Arthritis is one of the most prevalent health problems facing today's aging population.

The most common form of arthritis is osteoarthritis, which usually strikes weight-bearing joints such as the ankles, knees and hips. Pain is caused by the gradual breakdown of cartilage, the soft "padding" material that cushions the joints.

About 85% of adults who reach the age of 85 will have osteoarthritis--unless they take a proactive approach to prevent it.

Exercise is very important. But what about diet?

For a long time, doctors doubted there could be any link between diet and osteoarthritis. They saw the disease as a natural result of wear and tear on the joints, something inevitable as we age.

But new research is making them reconsider that idea.

It now appears that nutrition plays a vital role in helping to prevent or ease the affects of osteoarthritis. One key element is vitamin C.

Vitamin C is a powerful antioxidant, and may protect the joints from the damaging effects of free radicals (unstable molecules that can cause joint inflammation).

Recent research is showing that vitamin C can help prevent bone loss and cartilage inadequacies associated with aging. Specifically, when your joint has cartilage that needs to be repaired, vitamin C is needed for such repairs. It helps to keep your cartilage "young."

According to Dr. Timothy McAlindon of the Boston University School of Medicine, "Vitamin C may also help generate collagen, which enhances the body's ability to repair damage to the cartilage."

When scientists at the Boston University School of Medicine studied the eating habits of people with osteoarthritis of the knee, they found that those getting the most vitamin C--more than 200 milligrams a day--were three times less likely to have the disease get worse than those who got the least vitamin C (less than 120 milligrams a day).

Dr. McAlindon recommends that people get a least 120 milligrams of vitamin C every day. "That's the amount in a couple of oranges," he says.

Dr. Michael F. Roizen and Dr. Mehmet C. Oz, co-authors of "You: The Owner's Manual," recommend even more. "Shoot for 1200 milligrams of vitamin C a day--spread between your diet and supplements throughout the day."

Be careful not to overdo it. Some data suggest that more than 2,500 milligrams a day can have the opposite effect and actually increase the risk of osteoarthritis.

Dr. Eve Campanelli, a holistic family practitioner in Beverly Hills, CA, recommends black cherry juice. She advises her patients to drink two glasses, twice a day, of four ounces of the juice diluted with four ounces of water.

Other fruits and vegetables rich in vitamin C include oranges, cantaloupe, broccoli, strawberries, peppers and cranberry juice.

A healthy diet, rich in fruits and vegetables, has been recommended by nutritionists for years. Now there's another reason to pay attention--it can help your joints to stay young!