Research: ST JOHN and COLLEAGUES,

Listed in Issue 220

Abstract

ST JOHN and COLLEAGUES, (1)Atherosclerosis Research Unit, University of Southern California, Los Angeles, California; Department of Preventive Medicine, University of Southern California, Los Angeles, California sought to determine the effect of change in urine excretion of isoflavonoids upon cognitive change.

Background

Methodology

Design: Post hoc analysis of isoflavonoid exposure (mean 2.7 years) during the randomized, placebo-controlled, double-blind Women's Isoflavone Soy Health trial. Setting: General community. Participants: Healthy postmenopausal women (N = 350). Intervention: Twenty-five grams of isoflavone-rich soy protein (91 mg of aglycone weight isoflavones: 52 mg genistein, 36 mg daidzein, 3 mg glycitein) or milk protein-matched placebo provided daily. Measurements: Overnight urine excretion, fasting plasma levels of isoflavonoids, and cognitive function measured at baseline and endpoint.

Results

Three hundred women (age: mean 61, range 45-92) completed both cognitive assessments and did not use hormone replacement therapy during the trial. Mean on-trial change from baseline in urine excretion of isoflavonoids was not significantly associated with change in a composite score of global cognition (P = .39). Secondary analyses indicated that change in urine excretion of isoflavonoids was inversely associated with change in a factor score representing general intelligence (P = .02) but not with factor scores representing verbal or visual episodic memory. Mean differences in this general intelligence factor score between women in the lowest and highest quartiles of isoflavonoid change were equivalent to an approximate 4.4-year age-associated decline. Analyses based on plasma isoflavonoid levels yielded similar but attenuated results.

Conclusion

In healthy postmenopausal women, long-term changes in isoflavonoids are not associated with global cognition, supporting clinical trial results, although greater isoflavonoid exposure from dietary supplements is associated with decrements in general intelligence but not memory; this finding requires confirmation in future studies.

References

St John JA(1), Henderson VW, Hodis HN, Kono N, McCleary CA, Franke AA, Mack WJ. Associations between urine excretion of isoflavonoids and cognition in postmenopausal women in the Women's Isoflavone Soy Health clinical trial.  J Am Geriatr Soc. 62(4):629-35. Apr 2014. doi: 10.1111/jgs.12752. Epub Mar 11 2014.

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