Vitamin D has rightfully assumed its place as the hot vitamin topic of the times. There is a lot of controversy about Vitamin D, its role in promoting health, and just how much intake is optimal, and should people be taking supplements. I’ll attempt to clarify some of the controversy as well as inject a personal bias with respect to dosing. It is fair to say that this is an evolving story and at present the questions far outnumber the answers. It’s also a story I suggest you follow closely.
Vitamin D, first of all, is really not a vitamin. It behaves more like a hormone in its diverse biologic effects throughout the body. Most cells in the human body have receptors for vitamin D on their surfaces. Vitamin D also seems to impact as much as 3% of our genome. In other words, several hundred genes in your genetic Book of Life, are regulated in some fashion by vitamin D. Vitamin D, it would appear, is a heavy hitter, worthy of attention.
So an important health question to consider is whether you are getting enough. Epidemiologic studies would suggest as many as 50-75% Americans (and probably as many as 75% in Albany area) may be deficient in vitamin D. Historically laboratory norms covered a wide range and many, many people in the low end of normal may biologically need more to function optimally e.g. due to less sun exposure, increased oxidative stress of the American diet, little activity, environmental toxins, sleep deprivation, increased inflammatory burden, etc.). Is it possible we unintentionally depriving ourselves of one of nature’s greatest gifts?
The overwhelming majority of vitamin D is manufactured in our skin by exposure to sunlight, specifically the UVB rays in sunlight. Of note, it is the same UVB rays that produce sunburn and increase one’s risk of skin cancer. Human beings, as it turns out, are vitamin D producing machines! Perhaps this says something about the value of vitamin D in human life as our design places great emphasis on its relationship with it. Under natural human conditions e.g. moving a lot outdoors, year-round it would be hard not to produce enough. During a sunny summer day at mid-afternoon, a person can make up to 20-25,000 units of vitamin D in 30 minutes! To put this in perspective, current recommendations (also known as RDA or recommended daily allowance) are in the range s of 600-800 units/day.
While the skin makes vitamin D, your liver and kidneys modify it to make it biologically active. Most of the “best evidence” i.e., the randomized-controlled studies have looked at vitamin D’s critical role in bone health and the prevention of osteoporosis. These studies have formed the basis of the recent recommendations of the Institute of Medicine’s (IOM) recommendations for 600-800 units/day.
What makes this story much more interesting is the growing data from what are called observational studies that low vitamin D levels seem to be associated with higher risks of most age-related chronic complex health diseases e.g. hypertension, cancer, diabtetes, Alzheimer’s, obesity, autoimmune diseases, heart disease, etc. Many autoimmune diseases e.g. Multiple Sclerosis are in fact more common at higher, more northern latitudes where one would expect much lower vitamin D production due to diminished sun exposure. Female RNs who have worked the night shift for many years have been found to be at greater risk of breast cancer. While these correlations are NOT cause and effect, they do raise very compelling questions as to how much vitamin D is optimal.
There is also a growing body of evidence that higher vitamin D levels reduce disease risk, improve muscle strength, and reduce fall-risk. The latter is a major public health concern. As people age, they progressively lose muscle mass, lose core strength, confront greater balance challenges, and are often one fall away from losing their independence or their lives!
So what is one to do with this seemingly contradictory information? It is important to note that RDA recommendations are based on levels below which, one sees disease e.g. Scurvy for vit C, rickets for vitamin D, Beri-Beri for Thiamine, a B vitamin. Are RDA recommendations adequate or the same as the amount of vitamin necessary to optimize health and function under rather hostile environmental conditions (e.g. poor diet, lack of movement, stress, etc, etc.)? This is a very different consideration than that lowest necessary intake needed to prevent disease.
The IOM’s report has created much debate in the medical community as many providers, myself included, feel more vitamin D may be necessary for many individuals whose underlying health and biology are associated with much higher disease risk-burden. I would recommend the following:
1. Continue to follow this story as this, in my humble objective opinion is a major public health issue.
2. Have your vitamin D levels checked (routine blood work). They will be at their lowest point over the mid-late winter months.
3. While a moving target, you want your (or should I say I want my) vitamin D levels at least 40+ (many labs have normal ranges from 20-100)
4. Get sensible sunlight exposure i.e., 15-20 minutes full arm and legs 3 days per week during peak season, remembering to use copious sun protection beyond that exposure. Moderation is clearly the rule here.
5. Most people require vitamin D supplementation in the Albany area and fortified foods will not get you where you need to be. Foods such as low fat dairy, fatty fish e.g. sardines, salmon, cod liver oil, are good sources. I usually recommend, based on blood levels, between 2,000 and 4,000 units per day. Vitamin D is inexpensive and non-prescription. Vitamin D3 (cholecalciferol) is the more active form. The products out there are usually D3. If a person has increased inflammation, insulin resistance, and increased cancer risk with low levels e.g. < 20, I might use higher doses or prescribe 50,000 units to take weekly, monitoring clinically and periodically with levels.
6. Cultivate more aerobic activity with some weight-resistance work to build critical lean body or muscle mass.
7. Toxicity from vitamin D is in fact very uncommon and would likely require doses of 10,000 units or more per day for many, many months.
For more information check out: http://www.vitamindhealth.org
Peace in health!