There are two main types of arthritis: osteoarthritis (caused by degeneration and wear and tear on joints) and rheumatoid arthritis (an inflammatory condition, thought to be an auto-immune disorder). Diet is an important aspect in the management of both types, but so-called "dietary cures" are controversial.
Patients with arthritis often have difficulties with cooking, shopping and preparing food, and pain may lead to poor appetite. This can result in a restricted diet (eg, limited vegetables and fruit) with a poor vitamin and mineral content. Many of the drugs used to treat arthritis (eg, non-steroidal anti-inflammatory drugs) have nutritional implications, such as gastrointestinal irritation and bleeding).
Body weight - Correct or prevent obesity or overweight. Excessive weight increases the strain on load-bearing joints, such as hips and knees. Weight reduction can reduce pain and improve mobility and may also reduce the risk of developing osteoarthritis.
Balanced diet - Eat a healthy, balanced diet with plenty of fruit, vegetables and grains. Use fatty and sugary foods in moderation.
Glucosamine - Several trials have shown that glucosamine (a synthetic glucose polymer based on a natural substance found mainly in joints) can improve symptoms of osteoarthritis, but all have contained study design flaws and problems with data analysis. Adverse effects are few and limited mainly to gastrointestinal disturbances, although studies have shown that glucosamine can impair insulin secretion and metabolism. Care should therefore be taken in patients with diabetes.
Antioxidants and vitamin D - There is some evidence that patients with an increased intake of dietary antioxidants (eg, vitamins C and E, selenium) and vitamin D reduce the risk of osteoarthritis progression.
Fish oils - There is anecdotal evidence that fish oils are useful in the management of osteoarthritis but clinical trials show more evidence of benefit in rheumatoid arthritis.
Body weight - Correct or prevent obesity and overweight and eat a healthy, balanced diet.
Food allergy - Food allergy has been suggested to be a cause of rheumatoid arthritis, and many popular books advocate exclusion diets to help identify possible dietary causes. An exclusion diet involves avoidance of potential allergens for two to three weeks and re-introduction of foods in a pre-determined sequence to see which cause symptoms. Common culprits are milk and dairy products, wheat, peanuts, beef, citrus fruits, tomatoes and coffee. Such action may help individuals to gain control of their condition, but may also cause nutritional deficiencies.
Fish oils - Fish oils contain omega-3 fatty acids (eicosapentaenoic acid [EPA] and docosahexanoic acid [DHA]), which may help to reduce symptoms of pain, morning stiffness and swollen joints. They appear to act by reducing production of pro-inflammatory prostaglandins and leukotrienes. Fish oils can be obtained from oily fish (eg, mackerel, herring, sardines) but, to obtain beneficial amounts of fatty acids, it is necessary to eat 8oz of oily fish each day. Fish oil supplements are a more manageable alternative and a supplement providing 1,000-1,500mg/day of omega-3 fatty acids is an appropriate choice.
Evening primrose oil - Evening primrose oil and starflower oil contain gamma-linolenic acid (GLA), which is necessary for the production of an anti-inflammatory prostaglandin (PGE1). Increased intake of GLA may increase the production of PGE1 and this may help to relieve pain and stiffness. People may want to try supplements, but it should be emphasised that there is no clear proof of clinical benefit.
This series of "dietary advice tips" is intended to be a reminder of the main points to be made by pharmacists when giving nutritional information to the public. The conditions included in the series are those where diet is a well recognised risk factor, those in which diet contributes to the management of the condition, and others for which patients may welcome sound dietary advice. The series is written by Dr Pamela Mason (a pharmacist with a postgraduate qualification in nutrition)
