Food intolerance myths & food intolerance facts

Baffled by all the different opinions on food intolerance? An hour researching this topic online can leave you feeling very confused indeed.

Remarkably few people have read the scientific research papers on intolerance to foods (more correctly called idiopathic food intolerance), but this doesn’t stop them having an opinion. There are more myths about food intolerance than about the Yeti. Some of these myths come from alternative websites run by people who mean well but have little or no medical knowledge. Some come from companies selling tests or products. And some come from the orthodox medical establishment which is not familiar with the scientific evidence either, and is generally dismissive of food intolerance.

The Complete Guide to Food Allergy and Intolerance is written by two people who have read all the scientific evidence about food allergy, sensitivity and intolerance: Professor Jonathan Brostoff, who has been successfully treating patients with food intolerance for over 30 years, and Linda Gamlin, a science writer who has herself suffered (and recovered from) food intolerance.

A dozen myths about food intolerance–
and the facts about each

Myth 1

“Untreated food intolerance can lead to heart disease and cancer.”

This alarmist story is being put about by people trying to sell a simplified (and unlikely-to-work) form of dietary diagnosis for food intolerance. It just isn’t true. The only small grain of truth here is that coeliac disease, if untreated, increases the risk of some kinds of bowel cancer. But coeliac disease is not the same thing as intolerance to food: the two are very different. There is no known link between food intolerance and cancer, nor between heart disease and food intolerance.

Myth 2

“People develop intolerances to foods because they produce high levels of IgG antibodies against those foods.”

There is no evidence for this, except possibly in some babies with some forms of food sensitivity – but even in such babies the patterns of IgG response to food are rarely consistent. What scientific research does show is that having food-specific IgG antibodies in our blood is a perfectly normal response. (Unlike producing IgE antibodies against foods, which can lead to classical food allergy.) In general, the more we eat of a food, the more IgG we produce against it. You can read the full evidence about food-specific IgG antibodies and food intolerance in The Complete Guide to Food Allergy and Intolerance.

Myth 3

“You can diagnose food intolerances by cutting out one food at a time and seeing if you get better.”

GPs (family doctors) often recommend this approach, but it doesn’t work unless you are intolerant of just one food – a few people are, but most people are intolerant of two or more foods. You have to cut them all out at once to see any improvement. Doctors who specialise in the treatment of food intolerance have developed elimination diets for diagnosing food intolerances. This is a method that reliably works for the majority of people with food intolerances.

How the words are used

There are no universally agreed definitions for terms such as ‘food intolerance’, ‘food allergy’ and ‘food sensitivity’, which adds to the muddle and controversy in this area. Often the definition being used isn’t stated clearly, and can even vary from one section of a book, or page of a website, to another. This can be very confusing.

The Complete Guide to Food Allergy and Intolerance states clearly what is meant by the terms it uses, and it sticks to those definitions.

Myth 4

“You can diagnose food intolerances by keeping a diary of what you eat and how you feel.”

Doctors who don’t understand food intolerance sometimes suggest this approach. And some alternative websites now recommend it (see above). It doesn’t work in most cases, because people tend to be sensitive to foods they eat every day, often several times a day. Symptoms of food intolerance are delayed, coming on hours, or even days, after eating the food. This means that the symptoms from one meal run into the symptoms from another meal. If you are intolerant to two or more foods (and many people with food intolerance are) you haven’t a hope of picking out the specific reactions from a diary. That is why you need to follow an elimination diet to diagnose food intolerance.

Myth 5

“There are only four types of food intolerance: to gluten, to milk, to yeast and to fructose.”

In fact you can develop food intolerance to almost any food. Commonly eaten foods such as milk are most likely to cause problems, but you can also be intolerant to a food you only eat occasionally. Some people are intolerant to ten or more foods. This particular myth comes from those trying to sell a over-simplified view of food intolerance, linked to a form of food-diary diagnosis. This system of diagnosis may work for a few people but won’t work for most with food intolerance. You can learn more about reliable and effective food intolerance diagnosis from The Complete Guide to Food Allergy and Intolerance. The book provides a truly effective, detailed, step-by-step guidance to diagnosing your own food intolerances.

Myth 6

“All milk intolerance is due to lactose.”

This is a common mistake. The fact is that some patients with milk intolerance are reacting to the proteins in the milk, rather than the lactose. And some people react to both – in other words, they have lactose intolerance, but also react to milk proteins.

Myth 7

“All wheat intolerance is due to gluten.”

Another widespread mistake. In fact there are other constituents of wheat that can cause intolerance reactions, apart from gluten. If you react to one of these, you may only have to avoid wheat, not rye and barley as well, whereas people with coeliac disease or gluten intolerance must avoid all of these grains.

Myth 8

“If you are intolerant to a food you have to avoid even the smallest trace of it.”

This myth tends to arise among people who don’t understand that food intolerances are very different from food allergies. With classical food allergy (‘true food allergy’), even a tiny trace of the offending food can cause a severe reaction by the immune system. Because food intolerance doesn’t involve this kind of immune reaction, people who are intolerant to foods can usually tolerate small amounts. (During an elimination diet, however, you must avoid every trace to get a clear result.)

Myth 9

“Food intolerance can be treated by taking enzymes.”

Selling enzyme treatments is a money-spinner for some. Treatment with lactase enzyme can be useful for lactose intolerance (as long as you use the enzyme in the right way), but most food intolerances are not caused by major enzyme deficiencies, so they can’t be treated with enzymes. Even where an enzyme deficiency is the source of a food problem, an enzyme treatment won’t necessarily work – learn more in The Complete Guide to Food Allergy and Intolerance.

Myth 10

“Someone with food intolerance can never eat the offending foods again.”

This mistaken idea tends to come about when people don’t understand the difference between food intolerances and food allergies. In fact, most people who are food-intolerant to get over the problem eventually, as long as they avoid the food for a time. But they do need to be careful with their diet in future – learn more from The Complete Guide to Food Allergy and Intolerance.

Myth 11

“All or most food intolerance is due to enzyme deficiencies.”

This isn’t so much a myth as a question of how the words are used. Some orthodox doctors and medical organisations who are sceptical about the existence of food intolerance sidestep the issue entirely by redefining ‘food intolerance’ so that it just means lactose intolerance, sucrose intolerance and other straightforward enzyme-deficiency conditions. This verbal manouevre – taking the term ‘food intolerance’ and using it in their own very restricted sense - allows them to duck the whole question of idiopathic food intolerance. This is the kind of food intolerance that lies behind symptoms such as migraine, IBS, and unexplained joint pain. Idiopathic food intolerance is probably a result of many different things going wrong, not just one thing, but nobody really knows as yet. Although unidentified minor enzyme deficiencies might play some part in causing idiopathic food intolerance, they are not the sole cause.

Myth 12

“Food intolerances are very rare.”

This is a common view among highly orthodox doctors who ‘don’t believe’ in food intolerance. They consider that most people who think they have food intolerance are imagining it, or are suffering from psychosomatic symptoms (unrecognised psychological problems that cause genuine physical symptoms). Nobody knows exactly how common food intolerance might be: no studies that might answer this question have been carried out. But there are good studies of the frequency of food intolerance/food sensitivity in atopic eczema, in IBS, in rheumatoid arthritis, and in severe childhood migraine. They show that food intolerance is a common cause of symptoms in all these conditions. All these studies are described in The Complete Guide to Food Allergy and Intolerance.

Order a copy of The Complete Guide to Food Allergy and Intolerance