Article

Structured Dietary Advice Incorporating Walnuts Achieves Optimal Fat and Energy Balance in Patients with Type 2 Diabetes Mellitus

Smart Foods Centre, University of Wollongong, NSW, Australia.
Journal of the American Dietetic Association (Impact Factor: 3.92). 07/2005; 105(7):1087-96. DOI: 10.1016/j.jada.2005.04.007
Source: PubMed

ABSTRACT

A cardioprotective dietary fat profile is recommended for the treatment of type 2 diabetes. The clinical feasibility of advice strategies targeting specific fatty acid intakes and the extent to which they can be achieved by free-living populations needs to be tested. Walnuts, with high n-3 polyunsaturated fatty acid (PUFA) content, may help optimize fatty acid intakes, but regular consumption might increase total fat and energy intakes. This study examined whether advice that refers to a total dietary pattern inclusive of walnuts would result in low-fat energy-controlled diets with optimal dietary fat proportions for patients with type 2 diabetes mellitus.
A parallel-design, controlled trial was completed by 55 free-living men and women with established type 2 diabetes mellitus. Participants were randomly assigned to one of three groups: low-fat (general advice), modified low-fat (total diet advice using exchange lists to differentiate PUFA-rich foods), walnut-specific (modified low fat including 30 g walnuts/day). Dietary intakes and clinical outcomes were measured at baseline, and at 3 and 6 months. Dietary goals were: less than 10% of energy from saturated fat, 7% to 10% of energy from PUFA, adequate n-3 PUFA (>or=2.22 g alpha-linolenic acid, >or=0.65 g eicosapentaenoic acid [EPA]+docosahexaenoic acid [DHA]) and n-6 to n-3 ratio less than 10. The proportion of subjects achieving dietary goals and major food sources of fat were determined.
At baseline, dietary intakes were not significantly different between groups. No group and few individuals (10%) were consuming adequate PUFA, with meat the main source of dietary fat (22% total dietary fat). At 3 and 6 months, energy and macronutrient intakes were similar among groups. The walnut group, however, was the only group to achieve all fatty acid intake targets (P <.01), and had the greatest proportion of subjects achieving targets ( P <.05). Walnuts were the main source of dietary fat (31%) and n-3 PUFA (50%), while 350 g oily fish/day provided a further 17% n-3 PUFA consumed by this group.
Specific advice for the regular inclusion of walnuts in the context of the total diet helps achieve optimal fat intake proportions without adverse effects on total fat or energy intakes in patients with type 2 diabetes mellitus.

Full-text

Available from: Lynda J Ross, Dec 13, 2013
RESEARCH
Current Research
Structured Dietary Advice Incorporating Walnuts
Achieves Optimal Fat and Energy Balance in
Patients with Type 2 Diabetes Mellitus
LYNDA J. GILLEN; LINDA C. TAPSELL, PhD, MHPEd; CRAIG S. PATCH, MBA; ALICE OWEN, PhD; MARIJKA BATTERHAM, PhD
ABSTRACT
Objective A cardioprotective dietary fat profile is recom-
mended for the treatment of type 2 diabetes. The clinical
feasibility of advice strategies targeting specific fatty acid
intakes and the extent to which they can be achieved by
free-living populations needs to be tested. Walnuts, with
high n-3 polyunsaturated fatty acid (PUFA) content, may
help optimize fatty acid intakes, but regular consumption
might increase total fat and energy intakes. This study
examined whether advice that refers to a total dietary
pattern inclusive of walnuts would result in low-fat en-
ergy-controlled diets with optimal dietary fat proportions
for patients with type 2 diabetes mellitus.
Research design and methods A parallel-design, controlled
trial was completed by 55 free-living men and women with
established type 2 diabetes mellitus. Participants were ran-
domly assigned to one of three groups: low-fat (general
advice), modified low-fat (total diet advice using exchange
lists to differentiate PUFA-rich foods), walnut-specific
(modified low fat including 30 g walnuts/day). Dietary in-
takes and clinical outcomes were measured at baseline, and
at 3 and 6 months. Dietary goals were: less than 10% of
energy from saturated fat, 7% to 10% of energy from PUFA,
adequate n-3 PUFA (2.22 g
-linolenic acid, 0.65 g eico-
sapentaenoic acid [EPA]docosahexaenoic acid [DHA]) and
n-6 to n-3 ratio less than 10. The proportion of subjects
achieving dietary goals and major food sources of fat were
determined.
Results At baseline, dietary intakes were not significantly
different between groups. No group and few individuals
(10%) were consuming adequate PUFA, with meat the
main source of dietary fat (22% total dietary fat). At 3 and
6 months, energy and macronutrient intakes were simi-
lar among groups. The walnut group, however, was the
only group to achieve all fatty acid intake targets (P.01),
and had the greatest proportion of subjects achieving
targets (P.05). Walnuts were the main source of dietary
fat (31%) and n-3 PUFA (50%), while 350 g oily fish/day
provided a further 17% n-3 PUFA consumed by this
group.
Conclusions Specific advice for the regular inclusion of
walnuts in the context of the total diet helps achieve
optimal fat intake proportions without adverse effects on
total fat or energy intakes in patients with type 2 diabe-
tes mellitus.
J Am Diet Assoc. 2005;105:1087-1096.
E
vidence-based guidelines for the management of type
2 diabetes mellitus and related cardiovascular dis-
ease (CVD) refer to cardioprotective dietary fatty
acid proportions (1). Converting macronutrient targets
into practical advice about what foods to eat, however, is
one of the most challenging aspects of nutrition manage-
ment. A total diet approach, “where all foods can fit into
a healthful eating style,” is recommended (2), and an
exchange system of food lists supports this process (3).
However, general low-fat advice strategies based on cur-
rent exchange list systems do not necessarily reduce the
proportion of saturated fat (SFA) intake (4). Adequacy of
the polyunsaturated fat (PUFA) fraction, concomitantly
reduced with low-fat advice, may also require attention
(5). Conversely, advice to increase unsaturated fat intake
may result in unintended increases in total fat and en-
ergy intake (6). Even when food-based advice matches
nutrient targets, achieving long-term adherence to di-
etary advice is problematic in free-living populations (7).
More research is needed to establish evidence-based
practices that ensure recommended fatty acid propor-
tions within low-fat, energy-controlled diets. For this,
new dietary advice approaches must be tested with free-
living subjects. An exchange system based on the fatty
acid content of foods has not yet been established, nor has
the position in the diet of significant delivery sources of
essential fatty acids.
