Last updated:29th September 2017

Diet and AS

When you have a long term medical condition such as AS it's important to make sure you have a healthy diet.

Key to a healthy diet are:

  • eating the right amount of food for how active you are
  • eating a range of foods to make sure you're getting a balanced diet

Maintaining a healthy weight

It is important you don't become overweight as this increases the burden on weight-bearing joints and can increase pain.

When you are walking, the hips, knees and ankles bear three to five times a person's total body weight. For every pound a person is overweight, 3 to 5 pounds of extra weight is added to each knee during walking. If you lost 10 pounds in  weight, 30 to 50 pounds of extra stress would be removed from the joints.

Healthy balanced diet

Eat at least 4 portions of vegetables (including at least 1 leafy green vegetable) every day, along with 2 portions of fruit.

As a child you might have been told to ‘eat your greens', but it's just as important to eat your reds, oranges, yellows, blues and purples, too. Scientists now know that many of the naturally occurring chemicals responsible for giving fruit and veg their bright colours actually help keep us healthy and free from disease.

Fruit and vegetables contain hundreds of colourful phytochemicals that act as antioxidants, which help to ‘mop up' potentially harmful molecules called free radicals before they get a chance to damage cells.

All those different colours will add plenty of flavours and textures to dishes, making meals not just more healthy, but more enjoyable and satisfying.

Also add:

Protein in the form of fish, beans, pulses, nuts, eggs and meat (not too much).

Calcium for bone health. You need around 700mg a day - equivalent to 200ml semi-skimmed milk, a 150g pot of low-fat yogurt and a small matchbox sized piece of cheese.

Don't forget starchy foods but try to choose wholegrain or wholemeal varieties, such as brown rice, wholewheat pasta and brown wholemeal bread. They contain more fibre and usually more vitamins and minerals than white varieties.

Omega-3 fatty acids 

Omega-3 polyunsaturated fatty acids have been shown to help some people with AS. 

Omega-3 fatty acids exist in two forms:

  • long-chain forms are found in higher levels in oily fish, e.g. pilchards, sardines, mackerel, salmon.
  • short-chain forms are found in rapeseed oil, flaxseed oil and walnuts.

Research suggests you need at least 2.7 g a day of the long-chain omega-3 fatty acids. Eating two portions of fish a week would only give you about 0.45 g per day, so you may want to take a supplement to reach the full amount. You can buy supplements from health food shops and some chemists, either in liquid forms or as capsules.

They act quite slowly so you'd need to give them at least a 3 month trial.

 High doses of omega-3 can give you mild stomach upsets 

 Don't confuse fish body oil with fish liver oil (e.g. cod liver oil and halibut liver oil). It’s not safe to take fish liver oils in the large doses recommended for arthritis because of the risk of overdosing with vitamin A. This is particularly important for pregnant women, or women who might become pregnant, because vitamin A can harm the unborn baby.

Trying a change in diet

Trying to make sense of nutrition and your condition can sometimes be difficult. You may find it helpful to talk your dietary needs through with a nutritionist. You can find a nutritionist in your area at the Nutritionist Resource website

 Don't make any huge changes to your diet until you have spoken to a dietitian.

Look at diet claims carefully

You should be suspicious of any diet that claims to treat or cure AS. If such a diet existed, GPs and rheumatologists would know about it and would be recommending it to you. If you are tempted to try a diet, do discuss your plan with your GP or rheumatology team  to help ensure that trying the diet will not cause health problems.  For example some diets can be deficient in calcium which you need for healthy bones.

Does the diet:

  • Eliminate any group of foods
  • Allow only a few food types
  • Require you to buy special products
  • Have potentially harmful effects
  • Provide scientific evidence to back its claims, rather than personal testimonies to support it

The low starch diet

This diet is based on research by Dr. Alan Ebringer, Professor of Immunology at King's College London. He is the lead figure in a group of researchers who have been working on the theory that some types of klebsiella bacteria in the gut of people with AS are involved in triggering the disease process via a complex immune response.

In 1996, in a paper supporting his theory, Dr. Ebringer published the chart of one of the patients that he had been following over a period of time. The patient's erythrocyte sedimentation rate (ESR) showed a clear decline over the time he had followed the diet (1983-1995). ESR is a measure of inflammation and Dr. Ebringer believes that the lowering of the patient's ESR demonstrated the success of this diet.

However, it is recognised that ESR levels in AS are not necessarily indicative of a person's actual symptoms. Some people with high ESR can experience little pain and stiffness, whereas people with low ESR might conversely be in a lot of pain and be very stiff.

Some people with AS have told us they have had a good experience with the low starch diet whereas others have found no benefit.

It is difficult to research into diet. When new medicines are tested the researchers might give one group the new medicine and another group a dummy or placebo medicine. Even the doctors treating the patients in the medical trial might not be told which patients are taking the trial medicine and which the dummy medicine so that this knowledge does not influence the results. This is known as a double blind trial. We know from research that double blind trials, in which neither the patient, nor the observer knows which treatment has been given, is the best way to show if a treatment actually works.

However, when researchers experiment with diet and try to look at how diet can influence disease, it is impossible to carry out certain research protocols such as using controls or dummy treatments. Neither the person eating the diet nor the person taking measurements after the diet can be blinded as to which diet has been used. It's also not possible to confirm that someone is sticking rigidly to the diet without any lapses.

For this reason NASS can neither give its sanction nor refute the hypothesis that the low starch diet will help patients with AS. It remains a hotly debated subject among doctors. We do however offer the main principles below. It is always important to check with your doctor or member of the rheumatology team before trying any new diet.





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