The Best Source of Vitamin D

If one is going to make an evolutionary argument for what a “natural” vitamin D level may be, how about getting vitamin D in the way nature intended—that is, from the sun instead of supplements? I run through the pros and cons in my video The Best Way to Get Vitamin D: Sun, Supplements, or Salons?. Though supplements may only cost about 10 dollars a year, sunlight is free. We never have to worry about getting too much vitamin D from sunlight, since our body has a way to regulate production in the skin, so if we get our D from the sun, we don’t have to trust poorly regulated supplement companies not to mislabel their products. Indeed, only about half the supplement brands that researchers tested came within 10 percent of their labeled amount.

Sunlight may also have benefits beyond vitamin D, such as how our body may use the sun’s near-infra-red rays that penetrate our skin to activate chlorophyll by-products in our bloodstream to make Co-Q10. (See my video How to Regenerate Coenzyme Q10 (CoQ10) Naturally for more on this.) There’s another way our body appears to use the sun’s rays to maximize the effects of the greens we eat: Within 30 minutes of exposure to the ultraviolet (UV) rays in sunlight, we can get a significant drop in blood pressure and improvement in artery function, thanks to a burst of nitric oxide-releasing compounds that flow into our bloodstream. We can even measure the nitric oxide gas coming straight off our skin. Of course, we have to eat greens or beets in the first place, but that combo of greens and sunlight may help explain some of the protection that plant-based eaters experience.

Morning sun exposure may help those with seasonal affective disorder, as well as improve the mood of wheelchair-bound nursing home residents. Previously, I’ve talked about the benefits of avoiding light at night—see my video Melatonin and Breast Cancer if you’d like to know more—but underexposure to daytime sunlight may also affect our melatonin levels, which don’t only regulate our circadian rhythms but may also be helpful in the prevention of cancer and other diseases. Older men and women getting two hours of outside light during the day appear to secrete 13 percent more melatonin at night, though we’re not sure what, if any, clinical significance this has.

The downsides of sun exposure include increased risk of cataracts, a leading cause of vision loss, though this risk can be minimized by wearing a brimmed hat and sunglasses. Sunlight also ages our skin. In my The Best Way to Get Vitamin D: Sun, Supplements, or Salons? video, you can see a dramatic photo of a truck driver who spent decades getting more sun on the left side of his face—though his driver’s side window. “The effects of sunlight on the skin are profound, and are estimated to account for up to 90% of visible skin aging”—that is, wrinkles, thickening, and loss of elasticity. Things like sun exposure and smoking can make us look 11 years older. Cosmetic surgery can make us look up to eight years younger, but a healthy lifestyle may work even better. Doctors don’t preach about sun protection for youthful facial looks, though, but because of skin cancer. Medical authorities from the World Health Organization, the American Cancer Society, to the Surgeon General warn about excess sun exposure and for good reason, given the millions of skin cancers and thousands of deaths diagnosed every year in the United States alone.

The UV rays in sunlight are considered a complete carcinogen, meaning they can not only initiate cancer, but promote its progression and spread. Melanoma is the scariest, which “makes the rising incidence of melanoma in young women particularly alarming.” This increase has been blamed on the increased usage of tanning salons. Tanning beds and UV rays in general are considered class 1 carcinogens, like processed meat, accounting for as many as three quarters of melanoma cases among young people and six times the risk of melanoma for those who visited tanning salons ten or more times before the age of 30.

The tanning industry is big business, bringing in billions of dollars. There may be more tanning salons than there are Starbucks, and they use those dollars like the tobacco industry: to downplay the risks of their products. Laws are being passed to regulate tanning salons, from complete prohibitions, like in the country of Brazil, to age restrictions for minors. But, unlike tobacco, tanning isn’t addictive. Or is it?

Have you heard of “tanorexia”? Some people tan compulsively and report a so-called tanner’s high. Describing tanning behavior like a substance abuse disorder might seem a little silly—that is, until you stick people in a brain scanner and can show the same kind of reward pathways light up in the brain, thanks to endorphins that are released by our skin when we’re exposed to UV rays. In fact, we can even induce withdrawal-like symptoms by giving tanners opiate-blocking drugs. So, tanning is potentially addictive and dangerous. Harvard researchers suggest that we should “view recreational tanning and opioid drug abuse as engaging in the same biological pathway.” But there’s a reason sun exposure feels good. Sunlight is the primary natural source of vitamin D, and, evolutionarily, it’s more important, in terms of passing along our genes, not to die of rickets in childhood. Unlike natural sunlight, tanning bed lights emit mostly UVA, which is the worst of both worlds: cancer risk with no vitamin D production. The small amount of UVB many tanning beds do emit, however, may be enough to raise vitamin D levels. Is there a way to raise D levels without risking cancer? Yes: vitamin D supplements.


Indeed, we can get some of the benefits of sun exposure without the risks by taking vitamin D supplements. But, for the sake of argument, what if such supplements didn’t exist? Would the benefits of sun exposure outweigh the risks? That’s the subject of my video The Risks and Benefits of Sensible Sun Exposure.

