Diet & Rheumatoid Arthritis

Dr Dorothy J Pattison PhD RD, Peer reviewed and updated by
Victoria Mann Specialist Dietitian MSc RD

Original article: 10/10/2007
Reviewed: 11/01/2014
Next review due: 11/01/2017

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. They have been seen to slow the development of RA in animal models and reduce disease severity. In a review of 23 studies a fairly consistent but modest benefit was seen on joint swelling and pain, duration of morning stiffness, global assessment of pain and disease activity, and use of NSAIDs in patients taking fish oils, 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. It can take up to 3 months to see the benefits of supplements therefore perseverance is important.

A recent publication concluded that the amount of omega-3 fats necessary to gain symptomatic benefit is around 3g/day (i.e. total EPA + DHA). The amount of EPA + DHA varies greatly between fish oil supplements. For example a typical 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 defined. Omega 3 fats from plant sources e.g. linseed and evening primrose have a weaker effect on inflammation and are of limited benefit.

Note: If taking fish oil supplements you should 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. Fish oils can interact with some medications e.g. Warfarin. Always seek medical advice before starting supplements.


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.

Whilst omega 3 fats reduce inflammation omega 6 fats may increase inflammation. It is therefore important for you to reduce omega 6 fats in the diet whilst increasing omega 3. 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). Omega-6 fats are found mainly in foods such as sunflower oils and margarines, seeds and nuts (though as you will see later on in the article, nuts are commonly taken as part of the Mediterranean diet, as the Mediterranean diet represents an overall healthy way of eating but might therefore need minor alterations).

Reducing inflammation is not just important for improving your joint pain and stiffness but it will also reduce your risk of heart disease, which people with RA are at increased risk of.

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.

As part of the inflammation associated with RA substances called free radicals are produced which can lead to damage in the body.

Antioxidants found in brightly coloured fruit and vegetables can help limit the damage that these do. They can also have an anti inflammatory effect. This is important for both improving your RA symptoms and reducing your risk of heart disease.

Antioxidants and the vitamins and minerals found in fruit and vegetables also support the immune system, which is of particular importance when taking many of the immune suppressing drugs used to treat RA.

Fruit and vegetables are also low in calories and can help support a healthy diet and weight loss.

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 (ie studies that look at how often/how common disease is in large populations) and is not supported by scientific 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. It is important to ensure that the resulting diet is well balanced. Other diets such as fasting and very restricted diets have shown benefits, however they are not sustainable and carry significant health risks. Also, when returning to a normal diet, symptoms quickly re-appeared. 

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. They had reduced swollen and tender joints, reduced duration of morning stiffness and improved general wellbeing. This is generally a healthy way to eat and will have many health benefits beyond improving RA such as reducing the risk of some cancers and heart disease.  

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. This is particularly important if you have ever been treated with steroids as these impair calcium absorption. Lower fat varieties of milk i.e. 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 ‘per se’ on its own contains no calcium. Vitamin D is needed to help the body absorb calcium. We get the majority of this through exposure to the sun. Small amounts come from the diet e.g. oily fish, fortified breakfast cereal and margarine. For those with little exposure to the sun or increased requirements, a supplement may be needed e.g. Adcal D3/ Calcichew. Speak to your GP or rheumatology team for more information.  

Watch your weight!

Excess weight is bad for joints and overall health. Because of the way our joints work the pressure on your knee joint is 5-6 times your body weight when you walk. If you are overweight even small amounts of weight loss can therefore have a big impact.  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 has been gained. So, if you are unable to aim to be more active, within your own limits take regular exercise, and monitor what you eat from time to time, to avoid gaining unwanted lbs or kgs. It can be helpful and is useful to keep a diet diary for a week or two which will help identify and spot when and why you eat where unnecessary and what you think could be reduced.  Snacks could be cut out or swapped for a less calorific food.

Being a healthy weight is essential. If you are overweight you are putting excess pressure on your joints and may increase levels of inflammation. Conversely if you are underweight there may not be enough muscle to help support your joints. You should aim to be a Body Mass Index (BMI) of 20-25kg/m2. Use a BMI calculator online or ask your GP to calculate this. Some treatments such as steroids can increase your appetite, it is therefore important to always consider what you are eating.

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 remedies at the expense of a healthy diet. Some supplements may be prescribed by your specialist team/GP e.g. folic acid if you are taking methotrexate and calcium and vitamin D if you are taking steroids. It is important that you take these supplements as they are to combat the side effects of medications. Always follow advice given by healthcare professionals.

Food safety
People with RA often have reduced immune function due to medications- particularly the newer ‘biologics’. This may increase your risk of infection. Following these simple tips will help reduce your risk of food poisoning/infection:
  • Always wash your hands before preparing food
  • Use an anti-bacterial spray in the kitchen 
  • Check the temperature of your fridge
  • Always check ‘use by dates’ 
  • Check food is well-cooked throughout before eating
  • Avoid meat pâté
  • Avoid blue vein (Stilton, Danish Blue) & mould ripened cheeses (Camembert, Brie)
  • Avoid raw egg and raw egg products
  • Avoid unpasteurised foods
  • Always wash fruit and vegetables before eating

Despite limited 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 dietician. Referrals are usually made via GPs or hospital specialists.

Further reading

Arthritis Research UK information on 'Diet & Arthritis'

References available on request


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