By Markham Heid
Knees not feeling great this time of year? You may need more of the sunshine vitamin, suggests new research from the Clinical Journal of Pain.
Compared to those osteoarthritis sufferers with adequate vitamin D levels, those short on D reported significantly more knee pain and loss of function, according to the study data. Those results held regardless of a person's weight, although the obese study participants were more likely to suffer from a vitamin D deficiency.
There are several different ways low D might mess with your knees, says study coauthor Toni Glover, PhD, of the University of Florida. For one thing, being short on D ups your inflammation levels, which in turn increases pain sensitivity associated with osteoarthritis. Having too little D also increases "bone turnover," which lowers bone quality, the study authors explain.
Vitamin D deficiency is a widespread problem, Glover says. In fact, one recent study from the journal Nutrition Research found roughly 42% of Americans are dangerously low when it comes to vitamin D. You get most of your D from sun exposure, Glover explains. So all the problems associated with low D tend to spike in wintertime, when most people aren't getting much sun.
A simple blood test from your doctor can determine whether you're low in the vitamin, Glover says. If you're deficient, she says taking a vitamin D supplement for several months can help you raise your levels. While it's difficult to get too much D, the amount you need depends on your weight and body composition, Glover explains. Your body stores D in fat cells, meaning those with greater amounts of body fat require more of the vitamin to limit pain and loss of function.
If pain and loss of movement aren't enough to make you worry about vitamin D, consider this: more research has found low D doubles your risk for dementia.