Vitamin D deficiency and sun protection, a difficult balance | Health and wellness

It has been known for almost a century that vitamin D is essential for maintaining blood levels of phosphorus and calcium within the range required for skeletal and muscle health, and in recent years its importance for regulation has been confirmed. immune system or brain development. For this reason, some epidemiological data are concerning, suggesting that up to 40% of the European population is deficient in this substance. This deficiency is more acute in older people, especially in menopausal women, since this vitamin is less synthesized with age, in pregnant women, obese people, since vitamin D is fat-soluble, and in children.

The main route of vitamin D production is through cholesterol in the skin, which generates it when exposed to ultraviolet radiation from the sun. Life changes that keep us indoors more and more may explain the lack of vitamin D, but some also blame the use of sunscreens that block the sun’s radiation.

At this point, two opposing health effects collide. Skin cancer, although most are not fatal, is most common among people with white skin, so sun protection is highly recommended, especially during the hottest months, during the middle of the day. Research in Australia has shown that the use of sunscreens can reduce the incidence of skin cancer by 10–15%, and it is estimated that increasing the use of these products in the population by 5% could reduce the incidence of melanoma by 10% over a decade.

The Spanish Photobiology Group of the Spanish Association of Dermatologists published tables in 2020 in which it is possible to see the approximate limits of sun exposure in both winter and summer in order to obtain an adequate stimulation of vitamin D production without causing burns, depending on skin type. If you have skin type 3, the most common among Spaniards, in summer eight minutes on your face or hands is enough to reach sufficient levels of vitamin D, and after 32 minutes you will begin to suffer from burns. In winter, the minimum dose of vitamin D is 25 minutes, and a burn occurs after an hour and a half of exposure. These numbers will vary depending on whether you have lighter or darker skin and depending on your latitude, because being in Spain is not the same as being somewhere in the tropics. Jose Aguilera and Maria Victoria Galvez, co-authors of the study, developed the UV Derma application, which helps to individually manage this information using a mobile phone.

Yolanda Gilaberté, head of the dermatology service at the Miguel Servet Hospital in Zaragoza and co-author of the document, acknowledges the difficulty of achieving a balance between the necessary skin protection and the need for vitamin D. “There are scientific societies that recommend 20 nanograms per milliliter of vitamin D, which guarantees musculoskeletal health and prevents rickets or muscle problems,” explains Gilaberte. “But in recent years it has been noticed that vitamin D has an important effect on our immune system: when its levels fall, we are more likely to get colds or the risk of developing cancer increases. Because of this immunoregulatory effect, some societies believe that levels should be above 30 nanograms,” he adds. “It’s very difficult to reach these levels in Spain in winter, we have to be in the sun for a long time and we also don’t know whether vitamin D levels should be the same in winter or summer,” says the dermatologist. “From twenty and below, it’s clear that it’s bad, but above that there are doubts. This is an area that still needs to be researched,” he concludes.

Regarding the balance between protection from excessive sun and vitamin D deficiency, Gilaberte recalls a study they did on children in Huesca, in which they saw that those who applied factor 30 sun protection had higher vitamin D levels. probably because they were exposed to the sun. longer in the sun. Sunscreen does not completely block UV rays the way clothing does. If the skin of an unprotected person turns red after 20 minutes of exposure to the sun, then with a factor of 2 it will take 40, and with 50 – 1000 minutes (16.6 hours). “This is a theory because we usually apply less than the amount that is used to calculate these factors in laboratories, and the actual factor on our skin is lower,” he concludes.

A 2019 review of research noted that while there are experimental studies suggesting a theoretical risk of vitamin D deficiency due to sunscreen use, there is no conclusive evidence that this occurs in real-world situations. This is probably because people don’t usually apply as much cream as in the experiments. This paper noted that more research is needed, particularly on high-factor sunscreens and under different UV conditions, but noted that overall the benefits of these products in preventing skin cancer appear to outweigh the risks. vitamin D deficiency.

Carmen Vidal, professor of nutrition at the University of Barcelona, ​​agrees there is still “quite a lot of uncertainty and research needed” around vitamin D. “Levels are found to be lower than established, which may be due to less sun exposure, use of more protection or lower fat intake, but we do not see this to be associated with an increase in comorbidities,” he said. explains. “This may be because recommended levels are excessive or due to differences in analytical methods,” he says.

As with sunscreen use, the amount of vitamin D obtained from food has also decreased due to health-promoting measures. “Fat consumption dropped because obesity is a problem, and there were foods like full-fat dairy that were a common source of vitamin D,” he summarizes. At this point, it will be necessary to refine our knowledge of what healthy vitamin D levels are at each age, taking into account individual differences, and seeking a balance between goals that sometimes require conflicting measures.

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