Although fish is recommended for its n-3 PUFA content
based on evidence from the general population (1), fish
and other individual food sources of n-3 fatty acids re-
quire further investigation in populations with diabetes.
The cardioprotective benefits of nuts and their unsatur-
ated fat content have been reviewed (8). Despite being
L. J. Gillen is a doctoral candidate, C. S. Patch is a
doctoral candidate, A. Owen is a research fellow, and
M. Batterham is a biostatistician and research fellow,
all at Smart Foods Centre, University of Wollongong,
Wollongong, Australia. L. C. Tapsell is a professor and
director of the National Centre of Excellence in Func-
tional Foods, University of Wollongong, Australia.
Address correspondence to: Lynda J. Gillen, Smart
Foods Centre, University of Wollongong, Northfields
Ave, Wollongong NSW 2522, Australia. E-mail: ljg01@
uow.edu.au
Copyright © 2005 by the American Dietetic
Association.
0002-8223/05/10507-0003$30.00/0
doi: 10.1016/j.jada.2005.04.007
© 2005 by the American Dietetic Association Journal of the AMERICAN DIETETIC ASSOCIATION 1087
Page 1
energy-dense, strong dietary compensation and little
change in energy balance have been reported during
chronic consumption of nuts (9). Hence, the incorporation
of nuts into low-fat, energy-controlled diets may be an
appropriate strategy for the adequate achievement of un-
saturated fatty acid targets. Walnuts in particular, with
high n-3 PUFA content, may provide an additional source
of these essential fatty acids (10).
The feasibility of advice for the regular consumption of
a high-fat food has not been previously assessed in free-
living subjects with diabetes. The study reported here
aimed to assess the achievement of dietary fatty acid
targets in a sample of patients with type 2 diabetes mel-
litus randomly assigned to one of three dietary advice
interventions for 6 months. The three groups were: a
control group given general low-fat advice, and two inter-
vention groups given total diet advice with one group
incorporating walnuts into the PUFA fraction of the diet.
METHODS
Subjects
The study was conducted in Wollongong, a major coastal
city 70 km south of Sydney, Australia. Subjects with estab-
lished type 2 diabetes mellitus were recruited by advertis-
ing through local media, at the Illawarra Health Diabetes
Centre in Wollongong and among University of Wollongong
staff. Inclusion criteria were: age 35 to 75 years, diagnosed
with type 2 diabetes mellitus for at least 1 year, and gener-
ally healthy. Exclusion criteria were: on insulin therapy (or
with glycated hemoglobin 9%), body mass index (BMI)
more than 35, diagnosed with major debilitating illness,
known food allergies, food habits inhibiting the study, illit-
eracy, or inadequate conversational English.
Study Design
The Human Research Ethics Committee of the Univer-
sity of Wollongong and Illawarra Area Health Service
provided ethical approval for this research. The study
was conducted under controlled trial conditions where
subjects were randomly assigned to one of three parallel
dietary advice groups each targeting 30% energy from
total fat: low-fat (control), modified low-fat, and modified
low-fat with specific advice to include 30 g walnuts per
day (walnut). To avoid contact between participants re-
ceiving and not receiving walnuts, the control and modi-
fied low-fat groups were seen at the Wollongong Diabetes
Centre, while those in the walnut group were seen in
clinic rooms at the University of Wollongong. An experi-
enced Accredited Practicing Dietitian counseled all indi-
viduals. Each participant was required to follow the re-
spective dietary advice for 6 months after randomization.
Dietary Advice and Targets
Dietary advice provided to each group is outlined in the
Figure. All participants were provided with an individu-
alized portion-controlled carbohydrate meal plan based
on the redistribution of habitual carbohydrate intake
(11). To support the meal plan, exchange lists of carbo-
hydrate-rich foods incorporating the glycemic index (12)
were also provided. In each group, participants were re-
ferred to core food guide recommendations outlined in the
Australian Guide to Healthy Eating (13), and individual
food preferences were considered.
Low-Fat Group
In addition to the intervention mentioned earlier, the
control group received general dietary advice that corre-
sponded to usual practice methods used at the Wollon-
gong Diabetes Centre for reducing total and saturated fat
in the diet. Distinctions between staple foods containing
mainly saturated or unsaturated fat were emphasized in
a “good” fat vs “bad” fat approach. The number of clinic
visits was based on individual need provided at the dis-
cretion of the dietitian, as per usual clinical practice at
the Centre.
Modified Low-Fat Group
Each participant in the modified low-fat group received
more structured advice in the form of a meal plan based
on energy requirements, established individually from
reported baseline intakes (Table 1). Development of the
meal plan has been described elsewhere (Gillen and col-
leagues, under review), and was based on a reference
model calculated from mean values representing the ma-
cronutrient and fatty acid content of exchange lists of
staple foods to provide 50% of energy from carbohydrate,
20% of energy from protein, and 30% of energy from total
dietary fat (in the proportions of less than 10% of energy
from saturated fat and approximately 10% of energy from
polyunsaturated fat).
To differentiate fat type, each meal plan referred to
nine categories of foods that corresponded to the macro-
nutrient exchange lists, a greater number than core food
Food category LF
a
(control) MF
b
Walnut
Carbohydrate-rich No. portions No. portions No. portions
Distribution Distribution Distribution
CHO
c
type CHO type CHO type
Protein-rich Serving size No. portions No. portions
Fish portions Fish portions
Milk allowance Type of milk Total (mL) Total (mL)
Type milk Type milk
(LF/PUFA
d
) (LF/PUFA)
Spreads/oils/nuts Type of spread/oil Total (g) Total (g)
Type fat Type fat
(MUFA
e
/PUFA) (MUFA/PUFA)
Walnuts 30 g/day
a
LFlow-fat group.
b
MFmodified low-fat group.
c
CHOcarbohydrate.
d
PUFApolyunsaturated fatty acid.
e
MUFAmonounsaturated fatty acid.
Figure. Outline of three different approaches to dietary advice accord-
ing to major food categories: general low-fat advice, advice to modify
the type of fat within a low-fat diet, and advice to regularly consume
walnuts as part of a modified low-fat diet (walnut).
1088 July 2005 Volume 105 Number 7
Page 2
groups (13). The extra groups provided specific advice for
the amount and frequency of individual PUFA-rich foods
such as soymilk and oily fish, and for high-fat foods high-
est in unsaturated fat, such as oils, margarines, and nuts.
