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Osteoarthritis and diet: clearing up the confusion

Jane Griffin
BSc SRD RNutr
Consultant Nutritionist
London

Arthritis is the general term used to describe inflammation of a joint. Although there are several types, osteoarthritis is the most prevalent form and is often referred to as "arthritis". It is a major cause of disability in the UK as it affects the main weight-bearing sites, particularly the hips, knees and spine. Indeed osteoarthritis is a common reason for hip replacement operations. For some the condition causes discomfort or occasional aches and stiffness, while for others it is an incapacitating and crippling disease.
At the end of each bone that forms a joint there is a pad of cartilage that prevents bones from rubbing together. With time and usage, the cartilage begins to degenerate and wear thin. This, in turn, causes pain, inflammation and restricted movement at the joints. New bone can develop where cartilage has worn thin, resulting in outgrowths, or osteophytes, which can deform the joint, exacerbate pain and restrict movement.
Although osteoarthritis is associated with the ageing process, it is not uncommon in relatively young sports people who have exposed certain joints to excessive wear and tear. By the age of 75, up to 85% of people may be affected to some degree by osteoarthritis.(1) Besides wear and tear, other contributing factors, such as genetics, hormones and diet, may play a part.

The role of diet
Although osteoarthritis has no specific dietary indications, nutritionally related health problems will certainly not help the condition and could compromise the nutritional status of the arthritic person. Physical disability may cause difficulty in shopping, preparing and cooking food, which could result in a nutritionally imbalanced diet. For instance, the intake of fruit and vegetables may be severely reduced because their weight and bulk make carrying them difficult.
Diet should be assessed to ensure not only that the patient is eating a sufficient amount of food, but also that their daily diet is nutritionally balanced. If not, then appropriate practical advice should be provided. Undernutrition is always a problem, and overnutrition is particularly detrimental to the condition.
The number of people who are overweight and obese has increased alarmingly over the past two decades and continues to rise. This can place a great strain on weight- bearing joints and exacerbate the symptoms of osteoarthritis. With every step taken, the load on the hips, knees and feet is increased by three to five times the bodyweight of an overweight, arthritic individual. A well- balanced diet will help maintain a healthy weight and thus alleviate some of the symptoms, as well as help to slow progression of the disease.

Body weight
Dietary intake, level of physical activity and behaviour are all key factors in body weight regulation. Exercise, or increased physical activity, can help to control weight, but restricted movement in an arthritic person may make this difficult, if not impossible. Therefore more emphasis must be put on diet management.
Research shows the amount of fat in the diet is directly correlated with body fat. In addition, research shows us that individuals who consume a greater proportion of carbohydrates in the diet, both from starches and sugars, consume less fat and tend to be leaner.(2)
The worst aspects of a restrictive diet are hunger and boredom. Eating plenty of carbohydrate-rich foods and reducing fat intake can reduce the hunger pangs. This will also reduce overall caloric intake and therefore promote weight loss. Some important benefits of increasing carbohydrate intake are:

  • Carbohydrate has less than half the calories of fat, weight for weight.
  • Research has shown that people accept reducing fat in their diet when they eat more carbohydrate.(2)
  • Carbohydrate plays a central role in controlling appetite. High carbohydrate intake reduces appetite and hunger far more successfully than high fat intake.

If weight loss or weight control is needed, success is more likely if the diet is tastier and less monotonous. This can be achieved by providing practical advice about cutting back on fat intake and eating more carbohydrates, from both starchy and sugary sources.

Diet myths
Special diets may work, or appear to work for a short time, but none has been proven as an overall treatment, remedy or cure. At best, they may be harmless, or beneficial for a short time due to the placebo effect (you do something that you believe will have a positive effect and it does, for a time, but it is the belief rather than an actual effect that is working). At worst, the adopted diet may be unrealistically restrictive, of doubtful value, and almost certainly nutritionally unsound.
Currently the only diet that is recognised and recommended by the medical profession is a nutritionally balanced diet. Detoxification diets have no scientific credibility, and there is no evidence of any systematic relationships between food allergy, food intolerance and osteoarthritis. Elimination diets, followed frequently or for prolonged periods, can result in profound nutritional imbalances and should be discouraged.
Diets popularly recommended for treatment of arthritis, with their unproven assertions, include:(3)

  • Vegetarian diet - because meat causes arthritis.
  • Vegetarian diet with no cooked or processed foods or grains except sprouted grains - because this has a cleansing effect.
  • No meat, dairy products or additives - because allergy to these foods causes arthritis.
  • Acid-reducing diets - because acids cause arthritis.
  • A diet of fish, brown rice and vegetables - because all other foods cause arthritis.
  • Having whole milk before meals and including butter in the diet - because this helps to lubricate the joints.
  • Fasting - because it cleanses the system of toxins and rests the body (enemas are sometimes used to speed up the process).

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Special foods or supplements
There is no proven scientific evidence that cider vinegar, garlic, alfalfa, honey, New Zealand green-lipped mussel, kelp, Devil's claw and ginseng are curative. Although individuals may find a particular supplement helps the symptoms of the disease, a cure has yet to be found.
Research is being undertaken into the role of omega-3 fatty acids in relieving arthritic joint pain and aiding joint mobility by reducing inflammation in the joints. Omega-3 fatty acids are found in oily fish such as salmon, herring, mackerel, sardines and trout, and the livers of other fish, the most notable being cod. The general recommendation is to include oily fish in the diet at least three times a week. Unfortunately, we are not a great oily fish-eating nation, so taking a supplement of cod liver oil is an easier option. Indeed much of the scientific research has been conducted using cod liver oil as a supplement. It takes about three months for the effects to be noticeable, and supplementation must be continued for the benefits to be maintained.
Glucosamine sulphate might also have a role in treating arthritis. Glucosamine is required by chondrocytes, cells involved in the formation and rebuilding of cartilage and other connective tissue. Although there is plenty of anecdotal evidence of its beneficial effects, results of clinical trials are needed to confirm these claims.
It is important that toxicity of supplements is considered and appropriate advice given to patients. The drawbacks of dietary regimens that are restrictive should also be highlighted. Many people are tempted to try unconventional remedies in the hope they might improve their condition. However, no proper research trials have been carried out to evaluate the benefit of such diets or supplements. The problem with alternative and complementary diets is that they are more likely to worsen nutritional status than improve it. Therefore it is important for the healthcare professional to inform and educate the arthritic patient on the facts of nutrition and arthritis.

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References

  1. Sack KE. Osteoarthritis: a continuing ­challenge. West J Med 1995; 163:579-86.
  2. West JA, de Looy AE. Weight loss in overweight subjects following low-sucrose or sucrose-containing diets. Int J Obes 2001:25:1122-8.
  3. Thomas B, editor on behalf of the British Dietetic Association. Manual of dietetic practice. 2nd edition. Oxford: Blackwell Science; 1994.