Objective: Phytoestrogens, which consist mainly of isoflavones, lignans, and coumestans have estrogenic and anti-inflammatory properties. Previous research suggests that higher dietary or supplemental intakes of isoflavones and lignans are related to better cognitive performance in middle-aged and older women.
Methods: We conducted longitudinal analysis of dietary phytoestrogens and cognitive performance in a cohort of African American, white, Chinese, and Japanese women undergoing the menopausal transition. The tests were Symbol Digit Modalities, East Boston Memory, and Digits Span Backward. Phytoestrogens were assessed using the Food Frequency Questionnaire. We modeled each cognitive score as a function of concurrent value of the primary predictors (highest tertile of isoflavones, lignans, or coumestrol) and covariates including the menopausal transition stage.
Results: Coumestrol and isoflavone intakes were 10 and 25 times greater, respectively, in Asian than in non-Asian participants. During late perimenopause and postmenopause, Asian women with high isoflavone intakes did better on processing speed, but during early perimenopause and postmenopause, high-isoflavone Asian consumers performed worse on verbal memory. The highest isoflavone consumers among non-Asians likewise posted lower verbal memory scores during early perimenopause. A verbal memory benefit of higher dietary lignan consumption was apparent only during late perimenopause, when women from all ethnic/racial groups who were in the highest tertile of intake demonstrated a small advantage. Coumestrol was unrelated to cognitive performance.
Conclusions: The cognitive effects of dietary phytoestrogens are small, seem to be class-specific, vary by menopause stage and cognitive domain, and differ among ethnic/racial groups (but whether this is related to dose or to host factors cannot be discerned).
From the 1Division of Geriatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA; 2Department of Preventive & Behavioral Medicine, University of Massachusetts Medical School, Worcester, MA; 3Department of Epidemiology & Preventive Medicine, University of California at Davis, Davis, CA; 4Department of Community Health Sciences, School of Public Health at UCLA, Los Angeles, CA; and 5Department of Obstetrics and Gynecology, UC Davis Medical Center, Davis, CA.
Received September 21, 2011; revised and accepted November 17, 2011.
Funding/support: The Study of Women’s Health Across the Nation (SWAN) has grant support from the National Institutes of Health (NIH), Department of Health and Human Services (DHHS), through the National Institute on Aging (NIA), the National Institute of Nursing Research (NINR), and the NIH Office of Research on Women’s Health (ORWH; Grants NR004061; AG012505, AG012535, AG012531, AG012539, AG012546, AG012553, AG012554, AG012495). The SWAN Phytoestrogen Ancillary Study was supported by grant AG030448.
Financial disclosure/conflicts of interest: None reported.
The content of this article manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the NIA, NINR, ORWH, or NIH.
Address correspondence to: Gail A. Greendale, MD, Division of Geriatrics, David Geffen School of Medicine at UCLA, 10945 Le Conte Avenue, Suite 2339, Los Angeles, CA 90095-1687. E-mail: email@example.com