One day, vitamin D seems like the cure for everything, and the next, we are inundated with warnings about dangers and lack of science. Confusion is rampant about the Dietary Reference Intakes (DRIs) for Calcium and Vitamin D recently released from the Institute of Medicine.
I have reviewed the report carefully and gathered input from international experts on vitamin D and the clinical team at my medical center — which includes four master’s degrees in nutrition, authors of textbooks on nutrition, and international leaders in nutrition education for physicians and dietitians. Collectively we have 100 years of reviewing nutrition research and applying it with thousands of patients. Here is what I think about the new vitamin D recommendations based on a synthesis of all this information.
New Vitamin D Recommendations: Are They Enough?
Although I agree with an increase in the DRIs for vitamin D, I feel the new DRIs are overly cautious, and I am disappointed that the panel failed to address a large volume of compelling research showing the benefits of optimal vitamin D intake in so many conditions. These go well beyond bone health and include cancer, depression, imbalances in the immune system, heart disease and many others.
An important distinction to keep in mind is that the DRIs are intended as general, population-based guidelines. They do not differentiate or take into account a person’s unique medical history, genetics, dietary intake, clinical symptomatology, environmental conditions (including exposure to sunlight), or biochemical and nutritional assessment.
My own practice-based clinical evidence from testing thousands of individuals with the goal of optimizing vitamin D status, correlated with other biomarkers, shows very positive effects on both skeletal and extra-skeletal conditions. At the UltraWellness Center we routinely check vitamin D levels, monitor clinical symptoms, evaluate our patient’s health status and tailor medical nutritional therapy accordingly.
Where the report falls short
Here are some of the highlights from the report and my own conclusions and responses based on my clinical experience with vitamin D:
1. The report recommended a 300 percent increase in vitamin D for most Americans and doubled the acceptable upper safe limit to 4,000 IU a day, which means they consider it completely safe to take 4,000 IU a day.
2. They appropriately conclude that most Americans are overdosing on calcium, which has been added to many foods. Countries with low calcium intake, a plant-based, low-acid diet, and plenty of sun exposure have very low rates of osteoporosis. I support the intake of adequate calcium from food, especially dark green leafy vegetables, tahini and nuts.
3. The Institute of Medicine’s conclusions and DRIs focus on the minimum amounts of nutrients needed to prevent deficiency diseases, not to create optimal health.
4. The report’s conclusions are based on proving the absence of something (like heart disease or cancer over decades), which is harder to prove than the presence of something. Spending decades of research looking for something not to happen is a tough game. Pharmaceutical agents are meant to alter pathology. Nutrients restore normal function, and they do so by optimizing normal biological functions, mostly by their action as coenzymes in thousands of biochemical reactions.
5. The conclusions are deliberately very conservative based on requirements for absolute proof, not implications from all the collective research. The IOM places the burden of proof on those who would suggest that higher levels are effective or safe. However, given the evolutionary human experience of sun exposure and the high doses of vitamin D we used to get from fatty fish — equivalent to up to 10,000 U a day — perhaps, the burden of proof should be on scientists to prove that lower intakes of vitamin D are, in fact, safe over long term. Nutrients are not drugs and cannot be studied or evaluated as drugs. They are multifunctional substances each responsible for hundreds of chemical reactions in the body necessary for life.
6. The conclusions are based on meeting the gold standard of research for evidence-based medicine — namely the randomized controlled trial. While useful for evaluating drug therapy, randomized control trials are extraordinarily expensive and difficult to perform for compounds such as nutrients that have their benefits over decades, not weeks.
7. Instead, conclusions should be based on the collective knowledge from paleobiology, basic science, gene expression data, and large population studies. In other words, synthesizing all the data, not simply judging the evidence based on a gold standard. This is simply not the appropriate lens for assessing complex nutritional data. Vitamin D, for example, regulates over 150 genes. Facts like these are not taken into account in the new DRIs.
8. The conclusion that the normal ranges for vitamin D blood levels have been inappropriately increased from 20 to 30 ng/dl is based on flawed reasoning. If everyone has a low level, that doesn’t make that low level normal — much less optimal. The report seems to suggest that since 80 percent of Americans are considered deficient in vitamin D we should adjust the “normal” range down so that all those people walking around who don’t appear to have health problems won’t be considered deficient. One could ask: Should we adjust the “normal weight” of Americans to include a BMI of over 25, since nearly three-fourths of our population is in that range? However, a better question may be: What are the evolutionary or ideal conditions for health?
9. Why are the 14 expert opinions of scientists who reviewed the report including Dr. Robert Heaney (one of the world experts on vitamin D who showed that 20 weeks of 10,000 IU a day of vitamin D3 had no adverse effects on healthy young men with normal vitamin D levels) and Dr. Walter Willett of Harvard, the most respected nutritionist in the world (who recommends 2,000 IU of vitamin D3 a day), kept secret? When is open scientific discourse a national security issue? Or does the IOM think we will be confused?
10. Why did the IOM leave Dr. Michael Holick, the discoverer of vitamin D3 (the active thyroid hormone), whose data show that blood levels up to 100 ng/dl are perfectly safe, off the panel despite the fact that his research and reviews have appeared in every major medical journal?
11. Here are some other compelling facts to consider:
- 70–80 percent of Americans are vitamin D deficient (this means 25 ng/dl or less for Caucasians and 16 ng/dl or less for African-Americans).
- Attaining optimal blood levels level of 45 ng/dl typically requires about 3,000-4,000 IU a day of vitamin D3 (6 times current recommendations).
- Achieving blood levels of 45 ng/dl (toxic is considered 250 ng/dl) would result in 400,000 fewer premature deaths per year including a reduction of cancer by 35 perecent, type 2 diabetes by 33 percent, and all causes of mortality by 7 percent.
- Studies show that vitamin D deficiency increases the risk of influenza 11-fold (1100 percent) and taking vitamin D reduces the risk by 42 percent.
- The economic burden due to vitamin D insufficiency in the United States is $40-$53 billion per year from cancer, heart disease, diabetes, influenza, autoimmune disease, depression, fibromyalgia, and other disorders.
What I recommend:
There is no question that in some cases, care is needed when taking vitamin D. For example, patients with autoimmune and inflammatory diseases must have their vitamin D status monitored carefully. But the bottom line is that taking supplemental vitamin D is safe and may be beneficial for a great majority of the population. Here is what I recommend in the face of the absence of evidence of harm and the plethora of evidence of potential benefit for taking supplemental vitamin D:
- The average child can conservatively and safely take 1,000 IU of vitamin D3 a day, and the average adults should take 2,000 IU a day. Some may need significantly more to raise and maintain vitamin D at adequate levels.
- For all of my adult patients who are taking > 4,000 IU /day, I monitor blood levels carefully over the long term. I recommend you do the same if you are taking large doses.
- Blood levels should be at least 30 ng/dl, and, for most, optimal levels are between 45 ng/dl to 60 ng/dl.
- I recommend you get most of your calcium from your diet. Don’t take more than 800 mg of calcium from supplements per day.
To learn more about vitamin D, see the article “The Sunshine Vitamin: A Closer Look at Vitamin D.”
To your good health,
Mark Hyman, MD