Where Vitamin D Supplements Fail

As I discuss in my video Do Vitamin Supplements Help with Diabetes, Weight Loss, and Blood Pressure?, review articles continue to be published touting vitamin D as a veritable cure-all. The vitamin D receptor is found in most tissues in the body, including the brain, and upwards of 2,000 genes may be regulated by vitamin D. Within 24 hours of vitamin D exposure, we can change the expression of hundreds of genes.

The term vitamin is a misnomer, though, because vitamins by definition cannot be synthesized within our body, but we can make all the D we need with sufficient sun exposure. So, rather than a vitamin, D is actually a hormone that’s produced by our skin in response to sunlight exposure. D is not just a hormone of calcium regulation and bone health; it’s also a hormone of fertility, immunity, and brain function. But is it a panacea or a false prophet?

Remember when vitamin E was the vitamin du jour, touted as a “curative for many clinical disorders”? Supplement sales of vitamin E, the “radical protector,” created a billion-dollar business that capitalized on the public’s fears. After all, those with low levels of vitamin E in their blood had a 50 percent higher cancer risk. Similar attention was directed towards vitamin A or beta-carotene. People who eat lots of greens, sweet potatoes, and other beta-carotene-rich foods have lower risk of cancer, so maybe we should give people beta-carotene pills? When they were put to the test, however, beta-carotene pills actually increased cancer rates. In fact, beta-carotene, vitamin A, and vitamin E supplements all may increase mortality, so when we buy these supplements, we’re potentially paying to shorten our lifespans. As such, I imagine you can understand the skepticism in the medical community regarding claims about vitamin D, which is now enjoying its moment in the sun.

Having a half-billion-dollar vitamin D supplement industry doesn’t help matters in terms of getting at the truth. And there’s also a highly lucrative vitamin D testing industry that loves to talk about the studies suggesting that having higher vitamin D levels may reduce the risk of heart disease, cancer, diabetes, autoimmune diseases, and infections. Most of this research, however, stems from observational studies, meaning studies that correlate higher D levels in the blood with lower disease risk, but that doesn’t mean vitamin D is the cause. It’s like the early beta-carotene data: Higher levels in the blood may have just been a marker of healthy eating. Who has high beta-carotene levels? Those who eat lots of greens and sweet potatoes. Similarly, higher levels of vitamin D may just be a marker of healthy behaviors. Who has high vitamin D levels? Those who run around outside, and those who run around outside, run around outside. Indeed, higher vitamin D levels may just be a sign of higher physical activity.

So, for instance, when you see studies showing significantly lower diabetes rates among those with higher vitamin D levels, it doesn’t mean giving people vitamin D will necessarily help. You have to put it to the test.  And, when you do, vitamin D supplements fall flat on their face, showing no benefit for preventing or treating type 2 diabetes.

So, when supplement companies wave around studies suggesting vitamin D deficiency plays a role in obesity, because most population studies show that obese individuals have lower vitamin D levels in their blood, is that simply because they’re exercising less or because it’s a fat-soluble vitamin so it’s just lodged in all that fat? We might expect obese sunbathers to make more vitamin D, since they have more skin surface area, but the same exposure level for them leads to less than half the D bioavailability, because it gets socked away in the fat. This is why obese people may require a dose of vitamin D that’s two to three times higher than normal weight individuals, although they may get it back if they lose weight and release it back into their circulation. This would explain the population data. Indeed, when you put vitamin D to the test as a treatment for obesity, it doesn’t work at all.

It’s a similar story with artery health. Those with low vitamin D levels have worse coronary blood flow, more atherosclerosis, and worse artery function, but if you actually put it to the test in randomized controlled trials, the results are disappointing. Vitamin D is also ineffective in bringing down blood pressures.

This all adds to the growing body of science “casting doubt on the ability of vitamin D supplementation to influence health outcomes beyond falls, fractures, and possibly respiratory tract infection and all-cause mortality.” Wait. What? Vitamin D supplements may make you live longer? That’s kind of important, don’t you think? I talk about that in my video Will You Live Longer If You Take Vitamin D Supplements?.


Explore the other videos in my series on vitamin D, including:

And check out these other videos on vitamin D’s potential benefits:

For additional videos on supplements, 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:

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:

The Best Diet for Depression

Depression affects more than 150 million people worldwide, making it a leading cause of losing healthy years of life as a result of disability. By 2020, depression may be second only to heart disease as the leading cause of healthy years of life lost. Why is depression so common? Well it’s said, “Nothing in Biology makes sense except in the light of evolution.” Why would we evolve to get depressed?

