It’s estimated that nearly one billion people around the world are deficient in vitamin D and need to be supplemented. We’ve discussed the important functions that vitamin D performs in earlier posts (see post of May 4, 2008) but let’s summate the highlights of its function.
Benefits of Vitamin D:
1. It strengthens your immune system, reducing your risk of cancer as well as colds and flu.
2. It affects the development and maintenance of bone health. In people who are vitamin D deficient, you will see a wide variety of bone disorders, such as osteoporosis, osteopenia and osteomalacia - the inability to mineralize bone, causing pain and weakness.
3. It has been shown to improve hypertension and drastically reduce the risk of heart disease.
4. It can help with diabetes, psoriasis and there are even some studies that link Alzheimer's disease, depression and multiple sclerosis to low vitamin D levels.
5. Deficiency is associated with musculoskeletal pain and fibromyalgia.
6. It is commonly malabsorbed in patients with celiac disease and gluten intolerance. Note: vitamin D deficiency subsequent to celiac disease and intestinal damage has been discussed previously and is not the focus of this post.
All too often patients are supplemented with vitamin D only to find in subsequent testing that they are still deficient. Knowing the importance of normalizing these levels for optimal health, the patient is left frustrated as they have followed their clinician’s instructions accurately.
What is the reason? There appear to be two major reasons vitamin D supplementation does not work adequately. The good news is that there IS a solution.
1. It has been a protocol for some time to use vitamin D2 as a supplement when D levels are found to be very low. Prescribing 50,000 IU for several weeks to a patient very deficient in vitamin D has been a standard accepted protocol.
Research reveals flaws in this protocol. The vitamin D2 potency is less than one third that of vitamin D3. Vitamin D2 has a shorter half-life in the blood and a lower affinity for the vitamin D binding protein. What this means is that according to a recent study in the French Internal Medicine Review, “vitamin D2 should not be regarded anymore as suitable for supplementation or fortification.”
So if you’ve been supplementing with vitamin D2 switch to D3 and recheck your levels in a few months. You should also feel much better with this preferred form.
2. Very recent research brings another very important issue to light. Retinol, a form of vitamin A, competes with vitamin D (even the preferred vitamin D3) and prevents its absorption. When you supplement vitamin A you can do it in two forms. Beta carotene, or pre-vitamin A derived from vegetables (or a supplement) which, in your intestines, is converted into the correct amount of retinol needed by your body. Your body will not convert beta carotene into excessive levels of vitamin A. Retinol, the other means of supplementing vitamin A, when given directly as a supplement, bypasses the natural controls of the body as seen above when beta carotene is the source. One could, therefore, get too much vitamin A in the form of retinol.
In an ideal world, all the vitamin A you require would come from vegetables you ate and all the vitamin D you need would come from sunlight. Unfortunately, we don’t live in such a place and many of us are deficient. And as discussed previously, we are not a culture that excels in consuming adequate quantities of vegetables.
Cancer, heart disease and diabetes are leading killers of Americans. As an example, a study by Dr. William Grant, Ph.D., a research scientist, found that about 30 percent of cancer deaths could be prevented each year with higher levels of vitamin D. That’s truly fantastic!
Since proper vitamin D status is known to lessen the incidence of these diseases, it is critical that you maintain an optimal status.
But what if another supplement interfered?
In the recent British Medical Journal 2010; 340:b5500, an article entitled:
“Association between pre-diagnostic circulating vitamin D concentration and risk of colorectal cancer in European populations: a nested case-control study” was published. In this article the researchers confirmed that low vitamin D levels are a risk for colon cancer and those with the highest levels are half as likely to develop the disease as compared to those with the lowest levels.
However, what they almost missed was that vitamin D levels are almost entirely negated in those with the highest vitamin A intake. Ingesting vitamin A, in the form of retinol could negate the effect of supplementing with vitamin D, even with levels as low as 3,000 IU/day. That is not a high dose.
Many people are completely losing the benefits they could receive from adequate vitamin D due to taking vitamin A (retinol), either in the form of multi-vitamins or cod liver oil.
Many people take cod liver oil based on the fact that it DOES contain vitamin D, A and omega-3 fatty acids. Now it appears that it should be avoided. Vitamin A and D do work together but the form of vitamin A (beta carotene vs retinol) and the ratio between the two must be balanced. On the other side of the coin consider this: being deficient in vitamin A precludes the proper function of vitamin D.
Like most things in nutrition (and life), neither too much nor too little is beneficial.
While it’s unclear what the exact correct ratio is, we do know this: vitamin A should be ingested in the beta carotene form, not retinol. Based on this research it seems unlikely that the amount of beta carotene gotten in a multiple vitamin would create any imbalance to vitamin D absorption.
Help me spread the word about this. In our clinic we see an abundance of patients deficient in vitamin D. Optimizing those levels create wonderful health benefits.
Please let me know if I can be of any assistance.
To your good health,
Dr Vikki Petersen
Founder of HealthNOW Medical Center
Co-author of “The Gluten Effect”