions. Subjects/Methods The project was performed at two research centers (Toronto, Winnipeg) as two separate studies each using a randomized, cross-over design with similar methods. The glycaemic and insulinaemic responses of overnight-fasted participants without diabetes (males:females: Toronto, 24:16; Winnipeg, 20:20) were measured for 3 h after consuming CR and ONO fed alone (Toronto) or with added sugar, nuts, and seeds (CRsns and ONOsns) (Winnipeg). Participants rated subjective hunger using visual analog scales. Data were analyzed by paired t-test. The primary endpoint was 0–2 h incremental area under the curve (iAUC) for glucose. Results Mean glucose iAUC was 33% less, after ONO than CR (mean difference was 39 (51–27) mmol × min/l, p < 0.0001) and 24% less, after ONOsns than CRsns (mean difference was 43 (65–21) mmol × min/l, p = 0.0003). Serum-insulin iAUC was 33% less, after ONO than CR (mean difference 57 (81–40) pmol × hl, p < 0.0001) and 32% less, after ONOsns than CRsns (966 (1360–572) pmol × h/l, p < 0.0001). In both Toronto and Winnipeg, subjective hunger ratings were similar across the two treatments. Conclusions Oats prepared by soaking overnight in skimmed milk without and with inclusions retain their relatively low glycaemic and insulinaemic impact.
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Gastrointestinal transit time may be an important determinant of glucose homeostasis and metabolic health through effects on nutrient absorption and microbial composition, among other mechanisms. Modulation of gastrointestinal transit may be one of the mechanisms underlying the beneficial health effects of dietary fibers. These effects include improved glucose homeostasis and a reduced risk of developing metabolic diseases such as obesity and type 2 diabetes mellitus. In this review, we first discuss the regulation of gastric emptying rate, small intestinal transit and colonic transit as well as their relation to glucose homeostasis and metabolic health. Subsequently, we briefly address the reported health effects of different dietary fibers and discuss to what extent the fiber-induced health benefits may be mediated through modulation of gastrointestinal transit.
Chapter
This chapter addresses first one of the key aspects of interpreting findings that is also fundamental in completing a ‘Summary of findings’ table: the certainty of evidence related to each of the outcomes. It then provides a more detailed consideration of issues around applicability and around interpretation of numerical results, and provides suggestions for presenting authors’ conclusions. Methods are presented for computing, presenting and interpreting relative and absolute effects for dichotomous outcome data, including the number needed to treat. For continuous outcome measures, review authors can present summary results for studies using natural units of measurement or as minimal important differences when all studies use the same scale. When studies measure the same construct but with different scales, review authors will need to find a way to interpret the standardized mean difference, or to use an alternative effect measure for the meta-analysis such as the ratio of means.
Chapter
This chapter describes the principles and methods used to carry out a meta-analysis for a comparison of two interventions for the main types of data encountered. A very common and simple version of the meta-analysis procedure is commonly referred to as the inverse-variance method. This approach is implemented in its most basic form in RevMan, and is used behind the scenes in many meta-analyses of both dichotomous and continuous data. Results may be expressed as count data when each participant may experience an event, and may experience it more than once. Count data may be analysed using methods for dichotomous data if the counts are dichotomized for each individual, continuous data and time-to-event data, as well as being analysed as rate data. Prediction intervals from random-effects meta-analyses are a useful device for presenting the extent of between-study variation. Sensitivity analyses should be used to examine whether overall findings are robust to potentially influential decisions.
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Assessment of risk of bias is regarded as an essential component of a systematic review on the effects of an intervention. The most commonly used tool for randomised trials is the Cochrane risk-of-bias tool. We updated the tool to respond to developments in understanding how bias arises in randomised trials, and to address user feedback on and limitations of the original tool.