Exchange lists of monounsaturated fatty acid (MUFA)-
rich and PUFA-rich foods were also provided. Monthly
clinic visits were supported by one telephone contact be-
tween each visit to check compliance, assessed by cross-
checking reported daily intakes from all food groups
against the meal plan provided.
Walnut Group
Individuals in the walnut group received a meal plan as
described for the modified low-fat group but with the
inclusion of 1 oz (30 g) walnuts per day as part of the
PUFA content of the diet. To facilitate intake, a 1-month
supply of individually wrapped daily portion packs of
walnuts were provided to each person at each clinic visit.
Contact and assessment of compliance was consistent
with those methods outlined for the modified low-fat
group.
Dietary and Clinical Data
At baseline, 3 months, and 6 months all participants
completed 3-day weighed food records and an interviewer-
administered, open-ended diet history questionnaire, pre-
viously validated within a diabetes population in the
Illawarra region (14,15). Each participant was individu-
ally instructed how to measure and record all foods con-
sumed for 2 typical weekdays and 1 weekend day. Stan-
dard metric household measures and standardized forms
were provided for this process. Two experienced dietetics
professionals, not involved in the dietary counseling for
this study, conducted diet history questionnaires, asking
each participant to describe his/her usual daily eating
pattern with variations. “Usual” was defined as foods
consumed regularly during the previous 3 months. A
short food frequency questionnaire of common food
groups was included in the interview to act as a cross-
check.
Data on age, family history of diabetes, country of birth,
and usual daily activity were collected by self-report.
Weight and body fat composition were measured and re-
corded at each time point. BMI was calculated for each
measured weight. Height and individual insulin require-
ments were recorded at baseline. Any change in the latter
was recorded as 3-month and 6-month data.
Reported daily activity was categorized as sedentary,
light, moderate, or active based on subjective judgment
using Food and Agriculture Organization definitions (16).
Dietary Analysis
Dietary data were entered into the FoodWorks nutrient
analysis software program (Xyris, Version 3.2, 2002, Bris-
bane, Australia) using the Australian nutrient database
AusNut Rev.14 (FSANZ, Canberra, Australia, 1999) and
the fatty acid database of Australian fatty acids (Rev 6
RMIT, 2002, Melbourne, Australia).
Food intake data were converted to energy and macro-
nutrient values, expressed as kilojoules (kJ) and percent-
age of energy, respectively. Primary outcomes were the
proportions of individuals from each group achieving
fatty acid targets, defined as mean intakes of less than
10% of energy as SFA (1), 7% or more of energy as PUFA
(PUFA to SFA [P:S] ratio 1) (1), minimum intakes for
n-3 fatty acids (17): 2.22 g
-linolenic acid (ALA), and
0.65 g eicosapentaenoic acid (EPA)docosahexaenoic
acid (DHA), and an n-6 to n-3 ratio less than 10 (18).
To assess the quality of the diet history data, com-
parisons were made with food record data collected at
the corresponding time point. An estimation of the
potential bias in reported energy intakes was under-
taken, where reported estimated intakes were com-
pared with estimated energy expenditure, calculated
using the Schofield Equation (19) with reference to
estimated activity levels (16). Finally, erythrocyte fatty
acid composition was assessed as a biomarker for re-
ported intakes (20).
Trained professionals drew blood samples that were
sent to a quality-assured pathology laboratory (Southern
IML Pathology, Wollongong, Australia), in keeping with
standard clinical practice. Biomarkers were assessed in
the University of Wollongong laboratory using standard
techniques. Erythrocyte fatty acid composition was deter-
mined by gas chromatography. Erythrocyte membrane
lipids were isolated by ultracentrifugation (21) and the
fatty acids derived using a direct transesterification
method (22). The resulting fatty acid methyl esters were
Table 1. Example of individualized advice provided to each subject in the walnut group based on a 2,000-kcal requirement in a study of optimal
dietary fat proportions for patients with type 2 diabetes mellitus
Bread/cereal/
rice/potato/
pasta Vegetables Fruit Milk Lean meat Oily fish Spreads/oils Walnuts
Daily servings 9 5 4 600 mL 600 g (20 oz)/wk 450 g (15 oz)/wk 2 tsp 30 g
Breakfast 3 1 330 mL
Morning tea 1 30 mL
Lunch 3 2 30 mL
Afternoon tea 1 30 mL
Dinner 3 3 30 mL
Supper 1 150 mL
July 2005 Journal of the AMERICAN DIETETIC ASSOCIATION 1089
Page 3
analyzed by gas chromatography using a Shimadzu GC-
17A equipped with a 30 m0.25 mm capillary column
(FAMEWAX, Restek GMbH, Bellefonte, PA) with hydro-
gen as a carrier gas. Fatty acid identification was based
on the retention time of authentic fatty acid methyl ester
standards (Sigma-Aldrich, Castlehill, New South Wales,
Australia).
Food Pattern Analysis
Foods were categorized based on predominant fatty acid
content: SFA, MUFA, or PUFA-rich. The contribution of
these foods to total dietary fat intakes at 0, 3, and 6
months was calculated as a percentage of the total fat
consumed from all foods by each group. Similarly, major
sources of n-3 PUFA were determined by calculating the
n-3 consumed from individual foods as a percentage of
total n-3 intake. Mean amounts of these foods consumed
by each advice group were also reported.
Statistical Analysis
All statistical analyses were conducted using SPSS for
Windows (Version 11.0, 2001, SPSS Inc, Chicago, IL).
Comparisons between treatment groups for data defining
subject characteristics and numbers of individuals
achieving fatty acid targets were performed using
2
tests. For baseline dietary data, assumptions of normality
were made. A one-way analysis of variance was used for
comparisons of clinical and dietary data at 0, 3, and 6
months. A repeated measures analysis of variance was
used to assess differences in macronutrient intakes over
time (0, 3, and 6 months) with treatment group as the
between-subjects factor. Results were expressed as
meanstandard deviation (SD) with the level of signifi-
cance reported at P.05 for all comparisons.
