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RPAH Elimination Diet: A Low-Food Chemical Approach

Food Chemical Elimination Diet

Food chemicals can play a role in a lot of conditions. Avoiding or limiting certain food chemicals could dramatically improve symptoms in some cases. In other cases, it might just be a frustrating and complex process undertaken for no reason.

We often think of food chemicals as things that are artificial or added to foods. But some relevant chemicals are naturally found in food as well. Just because something is “natural” does not mean it cannot cause symptoms.

As a generalisation, the stronger the flavour of the food, the higher its chemical content is likely to be.

It is also an area where the evidence can be relatively shaky at best. A lot of people who make strong claims about food chemicals causing X, Y and Z issues are often not necessarily the most evidence-based practitioners.

Outside of certain specific situations, the closest to an evidence-based approach appears to be The RPAH Elimination Diet.

Even this approach is not perfect. But it is based on over 20 years of research from the Royal Prince Alfred Hospital and Sydney University. While there arguably are still a lot of flaws in our understanding of this area, it seems like an appropriate option for specific situations.

What is the RPAH Elimination Diet?

RPAH Elimination Diet Process

The RPAH Elimination Diet goes by a few names. Another common name is The Failsafe Diet – which is the strict version of the RPAH Elimination Diet. This phrase is interchangeable with the Low Chemical Diagnostic Elimination Diet.

To give a clearer indication, FAILSAFE stands for Free of Additives and Low in Salicylates, Amines and Flavour Enhancers. Do not think about that too hard though because there seems to be an “I” missing.

It is an approach for handling food chemical intolerances. To be clear, this is for intolerances and not allergies which are separate.

The main chemicals that are restricted during the elimination phase of the diet are salicylates, amines, and glutamates. There is also a long list of additives that is excluded too.

In some cases, dairy and gluten are also excluded as well.

The Gold Standard Approach of the Diet

Phase One – Elimination Phase

Completely minimise food chemicals for this first phase. Ideally, this significantly reduces symptoms.

This phase can go for 2-6 weeks – but the typical approach is to do it until there are 5 days straight with minimal symptoms.

As a brief warning, sometimes symptoms get worse in the first few days before improving. Theoretically, this could be due to withdrawals from food chemicals.

RPAH Elimination Diet Withdrawal Symptoms

Phase Two – Re-Introduction Challenges

Individual challenge phases to identify which food chemicals contribute to your symptoms.

Phase Three – Modified Low Chemical Approach

After the challenges, you now know what chemicals do and do not cause symptoms. There are thresholds for symptoms and different combinations of foods could trigger symptoms. Because of this, there is still some trial and error, but it is significantly easier with the insight gathered earlier.

When Should It Be Utilised?

It is open to interpretation for when the RPAH Elimination Diet should be used.

Symptoms that potentially are related to food chemicals include:

  • Hives
  • Headaches
  • IBS symptoms
  • Sinus issues
  • Eczema
  • Fatigue
  • ADHD
  • Asthma
  • Nausea
  • Mouth ulcers

The list is even longer than that.

It is hard to identify whether food chemicals are the cause of those symptoms or other things.

Using IBS as an example. Most of the time IBS symptoms can be solved through approaches such as the low FODMAP diet or other IBS specific strategies completely unrelated to food chemicals.

I am aware of some dietitians who use the RPAH elimination diet as a treatment for IBS before even looking at FODMAPs though because they believe it is more effective than FODMAPs from what they have seen in practice. So arguably there is merit to it.

Since the RPAH Elimination Diet is restrictive and time-consuming, personally I think it makes sense to exclude other potentially easy wins first.

If you have struggled with symptoms for a long time and there are signs that make you think that it could be related to food chemicals, then it could be worth looking at.

What Are Salicylates, Glutamates and Amines?


Salicylates are natural chemicals produced by all plants for defence against insects, pests and microbial attacks.

Arguably, salicylates are one of the things people are referring to when they make statements like “plants have defence systems that are in place to discourage their consumption, as a survival mechanism.”

Some people use that as an argument for lower plant intake and higher meat intake.

But there is a spectrum for this. Not everybody gets noticeable symptoms from salicylates.

High levels of salicylates are found in many fruits, vegetables, nuts, herbs, spices, jams, honey, yeast extracts, mint, tea, coffee, juices, beer and wine.

