Three Things You Need to Know About Vitamin D
Vitamin D is an increasingly popular topic among medical professionals, patients and the media. I get asked about it all the time and I check Vitamin D levels on almost all of my patients. The available research and data on Vitamin D has grown exponentially over the past few years and it is becoming clear that this nutrient is more important that we ever could have imagined a few decades ago. That is why everyone needs to know why Vitamin D is important and how to get enough of it. The answers to the following three questions should demystify Vitamin D and illuminate the path to a healthier you.
1) What is Vitamin D and why do you need it?
Vitamins are a diverse group of organic compounds that are required nutrients for normal physiological function. Vitamins usually must be obtained through the diet. Vitamin D is unique in that regard, as the main natural source for humans is the sun. When human skin is exposed to ultraviolet (UV) rays from sunlight, a form of Vitamin D is created. In addition to sun exposure, a few foods, including fatty fish (particularly wild salmon), cod liver, egg yolks, and mushrooms, are natural sources of Vitamin D. Other foods that claim to have Vitamin D usually have been fortified with a synthetically derived form of the vitamin.
Low Vitamin D levels have been linked to a number of major health issues, such as:
• Osteomalacia – the softening of bones and loss of bone density
• Heart Disease
• High blood pressure
• Neurological problems
• Immune impairment
It is important to keep in mind that there are big differences in our understanding of the mechanisms and relative contribution of Vitamin D deficiency among these issues. For example, Vitamin D deficiency is clearly the cause of Rickets, a bone disease in children. But in the case of cancer, the link with Vitamin D deficiency is more of an observation that certain types of cancers occur more frequently in Vitamin D deficient persons for reasons that are still unclear.
2) How much Vitamin D do you need?
There are five forms of Vitamin D – D1, D2, D3, D4 and D5 – but the two types that are most important to human physiology are D2 and D3. Vitamin D3 naturally is generated in humans from exposure to the sun and is the source of Vitamin D found in seafood, whereas D2 is synthesized by some plants. Both are manufactured for supplemental use, though some studies suggest that D3 may be more effective than D2, and many experts (including those at our Center) only recommend D3 for supplementation.
In terms of amounts, Vitamin D is described using the international unit (IU). As a reference point, for every 30 minutes of full body sun exposure (without sun block), humans convert about 10,000 units of Vitamin D. The problem is that most of us do not get regular sun exposure, given the northern climate and the very real concern of skin cancer risk. And, most food sources are insufficient to help us maintain an ideal level. This leaves most of us with needing to supplement Vitamin D to enjoy the benefits of an optimal level. Government recommendations for daily allowances of a few hundred IUs are based on a disease model; i.e., how much Vitamin D is needed to prevent Rickets. However, all of the emerging data on the other health benefits suggests a much higher intake in the range of 1,000 IU per day or more. For general health purposes and in the absence of a blood level, we generally recommend supplementing 1,000 to 2,000 IU daily. We often supplement much more when there is a blood level showing deficiency or other clinical data. Remember that Vitamin D3 is the preferred form- most manufacturers clearly label the form on the bottle. Most pharmacies and health stores sell it, and the Jefferson walk-in pharmacy at 909 Walnut Street stocks the brands our Center recommends.
3) How to know when you are deficient in Vitamin D?
There is now an easy blood test for Vitamin D (Vitamin D 25 OH) that your doctor can order, and many insurance plans pay for it. Our patients are continually shocked by how low their levels are when we check them. I recently checked my own level, though I was convinced that my active outdoor lifestyle and use of a daily multi-vitamin would insure a good score. To my disappointment I was in the low normal range; I promptly went to the pharmacy and started the same Vitamin D supplement I recommend to my patients every day.
Blood levels are most often reported in nanograms per milliliter (ng/ml) and the normal reference range for the laboratory we use is 30-100. In our practice we aim for a level of about 50. Levels below 10 suggest sever deficiency, which we have seen more often than we would have imagined. Toxic levels are rarely seen and would require megadose supplementation.
Though it is clear that most of us should be taking some supplemental Vitamin D, some argue that we should still have some exposure to the sun itself. So, we sometimes additionally recommend getting some brief (e.g., 5-10 minutes) doses of sunlight during warmer months- but it is important to weigh the risk-benefit ratio with your doctor before doing so, particularly if you are at high risk for skin cancer.
Dr. Monti is the director of the Myrna Brind Center of Integrative Medicine at Thomas Jefferson University Hospital and the author of The Great Life Makeover. Read more about him here.