What is food intolerance, how is it diagnosed and what can be done about it?

Food intolerance is the name we give any adverse reaction to a food or food additive that is not caused by an allergy. It is the body’s metabolic reaction to various chemicals in food or drinks, to the extent that an adverse reaction occurs. While some of the symptoms of food allergy and intolerance may be similar, an allergy involves the immune system, while an intolerance does not.

Physical symptoms common to both intolerance and allergy include eczema, hives, rashes, anaphylaxis, dermatitis, hay fever, constantly running nose, sinus discomfort, ear aches, asthma, diarrhea, vomiting and constipation.

Physical symptoms usually not produced with allergy include headaches, migraine, irritable bowel syndrome (IBS), excess wind, reflux, colic, stomach aches, mouth ulcers, limb pains, lethargy/feeling hungover, fuzzy thinking, bad breath/body odour, car sickness and bedwetting.

Symptoms may also include ADHD, autism spectrum disorder, chronic fatigue, difficulty settling, restless sleep, nightmares and sleeplessness. Depending on the symptoms experienced, they might result in irritability, feeling touchy, or frequent mood changes.

Food sensitive people are those whose various symptoms improve when they use a diet that reduces a group of suspect food chemicals, which include food additive colour, flavour, most preservatives, natural salicylates and amines, and natural and added monosodium glutamate, as well as smells. Some people are sensitive to whole foods such as milk or wheat as well. An accredited practising dietitian (APD) can help your patients gradually work out their individual sensitivities and determine the best diet for them.

Those most likely people to respond to dietary investigation for food sensitivity include those with an atopic family history; those with another group of symptoms (migraine, headaches, irritable bowel syndrome, mouth ulcers, car sickness or limb pains); those with a family member who has adverse reaction to aspirin; those with an increased sensitivity to smell, both in food and in the environment; those with an increased sensitivity to taste; and those people who have seen a definite adverse reaction to a food or additive in the past. They may also have increased body odour or bad breath. They are less likely to have lifestyle disorders; for example, coronary heart disease, obesity, diabetes or high blood pressure.

At this time, the only way to know if someone is food sensitive is to run an elimination diet. As research develops, food sensitive people will benefit from the analysis of their genetic information. This will allow the best fit between genetic makeup, food present in the environment and individual preferences. Currently, using information from the family gives the most information available.

Food intolerance often runs in families. So when first investigating diet, it is important to fill out a family sensitivity history that shows the food intolerant symptoms present in different members. If the grandparent reacts to spice, the parent to chocolate, one child to additives and another to fruit juice, then this can help with investigation into the baby’s colic. It would be easier to understand if every family was the same, but food sensitivity does not happen that way. Many food sensitive people have more than one symptom, and their immediate family may have the same or different symptoms.

Food sensitivity is amazing. It is a multisystem disorder whereby an individual can have symptoms on their skin such as eczema, in their lungs such as asthma, and in their brain such as headaches. It is also interesting in that someone may have had reflux in infancy, ADHD problems mostly in school years, migraine in teenage years, hay fever in adulthood, and IBS in mid or later life.

It is interesting that symptoms can change over a person’s lifetime. One mother once said to me: “It is great to understand that my diarrhoea with milk in infancy, my headaches in my teens, especially when I ate away from home, and my IBS are all connected, and connected to the other symptoms my family has. It now all makes sense!”

Usually each person who suspects they have food intolerance has seen their symptoms come on or worsen after particular foods, even if it is not consistent. What is now known, from carefully collected information from many families using diet to manage their symptoms, is that it is wise to begin investigation by excluding all the known suspect chemicals. The common practice of excluding just additives or chocolate is unlikely to get the maximum benefit.

Not all food sensitivity symptoms and problem behaviours are due to food intolerance, some have other medical causes. Before concentrating on diet investigation, it is important that patients discuss symptoms with their doctor to eliminate medical causes for symptoms. Once the necessary medical tests have shown there are no medical issues to address, an APD can discuss diet.

Unfortunately, though, there is no test that shows who is food sensitive or what food chemicals they cannot tolerate. However, an APD can do what I call diet detective work to find out just what foods are a problem for each individual. Each person is different. An APD will help patients learn what they may have been excluding unnecessarily, and how to test foods carefully for tolerance so their personal diet can be as broad as possible.

Joan Breakey is an accredited practising Dietitian and author; more at foodintolerancepro.com. Find an APD via the Dietitians Association of Australia.

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