A meta-analysis suggests that vitamin D may be effective in treating depression

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Vitamin D generated a lot of talk at the beginning of the pandemic. COVID-19. This vitamin contributes to the proper functioning of the innate immune system and of infected people lower levels of vitamin D than the rest of the population. It also plays an important role in calcium and phosphorus absorption, bone mineralization and muscle function. A new study out today suggests that vitamin D supplements may ease symptoms in people with depression.

Vitamin D is synthesized directly in the skin, under the influence of the sun’s UVB rays, from cholesterol derivatives naturally present in the body. However, this source is very variable depending on the regions of the world that are more or less sunny. Fortunately, dietary supplements supplement this intake: fatty fish, eggs, meat, mushrooms and fortified dairy products are good sources of vitamin D. The recommended intake for adults is 15 micrograms per day. In fact, many people are deficient in vitamin D, especially in our latitudes and especially in the elderly – the ability to absorb and synthesize vitamin D decreases with age.

In recent years, several studies have suggested that there may be a link between vitamin D deficiency and depression, a common mental disorder that affects 5% of adults worldwide. according to the World Health Organization. Symptoms of depression (low mood, loss of pleasure or interest in activities, difficulty concentrating, loss of self-esteem, sleep disturbances, negative thoughts, etc.) have a significant impact on the daily life of affected people and are a disease with a high burden. Antidepressants can be effective, but sometimes they are not enough. Therefore, other methods of treatment are being sought, especially in the field of nutrition.

More than 40 studies were reviewed

Studies have shown that biologically active vitamin D, nuclear vitamin D receptors, and vitamin D-activating and metabolizing enzymes are present in brain neurons, glial cells, and macrophages. Therefore, it has been suggested that it may affect the regulation of central nervous system functions, the disorders of which have been associated with depression. This hypothesis has been supported by several cross-sectional studies that have shown an association between depressive symptoms and vitamin D deficiency.

However, meta-analyses of the effects of vitamin D supplementation on mental health to date have been inconclusive, with most providing no evidence of any beneficial effects. Researchers from the University of Eastern Finland have re-examined this question. They conducted a new meta-analysis of past research, sifting through the results of 41 studies conducted around the world. All were randomized, placebo-controlled trials in different adult populations.

The results of this new meta-analysis show that vitamin D supplements are more effective than placebo in reducing depressive symptoms in people with depression. The doses of vitamin D used varied widely, but a vitamin D supplement was usually 50 to 100 micrograms per day. ” Despite high heterogeneity, vitamin D supplementation ≥ 2000 IU per day reduces depressive symptoms “, the team concluded. However, the results must be qualified.

Potential efficacy in major depressive disorder

The 41 studies reviewed involved more than 53,000 individuals, the majority (84%) being women with or without depression; participants were supplemented with vitamin D or received a placebo. Sample sizes varied widely (n=42 to n=36,282). Similarly, interventions ranged in duration from five days to five years, and single doses of vitamin D ranged from 400 to 500,000 IU (and, calculated per intervention day, from 400 IU to approximately 14,000 IU).

Research shows that vitamin D supplements reduce symptoms of depression, especially in people diagnosed with major depressive disorder and in women with perinatal depression. In addition, the effects of dietary supplements are greater when the supplements are taken for a short period of time (less than 12 weeks). In terms of dosage, supplements below 4,000 IU per day had weak to moderate effects; moreover, the effect was greater. Furthermore, supplementation had only a small to moderate effect when subjects had low (≤ 50 nmol/L) or sufficient (> 50 nmol/L) serum vitamin D levels at baseline.

Our results suggest that vitamin D supplementation has beneficial effects in people with major depressive disorder as well as in those with milder, clinically significant depressive symptoms. “, summarizes the team. Even though their meta-analysis includes a very large number of individuals, the researchers remain cautious about their findings: they emphasize that the evidence for a link between vitamin D and depression remains fragile due to the heterogeneity of the populations studied and the risk of the disease. bias associated with multiple studies.

However, this meta-analysis supports the potential therapeutic utility of vitamin D in psychiatry, particularly in major depressive disorder and perinatal depression. ” These findings will prompt further high-profile clinical trials in depressed patients to better understand the potential role of vitamin D supplementation in the treatment of depression. », concludes Tuomas MikolaScientist at the Institute of Clinical Medicine, University of Eastern Finland and lead author of the meta-analysis.

Source: T. Mikola et al., Critical Reviews in Food Science and Nutrition

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