Could it be yeast rather than wheat that is the cause of so many cases of apparent food intolerance?

Mary Roe is a nurse and a food intolerance tester who has worked for many years with eczematous and intolerant patients. Click here for her article on treating eczema with diet. She ask whether the current accusatory finger being pointed at wheat should not, instead, be pointed at yeast?

I was interested to belatedly read your article of October last year, ’When is a wheat allergy not a wheat allergy?. I suspect that there are, as you suggest, many people who are just eating too much of the grain, but I also suspect that there are other reasons.

I am a registered nurse who for the last 15 years has been a food intolerance tester. I have always wondered about the numbers of people who consider that they have a wheat intolerance, in my view fuelled by the plethora of magazine articles which always suggest removing wheat from the diet in order to reduce symptoms, especially those of IBS. I have a few theories as to why this might be the case.

You mentioned in your article the FAIR research. (Basic allergy training for practice nurses which involved putting self diagnosed food intolerants on a 'healthy eating' diet for two weeks, followed by, if their symptoms had not resolved, a wheat and dairy-free diet.)

I was also really heartened to read online that following on from this research the Royal College of Nursing is starting training courses for nurses in mentoring and advising patients on food intolerance, as I know how great a part food intolerance plays in many chronic symptoms.  It is fantastic also to see evidence of main stream medicine taking an interest in food intolerance.  However I was surprised to find that wheat is seen as one of the two main problem foods.

Is wheat really the main problem?

In 2003 I conducted a survey of the intolerances of 364 clients.  In percentage terms the results were as follows:

80%   Cows milk products
27%   Orange
21%   Cocoa
19%   All cheeses and yogurts
17%   Coffee
14%   Yeast
14%   Tea
12%   Aspartame
11%   Malt
10%   Monosodium glutamate
5%     Hydrolysed vegetable protein
3%     Goats and sheeps milk products
3%     Wheat

Key symptoms were:
back pain
behaviour problems
joint pain
recurrent infections
sleep problems
tummy aches

I started another study in December, one which I hope to conclude this summer.

I find that a lot of my clients suspect that their problem is wheat, but when I test them, we find that the main problem is yeast. I would like to explain why I think that the perceived wisdom regarding wheat intolerance has come about, and why, if people during the exclusion phase of the FAIR diet avoid wheat rather than yeast, the symptomatic relief that they experience will be much lower than it might be.

Yeast – not wheat

I always find that when yeast is a problem, cheese and yogurt are too. There also seems to be a link between yeast and malt. I do not have precise figures yet, but suspect that around 15% of people have a ‘spin-off’ intolerance to malt.

So what might happen is that a person thinks that wheat is a problem because they get symptoms after eating bread, pizza, pasta, some biscuits and some breakfast cereals – all of which contain wheat.

But – all of the these foods contain yeast or malt, and / or might be eaten with cheese or yogurt.

• Bread contains yeast
• Pizza contains yeast and cheese
• Pasta may be with a cheese sauce, or have cheese grated onto it.
• Sweet and savoury biscuits may contain malt. Savoury biscuits may contain yeast, and may be eaten with cheese.
• Many breakfast cereals contain malt.  Or the person may be reacting to milk rather than the cereal.

If a person is advised to avoid wheat, when the problem is actually yeast, they are unlikely to see symptomatic improvement if:

• they use breads made from other grains than wheat, as these will still contain yeast;
• they still eat cheese with alternative pastas;
• there is malt in any alternative crispbreads or breakfast cereals that they eat;
• they use any alternative cheeses or yogurts in order to avoid cows milk products;
• if they consume malt vinegar.

They will therefore not get better

With regard to the FAIR study, results must have shown that in the second phase (excluding wheat and dairy), significant numbers of people felt better when excluding cows milk products and wheat. 

I suspect that because there is such a high percentage of people who react to cow's milk products (see figures above) the people who feel better on a wheat and cow's milk-free diet are mainly seeing benefit because they are not eating dairy products, and perhaps because they are not eating bread.  

Might the results be even better if the suggestion to patients was that their diet should be milk and yeast free?


The ‘gold standard’ in food intolerance has always been the exclusion diet.

Many books, backed up by research studies (notably the ones by Professor John Hunter) that are still being quoted in many books nearly 30 years later, state that wheat is a very common intolerance. In Professor Hunter's study people were advised to introduce yeast in the form of brewers yeast tablets.

I routinely test brewers yeast, and very rarely find that clients of mine who have a yeast intolerance also have one to brewers yeast.  I suggest that those people who introduced yeast in the form of brewers yeast will have thought that yeast was not a problem to them. 

Then when they had the opportunity to try out wheat, they may have tried it out in the form of bread, as yeast had been proven all right for them.  On reacting to bread, they will have considered that the problem was wheat when in fact it was bakers yeast.

You can find Mary at

First published in May 2012


October 2012

In response to a reader's question about yeast intolerance Mary wrote the following:

I am happy to explain my theory, which was initially just an anecdotal hunch between 15 and 18 years ago, but is now is based on on going analysis of my results starting in 2001/2, when out of 364 clients, there were 50 who were yeast intolerant. 49 of those were intolerant of cheeses and yogurt also.

So far this year, I have seen 204 clients, of whom 43 have been yeast intolerant, 42 of whom were also intolerant of cheese and yogurt. So my theory is just based on the analysis of my results. If, therefore, someone had a suspicion that they had a problem with yeast, and I were not able to test them [distance or financial constraints], I would always advise them to avoid all cheeses [cows, sheeps, goats, buffalo, soya, cottage, mascarpone, ricotta etc etc], all yogurts [cows sheeps, goats and soya] and creme fraiche. If they use soured cream I would suggest that they sour it themselves with lemon juice.

With regard to brewers yeast, I do test that routinely with my clients and rarely find that it is a problem. So my supposition is that the culprit is bakers yeast, and that natural yeasts, eg in alcohol, are not a problem for most people. If a client does have a sensitivity to any alcohol, it is usually their favourite brand of beer, lager or wine, especially if they drink it daily. I can test all of these things, so can be absolutely definite in my advice to a client.

I am confident in my ability because I know that a lot of key symptoms in my clients have percentage improvements of above 85%, and many above 92%. Please see my website for details.


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