By Linda Antinoro, R.D., L.D.N., J.D., C.D.E.
Through the centuries, many claims have been made about the influence of dietary habits and nutritional supplements on arthritis. Some of these claims are supported by medical evidence and some are reasonable theories. However, for most of these claims, we are just not sure.
Even without all the proof, there are many healthy nutritional ideas that you can consider.
This one has lots of evidence behind it. Being overweight is a major risk factor for osteoarthritis (the wear-and-tear type). Theoretically, losing just a few pounds might diminish the discomfort. Weight loss reduces the stress on joints. One study in particular found that a loss of just one pound of body weight reduces the load on knees by four pounds.
In addition, maintaining a desirable weight can reduce the chances of ever developing the disease. Your best chance of reaching that healthy weight is to engage in regular physical activity with a combination of aerobic and strength training exercises.
Dietary fats can influence inflammation, a major factor in rheumatoid arthritis. This is the type of arthritis that occurs as a result of the body's immune system mistakenly launching an attack on the joints. High dose fish oil capsules, which are rich in omega-3 fatty acids, have anti-inflammatory action. The clinical trials show modest benefit in patients with rheumatoid arthritis.
They can cause unpleasant stomach and intestinal side effects, are high in calories and rather expensive. In addition, an excess of omega-3 fatty acids potentially can lower the amount of omega-6 fatty acids from sources such as corn, safflower and cottonseed oils. This imbalance actually may promote inflammation.
It is too soon to know if foods rich in omega-3 fatty acids also will be helpful. However, these foods have other health benefits, especially in the prevention of heart disease. The best sources are from fish such as salmon, sardines, mackerel, herring and tuna. Other omega-3 sources (less potent than fish, however) include ground flax, flaxseed oil, walnuts and, to a limited degree, green leafy vegetables.
Preliminary studies suggest a possible link between chronic inflammation and saturated fats found in red meats, full-fat dairy foods, butter and poultry skin. Similar suggestions have been made for trans fats, found in hydrogenated and partially hydrogenated oils, some margarine brands, French fries and other fried foods.
Monounsaturated fats, namely olive oil, seem less likely to increase inflammation. So far there are no clinical trials that prove this type of heart-healthy diet is good for arthritis.
Research studies have linked low blood levels of D with increased risk of both osteoarthritis and rheumatoid arthritis. Additional research shows that osteoarthritis gets worse three times faster in people with inadequate vitamin D in their diets compared with those who have sufficient D. Currently, the standard recommendation is to get 400 to 600 International Units (IU) per day. Many experts advise 1,000 IU per day. Doses up to 2,000 IU per day are safe.
Only a few foods are particularly rich in vitamin D. These include oily fish and fortified milk and orange juice. Hence, most people need to supplement their diets with extra vitamin D. A multivitamin typically provides 400 IU. Seeking out some "safe sun" — 10 minutes without sunscreen a few times per week — provides a nice D dose too.
Brightly colored fruits and vegetables — such as oranges, bell peppers, pumpkins, tangerines and papayas — contain carotenoids called beta-cryptoxanthin and zeaxanthin. Some studies suggest that diets rich in carotenoids decrease inflammation. A small Swedish study of rheumatoid arthritis sufferers who ate a Mediterranean diet (including lots of vegetables and fruits) for three months found that it reduced inflammation and enhanced joint function. Aim for seven to nine servings of fruits and vegetables per day.
An unfounded myth that has circulated for years involves eliminating the so-called nightshade vegetables to help cure arthritis. The nightshade vegetables include tomatoes, potatoes, peppers and eggplant. The premise is that avoiding these foods eases joint pain and inflammation. Medical evidence does not support this claim.
Supplements abound when it comes to arthritis. But only glucosamine and chondroitin sulfate have some evidence to support their use. Glucosamine with chondroitin may decrease pain in people with moderate to severe osteoarthritis of the knee. But studies looking at osteoarthritis of other joints have not shown an advantage over a placebo.
Note that osteoarthritis is the only type of arthritis that may benefit from these supplements. They do not help people with rheumatoid arthritis.
In general, glucosamine and chondroitin have minimal side effects. Steer clear of glucosamine if you are allergic to shellfish, or consider only glucosamine derived from a vegetable source. Glucosamine may raise blood sugar. Chondroitin can interact with anticoagulant and antiplatelet drugs such as warfarin (Coumadin) and aspirin that can increase the risk of bleeding.
Even if the dietary suggestions don't seem to make a difference with your arthritis, they are all healthy recommendations that will improve your well being and decrease your risk of heart attack and stroke. People who follow these recommendations also are less likely to develop certain types of cancer.
Linda Antinoro, R.D., L.D.N., J.D., C.D.E., is a senior nutritionist at Brigham and Women's Hospital. She is also a certified diabetes educator. Ms. Antinoro counsels patients at the Nutrition Consultation Service.