Data from the diet histories and the food records were
compared using Bland-Altman plots, in which the 95%
limits of agreement are set as two standard deviations
from the mean of the difference between the two data sets
(23). A mean difference close to zero indicates minimum
Table 2. Energy and macronutrient intakes of all groups at 0, 3, and 6 months after intervention: amount consumed and number and percent
of subjects achieving dietary targets in a study of optimal dietary fat proportions for patients with type 2 diabetes mellitus
Variable Target
a
Control Group
0mo(n21) 3mo(n20) 6mo(n20)
4™™™™™™™™™™™™™™™™™ meanstandard deviation ™™™™™™™™™™™™™™™™™3
Amount consumed
Energy (kcal) 2,000 2,053.8568.1 2,128.2604.8 2,146.0431.8
Carbohydrate (% energy) 50 46.46.6 45.27.2 43.18.1
Protein (% energy) 20 20.82.8 21.02.0 20.72.7
Fat (% energy) 30 28.56.4 29.46.9 32.68.5
SFA
b
(% energy)
10 8.92.5 8.62.8 10.24.1
c
PUFA
d
(% energy)
7 5.31.3 5.91.3
e
5.81.8
e
P:S
f
ratio
1 0.61.2 0.70.3 0.60.3
ALA
g
(g)
2.22 1.30.7 1.51.1
e
1.40.7
e
EPA
h
DHA
i
(g)
0.65 0.50.3 0.40.2
e
0.40.2
c
n-6 to n-3 ratio 10 6.62.9 8.25.7
e
7.53.6
Subjects achieving dietary targets n % n% n%
SFA 14 67 15 75 11 55
j
PUFA 1 5 4 20
k
525
k
ALA 2 10 5 25
k
315
k
EPADHA 5 24 3 15
j
15
k
n-3 to n-6 ratio 19 91 15 75
j
15 75
l
a
Recommendations from American Dietetic Association, American Heart Association, International Society for the Study of Fatty Acids and Lipids, and the literature (18).
b
SFAsaturated fatty acid.
c
Significantly different between groups at the given time point (one-way analysis of variance, P.001).
d
PUFApolyunsaturated fatty acid.
e
Significantly different between groups at the given time point (one-way analysis of variance, P.01).
f
P:Spolyunsaturated fat to saturated fat ratio.
g
ALA
-linolenic acid.
h
EPAeicosapentaenoic acid.
i
DHAdocosahexaenoic acid.
j
Significant difference between groups in proportions achieving target at the given time point (
2
, P.01).
k
Significant difference between groups in proportions achieving target at the given time point (
2
, P.001).
l
Significant difference between groups in proportions achieving target at the given time point (
2
, P.05).
m
Significant effect due to treatment over time (repeated measures analysis of variance, control vs walnut group, P.001).
n
Significant effect due to treatment over time (repeated measures analysis of variance, control vs walnut group, P.0001).
o
Significantly different between groups at the given time point (one-way analysis of variance, P.05).
1090 July 2005 Volume 105 Number 7
Page 4
bias. A significant correlation between the difference
(diet historyfood record) and mean (diet historyfood
record2) provides evidence of systematic bias. For each
dietary variable, the range of consumption reported for
the two data sets were considered clinically acceptable
when limits of agreement were no more than 200 kcal for
energy, 2% of energy for macronutrients, and 1 g for n-3
PUFA. Differences in the extent of underreporting (esti-
mated energy expenditureestimated intakes) between
and within the method (diet history and food record) over
time were investigated using repeated measures analysis
of variance. Spearman correlation coefficient was deter-
mined to assess the relationship between reported
changes in dietary PUFA and erythrocyte levels in sub-
jects.
RESULTS
Of 101 volunteers, 58 men and women (21 control group, 20
modified low-fat group, and 17 walnut group) met the se-
lection criteria. With 34 men and 24 women, there was no
significant difference in the proportion of men and women
randomly assigned to each group. One participant from
each group withdrew during the 6-month intervention pe-
riod. Thus, 55 subjects (20 control, 19 modified low-fat, 16
walnut) provided complete data sets for all three time points
(0, 3, and 6 months) assessed during the trial.
There were no significant differences between groups
for age, height, weight, or BMI, with the average partic-
ipant borderline obese (BMI30) at commencement of
the study. The three groups were also similar for num-
bers of participants reporting a family history of diabetes,
ethnic origins, and categories of reported activity (data
not shown). Mean glycated hemoglobin for the total study
sample at baseline (6.75%1.0%) was within normal lim-
its, indicating good glycemic control for a diabetes popu-
lation. After 6 months, there were no significant differ-
ences in glycemic control between groups with glycated
hemoglobin levels remaining at or less than 7% and no
individual requiring insulin therapy during the study
period. The full extent of clinical outcomes is reported in
a separate paper (24).
Table 2. Energy and macronutrient intakes of all groups at 0, 3, and 6 months after intervention: amount consumed and number and percent
of subjects achieving dietary targets in a study of optimal dietary fat proportions for patients with type 2 diabetes mellitus (continued)
Modified-Fat Group Walnut Group
0mo(n20) 3mo(n19) 6mo(n19) 0mo(n17) 3mo(n17) 6mo(n16)
4™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™ meanstandard deviation ™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™3
2,090.5504.1 2,015.6541.7 1,977.8500.1 2,024.7664.6 2,139.9574.5 2,006.6376.2
44.17.7 42.26.4 41.46.0 46.96.5 43.95.7 43.53.8
20.64.5 22.53.1 22.63.6 21.93.4 20.93.3 21.52.5
31.27.1 31.75.9 32.76.1 27.77.2 32.25.2 31.84.1
9.73.1 7.82.1 7.72.3
c
9.02.8 7.82.4 6.91.6
cm
6.32.8 8.02.0
e
9.42.8
e
5.41.5 11.71.6
en
11.711.8
en
0.80.6 1.10.5 1.30.5 0.70.4 1.70.8
n
1.80.5
n
1.41.0 2.01.1
e
1.71.4
e
1.41.0 3.71.7
e
3.41.9
e
0.60.5 1.20.8
e
1.21.1
c
0.40.4 0.70.4
e
0.80.6
c
8.28.3 5.32.4
e
8.35.0 8.68.4 5.71.4
o
5.71.4
n%n% n% n%n% n%
10 50 17 90 15 79
j
8 47 15 88 16 100
j
4201263
k
15 79
k
1 6 17 100
k
16 100
k
420 737
k
526
k
2121694
k
15 94
k
5251474
j
14 74
k
318 847
j
956
k
17 85 19 100
j
12 63
l
12 71 17 100
j
16 100
l
a
Recommendations from American Dietetic Association, American Heart Association, International Society for the Study of Fatty Acids and Lipids, and the literature (18).
