Eating soya improves human memory.
BACKGROUND
Soya foods are rich in isoflavone phytoestrogens with weak agonist activity at oestrogen receptors. Oestrogen treatment has been found to improve memory in men awaiting gender reassignment and in post-menopausal women.


OBJECTIVE
To examine the effects of supervised high versus low soya diets on attention, memory and frontal lobe function in young healthy adults of both sexes.


METHODS
Student volunteers were randomly allocated to receive, 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 battery of cognitive tests at baseline and then after 10 weeks of diet.


RESULTS
Those receiving the high soya diet showed significant improvements in short-term (immediate recall of prose and 4-s delayed matching to sample of patterns) and long-term memory (picture recall after 20 min) and in mental flexibility (rule shifting and reversal). These improvements were found in males and females. In a letter fluency test and in a test of planning (Stockings 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 generation 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 did those on the control diet.


CONCLUSIONS
Significant cognitive improvements can arise from a relatively brief dietary intervention, and the improvements from a high soya diet are not restricted to women or to verbal tasks.
File
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SE
Psychopharmacology Research Unit, Centre for Neuroscience, Hodgkin Building, King's College London, Guy's Campus, London SE1 1UL, UK. sandra.file@kcl.ac.uk
Jarrett
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N
Fluck
E
E
Duffy
R
R
Casey
K
K
Wiseman
H
H
D000328:Adult; D000339:Affect / Q000187:drug effects; D001288:Attention / Q000187:drug effects; D004032:Diet; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects*; D011597:Psychomotor Performance / Q000187:drug effects; D012727:Sex Characteristics; D013025:Glycine max