Sunshine is necessary for human survival and the survival of every other plant and animal on the planet. But are we supposed to spend time in the sun or just enjoy the secondary benefit – that our planet isn’t a frozen ball of rock in deep space? The pendulum of medical opinion on sun exposure seems to swing regularly. We have all met someone with a deep tan who looks like a human Shar Pei at 45.
The case against spending time dozing in the sun, like a lizard, is strong. Sunlight has a lot of ultraviolet radiation. This radiation penetrates the skin and damages the DNA. Damaging DNA is a bad thing to do because sometimes the cells will die, and occasionally they will turn cancerous. Skin cancer is clearly associated with sun exposure. Unfortunately, the time your skin is most susceptible to sun damage is before you are old enough to read the sunscreen bottle. If that isn’t bad enough, ultraviolet radiation also breaks down the elastic elements in the skin. Destroy enough elastin, and you resemble that Shar Pei.
For the last 20+ years, the entire medical community has been yelling, “Stay out of the sun!” Then a funny thing happened – we started looking at vitamin D and cancer.
A bit of background. Vitamin D is made in the human body by sun exposure on your skin. The more intense the sun exposure, the greater the level of vitamin D produced. Doctors have known since the Mayflower that low vitamin D levels cause rickets. In modern times, most of us have seen skin cancer but never a single case of rickets, thus the advice, “Avoid the sun.”
About 10 years ago, scientists were studying sun exposure and deaths due to skin cancer. This was a pretty detailed and serious study. They found the expected modest increase in the number of skin cancer cases but a substantial decrease in deaths from all causes. Some head scratching ensued. The scientists then decided to measure vitamin D levels by areas of the country and compare them to various causes of death. They found people in sunny places like California and Arizona had less cancer, heart disease, multiple sclerosis, rheumatoid arthritis, and even Alzheimer’s disease. Places like Minnesota and North Dakota had less skin cancer but more of everything else.
Vitamin D acts as a hormone in the body and has its fingers in numerous biologic reactions. The current thinking is vitamin D protects against a number of different diseases. Unfortunately, vitamin D supplementation is a recent development. It hasn’t been around long enough to actually prove protection against all these various diseases (from cancer to Alzheimer’s).
Today I would tell you a modest dose of sunshine on a daily basis is a good thing. You should live longer for it. Move to Arizona or Florida; become a nudist. If that doesn’t fit in your life plan, you might just want to stick with vitamin D supplements.
- Dr. Don Bucklin, National MRO – a.k.a. “Dr. B”