For the last 30 years, the messaging has been clear: Slather your body with sunscreen if you so much as even think about going outside in the sun. Cloudy and rainy? Doesn’t matter. Wear the sunscreen. Want to build up a base tan? You’re killing yourself. Wear the sunscreen. It’s only ten minutes? That ten minutes of sunscreen-less sun exposure will shave a year off your life. Wear the sunscreen.
In more recent years, the tide has shifted. Research has come out showing that most commercial sunscreen contains chemical compounds that act as carcinogens when absorbed, at least in animal models. Maybe we don’t even want to block the sun at all. Or maybe we do, but there’s a better way to do it than using chemical filters that absorb into our skin. At any rate, I figured with summer rolling around that it was time to revisit the topic of sunscreen. So let’s do that, shall we?
Read MoreThe ancients prayed to it. Farmers relied on it. The seasons depend on the earth’s tilt toward it. The sun is always up there, shining down, filling the world with light and heat, sending down powerful rays of energy that scatter across the surface, sneak through windows, penetrate otherwise dark caves. You can’t avoid it, unless you shut yourself inside, draw the blinds, and close your eyes.
That’s what we’re supposed to do: avoid it. “Any amount of sun exposure is unsafe,” according to the experts, and will give us skin cancer. They tell us it’s a toxin. If we have to be outside, we’d better slather on the sunscreen, wear a hat that shields our entire body, and avoid the harsh midday sun at all costs.
Read MoreFrom the presence of vitamin D receptors in our cells and vitamin D factories in our epidermis, it’s pretty clear that having adequate vitamin D is an essential component of being a healthy, thriving Homo sapiens. Anything our body invests precious resources to make is obviously pretty important. Vitamin D plays a vital role in calcium metabolism, immunity, and gene expression. Deficiencies in this nutrient (which I argue should really have been classified as a hormone) are associated with brittle and misshapen bones, joint pain, hyperparathyroidism, autoimmune disease, severe COVID-19, and even some cancers. And yet, vitamin D insufficiency and deficiency are alarmingly common in children and adults of all ages. This has led many health experts to assert that everyone should be supplementing with vitamin D as a standard public health practice. The questions then arise: What’s the best way to get enough vitamin D? Can’t you get enough from food? What are the benefits of supplementing, and when is it necessary? And if you’re going to supplement, what’s the best way? How Much Vitamin D Do You Need Per Day, and How Do You Get It? The RDA for vitamin D is 400 IU (10 mcg) per day for babies up to one year old, 600 IU (15 mcg) for kids and adults (both men and women) until age 70, and 800 IU (20 mcg) thereafter. However, this is just the minimum amount needed to ward off deficiency, not the amount needed for optimum health. And anyway, most people don’t get anywhere near this amount. There are three ways to get vitamin D: from the sun, from your diet, and from supplements. Each has its own benefits, but it can be difficult to calculate how much vitamin D you’re actually getting on a daily, weekly, or monthly basis. Besides the fact that you can’t really measure how much you’re synthesizing from sunlight, people differ in their ability to absorb vitamin D from food and supplements. The only way to know if you’re getting the right amount is to get your vitamin D levels tested. Ask your doctor for a blood test measuring serum 25(OH)D. As for what constitutes “good” or “optimal” levels, that’s a contentious question. The Institute of Medicine guidelines say anything over 20 ng/mL (equivalent to 50 nmol/L) is fine, while the Endocrine Society and the American Association of Clinical Endocrinologists say over 30 ng/mL (75 nmol/L) is adequate. Again, I consider these the bare minimum. Personally, I shoot for 50 to 60 ng/mL (or over 125 nmol/L). Let’s look at how you get there: Sun: Nature’s Source of Vitamin D We humans are basically hairless, upright apes with hefty D3 requirements. Before oral supplements appeared, dietary vitamin D was not a very reliable source. We had to get it from the sun’s UVB radiation. I prefer getting my D3 from sunlight still, simply because it’s enjoyable to spend time in the sun, and it’s an effortless way to get something that’s critical to my health. … Continue reading “Vitamin D: Sun Exposure, Supplementation, and Doses”
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