Dear HEALTHbeat subscriber,

The Mediterranean region includes many countries, and the dietary staples in each vary as much as the people and countryside. But it’s the shared eating habits of this region that seem to matter most. This issue of HEALTHbeat discusses mounting evidence that supports the health benefits of the Mediterranean style of eating. Also in this issue, Dr. Donald T. Reilly, Harvard Health Letter editorial board member, discusses what a partial knee replacement can accomplish — and what it can’t.

Wishing you good health,


Nancy Ferrari
Managing Editor
Harvard Health Publications
HEALTHbeat@hms.harvard.edu

Salute!

Taming individual diseases is certainly a big step in the right direction, but that doesn’t necessarily mean longer life. Smaller studies have hinted, though, that the Mediterranean diet does have overall life-extending benefits, and a large European study (involving 75,000 people from nine European countries) also came to that conclusion in 2005.

There was more encouraging news late in 2007, when the Archives of Internal Medicine published results from an American study. Using food consumption questionnaires collected as part of the National Institutes of Health–AARP Diet and Health Study, the researchers classified respondents by how closely their eating habits matched a Mediterranean diet and then tabulated deaths over the next 10 years.

This was a huge study that included over 380,000 Americans with no history of chronic disease. When the researchers analyzed the data, they found that high conformity to the Mediterranean diet was associated with a lower risk of death in three categories: death from any cause, death from heart disease, and death from cancer. The benefits of the diet were especially pronounced among smokers.

The Mediterranean diet may have all of these good effects because it quells the low-grade inflammation that underlies so many disease processes. It also has powerful antioxidant effects.

Mete out the meat

So what exactly is this life-extending diet? It’s not a diet like, say, the Atkins diet or other highly scripted weight loss plans, although people can lose weight by “going Mediterranean.” Some experts are scrupulous about referring to the “Mediterranean-type” diet in hopes of conveying that it’s a pattern, and not a rigid, single way of eating.

According to some researchers, the heart of the diet is that it’s mainly vegetarian, includes far less meat and dairy than American and Northern European diets, and uses fruit for dessert.

Olive oil is often depicted as being absolutely essential, but researchers, at least, are getting away from that. In the large European study that showed reductions in mortality, the researchers measured the effects of a “modified Mediterranean diet” that grouped the polyunsaturated fat from a variety of vegetable oils with the monounsaturated fat from olive oil. So, with respect to fats, the main thing about the Mediterranean diet is to keep your consumption of saturated fat low, which, as a practical matter, means keeping the helpings of meat and dairy products (the full-fat variety) few and far between.

Other components of the Mediterranean diet include wine in small amounts (a glass or so a day), some fish, and cheese and yogurt. The à la carte aspect of Mediterranean eating is part of what makes it appealing. Researchers and the food industry have chiseled away, trying to figure out whether there’s a particular food or nutrient that confers most of the benefit, but the whole is probably greater than the sum of any particular parts.

For more information on maintaining a healthy diet, order our Special Health Report, Healthy Eating: A guide to the new nutrition, at www.health.harvard.edu/HE.

Q:  I am 55 and have a bad right knee from playing lots of sports. I am interested in getting a partial knee replacement. I’ve heard that the recovery is shorter and the result is better than a total replacement. What do you think?

A: The first decision that you and your orthopedic surgeon need to make is whether or not you need an operation. Joint replacement works to relieve pain and will help the knee to function better. If your knee pain prevents you from performing daily activities — walking, climbing stairs, light yard work — a replacement should be considered.

But don’t assume that a replacement will let you return to playing vigorous sports. No knee replacement, whether full or partial, should be subjected to impact loading — the pounding that occurs when you run or jump. The replacement joint will loosen up, and parts of it will wear out faster, so it will almost certainly not last as long.

In a total knee replacement, the portions of the femur and tibia that meet to form the joint are cut away and covered with prostheses to restore smooth movement. In a partial replacement, used when arthritic degeneration of the cartilage is more localized, smaller parts of the femur and tibia are cut away and resurfaced.

The recovery from a partial replacement is shorter and range of motion afterward is better. But they aren’t well suited for people with very bowed or knocked knees. And they’re a good choice only if the knee still contains a fair amount of healthy cartilage.

Most studies show that total knee replacements last longer than partials because the components that attach the prostheses to the bone are less likely to loosen up. Also, the healthy cartilage that wasn’t replaced initially may become diseased and arthritic later on, so people end up with the knee pain that the replacement was supposed to get rid of.

When a replacement fails, you can have it redone — a procedure orthopedic surgeons call a revision. But it’s major surgery and another big drawback is that the second set of prostheses usually won’t last as long as the first.

You should, of course, weigh the pros and cons of a knee replacement with your doctor. And it’s always a good idea to get a second opinion for something as major as knee replacement.

— Donald T. Reilly, M.D.
Harvard Health Letter Editorial Board
New England Baptist Hospital, Boston

This Question and Answer first appeared in the December 2007 Harvard Health Letter, available at www.health.harvard.edu/health.

Harvard Medical School publishes authoritative Special Health Reports on a wide range of topics. Each report delivers practical information on diagnosis, treatment, and prevention of major health concerns in clear, easy-to-understand language. For more information on a specific topic, click the appropriate link below:

Alzheimer’s, Arthritis, Bladder, Cholesterol, Depression, Diabetes, Digestion, Energy, Exercise, Eye Disease, Headache, Heart Disease, High Blood Pressure, Memory, Menopause, Prostate, Sexuality, Sleep, Stroke, Vitamins