Artisan Bread Organic is a bakery in Whitstable in Kent that only uses organic and biodynamic ingredients: whole grain flours freshly milled on a traditonal stone mill every day, revitalised water, natural leaven and Seagreens seaweed to add calcium and nutrients to their breads. On separate millstones they grind naturally gluten-free flours to use in the breads that they make for dairy-free, wheat-free, gluten-free, salt-free, baker's yeast-free, blood group and geno type diets.

Ingrid Greenfield, who runs Artisan Bread, has always been vocally opposed to factory made bread, and is especially upset by factory made 'freefrom' bread as she maintains that no one whose health is compromised, is ever going to get well by eating manufactured foods that include additives, enzymes and manufacturing aids. She particuarly objects to xanthan gum, the additive that has transformed commercially manufactured gluten-free bread, as she maintains that gluten-free breads such as Genius are no better for the health of coeliacs and wheat intolerants than eating Mother's Pride. Her basic objection to xanthan gum is that it is a totally unnecessary manufactured additive, but she has also warned that it could, in itself, be an allergen. And now it looks as though she could be right.

Xanthan gum is an exopolysaccharide which is grown or fermented from the bacteria Xanthomonas campestris, the bacteria which cause black rot on cruciferous vegetables such as brassicas (cabbages, cauliflowers etc). The bacteria can be grown on corn, wheat, soya, whey or dairy products. After around four days the fermented 'broth' is pasteurised and then dried to make a powder. When liquid is added to a tiny amount of this powder it forms a thick viscous syrup which is invaluable not only in gluten-free baking (where it largely replaces the 'gluey' properties of gluten) but in a wide range of other food products such as salad dressings, ice creams, sauces, frozen foods and drinks. It was discovered by researchers at the USDA and first appeared in food products in the 1960s under the brand name Kelco.

Xanthan gum is both cheap and easy to make and has been a boon to the freefrom industry as it makes the whole business of baking 'gluten free' very much easier. However, as its use has spread so, inevitably, have problems arisen.

Whatever you may think about the very wide use of a gum derived from a cabbage-rotting bacterium in food manufacture, if you are highly allergic/intolerant to corn, wheat, soya or dairy you should be concerned about what medium the gum was grown on as it is possible that residual protein fractions from the growing medium may make it through into the gum. The problem here is that, as of now, it is almost impossible to discover what growing medium might have been used for any specific batch of gum and although corn is probably the most common, it is certainly not universal.

A post from Wendy Cohan on celiac.com suggests that xanthan gum itself can cause an allergic reaction which is very similar to a coeliac reaction, except without the pain e.g. bloating, gas and diarrhoea. (She advises using guar gum instead, a more natural product in that it is just the ground starchy part of the guar bean.) However, xanthan gum is an efficient laxative according to a 1993 study from the University of Sheffield, so it might well be responsible for gassy and diarrhoea symptoms. There is also the possibility that, since it is a fermented product, it could affect someone who was super-sensitive to mould.

So, it looks as though that could be another whole range of products off the menu for those who are particularly sensitive. (For more on supersensitivity to gluten see Micki Rose's Truly Gluten Free site.) Indeed, there is an argument to suggest that even if you do not have any overt symptoms (silent coeliac disease, for example), that extra fraction of protein or allergen could be doing you harm even though you are not aware of it.

The way forward? Well, xanthan gum is far too useful a product for freefrom cooks and the freefrom food industry to give up without a struggle. So maybe the first move would be for xanthan gum manufacturers to specify the substrate on which the bacterium was grown so that at least the allergic/intolerant consumer can choose only to eat products using a xanthan gum grown on a base that they can tolerate.

A site visitor subsequently wrote in as follows:
As you say, xanthan gum is widely used in food, but I don't think that you mentioned that it is also widely used in topical applications too. I try to avoid all products, both topical and ingestible, that contain derivatives from my allergen grain, but on occasions when I have accidentally used a topical product which contains xanthan gum I have broken out in a rash and red blotches, which can also be very itchy. Another time, I used a hand cream and almost immediately got very wheezy and tight chested – the trigger could only have been the cream, as I had not been exposed to another else. On examining the ingredients, it contained xanthan gum. All of these occasions were 'blind', that is to say that I did not know that xanthan gum was in the ingredients and therefore assumed that they were safe for me to use and was not expecting any adverse reaction.

First published in 2012

• If this article was of interest you will find many other articles on unlikely allergies and allergy connections here – and links to many relevant research studies here.

• For more on the more 'mainstream' allergies check in to our 'allergy and intolerance home page' – and for ideas on alternative foods go here.

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