Getting the right dose of Vitamin D

Vitamin D has become a hot topic in recent years, largely because failure to get enough of it is associated with multiple diseases, and because much of the general population is deficient in this micronutrient.

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Since 1930, when its chemical structure was first identified, significant advances have been made in research into vitamin D's functions in the body. Initially, studies focused on the role of this compound and its metabolites in calcium homeostasis and bone metabolism. Later, with the discovery of the metabolised forms of 25-hydroxyvitamin D (25(OH)D) in 1968 and then 1,25-hydroxyvitamin D (1,25(OH)2D), research expanded and focused on the role it plays in the onset of immunological diseases, infections and cancer, as well as chronic non-communicable diseases such as cardiovascular conditions, obesity and type 2 diabetes.

Currently, there is no doubt that vitamin D plays a role in regulating the immune system; vitamin D deficiency is actually associated with a worse prognosis for COVID-19 infection.

Humans can meet part of their vitamin D requirements through skin synthesis from cholesterol, provided they are exposed to sufficient sunlight. However, it is difficult to specify the minimum recommended amount of time, as it depends on a range of factors, including the season, time of day, geographical latitude, age, and skin type.

An expert panel from the Spanish Society for Bone and Mineral Metabolism Research recommends that light-skinned people expose their face and arms to the sun for 15 minutes every day between March and October. For elderly people and patients with osteoporosis, the recommendation is to extend this to 30 minutes. In both cases, sunblock with an SPF between 15 and 30 should be used, depending on the latitude and intensity of UV (ultraviolet) radiation.