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  • Writer's pictureDoug Joachim

Re-Think Supplementing with Vitamin D

Updated: Jul 11, 2023

Vitamin D, the new ‘It Girl’ of the supplement industry, has been widely reported to do all sorts of miraculous things despite the lack of reliable scientific evidence. The number of blood tests for vitamin D levels among people 65 and older, increased 83-fold from 2000 to 2010, according to the Centers for Disease Control and Prevention. Labs performing these tests are reporting perfectly normal levels of vitamin D — 20 to 30 ng/mL of blood as “insufficient” (randomized trials had found no particular benefit for healthy people to have blood levels above 20 ng/mL). As a consequence, millions of healthy people, and virtually everyone I know, have been told by their physician they have a deficiency. Amazingly this is despite the lack of symptoms. Consequently, doctors are recommending exogenous vitamin D supplements to many of their patients under the belief it will be beneficial. Maybe just go outside in the sun for a few minutes a day or eat foods high in vitamin D. Below are some other tantalizing claims surrounding Vitamin D supplementation:

  1. Halts Growth of Breast Cancer

  2. Prevents Heart Disease

  3. Protects Against Strokes

  4. Save Your Life From Swine Flu

  5. Promotes Weight loss

  6. Slashes Risks of Cancer by 77%

  7. Strengthens your Bones (this is the only benefit backed by sufficient evidence)

  8. Lowers Risk of Diabetes and Parkinson’s

  9. Decreases Blood Pressure 

  10. Prevents Insomnia 

  11. ……….And much much more!

Do you believe it?  If you are like most Americans you’re probably caught up in the frenzy. Your doctor likely told you to take a vitamin D supplement after checking the levels in your blood and found them to be too low. A true vitamin D deficiency manifests in your bones causing rickets.  Have you ever met anyone with rickets? Thought so. Neither have I.  True D deficiency can also lead to hyperparathyroidism. There are numerous studies touting the benefits of vitamin D supplementation but very few are reliable. Because we get a healthy dose of natural D from the sun, milk, wild fish, mushrooms, eggs and some cereals, researchers would have to ensure their experimental group is not exposed to these things.  Complicating matters is the fact we all metabolize D at differing rates.  It becomes very difficult, if not impossible, to control these variables and compare research groups.  There are very few large, controlled, double-blind, randomized trials testing the true beneficial effects of Vitamin D in the human body. The majority of the research is observational/epidemiology, which draws correlations, not causations. People who have higher vitamin D levels also tend to be individuals who exercise outside, are health conscious, don’t smoke, have clean diets and are not obese. Healthier people do the sorts of things that raise D levels naturally and unhealthy people do things that lower their levels.  Those with heart conditions, cancer and obesity likely stay indoors and out of the sun more.  Low levels of D may indicate certain diseases are present but that doesn’t mean the deficiency is causing the condition. In other words, low vitamin D may be the consequence of poor health, not the cause.

A 2016 article published in the New England Journal of Medicine titled “Vitamin D Deficiency: Is There Really a Pandemic?” argued against most supplementation. In this piece, several of the leading epidemiologists and endocrinologists who were on the original IOM committee argue for a lowering of the currently accepted cutoff level of 20 ng/mL, stating that the level they estimated as acceptable was never intended to be used to define vitamin D deficiency. They feel that we are over-screening for vitamin D deficiency, and unnecessarily treating individuals who are perfectly fine. In fact, based on their analysis of a massive amount of data from NIH, a more appropriate cutoff for vitamin D deficiency would be much lower, 12.5 ng/mL.

Maybe just to be safe you’ll decide to take extra vitamin D.  Insurance vitamins; it can’t hurt, right? Not so fast.  The NYTimes reported in 2013:

“Nutrition experts argue that people need only the recommended daily allowance — the amount of vitamins found in a routine diet. Vitamin manufacturers argue that a regular diet doesn’t contain enough vitamins, and that more is better. Most people assume that, at the very least, excess vitamins can’t do any harm. It turns out, however, that scientists have known for years that large quantities of supplemental vitamins can be quite harmful indeed”

Furthermore, a New York Times article is April 2017 stated:

“Millions of people are popping supplements in the belief that vitamin D can help turn back depression, fatigue, muscle weakness, even heart disease or cancer. In fact, there has never been widely accepted evidence that vitamin D is helpful in preventing or treating any of those conditions.”

A recent re-analysis of the Women’s Health Initiative, which was published along with the meta-analysis of the available literature, concluded that calcium supplements with or without vitamin D increased the risk of cardiovascular events, particularly myocardial infarction. The United States and Canadian governments asked the Institute of Medicine to assess the current data on health outcomes associated with calcium and vitamin D supplementation because of all the conflicting messages about their benefits.  Here is what they had to say:

“…the evidence supports a role for vitamin D and calcium in bone health but not in other health conditions. Further, emerging evidence indicates that too much of these nutrients may be harmful, challenging the concept that “more is better.”

An interesting new theory has emerged positing we are getting something more from the sun (that we have not measured) and vitamin D is just correlated with health benefits. Let's call it the vis vitae of the sun.

"The popularity of vitamin D supplements is easy to understand, because there are so many health conditions that seem to correlate with vitamin D levels, including cancer and heart disease. But study after study has found that taking vitamin D supplements doesn’t change your risk of developing these conditions. An alternative explanation is that vitamin D is simply an indicator of how much sun you’re getting, and the health effects come from something else in sunlight." - Alex Hutchinson

Maybe a good practice should be to get 10 min of unprotected sun per day while ensuring you do not burn. For most people, this will be adequate and provide higher quality benefits than a pill.

Our bodies are a network of highly complex systems not yet fully understood by science. These systems crave homeostasis.  This means our bodies have built-in mechanisms whose jobs are to preserve a stable, constant environment. Throwing ‘extra’ vitamins into the body may cause an imbalance and block your body’s natural ability to regulate itself. By supplementing with D your body will turn down its natural vitamin D production by reducing the number of the receptors and instead develop a dependence on exogenous sources.  Dr. David Agus, professor of medicine at University of Southern California and author of “The End of Illness” states:

“When your cells are deluged with vitamin D…they will pull back on their sensitivity to vitamin D by reducing their number of receptors for vitamin D. But if there’s a perceived shortfall of vitamin D in the bloodstream, your cells will up-regulate— create more receptors for vitamin D— to become more sensitive to every vitamin D molecule that passes by. What happens, then, when we consume lots of vitamin D from unnatural sources such as supplements? (I use the term unnatural to imply that it’s not coming from the sun, which is a source of vitamin D that has built-in regulatory mechanisms.) No doubt our bodies are adept at adjusting using their feedback loops as I just described, and the constant surplus of vitamin D means our cells are constantly down-regulating. If we took the supplemental vitamin D away, our cells would up-regulate to make up the difference. Vitamin D has multiple downstream signaling molecules, for the vitamin D receptor signals several reactions.”

Disrupting a system we don’t fully understand may not be in your best interest.  There is widespread disagreement about how much D we actually need and which test is the most accurate in determining proper D levels. The medical community does know that vitamin D bone fractures are not on the rise and rickets is still a disease of the past.  So does supplementation help or hurt?  It is hard to say but most people will be just fine without it.  Here are some (evidence backed) exceptions. These groups would likely benefit from a D supplement:

  1. People who don’t get out in the sun (vampires and such) and/or general agoraphobics

  2. Pregnant or breastfeeding mothers

  3. Postmenopausal women and those who have weak bones

  4. People with multiple sclerosis

Exercise caution when supplementing. Not only is the industry uncontrolled it is fraught with deception. Please keep in mind that direct supplementation with man-made vitamins may actually shut down or impair your body’s ability to mount its own natural defense against oxidative stress and inflammation.  Clearly, vitamins are an integral part of one’s health, ideally consumed in their natural states (in food or sunlight). Eat whole foods, get adequate amounts of sleep, try some meditation and exercise on a regular basis. These will do much more for your overall health and well-being than a pill could ever do.  

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