Why sunlight is good for you

Most of us know the negative impact of sun exposure on our health, such as skin aging and skin cancer, but do you know the positive effects? Over the past several decades, a favorable association between sunlight and disease has been discovered, and there is growing evidence that regular exposure to sunlight benefits our overall health. 

Most of us do not get enough sunlight, as evidenced by the high rate of vitamin D deficiency in the United States. About 40 percent of Americans ages 50-80 are deficient. Turns out, it is difficult to naturally get vitamin D from food alone. Fatty fish (tuna, salmon), beef liver, egg yolks and mushrooms are foods that naturally contain vitamin D. Our bodies can manufacture vitamin D, but only if we are exposed to sunlight. Thus, vitamin D deficiency is a surrogate marker of inadequate sun exposure. 

It is becoming increasingly clear that sunlight contributes to the prevention of disease, including cancers such as colon, breast, prostate and non-Hodgkin’s lymphoma, as well as other conditions like multiple sclerosis, hypertension, insulin resistance, diabetes, Alzheimer’s disease and depression. Initially, the benefits of sun exposure were attributed to vitamin D, but as it turns out, there’s more to the story. In addition to producing vitamin D, sunlight affects our immune system, the production of substances like nitric oxide, melatonin and serotonin, and our circadian clock. All of these biologic effects are positive for our overall health. For instance, sunlight induces our skin to release nitrogen oxide, resulting in a decrease in blood pressure and suppression of glucose intolerance and insulin resistance. 

All that said, we must remember the negative impact of sunlight on our health. Sunlight is hard on our skin and the major cause of skin cancer. Non-melanoma skin cancer is the most common cancer in the United States, but the mortality from this is extremely low. Melanoma is a less common, but more serious, type of skin cancer. Sunburn increases the risk of melanoma and should always be avoided. In addition to sunburn, intermittent, high-intensity exposure to sun (for example, working indoors and not getting sunlight on most days, then soaking up a week of sun on vacation) increases the risk of melanoma — whereas a pattern of chronic daily exposure appears to be protective. 

Sunlight is good for you, and adequate exposure contributes to overall good health. For most people here in the South, 15 minutes of unprotected exposure a day should suffice, but for darker-skinned individuals, you may need 30 minutes. As with most things in life, moderation is key. 

Dr. Pamela Tuli is a hematologist-oncologist practicing with The Medical Oncology Group – Memorial Physician Clinics. She can be contacted at (228)-575-1234.