Picking up where we left off with this rather exciting story about Vitamin D…
The human genome project mapped 30,000 genes in our DNA. Of these 30,000 genes, vitamin D directly effects over 2000. Dr. Isaac Gardner calls vitamin D “an extremely novel and important prohormone.” He goes on to describe some of the different areas where vitamin D is used in the body:
There are receptors for vitamin D in pancreatic islet cells involved in insulin secretion. In fact low vitamin D levels are associated with type I and type II diabetes mellitus. Vitamin D is important in cellular immunity and prevention of the autoimmune diseases. It is actively involved in brain metabolism with links to depression. Fibromyalgia is a musculoskeletal syndrome characterized by muscle pain and fatigue of unknown origin. It has been found that a majority of patients presenting with symptoms of fibromyalgia are deficient in vitamin D. Treatment with vitamin D3 is successful in relieving the symptoms of fibromyalgia in these cases.[i]
(For those of you keeping track at home, we’re now up to cancer, diabetes, autoimmune diseases, depression and fibromyalgia on the list of common, or even epidemic health issues which are significantly improved simply by adding vitamin D to the mix.) Receptors that respond to vitamin D have been found in almost every type of human cell, from your brain to your bones. So, it is only common sense to surmise that vitamin D deficiency might have numerous ill effects on the body. But what exactly does it mean to be ‘deficient’ in vitamin D?
When you look at the studies showing dramatic changes in cancer rates you find that the daily supplementation levels are consistently at 1000 IU or higher, with recommended serum levels in the 40-60ng/mL range.[ii] This is where official recommendations regarding vitamin D and the last several decades of research part course because both intake and serum concentrations levels in these studies are several times higher than the current USRDA.
The National Institutes of Health latest recommendations[iii] (dated June 2011) regarding serum levels for vitamin D, describe a level of ≥20ng/mL as “Generally considered adequate for bone and overall health in healthy individuals.” “Generally considered adequate” is not a description ringing with certainty, and, this recommendation actually represents a recent upward change. For many years recommended levels had been 15-20ng/mL. This is the serum concentration below which vitamin D deficiency causes rickets in infants and children. In other words there are serious, and obvious, negative health consequences below this level. What is becoming clear however is that even these guarded upward revisions in recommended serum levels of vitamin D leave room for a range of health consequences which, while not as immediately apparent, are nonetheless serious and much more commonplace than previously understood.
The NIH data sheet lists RDAs for vitamin D between 400 IU (for 0-12 months of age) up to 800 IU (for those over 70). These recommendations explicitly assume minimum sun exposure, meaning that almost all of your vitamin D would be coming from supplementation, not sunlight. Contrast this with most vitamin D supplements off the shelf and you will see the disparity between current USRDA levels and recent research and experience. Most vitamin D supplements recommend dosages above 1000 IU per day. The one I take comes in 5000 IU tablets (about the size of children’s aspirin) and lists this as being 12,500% of the “US Daily Value”. If you are sick many doctors will recommend increasing vitamin D intake to 20,000-30,000 IU daily.
So when you ask the question, “Am I deficient in vitamin D?” or if you are a researcher trying to determine just how many people are “deficient” the answer would be quite different depending on whose standards you chose to use. Having said that, let’s look at our options for getting whatever amount of vitamin D we want.
Most of us aware that vitamin D3 is produced from exposure to sunlight and it is definitely possible to get all you need from the sun, but not for all of us and not all the time. Dietary vitamin D on the other hand is usually insufficient to significantly reduce the risk of most cancers since typical ingested amounts, up to 200 to 400 IU per day, are too low [Grant and Garland, in press]. Evidently, at least 600 to 1000 I.U per day are required to reduce the risk of vitamin-D-sensitive cancers.
As with many things, the ‘D’ is in the details as it were. The first important piece of information to know is that only UVB radiation produces D3. UVA radiation on the other hand reduces D3 levels. Which means that if you are sitting indoors on the other side of a pane of glass in the sun, you are actually causing yourself to lose D3 because the UVB radiation is absorbed by the glass while the UVA is not. This also means that if you are using sunscreen that only blocks UVB , you are quite literally increasing your chances of developing skin cancer compared to what would be the case if you left the sunscreen off altogether (assuming you don’t give yourself a bad burn).
Secondly, if you live in higher latitudes, say Boston or above, the sun does not get high enough in the sky for over four months of the year for you to receive UVB radiation at all because it is completely absorbed by the atmosphere. This is why it’s better, at any latitude, to get your sun exposure in the middle of the day when the sun is at its highest point in the sky in order to maximize the UVB/UVA exposure ratio. Yes, you read that right, it’s better to be out in the sun in the middle of the day when the sunlight is at its most intense. Who knew?
Now don’t get carried away and think I’m telling you to go out and get sunburned. In mid-latitudes at mid-day in the summer you need about 15-30 minutes with at least your hands and face exposed. This will produce about 20,000 units of vitamin D. Longer exposures will not produce any additional vitamin D and can potentially lead to premature skin aging and increase your risk of skin cancers. At higher latitudes, or in other seasons you will need a little more time, up to 30 to 40 minutes. The last rather important, and only recently understood factor in your Vitamin D absorption is that it takes up to 48 hours for the D3 that is made on the skin to get absorbed into the body. If you wash with soap, the D3 will be washed off with it. You can rinse with water, but you cannot use soap without losing the D3 off your skin.
So while sun exposure can be sufficient, most of us don’t get that much of our body in the sun on a daily basis, and in the winter months simply can’t get enough vitamin D from being outside. So you have two choices: supplements; or safe, UVB-only, tanning beds. Dr. Mercola recommends the use of safe tanning beds (ones that have shielding for non-UVB radiation) as a healthy way (I know…who knew…) of getting your body to naturally produce vitamin D.
So to wrap up, let’s check with Dr. Greg Plotnikoff, Medical Director of the Penny George Institute for Health and Healing, Abbott Northwestern Hospital in Minneapolis, who says:
“Because vitamin D is so cheap and so clearly reduces all-cause mortality, I can say this with great certainty: Vitamin D represents the single most cost-effective medical intervention in the United States.”[iv]
Sounds good to me.
References
Vitamin D Resource Page by Dr. Mercola http://www.mercola.com/article/vitamin-d-resources.htm
[ii] http://www.ncbi.nlm.nih.gov/pubmed/17556697 “Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial.” Am J Clin Nutr. 2007 Jun;85(6):1586-91.
[iii] http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/