Research: MANGANO and COLLEAGUES,

Listed in Issue 234

Abstract

MANGANO and COLLEAGUES,  (1)Department of Nutritional Sciences, University of Connecticut, Storrs, CT; Institute for Aging Research, Hebrew SeniorLife, Harvard Medical School, Boston,  MA evaluated the long-term effect of soy protein and/or soy isoflavones supplementation on serum lipids and inflammatory markers in women older than 60 years.

Background

Soy foods contain several components, notably, isoflavones and amino acids, that may improve cardiovascular health.

Methodology

The authors evaluated the long-term effect of soy protein and/or soy isoflavones supplementation on serum lipids and inflammatory markers using a 1-year randomized, double-blind, placebo-control, clinical trial in 131 healthy ambulatory women older than 60 years. We hypothesized that soy protein, in combination with isoflavones, would have the largest positive effect on coronary heart disease risk factors (serum lipids and inflammatory markers) compared with either intervention alone and that, within groups receiving isoflavones, equol [an isoflavandiol metabolized from daidzein, a type of isoflavone] producers would have more positive effects on coronary heart disease risk factors than non-equol producers. After a 1-month baseline period, participants were randomized into 1 of 4 intervention groups: soy protein (18 g/d) and isoflavone tablets (105 mg/d isoflavone aglycone equivalents), soy protein and placebo tablets, control protein and isoflavone tablets, or control protein and placebo tablets. T Tests were used to assess differences between equol and non-equol producers. Ninety-seven women completed the trial.

Results

Consumption of protein powder and isoflavone tablets did not differ among groups, and compliance with study powder and tablets was 79% and 90%, respectively. After 1 year, in the entire population, there were either no or little effects on serum lipids and inflammatory markers, regardless of treatment group. Equol producers, when analyzed separately, had significant improvements in total cholesterol/high-density lipoprotein and low-density lipoprotein/high-density lipoprotein ratios (-5.9%, P = .02; -7.2%, P = .04 respectively).

Conclusion

Soy protein and isoflavone (either alone or together) did not impact serum lipids or inflammatory markers. Therefore, they should not be considered an effective intervention to prevent cardiovascular disease because of lipid modification in healthy late postmenopausal women lacking the ability to produce equol.

References

Mangano KM(1), Hutchins-Wiese HL, Kenny AM, Walsh SJ, Abourizk RH, Bruno RS, Lipcius R, Fall P, Kleppinger A, Kenyon-Pesce L, Prestwood KM, Kerstetter JE. Soy proteins and isoflavones reduce interleukin-6 but not serum lipids in older women: a randomized controlled trial.  Nutr Res. 33(12): 1026-33. doi: 10.1016/j.nutres.2013.08.009. Dec 2013. Epub Sep 18 2013.

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