Over the last three years, Susan Sullivan of the Dept. of Food Science and Human Nutrition has monitored sun exposure, diet and blood levels of vitamin D in 23 girls from ages 10 to 13 years old. All of her subjects live in the Bangor, Maine area. She conducted the study with Dr. Cliff Rosen of the Maine Center for Osteoporosis Research and Education, St. Joseph Hospital in Bangor. In her research and previous experience as a clinical dietitian at Massachusetts General Hospital, Sullivan has focused on the medical consequences of dietary habits. For her 1995 doctoral degree at Boston University, she studied the relationship between fat intake and blood cholesterol levels in kidney transplant recipients.
Vitamin D is an emerging area of medical research, says Sullivan. Medical scientists have yet to understand the whole story about vitamin D and the body. "We've known for a long time that vitamin D has a role in getting calcium into bones. Researchers are now finding evidence that vitamin D could play other roles in health such as cancer prevention and controlling blood pressure. There are vitamin D receptors in lots of tissues in the body that aren't related to bone," she explains.
The largest single source of vitamin D is the skin, which makes the nutrient when it is exposed to sunlight. Diet plays a less important role but, for people at high northern latitudes, helps to supplement the body's vitamin D store during the winter months when sunlight is less intense.
Since having adequate levels of vitamin D supports bone growth, Sullivan monitored bone density in
Contact: Susan Sullivan, Ph.D.
University of Maine