b
SFAsaturated fatty acid.
c
Significantly different between groups at the given time point (one-way analysis of variance, P.001).
d
PUFApolyunsaturated fatty acid.
e
Significantly different between groups at the given time point (one-way analysis of variance, P.01).
f
P:Spolyunsaturated fat to saturated fat ratio.
g
ALA
-linolenic acid.
h
EPAeicosapentaenoic acid.
i
DHAdocosahexaenoic acid.
j
Significant difference between groups in proportions achieving target at the given time point (
2
, P.01).
k
Significant difference between groups in proportions achieving target at the given time point (
2
, P.001).
l
Significant difference between groups in proportions achieving target at the given time point (
2
, P.05).
m
Significant effect due to treatment over time (repeated measures analysis of variance, control vs walnut group, P.001).
n
Significant effect due to treatment over time (repeated measures analysis of variance, control vs walnut group, P.0001).
o
Significantly different between groups at the given time point (one-way analysis of variance, P.05).
July 2005 Journal of the AMERICAN DIETETIC ASSOCIATION 1091
Page 5
Dietary Intake
At baseline, there were no significant differences between
groups for intake of total energy, macronutrients, and
fatty acids (meanSD) (Table 2). In terms of dietary
recommendations, mean SFA intake for each group was
within the recommended range (10% of energy), with
more than half of all individuals already achieving this
target (Table 2). Mean PUFA intakes, however, were less
than target, with only 6 out of 58 individuals from the
total study sample consuming adequate dietary PUFA
(7% energy). Hence, P:S ratio and n-3 PUFA intakes
were less than target for all groups at commencement of
the study.
After 6 months, energy intakes remained similar be-
tween groups with no significant changes from baseline.
Significant differences between groups were confined to
the fatty acid profile, emerging as early as the 3-month
time point and maintained at 6 months (Table 3). The
walnut group was the only group to achieve all fatty acid
targets by the 3-month time point. These values were
maintained at 6 months, with 100% of individuals achiev-
ing desired intakes for total SFA (P.01), total PUFA
(P.001), and n-6 to n-3 ratio (P.05), with the majority
of subjects achieving minimum n-3 fatty acid intakes. The
modified low-fat group did not achieve minimum ALA
fatty acid intakes, with only 26% of subjects achieving
this target at 6 months, nor were they able to maintain
the reduction in n-6 to n-3 ratio seen at 3 months. In
contrast, the control group reported little change to mean
PUFA intakes, with few individuals achieving target
fatty acid proportions.
Diet history data compared well with food record data.
The mean difference was close to zero for each dietary
variable, and the range for the limits of agreement was
within defined and clinically acceptable values (data not
shown). Significant correlations were found between
mean and difference values for reported protein intakes
at 6 months (r0.311, P.05), SFA at 3 months (r0.319,
P.05), EPADHA at baseline (r0.353, P.05), and
ALA at baseline (r0.295, P.05) and 3 months
(r0.379, P.01). On observation of the plots for reported
protein, one extreme value at lower and higher intakes,
respectively, seemed to create the regression line. An
outlier in the SFA plot seemed to have a similar effect.
The plots for ALA and EPADHA, however, seemed to
show a general trend for greater differences at higher
intakes.
Reported energy intakes from the diet history were
within approximately 10% of estimated requirements at
all time points but the value was substantially higher for
the food record and this increased in magnitude with time
(Table 3).
Dietary intake of very-long-chain n-3 PUFA
(DHAEPA) was strongly related to the levels seen in
erythrocyte membranes at baseline, 3 months, and 6
months (P.01) (data not shown). At 6 months, signifi-
cant correlations were also seen for the n-6 to n-3 ratio
(P.05) and total n-3 fatty acids (P.02) (data not
shown). A significant change in the n-6 PUFA content of
erythrocyte membranes over the duration of the study
was determined due to treatment over time (P.01), with
the largest increases occurring in the walnut group
(Table 4).
Food Pattern Analysis
At baseline, foods rich in saturated fat contributed the
greatest proportion of fat intake for all groups (38% of
mean daily fat intake), with meat providing the main
source of dietary fat (approximately 22%), and nuts rich
in PUFA providing approximately 10% of total fat intake.
After 6 months, this profile remained much the same for
the control group, with SFA-rich staple foods (meat,
cheese, milk, and butter) providing 39% of total fat in-
take. If anything, a small shift in fat sources from PUFA-
rich to MUFA-rich foods was observed for this group. In
contrast, the modified low-fat group reported a shift from
SFA-rich to both MUFA-rich and PUFA-rich foods (29%
and 32% of total fat intake, respectively). For the walnut
group, however, there was a big shift to PUFA-rich foods
(45% of total fat), substantively walnuts (individuals re-
porting 100% compliance for consuming 30 g walnuts/day
throughout the length of the study). PUFA-rich nuts (al-
most exclusively walnuts) now contributed 31% of total
fat intake for this group, with oily fish providing an
additional 6%.
The major sources of n-3 PUFA for the walnut group
were walnuts, for which 30 g of walnuts per day provided
50% of the total daily intake, and oily fish (350 g/week)
provided an additional 17%. The major sources of these
fatty acids for the modified low-fat group were oily fish,
with 500 g of oily fish per week providing 42% n-3 intake,
and a combination of soy products, legumes, and n-3
enriched products providing another 22%. In contrast,
the low-fat group continued to report SFA-rich staple
Table 3. Group mean differences between reported energy intakes and estimated energy as an indicator of under- or over-reporting in the DH
a
and FR
b
Baseline 3 Month 6 Month
DH FR DH FR DH FR
Group mean difference
(SD)
c
12.733.2 17.628.2 9.325.2* 20.230.9* 10.824.0* 22.531.0*
a
DHdiet history.
b
FRfood record.
c
SDstandard deviation.
*Significantly different at P.05 between the groups at each time point; using repeated-measures analysis of variance.
1092 July 2005 Volume 105 Number 7
Page 6
foods (meat, cheese, milk, and butter) (39%) as the main
source of dietary fat.
DISCUSSION
Several large studies have demonstrated lifestyle modi-
fications as important strategies for the prevention and
treatment of type 2 diabetes mellitus and cardiovascular
disease complications (25-30). The approaches used in
these studies provide evidence for clinical practice. The
randomized controlled trial, representing the highest
level of research evidence (31), was the model used in this
study to assess the efficacy of three dietary advice ap-
proaches. Structured total diet advice incorporating 30 g
of walnuts per day was more likely to achieve essential
fatty acid targets than similar modified low-fat advice
(without specific reference to walnuts) or general low-fat
advice approaches. Importantly, this approach did not
adversely affect energy balance or blood glucose control in
our type 2 diabetes mellitus patients.
