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 Amount of Vitamin D Supplementation I Recommend

Randomized, controlled clinical trials have found that vitamin D supplements extend one’s lifespan. What is the optimal dose? What blood level is associated with living longest? In my nine-part video series on vitamin D from 2011, I noted that the relationship between vitamin D levels and mortality appeared to be a U-shaped curve, meaning low levels of vitamin D were associated with increased mortality, but so were levels that were too high, with the apparent sweet spot around 75 or 80 nmol/L based on individual studies. (See Vitamin D and Mortality May Be a U-Shaped Curve for more on this.)

Why might higher vitamin D levels be associated with higher risk? Well, the study I profile in my video How Much Vitamin D Should You Take? was a population study, so we can’t be sure which came first. Maybe the higher vitamin D higher risk, or perhaps higher risk led to higher vitamin D levels, meaning maybe those who weren’t doing as well were prescribed vitamin D. Maybe it’s because it was a Scandinavian study, where individuals tend to take a lot of cod liver oil as a vitamin D supplement, one spoonful of which could exceed the tolerable upper daily limit of intake for vitamin A, which could have negative consequences.

Anyway, the U-shaped curve is old data. An updated meta-analysis has shown that as population vitamin D levels go up, mortality appears to go down and stay down, which is good because then we don’t have to test to see if we’re hitting just the right level. Routine testing of vitamin D levels is not recommended. Why? Well, it costs money, and, in most people, levels come right up to where you want them with sufficient sun or supplementation, so what’s the point? As well, the test is not very good: Results can be all over the place. What happens when you send a single sample to a thousand different laboratories around the world? You’d perhaps expect a little variation, but results from the same sample ranged anywhere from less than 20 to over 100 nmol/L. Depending on what laboratory your doctor sent your blood sample to, the results could vary dramatically, so one could argue the test isn’t necessarily very helpful.

So, what’s a safe dose that will likely get us to the purported optimal level? A thousand units a day should get most people up to the target 75 nmol/L (which is 30 ng/mL), but by most people, researchers mean 50 percent of people. To get around 85 percent of the U.S. population up to 75 nmol/L would require 2,000 IU a day. Two thousand IU a day would shift the curve so that the average person would fall into the desired range without fear of toxicity. We can take too much vitamin D, however, but problems don’t tend to be seen until blood levels get up around 250 nmol/L, which would take consistent daily doses in excess of 10,000 IU.

Note that if you’re overweight, you may want to take 3,000 IU and even more than that if you’re obese. If you’re over age 70 and not getting enough sun, it may take 3,500 IU to get that same 85 percent chance of bumping up your levels above the target. Again, there’s no need for the average person to test and retest, since a few thousand IU per day should bring up almost everyone without risking toxicity.

Given this, why then did the Institute of Medicine set the Recommended Daily Allowance at 600 to 800 IU? In fact, official recommendations are all over the map, ranging from just 200 IU a day all the way up to 10,000 IU a day. I’ll try to cut through the confusion in my next post.


After all that work plowing through the new science, the same 2,000 IU per day recommendation I made in 2011 remains (for those not getting enough sun): http://nutritionfacts.org/2011/09/12/dr-gregers-2011-optimum-nutrition-recommendations/.

The other videos in this series include:

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

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 Treat Lupus with Turmeric

Different autoimmune diseases tend to target different organs. If our immune system attacks the insulin-producing cells in our pancreas, we can end up with type 1 diabetes. If it attacks our thyroid gland, we can end up with hypothyroidism. But, in the autoimmune disease lupus, our immune system attacks the very nucleus of our cells, often producing antibodies and attacking our DNA itself. So, lupus can damage any organ system and result in almost any complication. Women are nine times as likely to get it, and the peak age of diagnosis is too often at the peak of life. Hundreds of thousands, or even millions, of Americans suffer from this dreaded disease. One of the most common organ-threatening manifestations is kidney inflammation, occurring in as many as half of the patients.

Kidney inflammation is also one of the most serious effects of lupus, caused by the disease itself “or as a result of intense immunosuppressive drug toxicity.” Chemotherapy drugs like Cytoxan (cyclophosphamide), for example, can have severe, life-threatening side effects that may include leukemia and bladder cancer, and many women lose their hair and become permanently infertile. There is a desperate need for better treatment options.

As I show in my video Fighting Lupus with Turmeric: Good as Gold, oral supplementation of turmeric decreases proteinuria, hematuria, and systolic blood pressure—the cardinal clinical manifestations in patients suffering from relapsing or refractory (meaning, untreatable) lupus kidney inflammation––according to a randomized, double-blind, placebo-controlled study. The study looked at proteinuria, the spilling of protein into the urine, “an ominous prognostic sign.” In the control group, three people got better, three people got worse, and the rest pretty much stayed the same. In the turmeric group, one got worse, one stayed the same, but the rest all got better.

Note that the researchers used turmeric, the whole spice, and not curcumin, which is an extracted component often given in pill form. They took women with out-of-control lupus and had them take a quarter teaspoon of turmeric with each meal for three months. From my local supermarket, that would come out to be about a nickel a dose, compared with $35,000 a year for one of the latest lupus drugs. Which of the two treatments do you imagine doctors are more likely to be told about?


For more on the anti-inflammatory effects of turmeric, see:

What about its anti-cancer effects?

For practical considerations, see Boosting the Bioavailability of Curcumin and Who Shouldn’t Consume Curcumin or Turmeric?.

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: