Hopeful headlines often tout scientific studies showing the next great breakthrough in cancer prevention and treatment. But dig beyond the headlines and the facts are often murky.
So it is with Vitamin D.
Vitamin D is produced by the body when skin is exposed to the ultraviolet rays of sunlight. Although it is found naturally in certain foods, such as fatty fish and eggs, most dietary Vitamin D comes from foods that are fortified with it, such as milk, juices and breakfast cereals. Because it helps the body use calcium and phosphorus, Vitamin D is essential for making strong bones and teeth.
But it is possible Vitamin D may play a role in cancer prevention as well. Researchers began exploring the connection when they observed the incidence and death rates for certain cancers were lower among individuals living in southern areas where the level of sunlight was relatively high.
“There’s still a lot of controversy,” says Dr. Daniel Flora, a medical oncologist with OHC. While “there are several very large observational studies that show there are increased risks of certain types of cancer, particularly breast and colon cancers, in patients with low Vitamin D levels, what has not been clear is whether supplementing Vitamin D can have any influence on outcome.”
Indeed, a Cochrane database review of over 50,000 patients, predominantly focused on elderly women, showed no firm evidence that Vitamin D supplementation either decreases or increases cancer occurrence, he says.
So where does the lack of evidence leave science and patients? Researchers need to devise randomized controlled studies to see if Vitamin D plays a role in prevention and treatment, Dr. Flora says. In the meantime, he says, people may want to bear in mind that whether or not it plays a role in cancer prevention and treatment, Vitamin D is essential to cell metabolism and bone health.
Patients whose bone health may be at increased risk, including post-menopausal women, older people, those who have very little sun exposure, and those who may have a nutritional deficiency due to gastric bypass surgery or a chronic condition, such as Crohn’s disease, should talk to their primary care doctor about having their Vitamin D level tested or taking a supplement.
“There’s no harm in taking small doses of Vitamin D,” Dr. Flora says, but don’t overdo it, as too much can be harmful.
Assuming minimal sun exposure, the recommended daily allowance (RDA) for vitamin D set by the Institute of Medicine (IOM) is 600 International Units (IU) for people between the ages of 1 and 70 and 800 IU for those age 71 and older.
