Talk about backfiring. In our quest for longer, healthier, and more comfortable lives, we’ve removed ourselves so far from our evolutionary history that we’re perversely making ourselves less healthy.
Yes, pollution is an obvious culprit. We’ve known for decades that toxic chemicals used for modern conveniences can cause cancer, birth defects, and reproductive problems.
But I’m talking about something much simpler: sunshine. We don’t get it anymore. At least not enough of it according to Dr. Michael Holick, a medical doctor and researcher responsible for much of what we know about vitamin D and health. In his 2010 book The Vitamin D Solution, Holick presents compelling evidence that most Americans have insufficient levels of vitamin D, that this insufficiency contributes substantially to serious health problems such as cancer and heart disease, and that just 15 minutes or so a day of sunlight a few times a week can prevent the onset of health problems in many people. The Centers for Disease Control and Prevention recently released its own report on vitamin D levels (with a lower standard for what's considered acceptable levels), and reported that one-third of Americans have insufficient vitamin D levels.
Vitamin D is produced by our bodies in response to sunlight and plays a major role in bone and muscle health, cell growth and immune response. According to Holick, just about all land animals, including gorillas, polar bears and lizards just to name a few, create and need vitamin D. In humans, the central role of vitamin D in our evolution is obvious. Variations in human skin tone reflect evolutionary adaptations in our ancestors as they expanded north from Homo sapiens’ birthplace in the sunny African savannah. Lighter skin in people of European ancestry helps absorb reduced sunlight at northern latitudes. In short, sunlight and vitamin D have been a critical part of human health since our beginning, and as Holick catalogs, a mounting list of scientific studies have shown clear links between greater levels of sunlight and vitamin D, and lower levels of most cancers, autoimmune disorders, heart disease and diabetes. The only cancer rates not lowered are those for non-melanoma skin cancer, the least fatal form of skin cancer. But non-melanoma increases are dwarfed by the decreases in breast, prostate, and colon cancer.
Holick rails against the dermatology community for scaring everyone into staying out of the sun to avoid skin cancer, and covering up when they do. But blaming skin doctors misses the real point. Western civilization isn’t vitamin D deficient because we put on sunscreen at the beach (which Holick fully supports). We’re deficient because our lifestyle prevents us from getting outside on sunny days for a lousy 15 minutes even a few times a week. That’s a damning commentary on modern life.
I know what you’re thinking: “I’m sure I’m outside more than 15 minutes a day, so either (a) this doesn’t apply to me or (b) this is bogus.” That was my reaction, especially because I’ve had the luxury of taking a lunchtime run or walk several times a week for years, something that most busy people can’t do. I also spent as much of my free time outside as possible, at least during the warm months. But over the past three years I’ve had my vitamin D levels checked at the urging of three different doctors and the results all are essentially the same: My vitamin D levels are insufficient according to all of them.
Think about it. What time of day are you regularly outside? Is it in the morning when you commute to work? In the evening when you go for a run? The occasional weekend when you mow the lawn? How often does it rain where you live? Do you live in the northern two-thirds of the country that can’t provide sufficient sunlight through the winter months? As I considered this myself, I realized that a substantial part of my regular exercise route is shady, that much of the year I’m covered up against the cold, some days simply are not sunny, and of course, work and other commitments often prevent me from taking an outdoor break in the middle of the day. Combined, these variables add up to not enough time in the sun. Our predecessors on the savannah would be shocked.
Most people can take vitamin D supplements to make up for their indoor life, a simpler solution than rearranging societal demands. But somehow that feels like a failure. If we’ve gotten something as fundamental as sunshine wrong – the source of all food (plants at the base of the food web photosynthesize their growth with sunlight), most energy (all fossil fuels are essentially ancient plants buried underground), and at least some of our joy (sunlight on skin produces mood-elevating endorphins to supplement those produced in the brain) – what else are we messing up in our lives? Maybe this is a bigger sign that we need to heed the call of the Slow Movement, tame the tyrannical treadmill of modern life, and step outside to smell the (photosynthesizing) roses a bit more.
After all, sunlight is warm and cheery. It feels good. We didn’t need science to tell us this, but it turns out that science has confirmed it. This isn’t that complicated. Rather, it falls into the “everything I need to know I learned from my cat” category. If it feels good, do it. Ignore those instincts at your peril.