Are everyday foods making you sick?

Are everyday foods making you sick?
Our food is made up of chemicals. And when your body doesn’t feel quite right, it may be that you have a sensitivity to a particular chemical or group of chemicals.

Headaches? Sinus problems? Tummy pains? Hives? These are just some of the problems people sensitive to chemicals in food commonly report. But how do you know if your health issues are linked to chemicals in foods?

Consulting your doctor to rule out any medical conditions which could explain your symptoms is an essential first step. But if you suspect some foods may affect your symptoms or if you have a family history of sensitivity, investigating your diet could hold some answers.

The first thing most people think of when they think food chemicals are food additives such as colours, flavours and preservatives. And these can cause problems for some sensitive people, but natural chemicals in foods can be more problematic, spelling uncomfortable, painful or even debilitating symptoms.

Food sensitivity or intolerance is different to food allergy – an allergic reaction involves our immune system reacting to particular proteins in different foods. Allergy can be tested relatively easily (see ‘How do I find out if I’m affected?’ below). Food sensitivity, however, is a trickier prospect – working out which chemicals may be a problem for you and how much you can tolerate before you react takes time, perseverance and skilful guidance from a professional.

Common problem chemicals

If you’re allergic to a food protein, then you need to avoid just that type of food – for example, nuts or eggs. However, food chemicals are found in different concentrations across groups of sometimes very different foods – that’s why it can be difficult to spot problem foods. The most common chemicals that cause problems in food sensitive people are:


Found in many fruits and vegetables, some higher than others; also in nuts, honey, tea, coffee and wine and beer.


These come from the breakdown or fermentation of proteins. They are high in foods such as cheese, chocolate, wine and beer; some fruits and vegetables can be high in amines as well.


This is one building block of protein. It is found in MSG (additive 621), but it is also very high in ‘tasty/savoury’ foods such as tasty cheese, yeast extracts, soy sauce, gravies and tomato paste. Some fruit and vegetables are also very high in glutamate.

Food additives

If you are sensitive to natural food chemicals then you may also react to some food additives. The most likely problem additives for food sensitive people are colours (particularly artificial ones), preservatives (such as antioxidants, benzoates, and nitrates) and flavour enhancers (additives 620 to 635). Some flavourings may also cause a problem for some people.

Other things food-chemical-sensitive people may need to watch out for include perfumes and strong smells, components of cleaning products, cosmetics, medicines, toothpastes, soaps and deodorants.

Food labelling

Food additives are listed in the ingredient list of most packaged foods but if you are sensitive to food chemicals such as salicylates or amines, you will need to have a reliable list of ‘low-chemical’ foods to eat. Expert advice from a dietitian specialising in food intolerance is an important resource, although there are also other resources available (see ‘Useful resources’ below).

How do I find out if I’m affected?

There are many tests out there, some of which are very expensive. If you have an allergy, the only accurate form of diagnosis is in a medical setting using skin prick testing or blood allergy testing to detect allergen-specific antibodies called IgE.

There are several other types of test available such as cytotoxic testing, vega testing, kinesiology, radionics or hair analysis – but according to the Australasian Society of Clinical Immunology and Allergy (ASCIA), these are based on limited evidence and as such are not reliable (or recommended). If you have an intolerance, the only accurate way to pinpoint the offending chemical is to follow an elimination diet.

Elimination diets

Testing for food intolerance means carefully eliminating all possible suspects from your diet and then adding them back one at a time to check for reactions. There are no simple tests that can be done – instead you need to follow a low chemical diet (and possibly also one that removes other groups of foods, such as gluten or dairy, if there’s reason to suspect you might have problems with those, too). It can take months, but for many people improving their symptoms is worth the effort.

Following this low-chemical elimination diet means severely restricting the foods you eat, sometimes for many months while you see if symptoms disappear and then challenge your body with particular chemicals to see if they’re tolerated. Between each chemical challenge, you need to wait a week or more for symptoms to settle. All up the process can take months to carefully check and rule in or out the various likely suspects. For these reasons it’s important that you get expert guidance to keep your diet as balanced as possible, while systematically working though the process. Consult a specialist in this area.

The hay fever connection

In his book Allergies: New Zealand’s Growing Epidemic, Dr Vincent St Aubyn Crump explains that if you get hay fever, your immune system may also react to some fresh fruit, vegetables and nuts. These foods contain proteins which are similar in structure to proteins in pollen, so the immune system can confuse the proteins and start an allergic reaction. For most hay fever sufferers this shows up as Oral Allergy Syndrome which can cause itching or swelling of the lips, tongue and inside the mouth and throat. Note that heating fruit and vegetables generally destroys the allergens, so cooked or canned fruit and vegetables don’t usually affect sufferers.

People with a birch pollen allergy are most likely to react to apples, carrots, cherries, pears, peaches, plums, fennel, walnuts, potatoes and wheat. People with a grass allergy are most likely to react to melons, tomatoes, watermelon, oranges and wheat. And people with a pine pollen allergy may also react to pine nuts, while those with a hazel pollen allergy may react to hazelnuts.

Useful resources

  • Allergies: New Zealand’s Growing Epidemic by Dr Vincent St Aubyn Crump is an extremely useful guide to all kinds of allergies, their symptoms and management.
  • ASCIA’s website has resources and factsheets on allergy and allergy testing. Go to
  • For Allergy New Zealand, go to

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