By Dr. Mehmet Oz
If you're like me, you can't wait to get outside once the weather turns warm. In summer, you're likely to find me fishing with my son or relaxing with my wife, Lisa, on our deck. But it might surprise you to learn that I spend a few minutes outside enjoying the sun before I put on sunblock. We all know that too much time in the sun can be seriously damaging to your health, but a little exposure can actually do you some good. Doctors have known for years that sunlight has a profound effect on the body's production of vitamin D, which is often touted for its ability to maintain bone health. Several recent studies have found that there are other big benefits to soaking up sunshine.
Lower Blood Pressure
A small 2014 study in the Journal of Investigative Dermatology found that roughly 20 minutes of UVA exposure lowered subjects' diastolic BP (which measures the pressure in arteries between heartbeats) by nearly 5 points. Researchers believe that when UVA rays—the type of ultraviolet light most responsible for giving you a tan—reach your skin, they trigger the release of nitric oxide, a gas that dilates vessels, increasing blood flow and potentially lowering the risk of cardiovascular disease.
Lower Breast Cancer Risk
One study of more than 6,000 women found that those who had the highest sun exposure and, as a result, the most vitamin D, were less likely to develop breast cancer compared with those with the lowest exposure. Though the link between D and breast cancer is still unclear, lab studies have shown that the vitamin can help kill breast cancer cells and reduce the risk of metastasis.
Improved Brain Function
A recent study that looked at the effects of sun exposure over the course of a year found that people age 45 and older who got less sun were more likely to experience cognitive decline. While there's conflicting evidence on whether vitamin D plays a role in brain health, scientists hypothesize that improved cognition may be linked to the sun's effect on the body's internal clock; exposure to daylight may boost the production of the neurotransmitter serotonin. Research suggests that increasing serotonin could help spur nerve cell growth in the hippocampus, the part of the brain crucial to the forming and storing of memories.
Less Joint Pain
Your risk of developing rheumatoid arthritis, an autoimmune disease that causes the body to attack its own tissue, may be linked to your exposure to UVB rays, a type of UV light that can't fully penetrate glass, so you get adequate exposure outside only. In one Harvard study, women who had the highest exposure to UVB were at a 21 percent decreased risk of developing rheumatoid arthritis compared with women who had the lowest, possibly because vitamin D can help regulate the activity of immune cells and, in the process, may prevent the body from turning on itself.
But...How Much Sun Is Too Much?
Sunshine does have its benefits, but it's still the number one cause of skin cancer. To sunbathe safely, I recommend no more than 15 to 20 minutes of direct exposure daily. After that, slather on a sunscreen that offers broad-spectrum coverage with a minimum SPF of 30. Need incentive? A recent study in the Annals of Internal Medicine found that people instructed to use sunscreen daily had 24 percent fewer wrinkles than those who used it at their own discretion.
Mehmet Oz, MD, is the host of The Dr. Oz Show (weekdays; check local listings).