Vitamin D and alcohol: A review of the current literature.

Vitamin D is associated with bone mineral density, and its deficiency is a global health problem. In psychiatry, low vitamin D levels have been associated with schizophrenia, depression, psychotic symptoms, and, more recently, alcohol use disorders. Alcohol use disorders are among the most prevalent mental disorders worldwide. Therefore, our aim was to evaluate the association between alcohol use and vitamin D serum levels. The PubMed, SCIELO, and Lilacs databases were searched for this systematic review. We assessed all articles published from 1976 to December 2015, and we examined the associated reference lists to retrieve articles that appeared to fulfill our criteria. Of 932 articles, 49 met our inclusion criteria. The majority of the papers (71.4%) were cross-sectional studies. Alcohol intake was found to be positively associated with vitamin D status in 15 articles and negatively associated with vitamin D in 18 articles; no association was found in 16 articles. Heterogeneous results were found in our review, with a similar number of papers indicating a positive association, a negative association or the absence of any association between alcohol use and vitamin D levels. Nevertheless, it is important to note that the studies in which a positive association was found were more recent papers that involved considerably larger sample sizes than those in other studies. The older studies compared vitamin D levels in alcoholic and non-alcoholic patients, in contrast to more recent studies, which focused on more specific populations. In addition, most of the selected papers were from high latitude countries, where exposure to sunlight tends to be lower than in tropical countries. The data concerning vitamin D levels in patients with alcohol use disorders remain controversial. Additional research using a standardized methodology is necessary to demonstrate the real impact of alcohol consumption on vitamin D serum levels as well as on the health status of alcohol users.