Summer is coming, we will be able to fill up on Vitamin D by exposing ourselves to the sun for 10-15 minutes a day. Vitamin D continues to provide evidence of its importance in the protection against a dozen cancers. A major recent study confirms in particular that high blood levels of vitamin D are associated with a significant reduction in the risk of cancer.
Vitamin D is often referred to as the sunshine vitamin because it is primarily formed by the action of the sun’s UVB rays on the skin. This vitamin plays several very important roles in the maintenance of good health, including controlling the absorption of calcium and phosphorus from the intestine to maintain the integrity of bone mass.
It is also likely that the white skin of the inhabitants of colder regions of the globe is an adaptation intended to maximize the production of vitamin D. Originally, the human species had black skin to protect itself from the strong radiation. from the sun that floods the African continent, but by migrating to less sunny regions (in Northern Europe, for example), this dark skin became a handicap by preventing the adequate production of vitamin D.
Recent genetic analyzes suggest that around 15,000 years ago, a series of mutations affecting three main genes allowed the appearance of whiter skin, which provided a distinct survival advantage by allowing deeper penetration of rays of the sun in the epidermis and an increase in the synthesis of vitamin D.
15 different cancers associated with a lack of Vitamin D
Another factor that makes vitamin D synthesis so important is the vitamin’s role in preventing cancer. The first clue in this direction comes from observations showing that the mortality associated with colon cancer was highest in people who were less exposed to sunlight, such as inhabitants of large cities or those in regions located at high latitudes.
Blood levels of vitamin D also appear to play an important role in the survival of people who are affected by cancer: for example, women affected by breast cancer and who have insufficient vitamin D levels are twice as likely recurrence and death from the disease.
According to the results obtained so far, it is estimated that at least 15 different types of cancer are associated with lack of sun exposure, this relationship being particularly important for those of the colon, breast, prostate and non-Hodgkin lymphomas.
To better characterize this protective effect, a team of scientists from the University of California at San Diego examined the association between the blood levels of vitamin D in women aged 55 and over and the total risk of cancer (at the exception of skin cancers). Using data accumulated over two studies of 2,304 people, they found that women with vitamin D levels above 40 ng/mL had a 67% lower risk of cancer than those with lower levels. at 20 ng/mL. These observations are in agreement with the results of other studies showing a reduction in the risk of breast and colon cancer by vitamin D, illustrating the importance of maintaining adequate blood levels of vitamin D.
Avoid sunburn at all costs
How to achieve it? In people who work outdoors in temperate regions, analysis of vitamin D levels reveals concentrations around 60 ng/mL, which corresponds to an intake of around 10,000 IU per day. You have to be outdoors to make vitamin D, because UVB rays are absorbed by clothing or windows. But it’s easy in summer, a simple exposure of 10 to 15 minutes in the sun being more than enough to allow the skin to synthesize this amount of vitamin D, without increasing the risk of skin cancer.
Perhaps the most important aspect is to avoid sunburn at all costs: occasional and excessive exposures that burn the skin are the main risk factors for melanoma, especially when they occur at a young age and in fair-skinned people. The vast majority of studies indicate that regular and moderate exposure to the sun does not represent an important risk factor for skin cancer, and could on the contrary reduce the incidence of several types of cancer.
Beleza S et al. The timing of pigmentation lightening in Europeans. Mol Biol Evol.; 30: 24-35.
McDonnell SL et al. Serum 25- Hydroxyvitamin D concentrations 40 ng/ml are associated with >65% lower cancer risk: pooled analysis of randomized trial and prospective cohort study. PLoS One