Photo by Devon Stephens, istock
My husband came home recently after his annual medical exam with news that his vitamin D level was low. I wasn't surprised. Our physician, Dr. Matthew Marchal of Altius Family & Sports Medicine on Gaskins Road, has been talking about vitamin D for several years. Based on patient physicals in the last two years, he estimates that nine out of 10 of Richmonders have low levels of the vitamin, which is essential to maintain strong bones by helping the body absorb the mineral calcium.
Many physicians share his concern. We've become an indoor society that gets much of our vitamin D from fortified foods. (Very few foods naturally contain vitamin D, making it difficult to get enough from diet alone. Fatty fish such as salmon and tuna are among the best sources.) Sunscreen protects us from skin cancer while reducing our skin's ability to manufacture vitamin D from the sun's ultraviolet light. Fewer hours of daylight and less time spent outdoors in winter contribute to the problem.
People with too little vitamin D may develop soft, thin and brittle bones, which in children is called rickets and in adults, osteomalacia. Along with calcium, vitamin D protects against osteoporosis. The current daily recommended intake by the Institute of Medicine's Food and Nutrition Board for vitamin D is 200 international units (IU) daily through age 50; 400 for adults aged 50 to 70; and 600 for those older than 70. The recommendations were set to prevent rickets, but are generally recognized by physicians, as well as researchers, to be so low as to leave many people deficient in wintertime, says Dr. Robert W. Downs Jr., acting chairman of the division of endocrinology and metabolism at Virginia Commonwealth University.
A report released in November by the Institute of Medicine (IOM) should help ease physicians' concerns about vitamin D, Downs says. The report, based on nearly 1,000 studies, concluded that most Americans do get enough vitamin D and suggested a modest increase in recommended daily intake. For most people, 600 IU daily suffices, although people 71 and older may require as much as 800 IU per day. "There are certainly people in the scientific community who will not think the IOM has gone far enough," he says. "Others will applaud the strict standard of evidence applied."
Recent research suggests that vitamin D plays a protective role against colorectal cancer, but not prostate cancer, and is inconclusive regarding its effects on breast cancer. There are hints that vitamin D deficiency is linked to high blood pressure and cardiovascular disease, osteoarthritis and immune-system abnormalities.
However, in June, several studies in the American Journal of Epidemiology looked at whether high levels of vitamin D decrease the risk of certain cancers and found what the journal called "compelling evidence" against vitamin D and its protective effects. In an editorial, the journal noted the apparent difference between taking several pills of vitamins and getting those vitamins in your diet. And, the editorial warned, "we now know that taking vitamins in supernutritional doses can cause serious harm."
So where does that leave my husband? He's following Marchal's suggestion of taking more, but not super-high, supplements. And Marchal says he will urge his patients to pursue a balanced and moderate approach to diet and lifestyle, saying that it "will prove to be the path to healthy living almost every time."