What to do when eating becomes intolerable

Food intolerance feature images

Do you constantly feel tired or bloated? Do you suffer from severe nausea, sinusitis and dark circles under your eyes? If you answered yes to any of these questions, a food intolerance might be your problem.

Food intolerance occurs when the digestive system is unable to produce the right quantity of enzymes or chemicals to digest a particular food or ingredient. This causes can include:

Enzyme deficiency

Food is broken down by enzymes and proteins produced by our own body, which are needed for the complete digestion of food.

Inadequate amount of these enzymes can cause some of the food (if not all) to remain in larger components, unable to pass into the blood stream from the small intestine.

This undigested food exerts osmotic effects and draws fluids and salts that are rapidly moving towards the large intestines into the gut. This leads to an elevated level of fluid and salt in the colon. This causes the naturally-residing bacteria to ferment the undigested food into acids like carbon dioxide, hydrogen and hydrogen sulphide, which manifests as flatulence.

Pharmacological effects

Food intolerance is likened to the side effects caused by drugs, but in this process the reactions occur with the chemicals found in foods, such as caffeine, salicylates and naturally occurring chemicals like histamines.

Another possible cause of food intolerance is the additives found in foods, in the form of sulphites, which are added to processed foods to give them a longer shelf life. They can also be found in fruit drinks and wine.

Drug interactions

Combinations of certain amine compounds in some foods and medications can also lead to food intolerance.

Toxic compounds

A number of foods contain naturally-occurring toxic compounds, which can interfere with the digestive system. For example, inadequately cooked kidney beans contain compounds called lectins that can cause a toxic effect on the blood and result in food intolerance.

The result reactions can be delayed by up to 48 hours or more, and the effects can be cumulative. Although not life threatening, the effects can have a major impact on your health.

Common food intolerances

  • Lactose intolerance results from a deficiency of the enzyme lactase, which is needed to digest the sugar in milk. At least one out of 10 people worldwide have this deficiency, which results in bloating, abdominal pain and often, diarrhoea when consuming milk.
  • A gluten intolerance is caused by an abnormal immune response to the major protein in wheat barley, rye and oats. This, at times, leads to Celiac disease.
  • Alcohol intolerance is another common enzyme-related deficiency, where a lack of aldehyde dehydrogenise results in an inability to break down alcohol. Drinking even small amounts can make susceptible people feel ill.
  • Fructose intolerance is a rare genetic disorder associated with fructose metabolism. This occurs due to a deficiency of the enzyme, aldolase B, which is needed to complete the conversion of partially converted fructose into glucose.
  • Additive intolerances to substances such as flavour enhancers like monosodium glutamate or preservatives used in food like MSG are also common.
  • A yeast intolerance is also very common. There are a wide variety of symptoms from yeast sensitivity, which include headaches, breathing problems, abdominal cramps, skin problems and mood swings.

Managing a food intolerance

Treatment is based on avoiding or reducing your intake of problem foods and treating symptoms when they arise.

An elimination diet is found to be the most accurate way of testing food sensitivities by nutritional medicine practitioners. All likely food problems are eliminated from the diet for a period of time. Once the symptoms being treated alleviate, foods are added back to the diet one at a time and a note is made of which foods cause a recurrence in symptoms.


  1. Eliminate all sources of wheat, as found in bread, pizza, pasta, pastry, biscuits, cakes and wheat-based breakfast cereals (i.e. in anything containing flour), as this is a common problem food.
  2. Eliminate milk, cheese and yoghurt from the diet, as dairy products are also a common problem.
  3. Eliminate foods that you consume frequently, say on four or more days a week. The more of a food you eat the more of a problem it is likely to be.
  4. Eliminate foods and drinks which you crave and things you think you can’t do without. We often feel we need foods that we are sensitive to.
  5. Eliminate foods and drinks that you suspect make you feel bad.

Author: Pedro van Gaalen

When he’s not writing about sport or health and fitness, Pedro is probably out training for his next marathon or ultra-marathon. He’s worked as a fitness professional and as a marketing and comms expert. He now combines his passions in his role as managing editor at Fitness magazine.

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