For other videos in this vitamin D series, see:

I also explore Vitamin D as it relates to specific diseases:

Here’s the video about that amazing chlorophyll activation: How to Regenerate Coenzyme Q10 (CoQ10) Naturally.

What do greens and beets have to do with artery function? Check out some of my latest videos on the wonders of nitrate-rich vegetables:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

How to Make Your Own CoQ10

Chlorophyll is the green pigment that makes green leaves green. If you search for chlorophyll in the medical literature, a lot of what you find is about fecal fluorescence, a way to detect the contamination of carcasses in the slaughterhouse with feces to reduce the risk of food poisoning from pathogens harbored within animal feces. Fecal matter gets on meat either “with knife entry through the hide into the carcass, and also splash back and aerosol [airborne] deposition of fecal matter during hide removal”—that is, when they’re peeling off the skin. If, however, the animals have been eating grass, you can pick up the poo with a black light. As you can see in my video How to Regenerate Coenzyme Q10 (CoQ10) Naturally, a solution of chlorophyll is green, but, under a UV light, it lights up as red. So, if you have a black light in a chicken slaughter plant, you can get a drop on the droppings. The problem is most chickens aren’t outside anymore. They’re no longer pecking at grass so there’s less fecal fluorescence. We could let them run around outside or we could save money by just adding a chlorophyll supplement to their feed so we can better “identify areas of gut-spill contamination” on the meat.

The reason I was looking up chlorophyll was to follow-up on the data I presented in my Eating Green to Prevent Cancer video, which suggests that chlorophyll may be able to block carcinogens. I found a few in vitro studies on the potential anti-inflammatory effects of chlorophyll. After all, green leaves have long been used to treat inflammation, so anti-inflammatory properties of chlorophyll and their break-down products after digestion were put to the test. And, indeed, they may represent “valuable and abundantly available anti-inflammatory agents.” Maybe that’s one reason why cruciferous vegetables, like kale and collard greens, are associated with decreased markers of inflammation.

In a petri dish, for example, if you lay down a layer of arterial lining cells, more inflammatory immune cells stick to them after you stimulate them with a toxic substance. We can bring down that inflammation with the anti-inflammatory drug aspirin or, even more so, by just dripping on some chlorophyll. Perhaps that’s one of the reasons kale consumers appear to live longer lives.

As interesting as I found that study to be, this next study blew my mind. The most abundant energy source on this planet is sunlight. However, only plants are able to use it directly—or so we thought. After eating plants, animals have chlorophyll in them, too, so might we also be able to derive energy directly from sunlight? Well, first of all, light can’t get through our skin, right? Wrong. This was demonstrated by century-old science—and every kid who’s ever shined a flashlight through her or his fingers, showing that the red wavelengths do get through. In fact, if you step outside on a sunny day, there’s enough light penetrating your skull and going through to your brain that you could read a book in there. Okay, so our internal organs are bathed in sunlight, and when we eat green leafy vegetables, the absorbed chlorophyll in our body does actually appear to produce cellular energy. But, unless we eat so many greens we turn green ourselves, the energy produced is probably negligible.

However, light-activated chlorophyll inside our body may help regenerate Coenzyme Q10. CoQ10 is an antioxidant our body basically makes from scratch using the same enzyme we use to make cholesterol—that is, the same enzyme that’s blocked by cholesterol-lowering statin drugs. So, if CoQ10 production gets caught in the crossfire, then maybe that explains why statins increase our risk of diabetes—namely, by accidently also reducing CoQ10 levels in a friendly-fire type of event. Maybe that’s why statins can lead to muscle breakdown. Given that, should statin users take CoQ10 supplements? No, they should sufficiently improve their diets to stop taking drugs that muck with their biochemistry! By doing so—by eating more plant-based chlorophyll-rich diets—you may best maintain your levels of active CoQ10, also known as ubiquinol. “However, when ubiquinol is used as an antioxidant, it is oxidized to ubiquinone. To act as an effective antioxidant, the body must regenerate ubiquinol from ubiquinone,” perhaps by using dietary chlorophyll metabolites and light.

Researchers exposed some ubiquinone and chlorophyll metabolites to the kind of light that makes it into our bloodstream. Poof! CoQ10 was reborn. But, without the chlorophyll or the light, nothing happened. By going outside we get light and, if we’re eating our veggies, chlorophyll, so maybe that’s how we maintain such high levels of CoQ10 in our bloodstream. Perhaps this explains why dark green leafy vegetables are so good for us. We know sun exposure can be good for us and that eating greens can be good for us. “These benefits are commonly attributed to an increase in vitamin D from sunlight exposure and consumption of antioxidants from green vegetables”—but is it possible that these explanations might be incomplete?


This blog post has it all: a mind-blowing mechanism, practical applicability, and poop. What more could you want?

Interested in learning more about the potential downsides of cholesterol-lowering statin drugs? I’ve produced other videos on the topic, including Statin Cholesterol Drugs and Invasive Breast Cancer and The Actual Benefit of Diet vs. Drugs.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: