Natural food chemicals

Corn chipsThere are many natural chemicals present in our foods, including nutrients such as vitamin C as well as chemicals responsible for the aroma and flavour that we love in our foods. Natural food chemicals may also be poisonous to humans, which is why some plants are poisonous to eat. Sometimes we add extra chemicals to our foods as food additives, which may be artificial, or the same as natural food chemicals. Some natural food chemicals, in particular salicylates, amines and monosodium glutamate (MSG), can cause reactions in sensitive people, where they are often labeled food intolerances.
People with sensitivities to specific natural food chemicals may experience reactions including headaches, bowel irritation or upset, mouth ulcers, hives and sensations of being generally unwell when they eat certain foods. They have also been reported as causes of irritability and restlessness in children. The natural chemicals in foods can be as much of a problem for people who are sensitive to them as artificial food additives.

Adverse reactions to food chemicals

Approximately 1% of the population experience significant adverse reactions to natural food chemicals. Food intolerances are difficult to characterise, and hereditary components are yet to be defined. They are often worse in women of childbearing age and are usually lifelong.
People with food intolerances may experience either a constellation of symptoms, or a specific symptom, for example migraines triggered by amines. It is often difficult to determine what specific natural chemicals are causing the symptoms, as they are often present in many different foods. Keeping a food diary often helps to determine what you react to.

Common food intolerances

  • Asian foodSalicylates
    • Fruits, vegetables, nuts, herbs and spices, jams, honey, yeast extracts.
    • Tea, coffee, juices, beer, wines.
    • Peppermint flavouring.
    • Perfumes, scented toiletries, eucalyptus oils, some medications (including aspirin).
  • Amines
    • Cheese, chocolate, yeast extract, fish products, bananas, avocado, tomatoes, broad beans.
    • Wines, beer.
  • Monosodium glutamate (MSG)
    • Tomatoes, cheeses, mushrooms, stock cubes, sauces, meat extracts, yeast extracts.
    • As an additive in soups, sauces, Asian cooking, snack foods.

Different people react to different levels of natural food chemicals in different ways. People often have a threshold for symptoms, after which they will experience a reaction. For some people they will only need to ingest a small amount of a natural food chemical to trigger a reaction, and may experience frequent reactions, while other people need to ingest a large amount of the same chemical to trigger a reaction, and therefore only experience infrequent symptoms.
Because the same natural food chemicals are presenting in several different foods, people do not react to a single food, but rather it is the total level of ingestion of that particular chemical that is important in determining whether they experience an adverse reaction. It is therefore quite difficult to identify the substance that is problematic for a particular person.
Food intolerances can be difficult to treat as the specific components causing problems are difficult to identify, and it is often difficult to eliminate them from the diet. Trial and error is often recommended to try to identify foods that are more likely to cause symptoms. It is important to remember that buying organic foods will not help food intolerances caused by naturally occurring chemicals in foods, as organic foods contain the same level of these chemicals as food that is not organic.

More information

Nutrition For more information on nutrition, including information on types and composition of food, nutrition and people, conditions related to nutrition, and diets and recipes, as well as some useful videos and tools, see Nutrition.


  1. Sampson, H. 9. Food Allergy. J Allergy Clin Immunol. 2003; 111(2 Suppl): S40-7
  2. Swain, A. Soutter, V. Loblay, R. Friendly Food. 2002. Murdoch Books. Sydney

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