UW Research Finds Athlete Vitamin D Levels Wobbly; General Public Probably Worse
June 26, 2009 — That "ahhh" feeling that comes with feeling warm sunlight on your face after a long Wyoming winter could be more than a feeling - your body could be thanking you for the vitamin D.
Making vitamin D doesn't work like that, of course, but vitamin D supplements or sun in appropriate amounts do a body good at Wyoming's latitudes. Research of athletes at the University of Wyoming is finding their vitamin D levels fluctuate with the seasons, and the lead researcher says the general public may not be as well off as the athletes.
"We know that people who live at greater than 35 degrees north or south latitude can't make vitamin D in the winter months, which, for us, is probably late October through March," said Enette Larson-Meyer, an assistant professor in the Department of Family and Consumer Sciences in the College of Agriculture. "We need to take supplements or get it from our diet."
Low vitamin D levels affect calcium absorption, which affects bone health and strength. Low levels are linked to an increase in type I and II diabetes, multiple sclerosis, rheumatoid arthritis, hypertension and many common cancers, according to Larson-Meyer. Low levels in children may cause rickets.
"But, what we are learning is that having low levels impacts inflammation and the immune system," she said. "It's important to have adequate vitamin D levels to fight off what you may come in contact with to make sure your immune system is healthy."
There are a few natural sources of vitamin D - primarily fatty fish, although products like milk and cereal have been fortified to meet current required daily standards; however, Larson-Meyer said many experts say the level should be increased from 200 international units (IU) to 1,000 minimum IU.
Larson-Meyer, in an earlier study with Louisiana State University of runners in the Baton Rouge area, found more than 41 percent of long-distance runners were vitamin D deficient. The subjects ran at least 25 miles a week.
"You might assume they spent a lot of time outdoors," she said. "But what we decided is that, because it is so hot there, people were likely to run in the early morning."
Larson, with UW athletic trainer Joi Thomas and family and consumer science undergraduate students Tanya Halliday and Nikki Peterson, are studying vitamin D levels in UW athletes in football, wrestling, track and field, cheerleading, swimming, men's and women's basketball and women's soccer.
Blood samples were taken in the fall, just before spring break and at the end of the spring semester. The end-of-semester results are not yet available, but the other tests showed dramatic drops in vitamin D levels after fall and during winter.
"Over the course of the winter, people living in Wyoming cannot synthesize vitamin D, and their status drastically dropped," said Larson-Meyer. "It's not surprising. Hardly any of the athletes are taking any vitamin D supplements."
About 88 percent had sufficient levels in the fall but only 36 percent in the winter.
Members of the general public are probably not as well off as the athletes, she said. Some people do not want to take supplements, and some people fearful of skin cancer are careful about how much sun they receive.
Most at-risk to complications from inadequate vitamin D are those
hospitalized or homebound. Also, obesity seems to cause lower levels of
the vitamin, she said.
Larson-Meyer recommends exposing arms and legs to sunlight for five to 30 minutes between 10 a.m. and 2 p.m. twice weekly without sunscreen, depending upon the season, latitude and skin pigmentation. Sunscreen with SPF 15 or more should be applied for longer durations of skin exposure.
Or, supplements at 1,000 to 2,000 IU daily are a solution. "There is no risk to it, and they are not very expensive," said Larson-Meyer. It may optimize one's immune system and reduce risk of chronic diseases.
Assistant Professor Enette Larson-Meyer conducts a bone density scan of Emily Byra of Laramie, a junior at the University of Wyoming and a cross country runner and member of the women's track team. Larson-Meyer, a faculty member in the Department of Family and Consumer Sciences, uses equipment in a Corbett Building laboratory that utilizes dual-energy X-ray absorptiometry, an enhanced form of X-ray technology.
Posted on Friday, June 26, 2009