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 Health Effects of Heavy Metal Music

As I discussed in my video Music as Medicine, the stress-reducing effects of music appear to extend throughout the clinical spectrum—even to the critically ill, intubated in an intensive care unit. Those listening to Mozart through headphones cut stress hormones like adrenaline in half compared to those with headphones playing nothing, which resulted in a lower mean arterial blood pressure. But are all types of music just as relaxing? That’s the subject of my Music for Anxiety: Mozart vs. Metal video.

Researchers compared the effects of Mozart, Pearl Jam, and Enya on normal, healthy subjects. After listening to Mozart for 15 minutes, people reported a significant reduction in tension. With new age music, they also felt a reduction in tension, as well as greater relaxation and less hostility, but they reported significant reductions in mental clarity and vigor. After listening to grunge rock, people said they felt more hostile, tired, sad, and tense, with reductions in caring, relaxation, clarity, and vigor. But these were subjective measures—asking people how they felt. What about objective measures?

After 30 minutes of classical music, the stress hormone cortisol significantly dropped in the research subjects. But if instead of listening to Beethoven’s Symphony no. 6, Opera 68, they listened to techno—Cyber Trip, Techno Shock, or Techno Magnetiko—their stress hormone levels went up. Endorphin levels also went up, which may make you think, “Oh that’s nice,” until you realize that endorphins are our body’s natural painkillers—they go up after a variety of aversive stimuli, like getting burned or prodded.

These results may just be a function of the music’s tempo. The research shows that people get the same bump in breathing and blood pressure from listening to fast classical music like Vivaldi’s Presto, which was found to be as stimulating, or even more so, than the Red Hot Chili Peppers.

What about heavy metal music? Researchers randomly assigned participants to self-selected music, classical, heavy metal, or silence. “Listening to self-selected and classical music produced increased feelings of relaxation as well as sitting in silence, but not for the heavy metal condition.” Compared to relaxing and pleasant Renaissance music, exposure to arousing and “unpleasant” heavy metal causes a heightened amylase response in men. Amylase is an enzyme in our saliva that digests starch. When we go into fight or flight mode, we start immediately churning out the enzyme to provide sugars for quick energy. So, you get a spike in amylase when you go skydiving, if you’re dunked into cold water, or… if you make a guy listen to heavy metal for ten minutes. With all that extra enzyme, if he’s eating bread while banging his head, he can end up digesting it better!

Metal is more likely to cause the medical community indigestion, though. Although the American Medical Association’s Group on Science and Technology admits there’s “no evidence that this music has any deleterious effect on the behavior of adolescents,” that doesn’t stop them from suggesting there’s anecdotal evidence that those who identify with such bands as “Slayer” and “Metallica” may be at risk for drug abuse or even “participation in satanic activities.” In response, one doctor wrote to the medical journal to reply: “for every teenager who commits suicide or some crime under the influence of heavy metal music, there are dozens of white-collar criminals engaged in such activities as insider trading, savings and loan fraud, [and] government corruption….”

Maybe we should instead be blaming Bach or Barry Manilow.


What about smells instead of sounds? See Orange Aromatherapy for Anxiety, Lavender for Generalized Anxiety Disorder, and Wake Up and Smell the Saffron.

Don’t forget about dietary interventions for pain and emotions. Check out:

You can also learn about another dimension of mental health in my video Plant-Based Diets for Improved Mood and Productivity.

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: