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Soy Protein, Isoflavones, and
Cardiovascular Health. An American Heart Association Science Advisory
for Professionals From the Nutrition Committee
Frank M. Sacks MD, Alice
Lichtenstein DSc, Linda Van Horn PhD, RD, William Harris PhD, Penny
Kris-Etherton PhD, Mary Winston EdD, for the American Heart
Association Nutrition Committee
Soy protein and isoflavones (phytoestrogens)
have gained considerable attention for their potential role
in improving risk factors for cardiovascular disease.
This scientific advisory assesses the more recent work
published on soy protein and its component isoflavones.
In the majority of 22 randomized trials, isolated soy
protein with isoflavones, as compared with milk or other
proteins, decreased LDL cholesterol concentrations; the
average effect was ≈3%.
This reduction is very small relative to the large amount
of soy protein tested in these studies, averaging 50 g,
about half the usual total daily protein intake.
No significant effects on HDL cholesterol, triglycerides,
lipoprotein(a), or blood pressure were evident.
Among 19 studies of soy isoflavones, the average effect on
LDL cholesterol and other lipid risk factors was nil.
Soy protein and isoflavones have not been shown to lessen
vasomotor symptoms of menopause, and results are mixed with
regard to soy’s ability to slow postmenopausal bone loss.
The efficacy and safety of soy isoflavones for preventing or
treating cancer of the breast, endometrium, and prostate are
not established; evidence from clinical trials is meager and
cautionary with regard to a possible adverse effect.
For this reason, use of isoflavone supplements in food or
pills is not recommended.
Thus, earlier research indicating that soy protein has
clinically important favorable effects as compared with
other proteins has not been confirmed.
In contrast, many soy products should be beneficial to
cardiovascular and overall health because of their high
content of polyunsaturated fats, fiber, vitamins, and
minerals and low content of saturated fat.
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