This list, like the ones in this section below, is not comprehensive. For a thorough list (including additives) check out our resource on the topic to see what needs to be avoided during the elimination phase.

Biogenic Amines

Biogenic amines are found in both animal and plant foods. They act as neurotransmitters, hormones and inflammatory mediators.

Amines are found in increased levels as a result of protein breakdown due to bacterial action as foods age, or from high-temperature cooking, or from the ripening of fruits.

High levels of amines are found in some fish, cheeses, sauces, fruit juices, chocolate, jams, nuts, seeds and in some alcohols like beer and wine.


Glutamate is an amino acid that is found in most foods. Obviously, some foods have higher amounts than others though.

Aged, fermented or extensively cooked food will typically have higher levels of glutamate.

It is known for enhancing the flavour of food. Foods rich in natural glutamate include cheese, tomato, mushrooms, stock, soy sauce, meat extracts and yeast extracts. And obviously, these foods are often used as flavour enhancers in meals.

Monosodium Glutamate (MSG) is probably the most famous example of glutamate.

This is a bit of an area of controversy with the RPAH Elimination Diet. When you look at the research specifically done on MSG, it does not seem to be linked with symptoms such as headaches.

But there is a lot of anecdotal evidence linking it with symptoms. And there are a lot of reports of people who find they get symptoms from it when they re-introduce it specifically in the challenge phases, even if the research has not made a linkage consistently.

Beyond MSG though, glutamates as a group are a major part of the elimination diet.

Food Additives

The below list of food additives covers what to look out for on food labels during the elimination phase. They are the most likely to cause adverse reactions. Other additives not on this list are generally safe unless there is another specific issue.

They are listed by code but sometimes go by different names on food labels. One example of this is that propionates often go by the name “cultured” something e.g. cultured dextrose.

Food Additives RPAH Elimination Diet

Tolerance and Thresholds for Symptoms

A final thing to consider before going through the process of how the diet is laid out is that there are different tolerance levels and thresholds.


Tolerance changes over time.

For example, if you have a low intake of certain chemicals, your tolerance is usually lower than if you have a higher intake.

Tolerance can build over time with greater exposure. Although this problem overall would not really exist in a meaningful way if just increasing exposure was a simple solution to solving symptoms obviously.

Chemical Stacking

RPAH food chemical thresholds

Another thing to consider is the concept of chemical “stacking.”

You could tolerate one type of food in a specific amount with no symptoms. And you could tolerate another food in a specific amount with no symptoms. But adding them together could push you over the threshold.

Step 1: Elimination Diet

For the first phase of the diet, you completely minimise food chemicals. You avoid all the foods that are not listed as low food chemical on this list.

If you are not doing it as strictly, you could include moderate chemical foods.

This phase goes on for 2-6 weeks.

If this approach works for significantly reducing symptoms, it should be clear within this timeframe.

After 5 days of being symptom-free, or with significantly reduced symptoms, you can move to the next step.

Step 2: Challenge Phases

RPAH Challenge Phases

This step involves individually testing each food chemical.

Because of the threshold issue, you need to do washout phases between each test where you go low chemical again. You need to do this even after testing foods that did not appear to cause symptoms.

Foods are typically reintroduced in order of what is considered most important from a nutrition perspective.

If you eliminated wheat and dairy, they are typically reintroduced first.

The order following that is usually salicylates, amines, glutamates and then additives in that order.

To do the challenge phases, eat at least the amounts recommended in the chart below, for the duration recommended.

Keep going until symptoms develop or you reach the designated duration.

Stop if symptoms recur or worsen. Then return to the full elimination diet until symptoms settle.

Even if there is no reaction, wait at least 3 days before the next challenge to:

  1. See if there is a delayed reaction.
  2. Do a washout before the next challenge.

The process looks like this:

FoodQuantityLength of Challenge
1.Milk1-3 cups of milk.Seven days
2a.Wheat Flour1 cup plain cooked pasta and 12 water crackers.Three days, and if no reaction start 2b
2b.BreadContinue with pasta and water crackers. 4 slices of bread that do not contain propionates, whey, milk powder or vinegar.Seven days
3.SalicylatesChoose 6 foods from the list below and eat them each day of the challenge in any combination:
Fruit: 1 large Granny Smith apple, 1 50g stone fruit, fresh or canned, 1 mango, 1/4-1/2 rockmelon, 1 cup strawberries, 1 large slice watermelon.

