Food Intolerance & RPAH/failsafe Diet

How a Dietitian and Clinical Nutritionist Can Help with Food Chemical Intolerances

Another cause of abdominal discomfort and altered bowel habits is food intolerance or food chemical sensitivity. Food chemicals irritate the nerve endings in the body causing these uncomfortable symptoms as well as skin irritation, asthma, headaches or mood problems. Our accredited dietitians and nutritionists are trained in the RPAH food chemical elimination diet and will help you with implementing the elimination and re-challenge diet that is needed to diagnose food chemical sensitivity. Make an appointment now with a dietitian and clinical nutritionist in Melbourne at Everyday Nutrition to learn about food chemicals and their effect on your body.

What Are Food Chemicals?

Chemicals are found everywhere in nature, including in the food we eat and the water we drink. Some of these, like vitamins, contribute to maintaining good health, while others increase aroma and flavour and make food enjoyable. Some plants also contain chemicals that are poisonous to humans and we have learnt to avoid eating these.

Can Some Natural Food Chemicals Cause Unpleasant Symptoms?

Some people are more sensitive to these natural food chemicals and find when they eat large amounts of them, they experience distressing symptoms. The most common natural food chemicals that can cause unpleasant symptoms include:


Salicylates are naturally occurring in many fruits, vegetables, herbs, spices, tea, coffee, honey and mint flavours. They are more or less a natural pesticide that plants produce to protect themselves from predators or nature. Sometimes salicylates have a bitter flavour or make animals or insects feel unwell when they eat them. Fruits and vegetables are higher in salicylates when they are first picked or less ripe, and levels drop as they ripen. They are also present in higher amounts in the skin or outer layers.


Amines are produced as a result of protein break down. Foods like meat, cheese and fish increase in amines as they age or mature, and in fruits and vegetables as they ripen or ferment.


Glutamates are an amino acid and a part of all proteins. In foods they may be found attached to a protein or in their “free” form.  When they are found in their free form, they enhance the flavour in food. Foods rich in natural glutamates like cheese, tomato, mushrooms and meat/yeast extracts are often used to flavour cooking, and MSG (pure monosodium glutamate) is used as an additive in savoury snack foods, soups and Asian cooking.

Additives and preservatives

Additives and preservatives used in food processing can also trigger unpleasant symptoms. People who are sensitive to natural food chemicals are usually sensitive to one or more of the common food additives such as preservatives, artificial colours or flavours. An appointment with a dietitian and clinical nutritionist in Melbourne can help you pinpoint any particular additives or preservatives that might trigger an adverse reaction within the body.

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How do food chemicals trigger symptoms?

When foods that contain natural food chemicals are eaten, they are digested and absorbed normally. They do not trigger an allergic reaction or involve the immune system at all. Instead, reactions occur in sensitive people when food chemicals irritate nerve endings in different parts of the body – much in the same way that some people experience tougher side effects from medications than others.

Do people have different tolerance levels to food chemicals?

How much you can tolerate will vary depending on how sensitive you are, which can be determined with an appointment with a Dietitian and Accredited Nutritionist in Melbourne at Everyday Nutrition. Some people have a much lower tolerance threshold than others and will experience a reaction to smaller amounts. Others though will find that levels build up over a few days before their tolerance threshold is breeched and they experience symptoms.

Chronic or recurrent symptoms can occur when small amounts of high chemical foods are eaten regularly. When this happens, levels build up in your system gradually and specific triggers are not obvious.

What symptoms do they cause?

Symptoms vary in appearance and severity from person to person. Since they are systemic, they can occur throughout the body. The most common ones are:

  • Skin irritation like rashes, eczema or hives
  • Airway irritation like sinus or asthma
  • Nervous system irritation like headaches, fatigue, flu like aches and pains, moodiness or in children behavioural problems including ADHD.
  • Gastrointestinal irritation, including reflux, mouth ulcers, bloating, cramps, diarrhoea or constipation or both.

How do you know if you are sensitive?

Since the immune system is not involved, there are no reliable diagnostic tests and the only way to know for sure if a food is triggering your symptoms is through a strict elimination and structured re-challenge process. This can be a difficult process and there are many factors that could mislead results, so this is best done under the guidance of a dietitian and clinical nutritionist in Melbourne or a dietitian with expertise in food intolerances.
There are many tests that claim to diagnose food intolerances, but most are unreliable, expensive or both. You can read more about this at the Australasian Society of Clinical Immunology and Allergy here.
If you think that gluten or wheat may be contributing to your abdominal symptoms, it is important to be tested for Coeliac Disease. Your GP can request a blood test or refer you to a specialist for assessment. It is important to note that for a blood test or biopsy to accurately diagnose coeliac disease, you must be eating gluten regularly for at least 6 weeks prior to testing. If you are already following a gluten-free diet, you can request a gene test. While the gene test does not diagnose coeliac disease, it can exclude coeliac disease.

Onset of a food allergy in adults is rare, as allergies such as nuts and shellfish are most often diagnosed in childhood. If you are reacting to certain foods, you may have food intolerance.

If you have had a positive breath test to fructose or lactose malabsorption, it’s important to know this isn’t a diagnosis. You will still need to undergo the elimination and challenge phase of the low FODMAP diet to identify if these are triggering your symptoms.

Similarly, if you have had a negative test result, it is still important to seek help from an Accredited Practising Dietitian to determine if other FODMAPs (oligosaccharides or polyols) or other molecules in food are causing your symptoms.

Marnie and Joanna are gut health expert dietitians with the knowledge and skills to support you with personalised advice and solutions for managing all types of food intolerances, allergies and IBS. We consult privately in Melbourne’s inner South East and via Skype. To make an appointment or seek advice from an accredited practising dietitian accredited clinical nutritionist in Melbourne, you can call any of the consulting rooms directly or email us.