 Vitamin D may help fight everything from diabetes and heart disease to cancer and osteoporosis. Yet the number of people who don’t get enough is reaching near-epidemic proportions.
Calling vitamin D just another vitamin is like calling the Rosetta Stone just another rock. Estimates are that it could help prevent more than 254,000 cases of colorectal cancer and 220,000 cases of breast cancer annually worldwide (Annals of Epidemiology, July 2009). Other research suggests it may decrease the risk for a laundry list of medical conditions—diabetes, cardiovascular disease, multiple sclerosis, osteoporosis and some infections, to name a few. If it were a medication, people would undoubtedly be clamoring for a prescription. The fact that vitamin D is readily available to everyone makes it all the more surprising that most people aren’t getting enough of this vital nutrient.
Many experts believe vitamin D insufficiency has reached epidemic proportions. Hard numbers are difficult to come by, in part because of debate over how much vitamin D people really need. But a recent national study found that 77 percent of the U.S. population fell short of the vitamin D level thought to be needed for optimal health (Archives of Internal Medicine, March 2009).
Ironically, one reason many people aren’t getting enough D may be health consciousness. Vitamin D is nicknamed the “sunshine vitamin” because it’s made by the body after exposure to sunlight. But as people heed advice to cover up or wear sunscreen, their body’s production of vitamin D decreases. As a result, dietary sources and/or supplements become even more important.
Key to the Code
How is it that a lack of vitamin D can be associated with so many diverse health problems? When specialized tissues throughout the body have a job to do, they may not have all the tools they need on hand. What they do have is a DNA library—a genetic blueprint that allows them to make what they need.
“Vitamin D is the key that unlocks the DNA library,” says Robert Heaney, M.D., professor of medicine at Creighton University in Omaha, Nebraska. Because it serves this role for many types of cells, it affects a wide range of normal body functions.
It has long been known that D and calcium work together to help build and maintain strong bones. More recently, a raft of studies has focused on D’s ability to reduce inflammation and regulate immune and neuromuscular activity.
“Many of these studies are associational, not causative,” says Julie Miller Jones, Ph.D., professor emeritus of foods and nutrition at St. Catherine University in St. Paul, Minnesota. “And while some show a positive effect, you can also find studies that don’t show any effect.” But, taken as a whole, a growing body of research shows that D is critical for overall good health.
Cancer Connection
Some of the most compelling evidence comes from recent clinical trials using vitamin D for cancer prevention. In one study coauthored by Heaney, nearly 1,200 healthy women over age 55 were randomly assigned to take 1,100 IU of vitamin D plus calcium, calcium alone or a placebo daily for four years. Those who took vitamin D plus calcium had a dramatic 60 percent reduction in cancer risk, compared to those who took the placebo (The American Journal of Clinical Nutrition, June 2007). If you want to reap this potentially wide range of benefits, ask your doctor if you should be tested for adequate levels of D or consider a supplement.
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