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An estimated one out of four older adults have chronic knee pain, usually because of osteoarthritis.
“It’s very, very common,” says Karen Costenbader, a rheumatologist at Brigham and Women’s Hospital and professor of medicine at Harvard Medical School. So she and her colleagues decided to see if vitamin D and fish oil omega-3s could help participants in the VITAL trial.
VITAL randomly assigned nearly 26,000 people in their 50s or older to take either vitamin D (2,000 IU), fish oil omega-3s (460 mg of EPA plus 380 mg of DHA), both, or two placebos every day for roughly five years. Costenbader's study looked at the roughly 1,400 participants in VITAL who had knee pain.
“These people were diagnosed with osteoarthritis by a doctor, they had chronic daily knee pain, they had limitations on how much they could walk, and many were taking medications,” says Costenbader. “So their pain was fairly severe.”
Unfortunately, the results were disappointing.
“The supplements didn’t do much for their pain,” says Costenbader.
Other studies of knee arthritis
Those results fit with three other recent trials that found no effect of vitamin D on knee pain or cartilage.
The largest trial on glucosamine, chondroitin, or both supplements also came up empty. And arthroscopic surgery works no better than physical therapy.
“We don’t have any great medications for osteoarthritis,” says Costenbader.
Corticosteroid injections only relieve pain for short periods. NSAIDs like Advil or Aleve can curb pain, but they can have adverse effects like GI bleeding. Topical NSAIDs like Voltaren (a gel) are safer but don’t work for everyone.
What exercise and weight loss can do
So far, your best bet—other than a knee replacement—is a mix of strength training plus aerobic exercise and losing excess weight.
“Building up muscle strength can protect the knee,” says Costenbader, adding that “high-intensity was no better than low-intensity strength training in a recent trial.”
What may matter most: getting people to stick with an exercise program.
Costenbader cites a recent Veterans Affairs trial that assigned 345 vets (mostly men) to either an exercise or a control group.
“The exercise group was given a prescription to an online exercise program at home, and if they didn’t improve after three months, they went to the next step, which was biweekly coaching calls, and if they still didn’t improve after three more months, they went on to in-person physical therapy visits.”
After nine months, the exercise group reported significantly less pain than the control group.
“That kind of tailored exercise prescription may have the best effect,” says Costenbader.