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:

The Disconnect Between Science and Policy

Back in 1912, when hardly anyone smoked cigarettes, lung cancer was like a museum curiosity: extremely rare. In the next few decades, however, it rose dramatically around the world, roughly fifteen-fold. But researchers had already nailed it way back then. By mid-century, the evidence linking lung cancer and tobacco was considered overwhelming. Says who? Says the tobacco industry’s own research scientists in an internal memo. We now know that “senior scientists and executives within the cigarette industry knew about the cancer risks of smoking at least as early as the 1940s.”

Publically, though, they said things like, “Sure there are statistics associating lung cancer and cigarettes. There are statistics associating lung cancer with divorce, and even with lack of sleep. But no scientist has produced clinical or biological proof that cigarettes cause the diseases they are accused of causing.”

What was the government saying? My video American Medical Association Complicity with Big Tobacco includes several real cigarette advertisements, including one in which a leading U.S. Senator advises readers to smoke Lucky Strikes. Who wouldn’t want to “give [their] throat a vacation,” as another ad proclaimed? Others assured “not one single case of throat irritation,” and how could your throat and nose be adversely affected when cigarettes “are just as pure as the water you drink”? What if you do feel irritation from smoking? No problem—your doctor can write you a prescription for cigarettes, according to an ad from the Journal of the American Medical Association. After all, “don’t smoke” is advice hard for patients to swallow, as we’re told in another ad.

This reminds me of the recent survey of doctors that found the number-one reason doctors don’t prescribe heart-healthy diets was their perception that patients fear being deprived of all the junk they’re eating. After all, Philip Morris reminded doctors in an ad that we want to keep our patients happy and to “make a radical change in habit…may do harm.”

The tobacco industry gave medical journals big bucks to run ads like the ones I’m sharing with you. Should we be concerned about a conflict of interest? Not if we listen to Philip Morris, who assured us their “claims come from completely reliable sources” based on studies conducted by “recognized authorities…whose findings have been published in leading medical journals.” They even kindly offered to send free packs of cigarettes to doctors so they can test them out themselves and invited physicians to “make the doctors’ [smoking] lounge your club” at the American Medical Association convention.

What did the AMA have to say for itself? Like most other medical journals, they accepted tobacco ads but asserted that “[p]ostmortem examinations do not reveal lesions in any number of cases that could be definitely traced to the smoking of cigarettes.” So, as far as the AMA was concerned, case closed.

In fact, even after the Surgeon General’s Report on Smoking and Health came out, the American Medical Association, American Cancer Society, and Congress continued to drag their feet. The government was still subsidizing tobacco, just as our tax dollars subsidize the sugar and meat industries today. The AMA actually went on record refusing to endorse the Surgeon General’s report. Could that have been because they had just been handed ten million dollars from the tobacco industry?

Today the money is coming from big food. The American Academy of Family Physicians has accepted large sums of money from Coca-Cola “to fund patient education on obesity prevention.” I wonder what that pamphlet will say.

Who was featured as a top partner on Coca Cola’s website? The American College of Cardiology.

Just as it would have been hazardous to your health to take the medical profession’s advice on your smoking habits in the 1950s, it may be hazardous to your health today to take the medical profession’s advice on your eating habits.


If the balance of scientific evidence favors plant-based eating, why isn’t the medical profession at the forefront of encouraging people to eat healthier? That’s the question this video tries to answer. Looking back to smoking in the 1950s, we can see how all of society, the government, and even the medical profession itself could be in favor of habits that decades of science had already overwhelmingly condemned as harmful.

For more on the influence industry can have on food policy, see:

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:

Does Smoking Really Protect Against Parkinson’s Disease?

The Centers for Disease Control and Prevention recently celebrated the 50-year anniversary of the landmark 1964 Surgeon General’s report on smoking, considered one of the great public health achievements of our time and the first of 30 other such reports from the Surgeon General on smoking. Internal tobacco industry memos, which you can see in my Is Something in Tobacco Protective Against Parkinson’s Disease? video, document their response. Major criticisms of the report include a “[c]avalier treatment of costs of smoking”: The Surgeon General argued that smoking costs the United States billions, but the tobacco industry noted that “smoking saves the country money by increasing the number of people dying soon after retirement,” so we don’t have to pay for Social Security, Medicare, and the like. In fact, the industry argued, if we were truly patriotic, maybe we should encourage smoking to help balance the budget!

The tobacco industry also criticized the Surgeon General for a “[l]ack of balance regarding benefits of smoking,” asserting that “[o]ne has to search pretty hard to find any concession anywhere in the Report that smoking is not all bad.” This is something the tobacco industry liked to bring up when testifying before Congress, saying that health benefits include “the feeling of well-being, satisfaction, and happiness and everything else.” But beyond just all the happiness the Surgeon General was trying to extinguish, he failed to even mention that smokers appear protected against Parkinson’s disease.

“Quite unexpectedly…[m]ore than 50 studies over the last half century consistently demonstrated reduced prevalence of Parkinson’s disease among smokers compared with never-smokers.” Now there are more than five dozen studies.

But smokers are probably dying before they even have a chance to get Parkinson’s, so is that the explanation? No, that didn’t seem to be it. Researchers found a protective effect at all ages. Maybe it’s because smokers tend to be coffee drinkers, and we know coffee consumption alone appears protective. But, no. The protective effect of smoking remained even after carefully controlling for coffee intake. Well, maybe we inherit some propensity to not smoke and to get Parkinson’s. If only we could clone someone to have the same DNA. We can! They’re called identical twins. And still, the relationship remained, suggesting “a true biologic protective effect of cigarette smoking.”

Not so fast. Maybe finding unusually low rates of Parkinson’s among smokers is an example of reverse causation. That is, maybe smoking doesn’t protect against Parkinson’s—maybe Parkinson’s protects against smoking. Could there be something about a Parkinson’s brain that makes it easier to quit? Or perhaps failure to develop a smoking habit in the first place is an early manifestation of the disease.

To put that to the test, researchers studied children exposed to their parents’ smoke. If they grew up to have less Parkinson’s, that would confirm the protective link—and indeed they did. So, smoking really does seem to be protective against Parkinson’s disease, but who cares? How does that help us? “More than 20 million Americans have died as a result of smoking since the first Surgeon General’s report…” Even if we didn’t care about dying from lung cancer and emphysema, even if we only cared about our brain, we still wouldn’t smoke because smoking is a significant risk factor for having a stroke, as well.


Is there a way we could get the benefits of smoking without the risks through our diet? I discuss this in my Peppers and Parkinson’s: The Benefits of Smoking Without the Risks? video.

Other Parkinson’s videos include Preventing Parkinson’s Disease with Diet and Treating Parkinson’s Disease with Diet.

Diet may play a role in other movement disorders. For example:

Surprised about the potential benefits of coffee? See:

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: