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.
 . Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction?. FASEB J. [Internet]. 2008 ;22(4):982 - 1001. Available from: http://www.fasebj.org/cgi/content/abstract/22/4/982