The May/June issue of Alternative Therapies featured an interview with Michael Hollick, Ph.D., M.D., about Vitamin D. The information he provides is particularly pertinent since he is one of the researchers who determined the mechanism for how Vitamin D is synthesized in the skin.
It also has some very interesting information regarding Vitamin D deficiency and overweight and obese people.
Dr, Hollick agrees with the common medical assessment that somewhere between 30 and 80% of the American population is Vitamin D-deficient. He also agrees with the research showing that people with lower Vitamin D levels are at higher risk of developing many conditions, including cancer. However, he does not recommend the use of supplements, fortified foods and oily fish to compensate for this deficiency. In fact, Dr. Hollick states that for every 100IU of Vitamin D you ingest orally, you raise blood levels of 25 hydroxyvitamin D by only 1 nannogram per milliliter.
Dr. Hollick instead recommends getting sun exposure as a way of increasing blood levels of vitamin D. Just 10-15 minutes in the sun is the equivalent of taking between 15,000 and 20,000 IU’s of Vitamin D, but without the potential for toxicity that is becoming more common as people take larger doses of it orally.
Dr. Hollick criticizes the use of sunscreen in order to avoid all sun exposure. A sunscreen with SPF of 8 reduces the ability of the skin to make Vitamin D by 92.5%. Sunscreen with SPF 15 reduces it by 99%.
During the winter months, the inactive, storage form of Vitamin D is drawn upon for use when sun exposure is limited or non-existent. Dr. Hollick does not discuss this in his interview, but the conversion process can be hampered by the consumption of a diet rich in animal foods, fat and refined foods, so adequate Vitamin D levels are dependent on both diet and sun exposure.
Supplementation and milk are often offered as alternatives to sunlight by those who are unenlightened and still believe the outdated theory that sun exposure causes skin cancer. Dr. Hollick states that he recently conducted a study at his hospital evaluating Vitamin D levels in women immediately after giving birth. The women were told to consume 2 glasses of fortified milk per day and to take a pre-natal vitamin containing 400 IU of Vitamin D per day. By the time they gave birth, 76% of moms and 81% of newborns were deficient.
Dr. Hollick does not call for the complete ceasing of promotion of fortified foods and supplements, but does say that we need to “recommend some sensible sun exposure and do away with this issue of being sun-safe by never being exposed to direct sunlight without sun protection.” In fact, he cites research indicating that the more sun exposure an individual gets as a child and young adult, the less likely he will be to die from melanoma if he develops it later in life.
He also states that there is a difference between Vitamin D synthesized from the sun and Vitamin D taken orally, since there are at least 5-10 additional photoproducts made in response to sun exposure that are not in the supplement form of Vitamin D. He is currently involved in research to determine the role of those photoproducts and investigating the differences in prostate cancer patients who are exposed to sunlight vs. given Vitamin D as a supplement.
Dr. Hollick discusses the connection between Vitamin D and several diseases, but his most interesting comments were about obese people and Vitamin D levels. Hollick states that research shows most obese people to be Vitamin D deficient, which is not surprising since their diets and lifestyles are unhealthful. The interesting point was that Hollick conducted a study placing both non-obese and obese people on Vitamin D supplements and the obese patients experienced a 50% less increase in Vitamin D levels than the normal weight subjects. This is one more reason why we must convince overweight people to lose weight – their condition places them at risk for serious health issues.
Hollick is considerably more conservative than I am – I generally recommend doing away with fortified foods and supplements, including Vitamin D since the body in its infinite wisdom can achieve and maintain optimal health naturally through dietary excellence and optimal habits.