Researchers at the Wake Forest University of Medicine in Winston-Salem, North Carolina in the U.S. have voiced concern that many of the country's elderly are deficient in vitamin D.
The researchers say a failure amongst the elderly to get enough vitamin D either from their diets or exposure to the sun, heightens their risk for muscle weakness and poor physical performance.
This they say is a worry as vitamin D plays an important role not only in bone health but research also suggests it may help protect against diabetes, cancer, colds, and tuberculosis, especially in view of the number of seniors who are deficient in vitamin D.
The research team found that in a sample of 976 adults who were 65 or older when tested, 75 percent of women and 51 percent of men had insufficient vitamin D levels.
The researchers tested the participants' physical performance by timing their walking speed, as well as their ability to get up from a sitting position and keep their balance while standing in increasingly more challenging positions.
They also measured handgrip strength, a predictor of future disability.
Lead author Dr. Denise K. Houston found that physical performance and grip strength were 5 to 10 percent lower in people with low blood levels of vitamin D levels, compared with those with normal levels.
Even after factors which might influence the results were taken into account, such as a person's weight, level of physical activity, the season of the year, mental abilities, overall health condition and anemia, the finding remained.
Vitamin D is derived from the sun's ultraviolet rays and from certain foods such as fortified milk, juice and cereals but it can be difficult to absorb sufficient amounts of the vitamin through diet alone.