Let the Sunshine In

Illuminating the impact of vitamin D insufficiency.

It’s generally accepted that most adults in the U.S. don’t get enough vitamin D, but how that affects physical health over the long term is not well understood.

Now, however, University at Buffalo researchers have taken a big step forward with a study that examines how low levels of vitamin D in mice affect their muscle mass and function over time.

“The take-home message of this study is that while having low serum vitamin D for a month or even a year or two may not matter for a person, over several decades it may have clinical ramifications,” says Kenneth L. Seldeen, research assistant professor of medicine in the Jacobs School of Medicine and Biomedical Sciences at UB.

“This is particularly concerning since an estimated 50 to 70 percent of the national population is either vitamin D deficient or insufficient,” he adds.

Low levels impair stamina and performance over time

Vitamin D insufficiency was induced in mice aged six months—the equivalent of a 20- to 25-year-old human—and continued for a full year, the equivalent of an additional 25 to 30 human years. A control group received vitamin D at normal levels.

After two weeks, the mice with low vitamin D exhibited a rapid decline in their serum vitamin D levels, where they remained for the duration of the study.

After eight and 12 months the mice performed worse than controls on several measures, including grip endurance, which is the ability to maintain strength in a grip and likely indicates a decline in anaerobic capacity, or the ability to maintain peak performance. They also lost sprint speed and stride length, a potential indication of slow gait speed, which is an important clinical parameter in geriatric medicine.