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Could a low-oxalate diet reduce the symptoms of fibromyalgia?

I recently wrote a couple of articles for the Daily Mail describing my experience of dietary management of fibromyalgia as ‘the GP who gave up fruit and veg to cure her aches and pains'.

During my career, I had sometimes met middle-aged, female patients suffering from a combination of widespread muscle aches and stiffness, chronic fatigue, poor sleep, restless or ‘tingly' legs, ‘brain fog, urinary frequency, irritable bowel and cold intolerance. They satisfied the criteria for fibromyalgia as the symptoms were widespread, blood tests were normal, and they had muscular tenderness.

As a 46-year-old, I also experienced all these symptoms for about two years – the fatigue and pain were so debilitating, I thought I might have to quit work. However, I discovered that I could eliminate all my symptoms by cutting out foods containing a little known chemical called oxalate. 

Oxalate is present in most plants, to a variable extent - it deters insects and pests from eating them, and sequesters calcium. Spinach, for example, contains 750mg per 100g. In fact, small amounts of oxalate are present in most ‘healthy' plant-based foods including vegetables, fruit (especially rhubarb), potatoes, carrots, beans, nuts, wheatgerm (wholemeal bread), tea, coffee, soya and chocolate.

It  is lethal at doses of around 400mg/kg – ingesting very high-oxalate plants can kill farm animals such as horses and cows. It is also a metabolite of several noxious chemicals, including anti-freeze, and the chemotherapy agent oxaliplatin (the side effects of which include leg cramps, jaw pain, paresthesia and cold hypersensitivity).

I would guess that dietary oxalate, normally degraded by bowel flora and expelled harmlessly, can sometimes be absorbed - perhaps due to increased bowel permeability, or a change in bowel flora, and hence reach organs, including muscles, brain, hypothalamus, and urinary system. Oxalate is known to disturb mitochondrial function. In this case, you can avoid it by restricting fruit/veg to low oxalate examples such as peas, cucumber, bananas, mushroom, onions, cauliflower, sweetcorn and melon - also dairy, meat, eggs, fish, rice and white bread. Since eliminating oxalate nine months ago, I have remained free of symptoms - and I was so impressed that I recommended the diet to patients who had similar complaints – and they all improved considerably.

I wanted to share my experience, but I felt that the diet was too controversial to be taken seriously by my peers. It is, after all, the exact opposite of what we have been recommending to our patients at every opportunity! Other doctors have, not surprisingly, been skeptical about my ideas.

I wrote about my experiences for the Daily Mail, because I wanted to express my ideas to the sufferers directly. The health section often describes various diets, some of which were almost as eccentric as mine, so I reasoned they would be open-minded about it.

My decision lead to a certain degree of ridicule and bemusement among fellow doctors – some suggested that it was a very unhealthy diet - even raising the risk of cancer, as fruit and veg are quite restricted. However, the editor was helpful and supportive – she correctly predicted that readers would be interested. She helped me with the style, and encouraged me to write the second article, which gives specific dietary advice, including how to have your ‘five a day'.

Since then, people from all over the country have responded, desperate to relieve the pain and debility, having tried painkillers, antidepressants and sleeping tablets, with no lasting relief. I have received numerous positive responses – one reader said: ‘I am feeling a lot better two weeks in. Just wanted to thank you for getting the information out there and sharing it. Without it I get the feeling I would still be suffering a lot more than I am at the moment. Simply having some energy back has been great and the aching is now far more manageable.' Others, diagnosed with fibromyalgia, but presumably with a different underlying aetiology, haven't improved, but no-one has reported that the diet made them feel worse.

Several theories have been suggested for fibromyalgia, but none proven. I think that some patients are ‘oxalate-absorbers', and are suffering from the effects of chronic low-grade oxalate poisoning. This explanation is compatible with the multi-system, symmetrical nature of the condition, the apparently random fluctuations, and the fact that routine blood tests are normal.

If a patient complains of gradually worsening muscle aches, profound fatigue, insomnia and poor concentration, and tests are normal, you could suggest a trial of the low oxalate diet. It would cost nothing, cause no harm, and any response should occur within three weeks – if it doesn't they are simply back to square one. If they do respond, as I did, their quality of life will improve immeasurably, and they won't be able to thank you enough.

Dr Clare Morrison is a GP in Havant, Hampshire


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