Vitamin D has generated a lot of interest in recent years, not only for its role in calcium metabolism and subsequently the health of our bones, but also for its potential health benefits at other levels such as in the immune system.
Much more than a vitamin, it is a hormone which acts on different organs in the body.
In humans, its fundamental contribution is the transformation of dehydrocholesterol in the skin into cholecalciferol by the action of the sun’s ultraviolet rays. To a lesser extent, vitamin D can also be obtained from foods of both animal (salmon, tuna, mackerel, dairy) and vegetable (avocado, mushrooms, oranges) origin.
The only benefit currently demonstrated is its influence on the health of our bones by regulating the absorption of calcium, therefore protecting bone integrity and modulating growth.
Although it appears that vitamin D may have an influence on cardiovascular disease, cancer, the immune system, COVID and other respiratory diseases, more studies demonstrating a causal relationship are required to be able to provide recommendations to the general population in this regard.
There is no evidence that generalised supplementation of the population improves people’s health.
The groups of patients in which it is advisable to measure blood levels and supplement if required are institutionalised elderly patients, those with osteoporosis, pigmented skin or malabsorption problems (celiac disease, bariatric surgery), obese patients and patients on treatment with drugs which accelerate vitamin D metabolism such as some epilepsy medication.
In children under the age of one year, a daily vitamin D supplement (400 IU daily) is also indicated, and measurement of blood levels is not required.
Higher than recommended doses can result in an overdose leading to symptoms such as constipation, nausea, loss of appetite, depression or general malaise. In more severe cases of intoxication, the most common side effect is hypercalcaemia, or increased blood calcium levels, which can weaken bones leading to fractures and damage organs such as the kidney.
- Supplementation with this vitamin has no significant health benefits for adults in general, except in those who are at high risk of deficiency.
- Vitamin D supplementation has not yet been shown to prevent cancer, cardiovascular disease, COVID or other respiratory diseases.
- We have no scientific evidence of its benefit on longevity.
- Do not take vitamin D supplements without medical supervision. See your doctor to find out if you belong to the group of people who can benefit from taking supplements.
- Follow safe sun exposure advice, avoiding the hours in the middle of the day (12:00-16:00).
- Follow a healthy diet rich in vitamin D (fish, such as salmon, and avocados are healthy sources).
Dr. Cristina Garrido
Family and Community Medicine Specialist
June 7, 2024
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