A study of over 3,100 older men (49-71) from across Europe has found that men with higher levels of vitamin D performed consistently better in an attention and speed of processing task. There was no difference on visual memory tasks. Although previous studies have suggested low vitamin D levels may be associated with poorer cognitive performance, findings have been inconsistent. Vitamin D is primarily synthesised from sun exposure but is also found in certain foods such as oily fish.
(2008). Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction?.
FASEB J.. 22(4), 982 - 1001.