ArticlePDF AvailableLiterature Review

Abstract

Background: Soy has several beneficial effects on cardiovascular disease (CVD); however, results of clinical trial studies are equivocal. Thus, the present study sought to discern the efficacy of soy intake on blood pressure. Methods: The search process was conducted in PubMed, Scopus, Web of Science, and Cochrane Library, to ascertain studies investigating the efficacy of soy intake on blood pressure in adults, published up to June 2020. A random-effects model was applied to pool mean difference and 95 % confidence interval (CI). Begg's and Egger's methods were conducted to assess publication bias. Results: Pooled effects from 17 effect sizes revealed a significant improvement in systolic blood pressure (SBP) (-1.70; -3.34 to -0.06 mmHg; I2 = 45.4 %) and diastolic blood pressure (DBP) (-1.27; -2.36 to -0.19 mmHg, I2 = 43.9 %) following soy consumption, in comparison with controls. Subgroup analysis demonstrated a reduction in both SBP and DBP in younger participants with lower baseline DBP and intervention durations of <16 weeks. Conclusion: Our results suggest that soy intake is associated with an ameliorating effect on blood pressure in adults.
Complementary Therapies in Medicine 59 (2021) 102692
Available online 24 February 2021
0965-2299/© 2021 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Soy intake is associated with lowering blood pressure in adults: A
systematic review and meta-analysis of randomized double-blind
placebo-controlled trials
Zahra Mosallanezhad
a
,
b
,
1
, Marzieh Mahmoodi
a
,
b
,
1
, Sara Ranjbar
a
,
b
, Razieh Hosseini
c
, Cain C.
T. Clark
d
, Kristin Carson-Chahhoud
e
,
f
, Zahra Norouzi
g
, Ali Abbasian
h
, Zahra Sohrabi
i
,
Mohammad Jalali
a
,
*
a
Nutrition Research Center, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
b
Student Research Committee, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
c
Student Research Committee, Department of Nutrition, School of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran
d
Centre for Sport, Exercise and Life Sciences, Coventry University, Coventry CV15FB, UK
e
Australian Centre for Precision Health, School of Health Sciences, University of South Australia, Australia
f
School of Medicine, the University of Adelaide, South Australia, Australia
g
Golestan Research Center of Gastroenterology and Hepatology, Golestan University of Medical Sciences, Gorgan, Iran
h
Department of Physical Education & Sport Sciences, Masjed-Soleiman Branch, Islamic Azad University, Masjed-Soleiman, Iran
i
Department of Community Nutrition, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
ARTICLE INFO
Keywords:
Soy
Blood pressure
Hypertension
Review
Meta-analysis
ABSTRACT
Background: Soy has several benecial effects on cardiovascular disease (CVD); however, results of clinical trial
studies are equivocal. Thus, the present study sought to discern the efcacy of soy intake on blood pressure.
Methods: The search process was conducted in PubMed, Scopus, Web of Science, and Cochrane Library, to
ascertain studies investigating the efcacy of soy intake on blood pressure in adults, published up to June 2020.
A random-effects model was applied to pool mean difference and 95 % condence interval (CI). Beggs and
Eggers methods were conducted to assess publication bias.
Results: Pooled effects from 17 effect sizes revealed a signicant improvement in systolic blood pressure (SBP)
(1.70; 3.34 to 0.06 mmHg; I
2
=45.4 %) and diastolic blood pressure (DBP) (1.27; 2.36 to 0.19 mmHg,
I
2
=43.9 %) following soy consumption, in comparison with controls. Subgroup analysis demonstrated a
reduction in both SBP and DBP in younger participants with lower baseline DBP and intervention durations of
<16 weeks.
Conclusion: Our results suggest that soy intake is associated with an ameliorating effect on blood pressure in
adults.
1. Introduction
Soy is a traditional food that is globally popular, especially in Asia, and
is widely used to produce various food products, such as soybean oil, soy
milk, soy our, and many retail food products.
1
Utilizing soy products in
the food processing industry makes it possible to achieve signicant
economic effects by reducing production costs and standardizing qual-
ity.
2,3
Soybean contains compounds such as protein, ber, vitamins,
minerals, and phytochemicals, which has led to considerable research
interest regarding its effects on various diseases.
1,4
Accordingly, previous
studies have reported protective features of soy in diabetes, cancer,
osteoporosis, and menopausal problems,
3
with further studies conrming
its benecial effects on cardiovascular disease (CVD).
5
One of the most important risk factors of CVD is hypertension, which
represents one of the most prevalent non-communicable diseases,
worldwide.
6
Several strategies, including medication and lifestyle
* Corresponding author at: Nutrition research Center, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Razi Ave, Shiraz, 7153675541,
Iran.
E-mail address: Mj.artak@gmail.com (M. Jalali).
1
These authors contributed equally to the work and should be regarded as equal rst authors.
Contents lists available at ScienceDirect
Complementary Therapies in Medicine
journal homepage: www.elsevier.com/locate/ctim
https://doi.org/10.1016/j.ctim.2021.102692
Received 17 January 2021; Accepted 20 February 2021
Complementary Therapies in Medicine 59 (2021) 102692
2
modication are recommended to manage the disorder,
7
whilst
numerous studies have been performed to investigate the effects of nu-
trients on blood pressure.
8
For instance, the Dietary Approaches to Stop
Hypertension (DASH) diet has been advocated as part of the treatment
protocol for hypertensive patients.
9
Moreover, there are several studies
demonstrating the effectiveness of macronutrients on blood pres-
sure.
10,11
In the case of total protein intake, however, the results man-
ifest in the literature are contradictory, although the positive effect of
plant based protein on blood pressure has been conrmed.
12
In addition,
although observational studies
13,14
have conrmed the efcacy of soy
as a vegetable protein on blood pressure, the results of clinical trial
studies are equivocal.
15,16
Due to the limited number of participants in previous clinical trial
studies,
17,18
as well as differences in intervention duration,
19,20
age,
21,22
and baseline blood pressure,
18,21,23
it is not possible to draw any rm
conclusion regarding the effect of soy on blood pressure. Therefore, in
this study we aimed to identify the effect of soy intake on blood pressure
by performing a systematic review and meta-analysis of randomized
clinical trials.
2. Methods
We undertook our study in accordance with guidelines proposed by
the Preferred Reporting Items for Systematic reviews and Meta-Analyses
(PRISMA).
24
The review protocol was registered with PROSPERO
(CRD42020214728).
2.1. Search process
To identify relevant papers investigating the effect of soy on blood
pressure, we undertook a systematic search in PubMed, Embase, Scopus,
Web of Science, and Cochrane Library, for all available publications up
to June 2020, using a combination the relevant terms in titles and ab-
stracts, without making any restrictions (Supplementary material 1). In
some cases, we used the wildcard term *to increase sensitivity and
checked the reference lists of the relevant reviews and Google Scholar to
supplement the database search strategy, which was prepared with in-
group consensus. After loading retrieved records into EndNote, dupli-
cates were removed.
2.2. Inclusion and exclusion criteria
Four authors independently assessed the records retrieved from the
database search. Randomized controlled trials (RCTs) investigating the
association of soy intake and blood pressure in adults (>18 years of age)
were identied for inclusion. To maximize methodological rigor, only
double-blind placebo-controlled trials were then shortlisted for inclu-
sion, to increase quality of evidence, and reduce potential bias in the
meta-analysis. Review articles, dissertations, brief reports, observation-
designed and non-English language studies were excluded, as were those
lacking clinical information or statistical data required for analysis (e.g.
baseline of blood pressure, standard deviation (SD), standard error (SE),
95 % condence intervals (CIs) and interquartile (IQR)). Disagreements
in the inclusion or exclusion of any study were resolved by group dis-
cussion. For example, one study did not clearly mention term placebo
Fig. 1. The process of study selection.
Z. Mosallanezhad et al.
Complementary Therapies in Medicine 59 (2021) 102692
3
Table 1
Characteristics of the included RCTs.
Study Country Type of study Population Age
group
(C vs.
I)
Body
weight
(C vs. I)
BMI (C
vs. I)
Intervention
type
Sample
size
Duration
(weeks)
Baseline
SBP
(mmHg)
Baseline
DBP
(mmHg)
Teede
(2001)
Australia Randomized,
double-blind,
placebo-
controlled trial
Men and
Postmenopausal
Women
60 vs.
61
74 vs.
72
26 vs.
25
Soy protein 179 12 130 76
Sagara
(2004)
Scotland Randomized,
double-blind,
placebo-
controlled trial
Hypercholesterolemic
and / or hypertensive
52.2
vs.
52.2
83.8 vs.
85.1
27.2
vs.
27.6
Soy protein 50 5 142 87.1
He (2005) China Randomized,
double-blind,
controlled
trial.
Healthy 51.4
vs.
50.8
70.6 vs.
70
26.8
vs.
26.9
Soybean
protein
276 12 134.7 84.7
Kim (2005) Korea Randomized,
double-blind,
placebo-
controlled trial
T2DM 61.7
vs.
59.9
61.1 vs.
64.1
23.8
vs.
24.4
Soybean 30 13 137.5 86.6
Hermansen
(2005)
Denmark Randomized,
double-blind,
placebo-
controlled trial
Hypercholesterolemic 58 vs.
60.6
75.3 vs.
77.1
25.6
vs.
26.4
Soy protein 100 24 133 80.2
Aubertin-
Leheudre
(2008)
Canada Randomized,
double-blind,
placebo-
controlled trial
Obese Postmenopausal
Women
57.7
vs.
57.1
82.5 vs.
79.6
32.8
vs.
31.2
Soy
isoavone
39 25 125.1 79
Chan (2008) China Randomized,
double-blind,
placebo-
controlled trial
Ischaemic stroke 65.8
vs.
66.8
NR* 25 vs.
26.2
Soy
isoavone
102 12 141 77
Kwak
(2010)
Korea Randomized,
double-blind,
placebo-
controlled trial
Prediabetes and newly
diagnosed T2DM
57.6
vs.
56.8
65.8 vs.
62.6
24.8
vs.
24.1
Black soy
peptide
42 12 125.1 73.6
Wong
(2012)
Netherlands Randomized,
double-blind,
placebo-
controlled trial
Menopausal women
with high or normal
blood pressure
55.5
vs.
55.8
68.9 vs.
67.6
25.4
vs.
25.3
Soy
hypocotyl
isoavones
24 6 140.1 82.8
Liu 1 (2013) China Randomized,
double-blind,
placebo-
controlled trial
Postmenopausal
women with mild
hyperglycemia
54.8
vs.
54.3
54.4
vs.56.1
22.6
vs.
23.6
Soy protein
and
isoavones
180 25 127.9 77
Liu 2 (2013) China Randomized,
double-blind,
placebo-
controlled trial
Postmenopausal
women with mild
hyperglycemia
54.8
vs.
56.3
54.4 vs.
56.8
22.6
vs.23.9
Soy
isoavones
180 25 125.9 78.2
Kim (2013) Korea Randomized,
double-blind,
placebo-
controlled trial
Postmenopausal
women
53.5
vs.
53.7
56.5 vs.
57.7
23.3
vs.
23.2
Soy
isoavone
85 12 116.1 74.6
Squadrito
(2013)
Italy Randomized,
double-blind,
placebo-
controlled trial
Postmenopausal
women with metabolic
syndrome
55.4
vs.
55.6
NR 31.8
vs.
31.8
Soy
isoavone
108 51 135.7 78.7
Cheng
(2013)
Taiwan Randomized,
double-blind,
placebo-
controlled trial
Healthy
postmenopausal
women
56.1
vs. 57
55.1 vs.
55.1
22.9
vs.
23.1
Soy
isoavone
82 52 119 77.3
Husain
(2015)
Iran Randomized,
double-blind,
placebo-
controlled trial
Postmenopausal
women
50.32
vs.
50.93
NR NR Soy 61 8 125.77 81.77
Liu 1 (2015) China Randomized,
double-blind,
placebo-
controlled trial
Postmenopausal
women with
prehypertension
58.5
vs.
57.6
57.6 vs.
56.5
NR Soy 180 24 130.7 81.6
Liu 2 (2015) China Randomized,
double-blind,
placebo-
controlled trial
Postmenopausal
women with
prehypertension
58.5
vs.
57.7
57.6 vs.
56.5
NR Soy
isoavone
180 24 131.9 81.6
C (control group); I (intervention group); BMI (body mass index); T2DM (type 2 diabetes mellitus), NR (not reported).
Z. Mosallanezhad et al.
Complementary Therapies in Medicine 59 (2021) 102692
4
as the control,
21
however, the study-design was comparable to a
placebo-controlled design. Following discussion with clinical and sta-
tistical experts, this study was included. In addition, studies were
excluded if the control group was not clinically comparable with the
intervention, and therefore inclusion would have biased the results.
Trials that prescribed effective nutrients, diet, medicines, or other
combinations concomitant to soy, in comparison with controls were also
excluded.
2.3. Data extraction
After identifying studies for inclusion, a combination of four authors
extracted clinical and statistical data, including: rst authors last name,
corresponding authors e-mail, publication year, country, population,
participantscharacteristics, intervention and control type, dose and
type of supplement, treatment duration, sample size, methodological
quality, mean change of interested outcome from baseline at the end of
trial, related SD, SE, 95 % CI or IQR. Where required appropriate
transformations were undertaken to calculate the SD from studies
reporting: SE (SD =SE ×n), 95 % CI (SD =n ×(upper limit lower
limit)
3.92) or IQR (SD =IQR / 1.35).
25
In addition, WebPlotDigitizer
(https://automeris.io/WebPlotDigitizer) was used to derive the mean
change and the corresponding SD when the data were plotted, but not
reported. In the case of an article with two different intervention groups
and one control group, the intervention groups were considered as
different studies, and to avoid giving more weight to them; number of
participants in the control group was divided by 2.
2.4. Quality appraisal
Two authors independently assessed quality in the included studies
using the Cochrane Collaboration risk of bias assessment tool,
26
which is
scored across seven domains being: random sequence generation (se-
lection bias), allocation concealment (selection bias), blinding of par-
ticipants and personnel (performance bias), blinding of outcome
assessment (detection bias), incomplete outcome data (attrition bias),
selective reporting (reporting bias), and other sources of bias. Each
included study also received an overall grading of Good (>2 low risk
domains), Fair (=2 low risk domains), or Poor (<2 low risk domains).
2.5. Statistical analysis
Weighted mean difference (WMD) and 95 % CI was calculated in
Stata v.13, applying a random-effects method. Inter-study heterogeneity
was evaluated by checking I
2
index (low: <50%, hight: >50%).
27
Sub-
group analyses were planned by effective clinical covariates i.e. age (>
56, <56 years old), baseline blood pressure (SBP: >130, <130 mmHg;
DBP: >80, <80 mmHg), and intervention duration (<16, >16 weeks).
Table 2
The methodological quality of included RCTs on effect of soy intake on blood pressure based on review authorsjudgments about each risk of bias item for each
included study.
Z. Mosallanezhad et al.
Complementary Therapies in Medicine 59 (2021) 102692
5
Fig. 2. Forest plot detailing WMDs and 95 % CIs for the meta-analyses of SBP (A) and DBP (B).
Z. Mosallanezhad et al.
Complementary Therapies in Medicine 59 (2021) 102692
6
Mean changes and their SDs of relevant outcomes were obtained by
using the following equations: [mean-post mean-baseline] and [(
([(SD pre)
2
+(SD post)
2
] [2 r ×SD pre ×SD post]))],
28,49,50
respec-
tively. In addition, a sensitivity analysis was applied by discarding each
trial in turn, to ensure robustness of results. A Beggs rank-correlation
29
and Eggers regression asymmetry
30
were performed to evaluate po-
tential publication bias. P-values of less than 0.05 represented statistical
signicance.
3. Results
3.1. Results of the search and study characteristics
From 3163 records, 15 RCTs with 17 effect sizes were identied for
inclusion, all of which were able to be included in the meta-analysis
(Fig. 1). These studies were published between 2001 and 2015. Ten
were conducted in Asia,
17,19,20,21,22,31,32,33,34,35
four in Europe,
18,23,36,37
and another one in the United States of America.
38
Participant age
ranged from 50.3266.8 years. Intervention durations were less than 16
weeks
17,18,20,21,22,23,31,32,33
or more than 16 weeks
19,34,35,36,37,38
in
nine and six trials, respectively (Table 1).
Baseline blood pressure across studies was reported as SBP <130
mmHg
17,20,33,34,35,38
and >130 mmHg
18,19,21,22,23,31,32,36,37
in six and
nine RCTs, respectively. In addition, enrolled participants of seven and
eight studies had >80 mmHg
18,19,20,21,23,32,36
and <80 mmHg
17,22,31,33,34,35,37
DBP, respectively.
3.2. Quality assessment for included studies
Results of the quality assessment are shown in Table 2. Overall, study
quality was assessed as good, with a low risk of bias the dominant
classication across all domains. All studies were assessed as having low
risk of bias for sequence generation and blinding of participants. Six
studies were assessed as having unclear risk of bias for allocation
concealment, ve had unclear risk for blinding of outcome assessment,
one had unclear risk for selective reporting and three had unclear risk for
other potential sources of bias. Two studies were assessed as having high
risk of bias for incomplete outcome data, with three assessed as unclear
and the remaining 10 studies as low risk.
3.3. Meta-analysis of blood pressure outcomes
A signicant reduction in both SBP (WMD = − 1.70 mmHg, 95 % CI
=[3.34, 0.06], P =0.04, I
2
=45.4 %) and DBP (WMD = − 1.27
Fig. 3. Findings from subgroup analysis based on age (<56, >56 years old) (A), baseline blood pressure (<130, >130 mmHg) (B), duration (<16, >16 weeks) (C)
and region (Asia, Europe, America) (D) regarding the effect of soy consumption on SBP.
Z. Mosallanezhad et al.
Complementary Therapies in Medicine 59 (2021) 102692
7
mmHg, 95 % CI =[2.36, -0.19], P =0.02, I
2
=43.9 %) were observed
in the soy intake group when compared with controls (Fig. 2).
Subgroup analyses, identied a greater reduction in blood pressure
for participants aged younger than 56 years (Fig. 3, A and Fig. 4, A) and
lower baseline diastolic blood pressure (Fig. 4, B). In addition, both
systolic (Fig. 3, C) and diastolic (Fig. 4, C) blood pressure were signi-
cantly reduced when soy intake duration was <16 weeks.
3.4. Publication bias and sensitivity analysis
Eggers regression and Beggs rank-correlation tests indicated that
there was no signicant publication bias for SBP (P for Eggers test =
0.71 and Beggs test =0.99) (Fig. 5, A) or DBP (P for Eggers test =0.94
and Beggs test =0.51) (Fig. 5, C). According to the ndings from
sensitivity analysis, pooled eff ;ect sizes obtained for the effect of soy
intake on SBP (Fig. 5, B) and DBP (Fig. 5, D) were not sensitive to any
particular study or group of studies.
4. Discussion
Data from 17 effect sizes were available to examine efcacy of soy
consumption on blood pressure in adults. Our results showed that soy
consumption signicantly improves SBP and DBP. Subgroup analyses
identied a greater reduction in blood pressure among younger partic-
ipants with lower baseline diastolic blood pressure, and in trials lasting
for <16 weeks duration.
The effect of soy consumption on blood pressure has been previously
assessed in several RCTs. A study by Washburn et al. indicated that 40 g
of soy protein containing 68 mg of phytoestrogens, improved blood
pressure abnormality.
39
In Teede et al., it was demonstrated that
administration of 40 g of soy protein containing 118 mg of isoavones,
improved blood pressure in healthy men and women.
31
Furthermore,
Welty et al. showed that a soy nut diet (containing 25 g of soy protein
and 101 mg of aglycone isoavones) lowered systolic blood pressure in
hypertensive and normotensive patients
40
; whilst, Rivas et al. reported
that a 3-month intervention with soymilk reduced blood pressure in men
and women with mild-to-moderate hypertension, and that this hypo-
tensive effect was related to urinary excretion of the isoavonoid gen-
istein.
41
Indeed, it has been shown that the BP-lowering effect of soy
might be related to isoavones,
42
the suspected active ingredients in
soy, via the activation of endothelial nitric oxide (NO) synthase (eNOS)
and stimulation of NO production. Genistein is one of the soy isoavones
that can result in activation of eNOS and NO synthesis.
43
This is
conrmed in another study where it was demonstrated that higher soy
Fig. 4. Findings from subgroup analysis based on age (<56, >56 years old) (A), baseline blood pressure (<130, >130 mmHg) (B), duration (<16, >16 weeks) (C)
and region (Asia, Europe, America) (D) regarding the effect of soy consumption on DBP.
Z. Mosallanezhad et al.
Complementary Therapies in Medicine 59 (2021) 102692
8
consumption is related to higher plasma concentrations of NO.
44
It has been shown that oxidative stress and inammation play a
potential role in the development of hypertension
45
; thereby suggesting
that soy isoavones might lower BP through antioxidant and
anti-inammatory effects.
46,47
In line with the meta-analysis by Liu
et al.,
48
it is unsurprising that we did not observe an inverse relationship
of soy consumption with BP among older people, largely due to the
adverse structural changes in the vessel wall among this group.
5
It is
known that BP increases with enhancing arterial stiffness, concomitant
to aging, and the consumption of phytoestrogens have been inversely
related to arterial stiffness.
5
Moreover, soy consumption also reduces BP
through its natriuretic effect, which is similar to furosemide.
13
In the present study, we found that soy intake led to a higher
reduction in blood pressure in participants with lower baseline systolic
and diastolic BP, which is in contrast with result of the meta-analysis
conducted by Liu et al
48
One reason that should be noted for this
inconstancy is the difference in inclusion criteria regarding study design,
inter-study heterogeneity, and risk of bias, which was lower across our
pooled included studies.
4.1. Strengths and limitations
The present meta-analysis is the rst comprehensive study to have
assessed the inuence of soy intake on BP from randomized double-blind
placebo-controlled trials. We used a comprehensive and accurate sys-
tematic search strategy, that allowed us to examine both indexed and
non-indexed trials. To reduce between-study heterogeneity and
potential bias, and also enhance the power of results, we only included
studies in which the control group received a placebo and where a
double-blind design was employed. This approach improved quality of
pooled analyses and subsequently permitting more rigorous insights in
the effect of soy intake on BP. In addition, based on risk of bias assess-
ment using Cochrane methodology, the quality of all studies was
assessed overall as low risk. Subgroup analysis according to covariates
that have clinical importance regarding soy intake and blood pressure
improvements were pre-specied and provided additional insights to
inform subsequent recommendations. It should be noted that there was
no signicant publication bias found, whilst pooled results were not
sensitive to any individual study. Also, low amount of inter-study het-
erogeneity empowered the results. However, despite the clear novelty of
this work, our study has some limitations that should be noted. First, as
some included trials only reported dose of isoavones, whilst others only
reported soy, we were not able to apply a dose-response analysis. Sec-
ond, we could not conduct subgroup analysis for baseline BMI and body
weight of participants, which could be clinically important markers
related to the change of BP, because of their absence in some included
trials. Moreover, due to a variety of diseases among included study
participants and lack of essential clinical data about their metabolic
markers, we were not able to conduct additional subgroup analysis
based on type of diseases and different health conditions without
reducing the power of the analysis. Finally, although we contacted some
corresponding authors to request missing essential data, in most cases,
we received no response, or unsatisfactory responses.
Fig. 5. The funnel plot and the result of sensitivity analysis for SBP (A, B) and DBP (C, D).
Z. Mosallanezhad et al.
Complementary Therapies in Medicine 59 (2021) 102692
9
4.2. Conclusion
In the present study, pooled effect sizes from 17 studies revealed a
signicant improvement in SBP and DBP in adults following soy con-
sumption, in comparison with controls. In addition, subgroup analysis
indicated a further reduction in both SBP and DBP in younger partici-
pants with lower baseline DBP and intervention durations <16 weeks.
Thus, increases to soy consumption could be considered as an alterna-
tive or complementary approach to improving BP outcomes among
adults, and particularly among younger adults.
Authors contribution
All named authors meet the International Committee of Medical
Journal Editors (ICMJE) criteria for authorship for this article, take re-
sponsibility for the integrity of the work as a whole, and have given their
approval for this version to be published.
Funding
None.
Ethics approval and consent to participate
Not applicable.
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgements
We thank Morteza Zare (https://www.researchgate.net/prole/Mor
teza_Zare), the expert statistician and head of Meta-Research Innovation
ofce (METRIO), Shiraz University of Medical Sciences, Iran.
Appendix A. Supplementary data
Supplementary material related to this article can be found, in the
online version, at doi:https://doi.org/10.1016/j.ctim.2021.102692.
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... No increase in HDL-C, however, was detected. Previous systematic reviews and meta-analyses of randomized controlled trials of soy protein and soy isoflavones have also shown significant but smaller reductions in systolic blood pressure (1.70 mmHg) and diastolic blood pressure (− 1.27 mmHg) [73] than was found in the current analysis. These reductions in LDL-C and blood pressure are further supported by reductions in clinical events with updated pooled analyses of prospective cohort studies showing that legumes including soy are associated with reduced incidence of total cardiovascular disease and coronary heart disease [74]. ...
... The reduction in blood pressure has been most linked to the soy isoflavones [83]. There is evidence that soy isoflavones may modulate the renin-angiotensin-aldosterone system (RAAS), with the capacity to inhibit the production of angiotensin II and aldosterone, thereby contributing to the regulation of blood pressure [73]. Another blood pressure lowering mechanism may involve the ability of soy isoflavones to enhance endothelial function by mitigating oxidative stress and inflammation, consequently promoting the release of the relaxing factor nitric oxide (NO) [73]. ...
... There is evidence that soy isoflavones may modulate the renin-angiotensin-aldosterone system (RAAS), with the capacity to inhibit the production of angiotensin II and aldosterone, thereby contributing to the regulation of blood pressure [73]. Another blood pressure lowering mechanism may involve the ability of soy isoflavones to enhance endothelial function by mitigating oxidative stress and inflammation, consequently promoting the release of the relaxing factor nitric oxide (NO) [73]. This potential mechanism of isoflavones may also explain the reductions seen in inflammation. ...
Article
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Background Dietary guidelines recommend a shift to plant-based diets. Fortified soymilk, a prototypical plant protein food used in the transition to plant-based diets, usually contains added sugars to match the sweetness of cow’s milk and is classified as an ultra-processed food. Whether soymilk can replace minimally processed cow’s milk without the adverse cardiometabolic effects attributed to added sugars and ultra-processed foods remains unclear. We conducted a systematic review and meta-analysis of randomized controlled trials, to assess the effect of substituting soymilk for cow’s milk and its modification by added sugars (sweetened versus unsweetened) on intermediate cardiometabolic outcomes. Methods MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched (through June 2024) for randomized controlled trials of ≥ 3 weeks in adults. Outcomes included established markers of blood lipids, glycemic control, blood pressure, inflammation, adiposity, renal disease, uric acid, and non-alcoholic fatty liver disease. Two independent reviewers extracted data and assessed risk of bias. The certainty of evidence was assessed using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). A sub-study of lactose versus sucrose outside of a dairy-like matrix was conducted to explore the role of sweetened soymilk which followed the same methodology. Results Eligibility criteria were met by 17 trials (n = 504 adults with a range of health statuses), assessing the effect of a median daily dose of 500 mL of soymilk (22 g soy protein and 17.2 g or 6.9 g/250 mL added sugars) in substitution for 500 mL of cow’s milk (24 g milk protein and 24 g or 12 g/250 mL total sugars as lactose) on 19 intermediate outcomes. The substitution of soymilk for cow’s milk resulted in moderate reductions in non-HDL-C (mean difference, − 0.26 mmol/L [95% confidence interval, − 0.43 to − 0.10]), systolic blood pressure (− 8.00 mmHg [− 14.89 to − 1.11]), and diastolic blood pressure (− 4.74 mmHg [− 9.17 to − 0.31]); small important reductions in LDL-C (− 0.19 mmol/L [− 0.29 to − 0.09]) and c-reactive protein (CRP) (− 0.82 mg/L [− 1.26 to − 0.37]); and trivial increases in HDL-C (0.05 mmol/L [0.00 to 0.09]). No other outcomes showed differences. There was no meaningful effect modification by added sugars across outcomes. The certainty of evidence was high for LDL-C and non-HDL-C; moderate for systolic blood pressure, diastolic blood pressure, CRP, and HDL-C; and generally moderate-to-low for all other outcomes. We could not conduct the sub-study of the effect of lactose versus added sugars, as no eligible trials could be identified. Conclusions Current evidence provides a good indication that replacing cow’s milk with soymilk (including sweetened soymilk) does not adversely affect established cardiometabolic risk factors and may result in advantages for blood lipids, blood pressure, and inflammation in adults with a mix of health statuses. The classification of plant-based dairy alternatives such as soymilk as ultra-processed may be misleading as it relates to their cardiometabolic effects and may need to be reconsidered in the transition to plant-based diets. Trial registration ClinicalTrials.gov identifier, NCT05637866.
... However, these Chinese studies were inconsistent, likely due to limitations such as small sample sizes [17] and short follow-up durations [14,16,20]. Moreover, previous studies showed the cardioprotective effects of soy and its constituents, including influences on lipids, glucose, blood pressure and obesity indicators [21][22][23][24]. However, whether these CVD risk factors mediate the association of soy product intake with CVD mortality remains unexplored. ...
... Furthermore, to investigate potential mechanisms, we used linear regression to examine the cross-sectional associations of soy product intake with CVD risk factors at baseline. Subsequently, we selected the risk factors showing significant associations with soy product intake based on our cross-sectional analyses and previous meta-analyses [22,24,37] to conduct mediation analyses for CVD mortality. We used the difference method [38] by the publicly available "mediate" SAS macro (https://cdn1.sph.harvard.edu/ ...
... Previous studies showed the cardioprotective effects of soy and its constituents, which could be due to improvement of lipid profiles, optimization of glycemic control, reduction in blood pressure, and facilitation of weight loss [21][22][23][24]. Our cross-sectional analyses showed that at baseline, higher soy product intake was associated with lower LDL-cholesterol, triglycerides, total cholesterol and waist circumference, and higher HDL-cholesterol, SBP, and BMI. ...
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Purpose We examined the associations of soy product intake with all-cause, cardiovascular disease (CVD), and cancer mortality and mediations through CVD risk factors based on the Guangzhou Biobank Cohort Study (GBCS), and conducted updated meta-analyses. Methods A total of 29,825 participants aged 50 + years were included. Causes of death were identified through record linkage. Soy product intake was assessed by food frequency questionnaire. Cox proportional hazards regression was used to analyze the associations between soy product intake and mortality, yielding hazard ratios (HRs) and 95% confidence intervals (CIs). Mediation analyses with CVD risk factors as mediators, and updated meta-analyses were conducted. Results During 454,689 person-years of follow-up, 6899 deaths occurred, including 2694 CVD and 2236 cancer. Participants who consumed soy product of 1–6 portions/week, versus no consumption, had significantly lower risks of all-cause and CVD mortality (adjusted HR (95% CI) 0.91 (0.86, 0.97) and 0.87 (0.79, 0.96), respectively). In participants who consumed soy product of ≥ 7 portions/week, the association of higher intake with lower CVD mortality was modestly mediated by total cholesterol (4.2%, 95% CI 1.0–16.6%). Updated meta-analyses showed that the highest level of soy product intake, versus the lowest, was associated with lower risks of all-cause and CVD mortality (pooled HR (95% CI) 0.92 (0.88, 0.96) and 0.92 (0.87, 0.98), respectively). Conclusion Moderate and high soy product intake were associated with lower risks of all-cause and CVD mortality. Our findings provide support for current dietary guidelines recommending moderate soy product intake, and contribute additional evidence regarding the potential protective effects of high soy product intake.
... Six SRs addressed plant proteins and BP [19,22,25,[37][38][39] (Table 1C). One SR analysed RCTs that replaced carbohydrates by plant proteins [19], three SRs analysed observational studies including cohort studies [22,25,37] and two SRs analysed soy products which included also studies with soy protein [38,39]. ...
... Six SRs addressed plant proteins and BP [19,22,25,[37][38][39] (Table 1C). One SR analysed RCTs that replaced carbohydrates by plant proteins [19], three SRs analysed observational studies including cohort studies [22,25,37] and two SRs analysed soy products which included also studies with soy protein [38,39]. According to the procedure of SRs with milk proteins, SRs which exclusively addressed soy were not used for the evaluation of the overall certainty of evidence of plant proteins on BP. ...
... These two RCTs did not find any effect of soy protein on SBP and DBP, and were in line with the overall findings of consumption of soy products on BP in this SR. The SR on soy conducted by Mosallanezhad et al. included four RCTs on soy protein [39], two of them showed a BP-lowering effect and the other two observed no effect on BP. ...
Article
Full-text available
Introduction This umbrella review aimed to investigate the evidence of an effect of dietary intake of total protein, animal and plant protein on blood pressure (BP), and hypertension (PROSPERO: CRD42018082395). Methods PubMed, Embase and Cochrane Database were systematically searched for systematic reviews (SRs) of prospective studies with or without meta-analysis published between 05/2007 and 10/2022. The methodological quality and outcome-specific certainty of evidence were assessed by the AMSTAR 2 and NutriGrade tools, followed by an assessment of the overall certainty of evidence. SRs investigating specific protein sources are described in this review, but not included in the assessment of the overall certainty of evidence. Results Sixteen SRs were considered eligible for the umbrella review. Ten of the SRs investigated total protein intake, six animal protein, six plant protein and four animal vs. plant protein. The majority of the SRs reported no associations or effects of total, animal and plant protein on BP (all “possible” evidence), whereby the uncertainty regarding the effects on BP was particularly high for plant protein. Two SRs addressing milk-derived protein showed a reduction in BP; in contrast, SRs investigating soy protein found no effect on BP. The outcome-specific certainty of evidence of the SRs was mostly rated as low. Discussion/conclusion This umbrella review showed uncertainties whether there are any effects on BP from the intake of total protein, or animal or plant proteins, specifically. Based on data from two SRs with milk protein, it cannot be excluded that certain types of protein could favourably influence BP.
... Soybean is considered a functional food due to its beneficial components such as polyunsaturated fatty acid, dietary fibers, and isoflavone. A previous metaanalysis suggested that soy consumption improved glycolipid parameters in patients with MetS (21) and was associated with lowering blood pressure in adults (22). In this study, intake of soybean products was associated with lower risk of new-MetS onset; however, a significant preventative effect was not observed. ...
... In this study, intake of soybean products was associated with lower risk of new-MetS onset; however, a significant preventative effect was not observed. Previous interventional studies used soy products and consumed not only soy but also soy protein and isoflavone (21,22); hence, the consumption of soy and its sources in the present study may be different from the previous studies. This may explain why "often eat soybean products" was not associated with risk of MetS in the present study. ...
Article
Dietary patterns, such as selecting what food to regularly eat, may play role in reducing the incidence of metabolic syndrome (MetS). This study examined the causal relationships of Japanese dietary patterns and the relationship with the risk of MetS onset using a prospective cohort design. Data of annual health checks between 2008 and 2017 were analyzed, and middle-aged men and women (n=3,298 and 3,925, respectively) were followed up for 15,498 and 19,459 person-years, respectively. We investigated six dietary patterns using a questionnaire, and the participants were divided into low, middle, and high dietary score groups. During the follow-up period, cases of new-onset MetS were found in 698 men (21.2%) and 350 women (8.2%). Covariate-adjusted Cox proportional hazard models revealed that the risk of new-onset MetS was significantly lower in the male participants who responded that they "often eat vegetables" (HR: 0.77, 95% CI: 0.66-0.91). For dietary score, the male participants had significantly lower adjusted HRs of MetS onset in the middle-score group (HR: 0.80, 95% CI: 0.69-0.94) and high-score group (HR: 0.54, 95% CI: 0.41-0.72) compared to the low-score group. On the other hand, there was no association of each dietary pattern and dietary score with new-onset MetS among the female participants. This study found that favorable dietary patterns are associated with a lower risk of MetS; thus, education that aims to encourage a favorable diet may have an important role in reducing the incidence of MetS in middle-aged men.
... Subgroup analyses showed greater reductions in blood pressure in participants under 56 years old and with lower baseline diastolic blood pressure. Additionally diastolic and systolic blood pressure were significantly reduced when the duration of soy consumption was < 16 weeks [32]. ...
Article
Full-text available
Introduction and Purpose Cardiovascular diseases (CVD) are the leading factor of mortality among people in the world. For this reason, people are trying to find factors that could improve the condition of the circulatory system. Soy is one of the most popular products in Asian cuisine. Its consumption is increasing due to a strong interest in vegetarian cuisine, in which soy is an important element. As its popularity grows, more and more research is being done to see if it has cardiovascular disease-preventing properties. Aim of the study This study aims to analyse the current state of knowledge regarding the effect of soy consumption on: hypertension, lipid profile, biomarkers of inflammation, vascular epithelium and impact on mortality caused by cardiovascular diseases. Material and methods For this review, we analyzed articles that we found in Pubmed and Google Scholar and that were related to our topic. Conclusion Many studies have shown a beneficial effect of soy products on lipid profile, especially in lowering LDL-C levels. Soy consumption may have an impact on modulating inflammatory markers, but further research is needed. Researchers have shown that soy may have a role in lowering blood pressure, especially in people with hypertension or an increased risk of CVD. Soy can be a part of our daily, healthy diet, but its impact on all-cause mortality and CVD depends on many factors such as people's age, comorbidity, dietary context and type of consumed soy ( e.g. fermented or not fermented).
... Because middle-aged and older women were included in the present study, there is a possibility that the sex-specific effects of soy products on lipid metabolism were associated with the lower risk of MASLD in non-obese women. Previous interventional studies reported that soy intake reduced both SBP and DBP in adults 54 . The glycemic effects of soy consumption were not evident in another study 55 , but prospective studies reported that dietary intakes of soy products were negatively associated with the incidence of type 2 diabetes 56 . ...
Article
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This longitudinal observational study aimed to evaluate whether cardiometabolic factors and dietary characteristics are determinants of metabolic dysfunction-associated steatotic liver disease (MASLD) in non-obese individuals (body mass index [BMI] < 25 kg/m²). The study was conducted at the Japanese Red Cross Society Kyoto Daiichi Hospital. Clinical data were longitudinally recorded at annual health checks. The diagnosis of MASLD was based on the results of abdominal ultrasonography and cardiometabolic criteria. Lifestyle behaviors and dietary characteristics were assessed using a self-administered questionnaire. A total of 4,100 non-obese middle-aged and older participants (1,636 men and 2,464 women) were followed up for an average of 6.44 ± 4.16 years. During the follow-up period, there were 410 new cases of MASLD in men (25.1%) and 484 in women (19.6%). The incidence rate was higher for men (39.7 per 1,000 person-years) than for women (30.1 per 1,000 person-years). Multivariable-adjusted logistic regression analyses using the rate of change per year with standardized values found that BMI gain was strongly associated with the onset of MASLD for both men (OR: 1.90, 95% CI: 1.64–2.19) and women (OR: 1.95, 95% CI: 1.72–2.21). Increased waist circumference and triglycerides were also associated with MASLD onset for both men and women. Lowering of high-density lipoprotein cholesterol was identified as a risk factor for MASLD in both men and women. Regarding dietary characteristics, the onset of MASLD was significantly and negatively associated with “often eating vegetables” for men (OR: 0.73, 95% CI: 0.57–0.93) and “often eating soy products” for women (OR: 0.71, 95% CI: 0.58–0.88), even after adjusting for BMI change and other covariates. These findings suggest that maintaining body weight and favorable dietary characteristics are key factors in the prevention of MASLD in non-obese individuals.
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Hypertension is one of the non-communicable diseases that causes most deaths. In the last six months, there have been ten cases of hypertension in pregnant mothers in the South City Health Center. Age, genetic factors, and parity can cause hypertension in pregnant mothers. This study aims to determine whether tempe yogurt and tempe spice juice help reduce hypertension in pregnancies in the South Puskesmas Working Region. The quantitative study was conducted from April to September 2023 and used a quasi-experimental design of two groups of pretest and posttest. A purposive sampling of forty individuals was used to collect the samples. The results of the study showed that respondents in group A were over 35 years old (35%), group B was 20-35 years old (45%), and group A had a parity of between 2 and 4 years (55%), and group B had a Parity of 2 to 4 years (80%). No history of hypertension in groups A and B (75%, 70%). It can be concluded that consuming tempe yogurt and tempe spice juice regularly is shown as one way to reduce hypertension during pregnancy.
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Hypertension is a global public health challenge, with a high prevalence across various regions and significant implications for cardiovascular risk. This article reviews the effectiveness of herbal medicine as a potential therapeutic approach for hypertension, offering an alternative or complementary solution to conventional pharmacological treatments. It highlights several natural agents that have demonstrated efficacy in lowering systolic blood pressure (SBP) in clinical and meta-analytical studies. The methodology involved a systematic review of articles that discuss herbal therapeutics for hypertension, focusing on their efficacy compared to placebo and standard treatments. The findings suggest that certain nutraceuticals, such as garlic, hawthorn, and CoQ10, can significantly reduce SBP, presenting a viable option for managing hypertension. This review underscores the need for further research to validate these findings and optimize herbal treatment strategies, potentially expanding the use of these natural products in clinical practice. The article aims to increase awareness among medical professionals and patients about the benefits and applications of herbal medicines in treating hypertension.
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Numerous studies have indicated that low levels of serum adiponectin are linked with the development of various chronic diseases. While some recent research has suggested that soy has a positive impact on serum adiponectin levels, the results are inconsistent. Therefore, we aim to conduct a thorough systematic review and meta-analysis of randomized controlled trials (RCTs) that investigate the effects of soy on serum adiponectin levels in adults. The search was conducted until March 2024 on PubMed, Scopus, Web of Science, and Cochrane Library databases to identify RCTs that studied the effects of soy supplementation on serum adiponectin levels. A random-effects model was used to pool the weighted mean differences (WMDs). Ten and nine RCTs were selected for the systematic review and meta-analysis, respectively. After analyzing data from 9 eligible RCTs, it was found that soy supplementation did not significantly impact the concentrations of adiponectin (WMD = -0.24 μg/mL; 95% confidence interval, -1.56 to 1.09; p = 0.72). However, there was significant heterogeneity between the studies (I2 = 89.8%, p < 0.001). Sensitivity analysis showed that overall estimates were not affected by the elimination of any study. We did not observe any evidence regarding publication bias. In conclusion, soy supplementation did not have a significant effect on adiponectin levels in adults. However, further RCTs are needed with longer intervention duration, higher doses, and studies conducted in different countries.
