Background/Aims: Cell culture studies suggest that phytoestrogens, abundant in soy products such as tempe and tofu, could protect against cognitive decline. Paradoxically, the Honolulu Asia Aging Study reported an increased risk for cognitive impairment and other dementia markers with high tofu (soybean curd) intake.
Methods: A cross-sectional study was carried out in 2 rural sites (Borobudur and Sumedang) and 1 urban site (Jakarta) among mainly Javanese and Sundanese elderly (n = 719, 52-98 years of age). Memory was measured using a word learning test sensitive to dementia and soy consumption was assessed using Food Frequency Questionnaire items.
Results: High tofu consumption was associated with worse memory (beta = -0.18, p < 0.01, 95% CI = -0.34 to -0.06), while high tempe consumption (a fermented whole soybean product) was independently related to better memory (beta = 0.12, p < 0.05, 95% CI = 0.00-0.28), particularly in participants over 68 years of age. Fruit consumption also had an independent positive association. The analyses were controlled for age, sex, education, site and intake of other foods.
Conclusion: The results for tofu consumption as a risk factor for low memory function may tie in with the Honolulu Asia Aging Study data. It is unclear whether these negative associations could be attributed to potential toxins or to its phytoestrogen levels. Estrogen (through which receptors phytoestrogens can exert effects) was found to increase dementia risk in women over 65 years of age.
Tempe contains high levels of phytoestrogens, but (due to fermentation) also exhibits high folate levels which may exert protective effects. Future studies should validate these findings and investigate potential mechanisms.
Interesting they never tried that with Nattokinase, as that's fermented soy, but possibly the bifidus cultures might have invalidated the study, or biased it in some way, adding a third factor.
Two hormone-like compounds linked to the consumption of soy-based foods can cause irreversible changes in the structure of the brain, resulting in early-onset puberty and symptoms of advanced menopause in research animals, according to a new study by researchers at North Carolina State University. The study is a breakthrough in determining how these compounds can cause reproductive health problems, as well as in providing a key building block for how to treat these problems.
The study is the first to show that the actual physical organization of a region of the brain that is important for female reproduction can be significantly altered by exposure to phytoestrogens – or plant-produced chemicals that mimic hormones – during development. Specifically, the study finds that the compounds alter the sex-specific organization of the hypothalamus – a brain region that is essential to the regulation of puberty and ovulation. The study also shows that the phytoestrogens could cause long-term effects on the female reproductive system.
While the study examined the impact of these compounds on laboratory rats, neurotoxicologist Dr. Heather Patisaul – who co-authored the study – says the affected "circuitry" of the brain is similar in both rats and humans. Patisaul is an assistant professor in NC State's Department of Zoology. Her co-author is Heather Bateman, a doctoral student in the department.
Patisaul says this finding is extremely important because, while the changes in brain structure cannot be reversed, "if you understand what is broken, you may be able to treat it." Patisaul says she is in the process of evaluating the effects of these compounds on the ovaries themselves.
Reference:"A preliminary study of the safety, feasibility and cognitive efficacy of soy isoflavone supplements in older men and women," Gleason CE, Asthana S, et al, Age Ageing, 2009; 38(1): 86-93. (Address: Section of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin, Madison, WI 53705, USA. E-mail: [email protected] ).
Summary: In a randomized, placebo-controlled, double-blind pilot study involving older non-demented men and women, aged 62 to 89 years old, results indicate that supplementation with soy isoflavones may exert beneficial effects on cognitive function. The participants were randomized to 100 mg/day soy isoflavones or placebo for a period of 6 months. At intervention end, subjects in the soy group showed improvement in visual-spatial memory and construction, verbal fluency and speeded dexterity, compared to baseline. Subjects in the soy-group showed improvement on 8 of 11 cognitive tests, while subjects in the placebo group showed improvement in 2 of the 11 tests. Thus, the authors of this study conclude, "data support the potential cognitive effects of soy isoflavones in older adults."
Soy and Memory
Linear Mode
