UV radiation and vitamin D production
One commonly cited benefit of UV radiation is that your body produces vitamin D after your skin is exposed to it. However, this can be affected by factors such as season, age, skin pigmentation and sunscreen use. Furthermore, there have not been studies to determine whether UV-induced vitamin D synthesis can occur without increased risk of skin cancer.
Because of public health concerns about UV exposure and skin cancer, nutrition-related recommendations for vitamin D have been set using the assumption that sun exposure is minimal. This means that the recommendations are adequate for those without any sun exposure. Other sources of vitamin D include fish, eggs and fortified products (like milk and margarine) and vitamin supplements. If you are concerned about vitamin D, see your health care professional for advice.