Spanish researchers have estimated the duration of solar radiation exposure required to obtain recommended doses of vitamin D. While 10 to 20 minutes in the sun in the spring and summer is enough, in the winter months we would need almost two hours, which the vast majority of the population doesn't get. Although ultraviolet (UV) solar radiation contributes to the development of cancer and aging of the skin, it also reduces blood pressure, makes vitamin D and improves the treatment of various diseases. Vitamin D deficiency in adults is linked to a higher risk of suffering from various diseases. Since few foods contain this vitamin, sun exposure is the most important natural source there is.
The study analyzed ultraviolet solar radiation around noon (12:30-13:30) for four months of the year (one in each season) from 2003 to 2010. As such, the facts show that in July, an individual with skin type III (the most common among the population of Spain) should not spend more than 29 minutes in the sun. In January, the same person can stay in the sun for 150 minutes.
It was found that around noon in January, with 10% of the body exposed, about 130 minutes would be needed to get the recommended daily dose of vitamin D. In contrast, in April and July, with 25% of the body exposed, about 10 minutes is enough to acquire the vitamin. In October, for example, 30 minutes would suffice.
The results show that while there is sufficient radiation in countries such as Spain, it is difficult to get the recommended doses of vitamin D in winter (November to February) in northern temperate latitudes, as the exposure time is considerable (130 minutes ).
In these months, two hours of sun exposure would be required to obtain an optimal dose of vitamin D in the afternoon; but in the morning about 9.7 hours and at 16:00 about 5.7 hours. In the spring and summer, with 25% of the body exposed, about 10 minutes of sun exposure at about 1:00 PM and 20 minutes between 3:00 PM and 5:00 PM would suffice.
A person's age also plays an important role in obtaining vitamin D, as the elderly are less likely to produce vitamin D:adults have 66% of the potential that children have.
