Increased one week soybean consumption affects spatial abilities but not sex hormone status in men

Background Increased soybean intake is often recommended for the prevention of hormone-dependent cancer, cardiovascular diseases and age- related cognitive decline. Although isolated phytoestrogens have shown these positive effects, the evidence for such influence of increased consumption of soybeans is lacking. Aim To prove the effects of short- term increased soybean intake on sex hormone levels and spatial cognitive parameters in men. Subjects and methods Seven young healthy men were asked to eat 900 g soybeans during one week. Sex hormone levels were determined in saliva and plasma, and mental rotation and spatial visualization were quantified by standard psychometric tests. All parameters were assessed before and after the study. Results Plasma estradiol, total and free testosterone, as well as salivary testosterone and estradiol remained unchained. Spatial cognitive performance was improved after increased soybean intake when considering spatial visualization ( P = 0.03). The results for mental rotation showed similar dynamics, but the changes were not significant. Conclusion Short- term increased soybean intake does not affect sex hormone status, but improves spatial cognitive performance in young healthy men.