Diet & Rheumatoid Arthritis

Dr Dorothy J Pattison PhD RD
Original article: 10/10/2007
Reviewed: 26/01/2010
Next review due: 26/01/2013

Introduction

There is a huge amount of dietary advice aimed at people with rheumatoid arthritis (RA). Unfortunately, the vast majority is unsubstantiated and cannot be generalised to everyone with the condition. This article summarises some of the dietary advice for which there is evidence of benefit for people with RA.

Fish Oils and Omega-3 fatty acids

The long chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid (known as EPA and DHA, respectively) have an important role in the inflammatory pathway. There is good evidence that omega-3 fats when taken as supplements can improve symptoms of RA, although none of these studies lasted more than 4 months, so longer term effects are unknown. Benefits have been noted to continue for 6 months after withdrawal of the omega-3 supplements. A recent publication concluded that the amount of omega-3 fats necessary to gain symptomatic benefit is around 3g/day (ie total EPA + DHA). The amount of EPA + DHA varies greatly between fish oil supplements. A typical 1000mg For example one fish oil capsule (1000mg) may containing  120mg EPA + 180mg DHA (=300mg total omega-3 fats). Thus, 3 capsules/day will provide almost 1g total omega-3 fats. Omega-3 fats can also be obtained from food. Natural sources of omega-3 fatty acids are oily fish such as mackerel, sardines, herring, salmon, trout and fresh tuna (not tinned tuna). Eating oily fish 2 or 3 times a week provides a reasonable intake of EPA and DHA, although the benefits on joint symptoms are not clearly difficult to defined.

Note: If taking fish oil supplements avoid fish liver oil capsules (e.g. cod liver oil). These supplements  contain high amounts of fat soluble vitamins A and D which, if taken in large quantities over a period of time can have toxic effects. Always use pure fish oil products instead.

Liquid fish oil may contain a higher concentration of omega-3 fatty acids and may be a preferable way of taking fish oil for some people. However, omega-3 fats are highly perishable and destroyed by light, heat and air and will become rancid quickly once the bottle is opened. Capsules help to prevent rancidity as the fish oil is stored in a sealed environment.

A different group of fatty acids known as omega-6 fats are thought to compete with the omega-3 fats for the same ‘pathway’. Omega-6 fats are found mainly in foods such as sunflower oils and margarines, seeds and nuts. Omega-6 fats are involved in the generation precursors of strongly inflammatory prostaglandins (PGs), whereas omega-3 fats are converted to less inflammatory PGseicosanoids. Therefore, to enhance the effect of omega-3 fats it would seem prudent to increase consumption of omega-3 fats and reduce intake of omega-6 fats, for example by replacing sunflower oils/margarines with olive oil/margarine or rapeseed oil. Vegetarians can get omega-3 fats from flaxseed oils, starflower and borage oils although research suggests that they are not as effective at relieving joint symptoms.

Fruits, Vegetables and Antioxidants

Antioxidants are of particular interest. These phytochemicals are found extensively in fruits and vegetables, particularly brightly coloured varieties such as oranges, apricots, mangos, carrots, peppers/capsicums, and tomatoes.

Right: Brightly coloured fruit and vegetables contain antioxidants

The most common antioxidants are vitamins C, E and A, but there are many more, such as the carotenoids e.g. βb -carotene, b -β-cryptoxanthin, luteins and lycopenes, but many remain, as yet unidentified.

Antioxidants play a crucial role in our internal defence system protecting against harmful organisms, particularly damaging ‘free radical’ molecules. A diet rich in antioxidants may help to reduce the risk of developing RA and possibly dampen down the inflammatory response in established disease. However, this theory is based on evidence from epidemiological studies of diet and arthritis and is not supported by researchscientific trials of  using individual antioxidant supplements in patients with RA.

Vegetarian diets have been investigated by several research groups with four well-designed studies finding general benefits for patients with RA following a vegetarian diet compared to those on their usual diet. However, the reasons for this are as yet unclear.

The Mediterranean Diet

This way of eating is based on daily intakes of fresh fruits and vegetables, nuts, beans and pulses, olive oil, wholegrain cereals and regular oily fish and poultry consumption.

Thus, the diet contains omega-3 fats, olive oil, antioxidants, dairy products and unrefined carbohydrates. A recent study found significant clinical benefits in patients who followed a modified Mediterranean diet for 3 months compared with those who followed their usual diet.

The Mediterranean-type diet

Dairy products
Of particular dietary importance to people with RA is calcium intake, necessary for maintaining strong and healthy bones and reducing the risk of osteoporosis. Lower fat varieties of milk ie semi-skimmed or skimmed have the same calcium, if not more than, whole milk. If using soya milk or other alternatives, use calcium enriched products. Soya milk on ‘per se’ its own contains no calcium.

Watch your weight!
Excess weight is bad for joints and overall health. Little or no exercise will greatly increase the risk of weight gain if dietary intake is not altered accordingly, particularly as we get older. It is much more difficult to lose excess body weight once it’s on. So, if unable toaim to be more active, within your own limits take regular exercise, and monitor what you eat from time to timeto avoid gaining unwanted Kgs. iIt can be helpful is useful to keep a diet diary for a week or two which will help identify and spot when and why you eat where unnecessarily and what you think could be reduced y snacks or swapped for a less calorific foodcould be cut out.

Dietary supplements
Again there is little convincing evidence that dietary supplements influence the course of RA. Of course, some supplements work for some people and not others, and that’s great as long as money is not being spent on an unproven remedysupplements at the expense of a healthy diet.

Despite limited research evidence some individuals may still gain benefits from dietary change. However, if making major dietary changes it is advisable to have a dietary assessment by a registered dietictian. Referrals are usually made via GPs or hospital specialists.

References

1. Goldberg R J & Katz J.  A meta-analysis of the analgesic effects of omega-3 polyunsaturated fatty acid supplementation for inflammatory joint pain. Pain 2007; 129: 210-23
2. Pattison D J, Silman A J, Goodson N J, Lunt M, Bunn D, Luben R et al. Vitamin C and the risk of developing inflammatory polyarthritis: prospective nested case-control study.  Ann Rheum Dis 2004; 63: 843-7
3. Pattison D J, Symmons D P M, Lunt M, Welch A, Bingham S A, Day N E et al. Dietary b–cryptoxanthin and inflammatory polyarthritis: results from a population-based prospective study.  Am J Clin Nutr 2005; 82: 451-5
4. Pattison D J, Lunt M, Welch A, Bingham S A, Symmons D P M. Diet and Disability in Early Inflammatory Polyarthritis.  Rheumatology 2007; 46 supplement 1): i122
5. Canter P H, Wider B, Ernst E.  The antioxidant vitamins A, C, E and selenium   in the treatment of arthritis: a systematic review of randomized controlled trials. Rheumatology Advance Access published May 23, 2007; doi:10.1093/  rheumatology/kem116
6. Sköldstam L, Hagfors L, Johansson G. An experimental study of a Mediterranean diet intervention for patients with rheumatoid arthritis. Ann  Rheum Dis 2003; 62: 208-14