Depression presents a baffling evolutionary puzzle. Despite its negative effects, it remains common and heritable, meaning a large part of the risk is passed through our genes. Presumably, there must be some kind of adaptive benefit or it would have been naturally selected against. Could depression be an evolutionary strategy to provide a defense against infection? Infection has been the leading cause of mortality throughout human history, making it a critical force in natural selection. Indeed, because of infections, our average life expectancy before the industrial period was only 25 years, and it was not uncommon for half of our children to die without reaching adulthood.

When we become infected, there is a surge of inflammation as our body mounts a counter-attack. Our body responds by feeling lousy, sick, weak, tired, and slow. We don’t want to socialize. The only thing we do want to do is sleep. These symptoms are similar to the ones we experience during depression and are great for fighting infection. Slowing down not only helps us conserve energy to put up a good fight; it also reduces social contact so we don’t infect others. We see this protective phenomenon in other social animals, like honeybees and mole rats, who feel compelled to crawl off and die alone to reduce the risk of infecting the rest of their community. Humans have even evolved to think poop and decaying flesh don’t smell particularly good to keep us safe from infection.

To explore the relationship between inflammation and mental health, we have to look back to 1887, when this connection was first noted by Dr. Julius Wagner-Jauregg, the only psychiatrist to ever win the Nobel Prize. What evidence have we accumulated in the past century that inflammation causes depression? We know that people who are depressed have raised inflammatory markers, such as C-reactive protein and that inflammatory illnesses are associated with greater rates of major depression. Indeed, we find depression in even more benign inflammatory conditions such as asthma and allergies. This is important as it suggests that the mood symptoms may be directly tied to the inflammation and are not simply the result of “feeling bad about having a terrible disease.”

We also know that you can induce depression by inducing inflammation. For example, when we give interferon for certain cancers or chronic infection, up to 50 percent of people go on to suffer major depression. Even just giving a vaccine can cause enough inflammation to trigger depressive symptoms. Taken together, these studies “are strongly suggestive of inflammation being a causative factor of mood symptoms.”

Can an anti-inflammatory diet help prevent depression? We didn’t know until researchers followed the diets of about 43,000 women without depression for approximately 12 years. Those who ate a more inflammatory diet, characterized by more soda, refined grains and meat, became depressed. “This finding suggests that chronic inflammation may underlie the association between diet and depression.”

Normally, we think of omega-3s as anti-inflammatory, but researchers found fish to be pro-inflammatory, associated with increased C-reactive protein levels. This is consistent with recent findings that omega-3s don’t seem to help with either depression or inflammation. As I discuss in my video Anti-Inflammatory Diet for Depression, the most anti-inflammatory diet is a plant-based diet, which is capable of cutting C-reactive protein levels by an impressive 30 percent within two weeks, perhaps because of the anti-inflammatory properties of the antioxidants found in plants. I talked about this in my Anti-Inflammatory Antioxidants video, but never explained why antioxidants are anti-inflammatory.

When free radicals cause oxidative damage, it may cause an autoimmune response in the body by changing the chemical structures of otherwise ubiquitous molecules to generate new structures that the body attacks as foreign. For example, when LDL cholesterol gets oxidized, our body creates antibodies against it that attack it. Likewise, clinical depression can be accompanied by increased oxidative stress and the autoimmune inflammatory responses it creates. Free radicals may thus lead to autoimmune inflammation.

Where else does inflammation in our diet come from? Endotoxins. It’s worth reviewing my videos on the subject—The Leaky Gut Theory of Why Animal Products Cause Inflammation, Dead Meat Bacteria Endotoxemia, and The Exogenous Endotoxin Theory—to see how the endotoxins in animal products can cause a burst of inflammation within hours of consumption. What does this burst do to our mood? Within a few hours of injecting endotoxin, inflammation shoots up, increasing feelings of depression and social disconnection.

Although previous research has demonstrated that inflammatory activity contributes to depressive symptoms, only recently did research show the effect of experimentally induced inflammation on anhedonia, the lack of reaction to pleasurable stimuli. In the study, subjects were injected with endotoxin. Within hours of the endotoxin hitting their bloodstreams, they began feeling depressed and had significant activity reductions in the reward center of the brain. The subjects, for example, were less excited about winning money playing video games. But as I discuss in my Plant-Based Diets for Improved Mood and Productivity and Antioxidants and Depression videos, we may be able to treat or even prevent depression by eliminating animal products and eating antioxidant-rich diets.


If you’re as much of a sucker for evolutionary biology theory as I am, you can learn more about it by checking out my High Blood Pressure May Be a Choice, The Problem with the Paleo Diet Argument and Why Do We Age? videos. 

I have several videos on inflammation, including: 

And in Biblical Daniel Fast Put to the Test, I discuss a study that shows a dramatic decrease in inflammation within weeks on a plant-based diet.

For more information on the effect diet can have on mental health, check out:

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: