[PHNUTR-L] Association Between Soy Nut Consumption and Decreased
fivestar at nutritionucanlivewith.com
Tue Jan 22 13:54:49 PST 2008
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Menopausal Symptoms, Blood Pressure and Soy Nut Consumption
Francine K. Welty, M.D., Ph.D.
Division of Cardiology
Beth Israel Deaconess Medical Center
One Autumn Street, 5th Floor
Boston, MA 02215, USA
(617) 632-7659 / (617) 632-9928 (FAX)
fwelty at bidmc.harvard.edu
“Effect of Soy Nuts on Blood Pressure and Lipid Levels in Hypertensive,
Prehypertensive and Normotensive Postmenopausal Women.”
Arch Int Med, 2007;167:1060-1067.
“The Association Between Soy Nut Consumption and Decreased Menopausal
J Womens Health (Larchmt), 2007;16(3): 361-9. 45256 (1/2008)
Kirk Hamilton: Can you please share with us your educational background
and current position?
Francine K. Welty: I earned my MD, PhD at Case Western Reserve
University, 1981. I am currently an
Associate Professor of Medicine, Harvard Medical School; a cardiologist
at Beth Israel Deaconess Medical
Center, Boston, MA; and Director of the NHLBI Specialized Center of
Research in Vascular Injury, Repair and
KH: What got you interested in studying soy nut consumption and the
relationship to menopausal symptoms?
FKW: I was interested in options other than hormone replacement therapy
for hot flashes for postmenopausal
women. As a preventive cardiologist, my research involves dietary
modalities, exercise and lifestyle
approaches to reduce cardiovascular risk.
KH: What is the biochemistry and components in soy nuts that might
reduce hot flashes?
FKW: Isoflavones are phytoestrogens (plant-based estrogens) which have
structural similarity to the estrogen
receptor and therefore, may bind to the estrogen receptor. As a result,
their actions may be similar to those of
estrogen. Estrogen replacement therapy reduces hot flashes.
KH: Where did you come up with a dose of 25 gms of soy nuts (½ cup = 101
mg of aglycone isoflanvones)?
FKW: I wanted to aim for about 100 mg isoflavones, and 25 grams of soy
nuts have 101 mg isoflavones. I also
wanted to use a lower dose of soy protein than other soy studies which
used anywhere from 30 to 60 g soy
protein daily. That is a large amount of soy protein for Americans to
consume on a daily basis who are
unaccustomed to eating soy. In other words, I wanted something that was
practical and feasible to use daily.
Soy nuts do not need to be refrigerated. They can be taken to work and
on vacation, etc.
KH: Can you tell us about your study and the basic results?
FKW: Our study was a randomized, cross-over design which means that the
women were randomized to either
the heart healthy diet (TLC diet) without soy or TLC diet plus soy and
followed for 8 weeks. They then
crossed-over to the other diet arm. A dietitian analyzed their diet
content on the TLC diet and then women were
individually advised from which sources to decrease their protein intake
to compensate for the 25 g of soy
protein in the soy diet arm to keep protein amounts similar on both diet
arms. We advised the women to eat the
soy nuts at 3 or 4 times throughout the day to keep their blood levels
more constant. Asian populations
consume soy throughout the day, and we wanted to reproduce what happens
in the Asian population.
During each 8-week diet period, subjects recorded the number of hot
flashes and amount of exercise daily. At
the end of each 8-week diet period, subjects filled out the menopausal
symptom quality of life questionnaire and
had blood pressure recorded. Compared to the TLC diet alone, the TLC
diet plus soy nuts decreased hot flashes
45% (7.5 3.6 vs. 4.1 2.6, respectively, p<0.001) in women with >4.5 hot
flashes/day and 41% in those with ≤4.5
hot flashes per day (2.2 1.2 vs. 1.3 1.1, respectively, p<0.001). Soy
nut intake was also associated with
significant improvement in scores on the menopausal symptom quality of
life questionnaire: a 19% decrease in
vasomotor score (p=0.004); 12.9% reduction in psychosocial score
(p=0.01), a 9.7% decrease in physical score
(p=0.045) and a trend toward improvement in the sexual score with a
17.7% reduction in symptoms (p=0.129).
The amount of exercise had no effect on hot flash reduction.
We also observed significant reductions in blood pressure. Compared to
the TLC diet alone, the TLC diet plus
soy nuts significantly lowered systolic and diastolic blood pressure
(BP) 9.9% (15 mm Hg) and 6.8%, (6 mm)
respectively, in hypertensive women (systolic BP > 140) and 5.2% ( 6 mm
Hg) and 2.9%, (2 mm Hg)
respectively, in normotensive women. Further subdivision of normotensive
women revealed that systolic and
diastolic BPs were lowered 5.5% ( 7 mm Hg) and 2.7%, ( 2 mm Hg)
respectively, in prehypertensive women
(systolic BP 120-139) and 4.5% (5 mm Hg) and 3.0%, (2 mm Hg)
respectively, in normotensive women
(systolic BP < 120). Soy nut supplementation significantly lowered LDL-C
and apo B 11% (p<.05) and 8% (p=
.04), respectively, in hypertensive women but had no effect in
KH: Were there any side effects with the soy nut consumption? How was
the patient compliance?
FKW: A few women had “gas”; however, patient compliance was very good.
Any type of nut can be a bit
difficult on the teeth in older people so we advised patients with tooth
problems to put the soy nuts in soups,
yogurt, rice, casseroles, etc., in an attempt to soften the nuts. This
KH: Is it the estrogenic effects of soy nuts (isoflavones) or some other
aspect of soy nut biochemistry that
resulted in a reduction of hot flashes?
FKW: We don’t know but assume it is the estrogen effect as noted in
answer to #3 above.
KH: Who would you recommend receiving soy nuts? Why not all
FKW: I think all women should be advised about the health benefits of
soy beans. In addition to having
isoflavones and protein, soy beans have other heart-healthy products
including fiber and alpha-linolenic acid, a
beneficial fat. I should caution though that we need a longer-term study
which examines potential adverse
effects from high amounts of soy protein. We believe that the 25 grams
which we used daily should not have
any adverse effects. Three major studies have now shown reduction in BP
with whole soy foods: soy nuts, soy
milk study and soy cookies. Therefore, any of these products could be
recommended to people who want to use
dietary changes (lifestyle) to lower BP. They should be consumed
according to what was done in the study. For
example, subjects ate soy nuts 3 or 4 times throughout the day in our
study. We used a low dose of soy protein,
25 g, (101 aglycone isoflavones). Many other studies used higher doses.
Until longer-term studies examining
safety of soy (on breast and endometrium) are carried out, we recommend
women stick with lower amounts of
soy. Longer-term studies are also needed to examine the effect on BP.
Thus far, studies have been 8-12 weeks.
KH: What amount of soy protein (in grams) do soy-consuming Asian
populations consume on a daily basis?
Why cannot we use these levels as safe upper limits of soy protein
FKW: I believe the average is around 16 to 25 g soy protein daily. Keep
in mind that Asians eat a variety of
soy foods. We can probably use these levels as estimates of safe upper
limits. However, strictly speaking, until
a trial examines long-term safety on the endometrium and breast, safety
cannot be guaranteed.
KH: Do you have any further comments on this very interesting subject?
FKW: Hypertensive women had a 10% lower systolic BP and 7% lower
diastolic BP. These reductions in
hypertensive women were twice as great as the 5% and 3% reductions
observed in normotensive women. These
results are comparable to those seen with antihypertensive drugs. A
12-mm Hg decrease in systolic BP for 10
years has been estimated to prevent 1 death for every 11 patients
treated in patients with stage 1 hypertension;
therefore, the average reduction of 15 mm Hg in systolic BP in
hypertensive women in the current study could
have significant implications for reducing cardiovascular risk and death
on a population basis. Since risk of
CVD doubles with each 20/10 mm Hg increase in BP beginning at 115/75 mm
Hg, the BP reductions in
normotensive women in the current study are also important. Moreover,
subdivision of normotensive women
into prehypertensive and normotensive (baseline BP < 120) groups showed
that both have significant reductions
in systolic BP.
Modest decreases in diastolic BP can also reduce cardiovascular risk.
One study estimated that a 2-mm Hg
reduction in diastolic BP (the mean reduction observed in normotensive
and prehypertensive women in current
study) resulted in a 6% reduction in CHD and a 15% reduction in stroke.
In a prospective, observational
analysis of 420,000 individuals, a 5 mm Hg lower diastolic BP (mean
reduction of 6 mm Hg observed in
hypertensive women in current study) was associated with at least a 34%
lower rate of stroke and 21% less
CHD at mean follow-up of 10 years. Therefore, the diastolic BP
reductions in the current study would be
predicted to translate into significant decreases in CHD and stroke for
normotensive, prehypertensive and
Finally, in terms of cost-effectiveness, dietary modalities are less
costly than drugs for long-term therapy
Kathrynne Holden, MS, RD < fivestar at nutritionucanlivewith.com >
"Ask the Parkinson Dietitian" http://www.parkinson.org/
"Eat well, stay well with Parkinson's disease"
"Parkinson's disease: Guidelines for Medical Nutrition Therapy"
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