Of the 101 men and women who volunteered, only
approximately 50% were eligible for the study due to the
strict selection criteria used. Although this may limit the
ability to generalize results, it ensured a homogenous
intervention group and thereby strengthened the ability
to detect differences over time. The number of partici-
pants who did not complete the study (one from each
group) was considered small and unlikely to affect re-
sults.
Primary outcomes were dietary variables and achieve-
ment of dietary goals. Dietary compliance, therefore, was
an important aspect of study design in which regular
contact and monthly provision of portion-controlled packs
of walnut supplies enabled regular monitoring. The qual-
ity of dietary data was also assessed as favorable for this
type of analysis, the diet history providing more accurate
values for energy intake and the food record showing
negative signs of subject burden (32). Bias was unlikely
or explainable for most variables. For example, although
differences in reported ALA and EPADHA intakes at
baseline were plausible, this was likely due to the effect of
foods such as fish not consumed during the 3 days of food
records. In contrast, the diet history covers all variation
in intake and therefore is more likely to capture irregular
consumption patterns. More regular intakes of foods high
in ALA and EPADHA at 6 months resulted in greater
agreement and justified the use of the diet history as the
reference method for studying dietary change. In partic-
ular, changes in reported n-3 fatty acids over time were
confirmed through biomarker analyses confirming the
regular consumption of walnuts by the walnut group
(Table 4). The strongest correlation with dietary intake
was for reported DHAEPA at all time points (P.01),
although significant correlations for n-6 to n-3 ratio and
for total n-3 PUFA at the completion of the study also
confirmed reported intakes.
Men and women with established type 2 diabetes
mellitus were randomly assigned to one of three dietary
intervention groups. There were no significant differ-
ences between groups for dietary intakes at baseline.
Mean total and saturated fat intakes were considered
reasonable and low. PUFA intakes, however, were also
low across all groups. Considering that the study sam-
ple would have been previously exposed to dietary ad-
Table 4. Erythrocyte fatty acid composition
a
for all groups at 0, 3, 6 months after intervention in a study of optimal dietary fat proportions for patients with type 2 diabetes mellitus
Variable Control Modified Fat Walnut RMANOVA
b
(P value)
Time 0 (n21) 3 (n20) 6 (n20) 0 (n20) 3 (n19) 6 (n19) 0 (n17) 3 (n17) 6 (n16) Time Treatment Interaction
4™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™ meanSD
c
™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™3
16:0 20.430.77 20.360.91 20.700.99 19.921.43 20.030.93 20.340.83 19.801.07 19.561.42 20.491.14 .000 .134 .328
18:0 14.790.75 14.700.69 15.320.50 14.980.83 14.960.93 15.410.49 15.450.94 15.071.18 15.580.88 .000 .348 .986
18:1n-9 11.701.11 11.601.00 12.451.17 11.420.64 11.320.66 12.000.70 11.930.85 11.470.97 12.360.89 .000 .301 .488
18:2n-6 8.201.11 8.391.27 8.601.21 8.481.42 8.601.43 8.681.35 7.791.21 8.841.60 8.920.96 .000 .878 .006
d
20:3n-6 1.820.48 1.720.48 1.860.53 1.800.31 1.750.32 1.720.34 1.600.31 1.580.39 1.750.38 .038 .437 .168
20:4n-6 13.911.59 13.661.43 14.191.34 13.530.89 13.141.02 13.471.66 13.381.36 13.061.32 13.861.41 .000 .344 .652
20:5n-3 1.350.44 1.210.35 1.320.44 1.230.25 1.360.40 1.751.14 1.240.55 1.320.70 1.840.68 .155 .415 .289
22:6n-3 5.670.88 5.741.00 5.280.90 5.871.20 6.191.04 6.101.24 5.601.37 5.611.30 5.311.38 .060 .232 .255
a
Erythrocyte membrane fatty acid composition is expressed as % of total fatty acids.
b
RMANOVArepeated-measures analysis of variance.
c
SDstandard deviation.
d
Interaction term significant 0-3 months, P.003 for contrast.
July 2005 Journal of the AMERICAN DIETETIC ASSOCIATION 1093
Page 7
vice, these results suggest that current advice practices
are supportive of total fat reduction, but do not enable
consumption of fatty acids in the recommended propor-
tions. These practices seem fairly universal in Western
cultures, so the findings would have reasonable rele-
vance to those outside Australia.
In an attempt to increase dietary PUFA, subjects in the
modified low-fat and walnut groups received structured
diet advice for all food groups, including specific advice on
food sources of PUFA, with those in the walnut group
given advice for the regular consumption of walnuts. Af-
ter 6 months, with no significant changes to mean energy
or major macronutrient intakes, fatty acid intakes di-
verged significantly from the control group. The modified
low-fat and walnut groups achieved desired increases in
the proportion of total PUFA as well as further reductions
in mean SFA, whereas the control group reported little
change to dietary fatty acid proportions. The previous
exposure to dietary advice would indicate the potential
for high compliance by all groups. However, the walnut
group was the only group to achieve all fatty acid targets.
Moreover, the early achievement (at 3 months) of target
PUFA and SFA proportions by 100% of individuals in this
group was a reflection of high adherence to the consump-
tion of walnuts. Notably, for most fatty acid targets, the
control group had fewer individuals achieving them than
at the beginning of the study, with mean SFA intake
increasing to a level more than the recommended range.
Energy balance is an important
aspect of type 2 diabetes mellitus,
and the impact of the regular
consumption of high-fat foods on
energy intake required assessment.
When explaining the results, differences in dietary ad-
vice protocols must be considered. Although our control
group reflected general dietary advice and flexible coun-
seling practices, the two intervention groups were
matched for the programmed delivery of structured ad-
vice for all food groups in the overall diet, including
exchange lists of MUFA-rich and PUFA-rich high-fat
foods. The greater success for individuals in the walnut
group therefore demonstrated the clinical utility of incor-
porating a functional food source into the total diet pat-
tern for the achievement of a specific nutrient intake (33).
Furthermore, greater success by both intervention
groups compared with the control group suggests the
need for more structured advice practices in the clinical
context.
