Can vitamin D and Sunlight make you smarter?

The preponderance of evidence suggests that higher blood levels of vitamin D correlate to better cognitive ability (ability to think), so if you want a higher IQ, it behooves you to keep your vitamin D levels high. In the winter in the Northern US, Northern Europe, Canada and other high-latitude countries, this may mean supplementing with 3,000-5,000 IU daily for most people and up to 6,400 IU daily for nursing mothers.[1] Another alternative is to use a tanning bed two or three times weekly or take frequent tropical vacations (unless you have type-one skin that does not tan—never burn).

The latest scientific paper on cognitive abilities as compared to vitamin D levels shows that persons who have the lowest levels are more than twice as likely to be cognitively impaired as those with the highest levels.[2] I was not surprised at the results of this study; in my book, I had documented other research indicating that in elderly people with the highest levels of vitamin D scored 3-5 times higher on two cognitive tests than those with the lowest levels.[3] Those with the lowest levels were also 12 times as likely to be depressed.

When we consider that vitamin D is absolutely essential to proper nerve function and development,[4] [5] and that there are vitamin D receptors throughout the central nervous system,[6] it stands to reason that mental abilities would be compromised by poor vitamin D status. It also follows that depression would be higher in those whose levels are low. Therefore, it follows that sunlight and vitamin D may make you both smarter and happier.

[1] Wagner C. et al. High-dose vitamin D3 supplementation in a cohort of breastfeeding mothers and their infants: a 6-month follow-up pilot study. Breastfeed Med 2006;1:59-70.
[2] Llewellyn, D. et al. Serum 25-Hydroxyvitamin D Concentration and Cognitive Impairment. J Geriatr Psychiatry Neurol Online. December 10, 2008.
[3] Wilkins C. et al. Vitamin D Deficiency Is Associated With Low Mood and Worse Cognitive Performance in Older Adults. Am J Geriatr Psychiatry;2006;14:1032–1040).
[4] McCann J. et al. Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain
dysfunction? FASEB J. 2008;22:982-1001.
[5] Carlson, A. et al. Is vitamin D deficiency associated with peripheral neuropathy? The Endocrinologist 2007;17:319-25.
[6] McCann J. et al. Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain
dysfunction? FASEB J. 2008;22:982-1001.