DEAR DR. ROACH: I am a 66-year-old male who often experiences achiness in my lower joints (hip arthritis and occasional knee pain). A good friend of mine who is also a doctor recommended that I consider taking a daily supplement of glucosamine and chondroitin.

Do you recommend it for reducing inflammation and joint pain? Does it work? I mostly manage my pain with Aleve, but long-term use of it is apparently not recommended as it can increase blood pressure in certain people.

My doctor friend’s wife says she has been taking it for 30 years and swears by it for helping her joint pain. What are the odds that it would be beneficial for me?

— V.F.

ANSWER: Aleve (naproxen) is a nonsteroidal anti-inflammatory drug, which is effective for many people with arthritis. It has many possible side effects, including high blood pressure, but the average rise in blood pressure is only 2 or 3 points. Still, Aleve can cause kidney damage, stomach ulcers, intestinal damage and many more problems, so there has been a long search for safer treatments. (I’m not suggesting that you stop taking Aleve.)

Glucosamine and chondroitin, taken individually or together, are used by millions, and they are generally safe. The main side effect I see is gastrointestinal, such as abdominal discomfort or diarrhea, but it is quite uncommon. They may help pain symptoms but are not effective anti-inflammatories.

Do they work? This is still uncertain. Some studies have shown that they do; most have shown that they work about as well as a placebo pill with no active ingredients. My experience with patients suggests about a third of people find them effective enough to keep taking them.

I tell my patients who want to take them that it’s worth a try, but if they haven’t helped by a month or two, they probably never will.

DEAR DR. ROACH: What does BMI stand for?

–Y.A.A.

ANSWER: BMI stands for body mass index, which is a way of describing a person’s body shape in a simplified way. The number is calculated by dividing a person’s weight by their height (squared) into metric units so that the units equal the kilograms per meter squared.

The usual definition is that a BMI of less than 18.5 is underweight; normal is 18.5-25; overweight is 25-29.9; obese is 30-35; and morbidly obese is above 35. These definitions are flawed. The average BMI in the U.S. is 29.1 for men and 29.6 for women. The BMI that has the lowest mortality is about 27, so it doesn’t make sense to me that this should be deemed less healthy.