Eating soya improves human memory

Rationale: Soya foods are rich in isoflavone phytoestrogens with weak agoni st activity at oestrogen receptors. Oestrogen treatment has been found to i mprove memory in men awaiting gender reassignment and in post-menopausal wo men. Objective: To examine the effects of supervised high versus low soya d iets on attention, memory and frontal lobe function in young healthy adults of both sexes. Methods: Student volunteers were randomly allocated to rece ive, under supervision, a high soya (100 mg total isoflavones/day) or a low soya (0.5 mg total isoflavones/day) diet for 10 weeks. They received a bat tery of cognitive tests at baseline and then after 10 weeks of diet. Result s: Those receiving the high soya diet showed significant improvements in sh ort-term (immediate recall of prose and 4-s delayed matching to sample of p atterns) and long-term memory (picture recall after 20 min) and in mental f lexibility (rule shifting and reversal). These improvements were found in m ales and females. In a letter fluency test and in a test of planning (Stock ings of Cambridge), the high soya diet improved performance only in females . There was no effect of diet on tests of attention or in a category genera tion task. Those on the high soya diet rated themselves as more restrained and, after the tests of memory and attention, they became less tense than d id those on the control diet. Conclusions: Significant cognitive improvemen ts can arise from a relatively brief dietary intervention, and the improvem ents from a high soya diet are not restricted to women or to verbal tasks.