Shifts in fatty acid profile could be explained by
changes in food choice patterns, in which fat from SFA-
rich staple foods (milk, cheese, meat, and butter) was
substituted with regular intakes from significant food
sources of PUFA. For the walnut group these foods were
walnuts and oily fish, whereas the modified low-fat group
reported oily fish, legumes (mainly calcium-enriched
soymilk), nuts, and n-3– enriched foods. In contrast, the
lack of change in sources of fat for the control group
concur with data from previous intervention trials (4,5)
and from Australian population surveys (34,35) that sug-
gest saturated fat remains the main type of fat despite
reduced fat intakes. Judicious food choices from existing
core food groups may also achieve desired fat proportions,
but we consider the guidance systems too blunt to make
this assumption.
Although our study has highlighted the impact that
targeted advice for an individual food may have on overall
dietary fat profile (5), this knowledge needed to be set in
the context of the whole diet. The relatively high n-6 to
n-3 ratio of walnuts and the considerable impact of their
regular consumption on PUFA intakes needed to be ad-
dressed through advice for the concomitant inclusion of
n-3–rich fish. Thus, 30 g of walnuts per day and 350 g of
oily fish per week provided 50% (mostly ALA) and 17% of
total n-3 intake, respectively, enabling adequate achieve-
ment of the n-6 to n-3 ratio by the walnut group.
The modified low-fat group relied more heavily on fish,
500 g oily fish per week providing 42% of n-3, with the
remaining n-3 coming largely from a range of food choices
including soymilk. This latter pattern of intake did not
enable adequate achievement of the ALA fatty acid target
by the modified low-fat group, with the n-6 to n-3 ratio
appearing less sustainable. The combination of walnuts
and oily fish, therefore, seemed more effective and more
sustainable than the larger intake of fish alone.
Energy balance is an important aspect of type 2 diabe-
tes mellitus, and the impact of the regular consumption of
high-fat foods on energy intake required assessment. At
commencement of the study, reported energy intakes for
the study sample were reasonable, within approximately
10% of estimated requirements. The lack of change in
energy intakes, despite marked increases in fish and nut
consumption by the two intervention groups, demon-
strated the utility of structured total diet advice for the
incorporation of high-fat foods. Another important aspect
of type 2 diabetes mellitus management is measures of
blood glucose control. These were considered within nor-
mal limits at the beginning of the study (mean glycated
hemoglobin6.75%1% for the total study sample), and
although some deterioration in glycemic control might be
expected over 6 months, glycated hemoglobin remained
at or less than 7% for each of the study groups, with no
significant differences among groups. These results dem-
onstrate the worthiness of all intervention protocols and
help allay concerns that increased PUFA consumption
(more than doubled in the walnut group) may have ad-
verse effects on glycemic control.
At the beginning of the study, subjects reported subop-
timal habitual PUFA intakes. A low-fat, total diet ap-
proach incorporating walnuts and oily fish successfully
modified the fat profile in line with current recommenda-
tions without increasing energy intake among patients
with type 2 diabetes mellitus. These results demonstrate
the clinical utility of total diet advice incorporating sig-
nificant individual food sources of PUFA under free-living
conditions.
CONCLUSIONS
Dietary assessment for individuals with diabetes should
consider the type of fat in the overall diet. Advice for both
reducing saturated fat and providing adequate amounts
1094 July 2005 Volume 105 Number 7
Page 8
of unsaturated fatty acids is necessary. This study dem-
onstrates the value of using a food group approach to total
diet advice, in which separating foods based on their fatty
acid profile is useful. In addition, including walnuts
within this framework is likely to assure adequate in-
takes of polyunsaturated fatty acids, including substan-
tial amounts of n-3 fatty acids.
The authors acknowledge: the participants of the study,
as well as Meredith Kennedy and Robert Moses, MD,
PhD, of the Illawarra Diabetes Service; Marian Bare, Sr
Sheena McGhee, Leisa Ridges, and Nicole Smede from
the Smart Foods Centre and Department of Biomedical
Science at the University of Wollongong; and Professor
Len Storlien. Research at the Smart Foods Centre is
supported by the Australian Research Council.
Funding for this study was provided by the California
Walnut Commission. A special mention goes to Carol
Sloane from the California Walnut Commission. Funding
Disclosure: Research at the Smart Foods Centre is sup-
ported by the Australian Research Council. Funding for
this study was provided by the California Walnut
Commission.
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APPLICATIONS
Essential Fats in Walnuts Are Good for the Heart and Diabetes
A
cardio-protective dietary fat profile is recommended
for the treatment of type 2 diabetes (1). There have
been major changes in the American diet in the past
few decades as people have increased their use of pro-
cessed foods containing saturated and trans-fats. This
has led to an unhealthful balance of essential fatty acids
(2,3). Ideally, the two families of essential fatty acids (n-6
and n-3) should be balanced in a ratio of no more than 4:1
for optimum health (2,3). The average American’s dietary
ratio can be in excess of 20:1, or more (2). According to
Simopoulos, “Walnuts are unique because they have a
perfect balance of n-6 and n-3 polyunsaturated fatty ac-
ids, a ratio of 4:1, which has been shown to decrease the
risk of sudden death in the Lyon Heart Study” (2). n-3s
are heart healthy because they reduce the bloodstream
levels of low-density lipoprotein cholesterol and maintain
or raise high-density lipoprotein cholesterol (2,3).
In the United States, 18.2 million people, or 6.3% of the
population, have diabetes, and most have the type 2 form
of the disease (4). The World Health Organization reports
that at least 171 million people worldwide have diabetes
and this number will likely double by 2030 (5). According
to the American Diabetes Association, more than 65% of
people with diabetes die from heart disease or stroke (4).
The heart benefits of walnuts include lowering choles-
terol, increasing the ratio of high-density lipoprotein choles-
terol to total cholesterol, reducing inflammation, and im-
proving arterial function (6-8). An April 2004 clinical study
from the University of Barcelona showed that substituting
walnuts for monounsaturated fatty acids in a Mediterra-
nean diet improved, and even restored, endothelial func-
tion. According to the researchers, walnuts are the first
whole food to show such cardiovascular benefits (8).
Cardio-protective dietary fat intakes are recommended
as part of the treatment for type 2 diabetes patients (1).
