A thorough review has evaluated whether a vitamin D supplement can help prevent non-skeletal disorders, including cardiovascular diseases and mood disorders.
Vitamin D and its most important forms, vitamin D2 (ergocalciferol) and D3 (cholecalciferol) are essential for the absorption of calcium, magnesium and phosphate in the intestine. Most of the vitamin D required for humans comes from chemical reactions that start in the skin, continue in the liver and are completed in the kidneys, while just a little vitamin D comes from nutrition. In the past, several studies have investigated the association between low vitamin D serum concentrations and a variety of non-skeletal conditions. However, no significant association has been established so far, which led a team of researchers to conduct a comprehensive review of the most recent data available on the topic.
In their study, recently published in the journal The Lancet Diabetes & Endocrinology, scientists from France selected the most updated and accurate papers and conducted comparative analyses, summarizing the results according to each category of non-skeletal disorders. The effects of vitamin D supplementation and vitamin D serum concentration were evaluated in cardiovascular diseases, cancerous and precancerous conditions, metabolic conditions, allergies, mood and chronic pain, and rheumatic conditions, among others. They established four categories for vitamin D doses: low (less than 10 μg/day); moderate (10–20 μg/day); high (21–49 μg/day) and very high (more than 50 μg/day).
Effect on All-Cause Mortality
When analyzing the effect of a vitamin D supplement on all-cause mortality, moderate doses of vitamin D3 were associated with a small but significant decrease of all-cause mortality in middle-aged and older adults. Regarding cardiovascular diseases, the researchers found that vitamins D, D2 and D3 supplementation, with or without calcium, had no protective effect on the risk of myocardial infarction, stroke, congestive heart failure, or high blood pressure. On the other hand, a vitamin D supplement was linked to high systolic pressure and high LDL cholesterol levels in overweight and obese individuals.
Effect on Cancer and Metabolic Disease
Analyses on cancerous and precancerous conditions revealed that a vitamin D supplementation did not influence cancer occurrence, and had little effect in reducing the risk of cancer death. When metabolic conditions were considered, researchers found that a vitamin D supplement did not affect blood sugar levels (progression of prediabetes or diabetes) or on serum concentrations of leptin (a hormone associated with satiety and hunger inhibition).
Effect on Upper Respiratory Tract Infections and Asthma
The results showed that a vitamin D supplementation decreased the risk of common upper respiratory tract infections by 12% in those with low serum concentrations. However, this vitamin did not improve the condition of patients with pneumonia, tuberculosis and pulmonary exacerbations of chronic obstructive pulmonary disease (COPD). Regarding allergic conditions, vitamin D supplements played a key role in reducing the risk of asthma exacerbations that required corticosteroid treatment in children, adults and pregnant women.
Effect on Mood Disorders and Other Conditions
When it came to daily functioning, mood and pain, vitamin D had no effect on improving multiple sclerosis function, mood disorders (e.g. depression), or chronic pain in patients with diverse conditions. The same was observed with regards to rheumatic conditions, such as rheumatoid arthritis and systemic lupus erythematous, and inflammatory states like Crohn’s disease. Finally, when the investigation was conducted on vitamin D supplement effects in maternal and perinatal health, researchers concluded that vitamin D and calcium supplementation could significantly reduce the risk of pre-eclampsia, while vitamin D alone would not have the same effect.
Vitamin D Supplements May Reduce All-Cause Mortality
Although previous studies have demonstrated that vitamin D supplementation has little to no effect on non-skeletal disorders, this current, more comprehensive and accurate study has found that such supplementation can reduce all-cause mortality and cancer mortality in middle-aged and older people, as well as the risk of common upper respiratory tract infections and asthma exacerbations. However, there is still little evidence that vitamin D might play a key role on most of the non-skeletal disorders, and the authors suggest that low vitamin D status is more likely a consequence of poor health, rather than its cause. They also state that larger trials are required. Current, ongoing trials are from high-resource countries, which call for the need for studies to be done with populations in different socioeconomic and health service environments.
Written by Gustavo Caetano, B.Sc., M.Sc.
References:
(1) Autier P, Mullie P, Macacu A, Dragomir M, Boniol Magali, Coppens K, Pizot C, Boniol Mathieu. Effect of vitamin D supplementation on non-skeletal disorders: a systematic review of meta-analyses and randomised trials. Lancet Diabetes Endocrinol 2017; 5: 986-1002.
(2) Vitamin D – Fact Sheet for Health Professionals. Retrieved from https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
(3) Gunnars, K. (June 4, 2017). Leptin and Leptin Resistance: Everything You Should Know. Retrieved from https://www.healthline.com/nutrition/leptin-101
