It turns out that Vitamin D is much, much more than just the bone nutrient. Researchers seem to agree that it helps prevent several cancers, heart disease, autoimmune conditions (e.g. multiple sclerosis), influenza, complications of the flu and in fact, death from all causes.1 (Hmm, what is helpful for prevention is often helpful in treatment.) It seems likely that in children, deficiency of Vitamin D may well be “THE [emphasis was in the original quote] leading cause of cancer, type 1 diabetes, asthma, allergies, atopy [e.g. eczema], and possibly epidemic autism*.2” The elderly should note that Vitamin D increases muscle strength and brain function while reducing chronic pain. One of my classmates was surprised when horribly painful breast lumps she’d had for decades resolved after she got her Vitamin D levels into a healthier range.
That’s an example of a benefit not yet specifically researched. (I did find one intervention study of almost 49,000 post-menopausal women. Researchers found that “a modest reduction in fat intake and increase in fruit, vegetable, and grain intake do NOT [emphasis mine] alter the risk of benign proliferative breast disease. The one variable that did seem to matter was Vitamin D intake.)3 . We shouldn’t be surprised at varied fringe benefits because most cells in the body have a receptor for Vitamin D and it appears to control 1,000 or more of our genes.4

THE NEWS: Given all that good news, I was extremely annoyed at recent media scare tactics. They were trying to tell us that people are taking too much vitamin D. The implication was to stop supplements and just get it from sun exposure. (Of course, the media also says to cover up with sunscreen to avoid skin cancer.)

MY 2 CENTS: Don’t these guys have access to the internet so they can read that medical journals worldwide show we’re not getting enough Vitamin D? Pregnant women and their breastfed babies are deficient.**,5,6 More than a third (36%) of healthy young adults are low.7 According to a German study of roughly 1,200 adults, 80% didn’t have blood levels supportive of bone health.8 A Stanford study says elderly folks aren’t getting enough and are therefore frailer.9 Perhaps as much as 80% of those with chronic illness are deficient. (Do you think there might be a connection?) Even people living in sunny US states have low blood levels. Furthermore, the timid 400 IU/day government intake guideline (or even its 2,000 upper limit) has not been enough to fix the problem.

About the only way currently to know if we are getting enough D is to test blood levels. Dr. Joseph Pizzorno, Editor in Chief of IMCJ (Integrative Medicine; A Clinician’s Journal) wrote 2 great articles reviewing of a number of studies and reported results of a corporate wellness program in which he participated. I’ve put his conclusions into the following chart.
Vitamin D test result reference ranges

SUPPLEMENT DOSES (proposed by Dr. Pizzorno unless otherwise indicated):10
Note: These are dependent on the amount of sun exposure, skin color and other factors. Therefore, it is recommended to have your blood levels tested and confirm the appropriate dose to reach the optimum range.
* Kids - The government says 200 IU. Many recommend 400 IU, but Dr. Pizzorno points to a study showing that, after 2 years on that dose, most children were still not into an optimum range. A Japanese study had good results with flu prevention and asthma at 1,200 IU per day.11 Some kids may need more especially if the only light on their skin is from the glow of the video game display. Again test, test, test and watch out for the liquid drops because it’s easy to measure incorrectly.
* Adolescents - A daily maintenance dose of 2,000 IU seems prudent.12
* Adults - 5,000 IU daily seems safe and may be a good level for the average adult who doesn’t spend time a lot of time in the sun. [My thought: If you are skittish, 4,000 IU is another common option for the winter at least.)
* Upper limits of daily dose - A routine dose of 10,000 IU/day seems to cause no harm13 (During the summer in the midday sun in a bathing suit, you’d make 10,000 in a few minutes.)
* Playing catch up - If a person’s blood levels are very low and especially if they live in a northern climate, they may need a “loading dose” of up to 20,000 IU per day for 3-6 months.

Toxicity is rare—it’s likely we were intended to spend some time daily in the sun without being coated in sunscreen. Of course, you can overdo anything. The issue is more what you do consistently than individual doses. French researchers gave adolescents single doses of 200,000 IU’s with no side effects observed.14 One reason for the relative safety is that over-the-counter Vitamin D supplements are in a storage form (Cholecalciferol). The body converts that form into the active form (Calcitriol) only as needed unless there is a massive overload of the storage form or some disease process. As always in nutrition, balance is very important. Vitamin A and Vitamin K compete with D and among their benefits help protect from overloading with D.15 (I think I’ll go into Vitamin K next week since many people don’t know there is such a thing.)

Patients have become toxic from being prescribed overly aggressive treatments of the active form. Accidental overdoses of the supplement form have been also been reported but mostly from milk fortification errors and mislabeled supplements (choose brands carefully). Overdoses can result in too much calcium in the blood and in excess that causes mischief. Sarcoidosis patients don’t tolerate vitamin D supplements well.

I’m quite encouraged that so many doctors now test their patients’ vitamin D levels. However, many are still afraid of theoretical toxicity and don’t give doses adequate to bring the blood levels into a healthy range where the patient is better protected. It’s your health and they work for you, so push a little.