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Background Excessive consumption of ultra-processed foods (UPFs) has been linked to an increased risk of cardiovascular disease. We aimed to investigate the association between the percentage of energy intake from UPFs and the American Heart Association’s cardiovascular health (CVH) metrics in Korean adults. Methods This study analyzed adults aged 40 years and older using data from the Korean National Health and Nutrition Examination Survey 2016–2018 ( n = 9,351). All foods or beverages reported in a 24-h dietary recall were categorized using the NOVA system, and the percentage of energy from UPFs was calculated. Each CVH metric was scored 0–2 (poor, intermediate, ideal). The sum of six component scores was classified as inadequate, average, or optimum. Multinomial logistic regression models were used to estimate the covariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for inadequate and average CVH versus optimum CVH. Results The mean percentage of energy from UPFs was 24.2%. After adjusting for covariates, participants in the highest UPF quartile had 26% higher odds of having inadequate CVH than those in the lowest quartile (OR 1.26, 95% CI 0.94–1.69, P -trend = 0.03). The percentage of energy from UPFs was positively associated with current smoking, physical inactivity, body mass index, and total cholesterol and was inversely associated with blood pressure and fasting glucose. Conclusion The percentage of energy from UPFs accounted for one-fourth of total calorie intake in Korean adults aged 40 years and older. Higher UPF consumption was associated with poorer CVH, underscoring the potential of limiting UPF consumption as a preventative measure for cardiovascular diseases.
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The present systematic review and meta-analysis was conducted to investigate the effects of soy intake on liver enzymes, lipid profile, anthropometry indices, and oxidative stress in non-alcoholic fatty liver disease (NAFLD). A systematic search was undertaken in PubMed, Embase, Scopus, Web of Science, and Cochrane Library covering up to 10 January 2020. A fixed-effect or random-effects models were applied to pool mean difference (MD) and its 95 % confidence intervals (CI). Four clinical trials comprising 234 participants were included in the meta-analysis. Compared to the controls, alanine aminotransferase (ALT) levels (MD=-7.53, 95% CI=[-11.98,-3.08], P=0.001, I 2 =0.0 %), body weight (MD=-0.77, 95 % CI=[-1.38,-0.16], P=0.01, I 2 =36.9%), and the concentration of serum Malondialdehyde (MDA) (MD=-0.75, 95% CI=[-1.29,-0.21], P=0.007, I 2 =63.6%) were significantly changed following soy intake. Lipid profile was not significantly affected by soy intake. Moreover, no evidence of a significant publication bias was found. The present study suggests lowering effects for soy intake on ALT levels, body weight, and MDA in nonalcoholic liver patients. Therefore, further large-scale and well-designed clinical trials are needed to find conclusive findings. ►Please cite this article as: Zarei A, Stasi C, Mahmoodi M, Masoumi SJ, Zare M, Jalali M. Effect of soy consumption on liver enzymes, lipid profile, anthropometry indices, and oxidative stress in patients with non-alcoholic fatty liver disease: A systematic review and meta-analysis of clinical trials. Iran J Basic Med Sci 2020; 23:
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PurposeSome but not all randomized controlled trials (RCTs) of soy isoflavones showed their beneficial effect on arterial stiffness, a predictor of cardiovascular events, dementia, and all-cause mortality, independent of traditional risk factors. To test the hypothesis that supplementation of soy isoflavones reduces arterial stiffness, we performed a systematic review and meta-analysis of RCTs of soy isoflavones on arterial stiffness.Methods The protocol of this systematic review was registered with PROSPERO (CRD42019126128) and written in accordance with PRISMA. The PubMed, Embase, and clinicaltrials.gov databases were searched using the following criteria: human subjects, soy isoflavones as intervention, and arterial stiffness as primary outcome. A random-effects meta-analysis was used to pool estimates across studies. Standardized mean difference (SMD) was used to synthesize quantitative results.ResultsAmong 998 articles retrieved, 8 articles met our criteria. Duration of intervention was relatively short (maximum of 12 weeks). Outcome measurements extracted were pulse wave velocity (PWV), systemic arterial compliance (SAC), augmentation index (AI), and cardio-ankle vascular index (CAVI). Soy isoflavones reduced arterial stiffness compared to placebo (standardized mean difference − 0.33, 95% confidence interval − 0.47, − 0.19). Subgroup analyses showed no difference between treatment effects for intervention duration (< 6 weeks vs. ≥ 6 weeks) or gender (women only vs. men only vs. combined). Sensitivity analysis showed no difference in the effect of soy isoflavones between PWV, CAVI, SAC, and AI.Conclusion Supplementation of soy isoflavones reduced arterial stiffness. Longer duration trials with larger number of participants are warranted.
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The revised edition of the Handbook offers the only guide on how to conduct, report and maintain a Cochrane Review. The second edition of The Cochrane Handbook for Systematic Reviews of Interventions contains essential guidance for preparing and maintaining Cochrane Reviews of the effects of health interventions. Designed to be an accessible resource, the Handbook will also be of interest to anyone undertaking systematic reviews of interventions outside Cochrane, and many of the principles and methods presented are appropriate for systematic reviews addressing research questions other than effects of interventions. This fully updated edition contains extensive new material on systematic review methods addressing a wide-range of topics including network meta-analysis, equity, complex interventions, narrative synthesis, and automation. Also new to this edition, integrated throughout the Handbook, is the set of standards Cochrane expects its reviews to meet. Written for review authors, editors, trainers and others with an interest in Cochrane Reviews, the second edition of The Cochrane Handbook for Systematic Reviews of Interventions continues to offer an invaluable resource for understanding the role of systematic reviews, critically appraising health research studies and conducting reviews.
Article
Background Dyslipidemia and hypertension are important risk factors for cardiovascular disease (CVD). Some studies have suggested that the consumption of nuts may reduce CVD risk. Objective The present systematic review and meta-analysis was conducted to investigate the efficacy of cashew nut consumption on lipid profile and blood pressure. Methods PubMed, Embase, Scopus, Web of Science and Cochrane Library were systematically searched to identify randomized control trials (RCTs) examining the effects of cashew nut intake on serum triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), serum total cholesterol (TC), systolic blood pressure (SBP) or diastolic blood pressure (DBP) until 15 November 2019. Random-effects or fixed-effects models were used to pool weighted mean difference (WMD) and 95% confidence intervals (CI). Potential publication bias was assessed using Egger’s test. Sensitivity analysis was performed to assess the impact of each individual study on the pooled results. Results A meta-analysis on 392 participants showed that cashew consumption had no significant effects on lipid profile and DBP. However, there was a significant reduction in SBP (WMD = -3.39, 95% CI = [-6.13, -0.65], P = 0.01, I² = 0.0%) in the group receiving an increased cashew nut intake compared to the controls. There was no significant publication bias in the meta-analysis. A sensitivity analysis, omitting single trials in turn, did not have a significant effect on the pooled results. Conclusion This meta-analysis demonstrated that cashew nut consumption might reduce SBP but has no effects on lipid profile and DBP.
Article
A low insulin‐like growth factor 1 (IGF‐1) level is known to be associated with many disorders. Several studies have shown that soy consumption may influence IGF‐1, but the findings remain inconclusive. In this work, we conducted a systematic review and meta‐analysis to provide a more accurate estimation of the effect of soy consumption on plasma IGF‐1. A comprehensive systematic search was performed in Scopus, Embase, Web of Science, and PubMed/MEDLINE databases from inception until October 2019. Eight studies fulfilled the eligibility criteria. The pooled weighted mean difference (WMD) of the eligible studies was calculated with random‐effects approach. Overall, a significant increment in plasma IGF‐1 was observed following soy intervention (WMD: 13.5 ng/ml, 95% CI: 5.2, 21.8, I2 = 97%). Subgroup analyses demonstrated a significantly greater increase in IGF‐1, when soy was administered at a dosage of ≤40 g/day (WMD: 11.7 ng/ml, 95% CI: 10.9 to 12.6, I2 = 98%), and when the intervention duration was <12 weeks (WMD: 26.6 ng/ml, 95% CI: 9.1 to 44.1, I2 = 0.0%). In addition, soy intervention resulted in a greater increase in IGF‐1 among non‐healthy subjects (WMD: 36 ng/ml, 95% CI: 32.7 to 39.4, I2 = 84%) than healthy subjects (WMD: 9.8 ng/ml, 95% CI: 8.9 to 10.7, I2 = 90%). In conclusion, this study provided the first meta‐analytical evidence that soy intake may increase IGF‐1 levels, but the magnitude of the increase is dependent on the intervention dosage, duration, and health status of the participants.
