Vitamin D is a fat-soluble vitamin that all vertebrates produce when sunlight reacts with cholesterol in the skin. Your liver and kidneys convert the vitamin D produced in the skin into a hormone that will then be turned into the active form of the vitamin. Vitamin D is also found in some foods and is available as a supplement. A variety of important health functions are attributed to vitamin D, including some effects on cognition.
Mental and Cognitive Illness
Vitamin D exerts a variety of effects in the brain, including activating neurons that regulate behavior, stimulating growth of neurons and protecting the brain from oxidation and inflammation, according to a study published in the January 2011 issue of the "Canadian Medical Association Journal." Growing evidence points toward an association between low vitamin D status and depression, bipolar disorder and schizophrenia. The researchers conclude that vitamin D may be a critical factor in the prevention and treatment of mental and cognitive illness in some people.
Women's Study
A study of more than 5,500 elderly women found that higher weekly vitamin D intake improved cognitive performance. In the study published in the November 2010 issue of the journal "Neurology," the participants, average age 80, reported their diets via questionnaire. Those with inadequate vitamin D consumption showed lower scores on a mental status exam. The results were significant after sun exposure, chronic diseases, use of mood-altering drugs and education level were accounted for.
Cognitive Impairment
The "Journal of Gerontology" reported in its January 2011 issue on a study that found an association between cognitive impairment and low vitamin D levels in a sample of elderly United States residents. The study included more than 3,300 participants aged 65 or older. Cognitive, medical and physical performance of the participants were evaluated and showed a correlation between vitamin D status and cognitive function. The researchers called for further studies to investigate the mechanism behind the observed effects.
Insufficiency
A study published in the October 2010 issue of the "European Journal of Clinical Nutrition" found a high prevalence of vitamin D insufficiency -- levels not low enough to be considered deficient -- along with reduced memory function in a sample of elderly Europeans. In the study, participants were divided into three groups based on vitamin D status over the course of one year. The group with the highest levels of vitamin D showed the fewest errors on a test of working memory. The researchers noted that the effect of vitamin D level and memory function was greater in women than in men.
References
- "Canadian Medical Association Journal"; Vitamin D for Mental Health and Cognition; Serdar M. Durson; November 2010
- "Neurology"; Dietary Intake of Vitamin D and Cognition in Older Women: A Large Population-based Study; Annweiler C, et al.; November 2010
- "The Journals of Gerontology"; Vitamin D and Cognitive Impairment in the Elderly US Population; Llewellyn DJ, et al.; January 2011
- "European Journal of Clinical Nutrition"; Vitamin D Status and Measures of Cognitive Function in Healthy Older European Adults; Seamans KM, et al.; October 2010
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