Joint care: running on glucosamine

I am an urban runner, covering 25-30 miles a week. Although my knees are holding up well (I'm only 26), I know that running on hard surfaces is punishing to knees and hips. Some of the people I run with take glucosamine tablets. I wonder if I really should be taking sometime to prevent problems later in life.

Dr Fred Kavalier answers your health question:

Glucosamine tablets are not a guarantee of healthy knees and hips in the future, but there is certainly some evidence that they do help people who already have knee arthritis. The purveyors of glucosamine claim that it helps maintain the cartilage lining that covers joints and prevents bone surfaces from grinding against each other. The best scientific studies have shown that people who take 1,500mg of glucosamine a day maintain their cartilages better than those who don't. The pill takers (including people who took chondroitin sulphate) also experienced less pain and maintained mobility better. You are subjecting your knees to a lot of punishment. Have you considered varying your exercise? Perhaps you should include swimming and cycling.

Please mail your questions for Dr Fred to health@independent.co.uk. He regrets that he is unable to respond personally to questions.