Thesis
Background: Recent studies indicate a possible association between soy isoflavones, a class of phytoestrogens, and arterial stiffness, a significant predictor of future cardiovascular events. We hypothesize that the supplementation of soy isoflavones compared to a placebo, would significantly reduce arterial stiffness. Objective: To evaluate the effect of soy isoflavones on arterial stiffness through the qualitative and quantitative analysis of relevant randomized controlled trials (RCTs). Methods: Selected studies were included in the systematic review process if they met the following criteria: participants were human subjects, primary treatment intervention was soy isoflavones, primary outcome was arterial stiffness, and the study was an RCT. Qualitative information extracted included study location, study design, sample size, population characteristics, intervention duration and dose, washout period, and the mean and standard deviation/error of baseline and after placebo or intervention. Studies of arterial stiffness based on pulse wave velocity (PWV), systemic arterial compliance (SAC), augmentation index (AI), and cardio-ankle vascular index (CAVI) were included in this review. Standardized mean difference (SMD) was used to synthesize the quantitative results. A subgroup analysis was conducted by intervention duration (<6 weeks vs. ≥6 weeks) and gender (women only vs. men only vs. combined). Results: A significant association that favored the positive effect of soy isoflavones on arterial stiffness was observed (Overall SMD: -0.37, 95% CI: -0.53, -0.21, p-value<0.01). A statistically significant effect was seen for PWV (SMD: -0.38, 95% CI: -0.71, -0.05), SAC (SMD: -0.39, 95% CI: -0.68, -0.11), and CAVI (SMD: -0.43, 95% CI: -0.83, -0.02), but not AI (SMD: -0.36, 95% CI: -0.85, 0.13). The subgroup analysis showed no significant difference between treatment effects of soy isoflavones on arterial stiffness for intervention duration and gender. Conclusion: Intake of soy isoflavones significantly reduced arterial stiffness. Therefore, soy isoflavones should be considered as a future intervention for arterial stiffness reduction. Public Health Significance: Arterial stiffness has major health implications for its connection to various adverse cardiovascular outcomes such as hypertension, chronic kidney disease (CKD), coronary heart disease (CHD), stroke, dementia, and all-cause mortality.
Article
Objective: Diet plays a critical role in the management of non-alcoholic fatty liver disease (NAFLD). Studies on the NAFLD's experimental models have reported that soy had positive effects on the improvement of metabolic parameters. However, there is a lack of clinical trials regarding the efficacy of whole soy foods. Therefore, this study was conducted to determine the effect of soy milk on some of the metabolic characteristics in patients with NAFLD. Methods: Sixty-sex patients diagnosed with NAFLD were included in this randomized, parallel, controlled trial and were randomly assigned to either the soy milk or control group. Both groups received a 500-deficit calorie diet plan. Also, patients in the soy milk group consumed 240 ml/day soy milk for 8 weeks. Fasting blood sugar (FBS), serum insulin, HOMA-IR, HOMA-β%, and QUICKI as well as serum malondialdehyde (MDA), plasma fibrinogen, and blood pressure (BP) were measured at the beginning and end of the study. Results: After 8-weeks of intervention, soy milk group had a greater significant reduction in serum insulin(-3.44 ± 5.02 vs. -1.09 ± 3.77 μIU/ml, P = 0.04), HOMA-IR (-0.45±0.64 vs -0.14 ± 0.47, P = 0.03), systolic (-3.81±4.15 vs -1.48±2.93 mmHg, P = 0.01) and diastolic (-2.39±2.80 vs. -0.94±2.76 mmHg, P = 0.04) BP, and also, a significant increase in QUICKI (0.02± 0.032 vs. 0.008±0.018, P = 0.04) compared to the control group. While, changes in the FBS, HOMA-β%, fibrinogen, and MDA were not significantly different between the study groups. Conclusion: A low-calorie diet containing soy milk had beneficial effects on serum insulin, HOMA-IR, QUICKI, and BP in patients with NAFLD.
Article
Background: Type 2 diabetes has a high spread and growing process. Using appropriate food diets is among therapeutic approaches has been applied for diabetic patients. Soya utilization has shown effective results in controlling metabolic abnormalities of these patients. The aim of this study is to investigate the effects of soy nut on glycemic conditions, blood pressure, lipid profile, antioxidant effects and vascular endothelial function of these patients. Methods: 70 patients with type 2 diabetes were randomly divided into two groups of the test (35 people) and control (35 people). The patients in the intervention group were subjected to 60 g soy nut diet as a part of daily protein for 8 weeks and the control group under the usual diet of diabetes. The fasting glucose, blood pressure, lipid profile, brachial blood flow, the level of serum E-Selectin and total antioxidant capacity in control and test group were assessed before and after diet. Results: Consuming 60 g soy nut for 8 weeks significantly decreased the fasting blood glucose (P = 0.03), total serum cholesterol (P < 0.01), LDL-c (P = 0.01), and E-Selectin (P < 0.01) and increased the capacity of serum total antioxidants (P < 0.01), brachial blood flow (P < 0.01) but didn't have any significant effect on systolic/diastolic blood pressure, HDL-c, and TG. Conclusion: Soy nut utilization in the patients with type-2 diabetes can significantly improve the glycemic condition, increase brachial blood flow, decrease E-selectin (improvement of endothelial function), increase serum total antioxidants and lipid profile but has no significant effect on blood pressure and HDL-c.
Book
While the western world has only recently become enamored with the soybean, East Asia has been consuming and enjoying the associated health benefits of this versatile proteinaceous legume for centuries. The Japanese in particular have devoted much energy to unraveling the mysteries and revealing the science of this oil-rich bean. The Fuji Foundation for Protein Research was established to support soybean studies, which have resulted in a considerable amount of profound literature on the soy-wellness connection. Unfortunately for westerners, very little of this information has been presented in English. Soy in Health and Disease Prevention, edited by the highly distinguished Michihiro Sugano, brings the west up to speed on the latest findings concerning this common, yet most powerful health aid. Perhaps, the most authoritative book on the subject available in any language, Soy in Health and Disease Prevention presents the very latest health and nutrition research and findings available on soy products. Functional food experts from Japan, as well as other parts of the world, explore the action and diverse health effects of the common soybean. Included is the latest information with regard to soy’s impact on · Cancer prevention · Immune system function · Osteoporosis · Atherosclerosis · Aging and longevity This book is essential reading for all researchers and students involved with the study and production of functional foods. Dr. Sugano who is the current director of the Fuji Foundation has published over 400 journal articles, as well as 80 book chapters. His primary area of research is in food functional factors, predominantly regulation of lipid metabolism.