However, even when food-based advice matches nutrient
This article was written by Gita Patel, MS, RD, a nu-
trition consultant in Etna, NH.
doi: 10.1016/j.jada.2005.05.193
1096 July 2005 Volume 105 Number 7
Page 10
  • Source
    • "One reason for this might be the “optimal” 4:1 ratio of n-6/n-3 PUFA and additionally the high content of tocopherols (mainly γ-tocopherol), phytosterols, polyphenolic antioxidants (ellagitannins) and fiber [25, 26]. With regard to a significant bioactivity, recent investigations have shown that a walnut-rich diet improved hyperlipidemia [26–30], type 2 diabetes [31, 32], cardiovascular disease [33–35], ameliorated the antioxidative status [36, 37] and provided general parenchyma-protecting effects in the liver [30, 38]. However, to our best knowledge, no data are published regarding bioactivity of walnut on NAFLD mainly focusing on the initial step of liver steatosis. "
    [Show abstract] [Hide abstract] ABSTRACT: Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome. We aimed to clarify the impact of dietary walnut oil versus animal fat on hepatic steatosis, representing the initial step of multistage pathogenesis of NAFLD, in Zucker obese rats. Zucker lean ad libitum (a.l.), Zucker obese a.l. or Zucker obese pair fed (p.f.) to the lean received isocaloric diets containing 8 % walnut oil (W8), W14 or 14 % lard (L14) (n = 10/group). Body weight, clinical serology, liver weight, lipid content and fatty acid composition and hepatic lipid metabolism-related transcripts were evaluated. Compared to lean, Zucker obese a.l. and p.f. showed hepatic triacylglyceride (TAG) accumulation. In Zucker obese p.f., W14 compared to W8 and L14 reduced liver lipids, TAG as well as hepatic omega-6 (n-6)/n-3 ratio and SCD activity index [(C18:0 + C18:1)/C18:0 ratio] paralleled by decreased lipoprotein lipase mRNA in obese p.f. and elevated microsomal triglyceride transfer protein mRNA in lean and obese. Further, W14 elevated the fasting blood TAG and reduced cholesterol levels in obese. In our model, consumption of W14 inhibited hepatic lipid accumulation along with modulated hepatic gene expression implicated in hepatic fatty acid influx or lipoprotein assembly. These results provide first indication that dietary lipids from walnut oil are modulators of hepatic steatosis as the initial step of progressive NAFLD pathogenesis.
    Full-text · Article · Aug 2013 · European Journal of Nutrition
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    • "For example, a Mediterranean-style diet was achieved in the PREvencion con DIeta MEDiterranean (PREDIMED) study by providing participants with regular amounts of palatable key high-fat foods [17], but its application may be difficult to replicate in free-living settings. In contrast, general approaches to advice, for example, choose low-fat (LF) foods and ad libitum fashion, do not appear to support significant changes to the macronutrient profile [18] [19]. Intervention trials can demonstrate adherence to dietary targets and expose the impact of consumption patterns and individual food choices under freeliving conditions. "
    [Show abstract] [Hide abstract] ABSTRACT: Dietary trials may link macronutrient intakes to health outcomes, but adherence to dietary targets requires advice based on an understanding of food composition and consumption patterns. Using data from a weight loss trial, we hypothesized that structured advice would be required for significant fat modification to occur. We compared participants' food choice patterns in response to advice based on a structured "whole-of-diet" model vs a general approach to healthy eating. Overweight participants (n = 122) were randomized to 2 advice arms (saturated fat [SFA] < 10% energy [E]): (1) general low fat (LF) control-(a) isoenergy, (b) -2000 kJ; and (2) structured LF high polyunsaturated fat (PUFA) (∼10% energy PUFA; PUFA to SFA ratio ≥1) (LF-PUFA)-(a) isoenergy, (b) -2000 kJ. Intakes of E and fat and fat from food groups (percentage of total fat intake) were compared at baseline, 3 months, P < .05. Baseline diets were similar, with most fat from high-SFA foods (59%): meat and milk-based staple meals and high-fat snacks. By 3 months, all groups reduced E and met the SFA target. Polyunsaturated fat targets were met by the LF-PUFA groups only (P < .001), enabling targeted between-group differences. In response to general advice, LF groups simply switched to LF alternatives of the same foods (P < .05). In comparison, LF-PUFA groups shifted fat intake to high-PUFA choices (54%), consuming more fat than controls from nuts (P < .001), whole grains (P < .001), and oils and spreads (P < .05). Significant reductions in E were achieved regardless of advice, but significant shifts in dietary fat profile relied on structured whole-of-diet advice on a range of meal and snack food sources of fat subtypes.
    Full-text · Article · Sep 2011 · Nutrition research
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    • "There are likely to be additional reasons why nuts, for example, have a place in weight management (Sabate, 2003). Likewise it is the total diet that has the effect, and here dietary modeling is important to control for confounding variables to match nutrient targets linked to mechanistic understandings (Gillen and Tapsell, 2005). This study exemplifies how food may deliver multiple compounds to multiple sites where the effects are subtle. "
    [Show abstract] [Hide abstract] ABSTRACT: Most dietary interventions have metabolic effects in the short term, but long-term effects may require dietary fat changes to influence body composition and insulin action. This study assessed the effect of sustained high polyunsaturated fatty acids (PUFA) intake through walnut consumption on metabolic outcomes in type II diabetes. Fifty overweight adults with non-insulin-treated diabetes (mean age 54+/-8.7 years) were randomized to receive low-fat dietary advice +/-30 g per day walnuts targeting weight maintenance (around 2000 kcal, 30% fat) for 1 year. Differences between groups were assessed by changes in anthropometric values (body weight, body fat, visceral adipose tissue) and clinical indicators of diabetes over treatment time using the general linear model. The walnut group consumed significantly more PUFA than the control (P=0.035), an outcome attributed to walnut consumption (contributing 67% dietary PUFA at 12 months). Most of the effects were seen in the first 3 months. Despite being on weight maintenance diets, both groups sustained a 1-2 kg weight loss, with no difference between groups (P=0.680). Both groups showed improvements in all clinical parameters with significant time effects (P<0.004), bar triacylglycerol levels, but these were just above normal to begin with. The walnut group produced significantly greater reductions in fasting insulin levels (P=0.046), an effect seen largely in the first 3 months. Dietary fat can be manipulated with whole foods such as walnuts, producing reductions in fasting insulin levels. Long-term effects are also apparent but subject to fluctuations in dietary intake if not of the disease process.
    Full-text · Article · Apr 2009 · European journal of clinical nutrition
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