Fitness and nutrition expert Mackie Shilstone is on a crusade to make people realize the importance of the under-appreciated secosteroid hormone vitamin D.
As executive director of the Fitness Principle at East Jefferson Hospital (4200 Houma Blvd., Metairie, 454-4000; www.ejgh.org/thefitnessprinciple/index.html), he works with people of varying ages as well as athletes like tennis star Serena Williams and the New Orleans Saints who want to improve their fitness and performance. What he finds surprising is the number of people he works with who don't have adequate levels of this fat-soluble nutrient in their bodies.
"We are seeing more vitamin D deficiencies in our program than you would believe," he says. "In our program, we've found one or two out of 10 are deficient." Shilstone now has Fitness Principle participants take a 25-hydroxy vitamin D blood test to determine whether they have adequate vitamin D in their systems.
For years, Dr. Michael F. Holick, whom Shilstone calls "the vitamin D guru," has touted the need for people to get "sensible" sun exposure, since the skin synthesizes ultraviolet (UV) rays to make vitamin D3, which is further metabolized through the liver and kidneys. Holick, a professor of medicine, physiology and biophysics at Boston University Medical Center as well as director of that institution's Vitamin D, Skin and Bone Research Laboratory, says exposing skin without sunscreen to 15 to 30 minutes of sunlight at noon is equivalent to taking 20,000 IU (International Units) of vitamin D in pill form. Using the sun is more efficient than taking supplements, however, because the body metabolizes it more efficiently, allowing it to be stored longer. To maintain an adequate supply of vitamin D in the body, Holick says people would need to take 1,000 IU of vitamin D3 supplements a day.
The National Institutes of Health's (NIH) Office of Dietary Supplements recommends daily vitamin D intakes of 200 IU for people from birth to 50 years old, 400 IU for 51 to 70 years old and 600 IU for 71 and older. It defines a deficiency of the vitamin as blood levels lower than 20 nanograms per milliliter (ng/ml), a measurement adopted by the 13th Workshop Consensus for Vitamin D Nutritional Guidelines in 2007.
Shilstone thinks those are too low: "The research is that the National Institute of Medicine will have to redefine the upper limits of recommendations," he says. "I think the recommendation is going to go to roughly 1,000 to 2,000 IU. You want (blood levels) to get up to 60 ng/ml.
"Dr. Holick himself takes 1,400 IU per day. I was taking 1,000 units a day and I actually upped my intake by 700 IU because my vitamin D level was 29. I'm exposed to the sun all day running around with these athletes. I wanted to get it up to 50."
The nonprofit Vitamin D Council, headed by Dr. John Jacob Cannell, suggests patients with a deficiency take 5,000 IU for three months, then have a blood test, with a sustained blood level goal between 50 and 80 ng/ml.
Shilstone warns that people should not start taking megadoses of vitamin D without a blood test to determine their serum level. "It's all determined by your lab values and your doctor," he says. "To just supplement with vitamin D without checking your levels is not recommended; you don't just go supplement on your own."
Though opinions about the amount of vitamin D necessary for optimum health may vary, there is no controversy when it comes to the importance of the nutrient.
The Vitamin D Council says when vitamin D is metabolized, it targets more than 2,000 genes in the body and that current research indicates people need about 4,000 units of vitamin D3 a day (through sun exposure and/or supplements). Furthermore, research has pointed to a deficiency of the vitamin as a major factor in the development of 17 types of cancer, as well as diabetes, heart disease, high blood pressure, osteoarthritis, multiple sclerosis, birth defects, autoimmune diseases, depression, muscle problems and even periodontal disease. The NIH acknowledges research that indicates vitamin D has a role in preventing and treating these conditions, but states the implications of such results are debatable because the testing was conducted in vitro and in animals as opposed to more definitive epidemiological human studies and randomized clinical trials.
The NIH also warns that vitamin D toxicity can cause nausea, vomiting, weight loss and constipation as well as raising blood levels of calcium, which can cause changes in mental acuity and heart rhythm abnormalities, and that the vitamin could have adverse interactions with several medications. It also points to a Women's Health Initiative study that showed postmenopausal women who took 1,000 mg of calcium and 400 IU of vitamin D a day had a 17 percent increased risk of developing kidney stones over seven years.
Two forms of vitamin D are important. Vitamin D2 is synthesized by plants, and vitamin D3 is synthesized by human skin exposed to UV rays. The major biological function of vitamin D is to help the body absorb calcium and maintain normal blood levels of calcium and phosphorus.
It is difficult to get enough vitamin D from foods alone, because it occurs naturally in only a few, such as some fish, liver, egg yolks and some cheeses. Foods such as milk and orange juice may be fortified with vitamin D2 or D3, but it would require ingesting large amounts to get what your body needs.
"You won't get enough in your food, and it's important," Shilstone says. "In addition to giving us strong bones, it bolsters the immune system and reduces our risk of immune dysfunction. In the sports area, some of the research (published in Medicine & Science in Sports & Exercise) points to the effect on testosterone." In one study, Olympic sprinters were tested for vitamin D deficiencies in an effort to prevent fractures. Researchers found that when the athletes took vitamin D, their testosterone levels rose and they got faster, he says.
"I think the (blood test) ought to be included in a physical," Shilstone says. "I think doctors need to become more aware of vitamin D and its importance in an overall prevention program.
"What I'm afraid of is that it will end up as this end-all, cure-all. I think we need to say it's a secohormone that affects many processes in the body, but the treatment is based on your compliance and follow-up. There are times and places, under some guidance, where it's advantageous to supplement."