Vegetables: 6-8 asparagus spears, 1/2-1 capsicum, 1 cup carrot, 1/2-1 cucumber, 1 cup pumpkin, 1 cup sweet potato, 1 medium zucchini.

Sweets: 1 tablespoon honey, 10 peppermints without colour.

Spices: 1 teaspoon cinnamon, 1 teaspoon curry powder.

Drinks: 150ml apple juice (unpreserved, sulphite free), 1 cup strong tea or peppermint tea.
Seven days
4.Amines2-3 bananas and 60-120g plain chocolate (dairy-free if needed).

The following amine-containing foods can also be eaten freely: cocoa powder and drinking chocolate, pawpaw, pork (but not ham or bacon which are preserved), tinned salmon, tinned sardines, tuna (fresh or tinned), mild yellow cheese (if dairy is allowed).
Seven days
5.Glutamates (MSG)4 tablespoons soy sauce. Parmesan cheese sprinkled liberally (glutamates and amines). 500ml chicken noodle packet soup (glutamates and salicylates).  

Because glutamates and amines are often found in the same foods, you only need to test MSG separately if you haven’t reacted to amines.
Three days (longer if needed)
6.Propionates (280-282)4 slices of preserved bread, crumpets, muffins, wraps or rolls containing propionates using the code alternative names mentioned above.Three days (longer if needed)
7.Sorbates (200-203)25g low fat spread with sorbate preservative (must not contain 160b colour annatto). 100g cottage cheese in tubs with sorbate on the label.Three days
8.Benzoates (210-218)1L lemonade preserved with benzoates (only do this if you did not react to salicylates or amines.Three days
9.Antioxidants (gallates 310-312 and butylates 319-321)3 tablespoons of any cooking oil with antioxidants.

Or consume any commercially cooked chips, fries, or crisps with antioxidants on the label.
Three days
10.Colours6 tablespoons 100s and 1000s cake decorating sprinkles. Avoid sprinkles made with natural colours.

Add the below number of drops to a glass of unpreserved lemonade or soda water and repeat 2-3 times a day. Try a different colour each day.

Yellow (102 & 124) – 10 drops.
Red (102 & 122) – 10 drops.
Green (102 & 142) – 5 drops.
Three days
11.Nitrites (249-252)If you had no reaction to amines, test nitrites to find out whether you can eat preserved meats. 120g of ham, bacon, or corned beef.Three days
12.Sulphites (220-228)Dried apricots (only if salicylates did not cause issues) or 6-8 dried pear halves preserved with 220-228 or sulphur dioxide.Three days

Step 3: Modified Low-Chemical Diet

In this final stage, you now can follow a modified low-chemical diet where you balance minimal symptoms with maximum food flexibility based on the challenge results.

You can add back all the foods containing chemicals that you did not react to. This is now your personal low food chemical diet.

Your threshold levels can change over time due to a combination of things. Exposure to chemicals can improve your tolerance. But things like stress or the flu could reduce your tolerance.

If you find yourself with serious symptoms again, it can make sense to go back to the full diet for a short period of time before liberalising things again.

There can be a lot of trial and error in this phase to find the best approach for you personally.

Gluten and Dairy

Gluten and dairy are interesting because technically they are fine on the elimination diet if they do not contain any of the other factors previously mentioned.

There is a huge overlap though. For example, bread often contains propionates. A lot of cheeses are high in amines.

Beyond that, there is the option to completely exclude gluten and dairy on the elimination diet.

Part of this is because these foods are often triggers for symptoms even if food chemicals are not the cause.

Around 24% of the people with IBS appear to get symptoms from fructans in wheat.

A large percentage of people have lactose intolerance too.

There are heaps of other potential explanations. A lot of people can have dairy and gluten without symptoms. But there are also a lot who do get symptoms from them.

If you either think or know that gluten or dairy causes issues, or you want to absolutely cover all your bases, dropping gluten and dairy is an option for the elimination phase.

Modifications in Severity of Elimination

Another option to consider is that you do not necessarily need to do the full strict version of this diet.

It is a hard, restrictive and time-consuming process.

Depending on the circumstances, you can just do a modified version of it.

One example of this that I use with some of my clients is allowing both low and moderate food chemicals rather than just low.

There is a massive difference in the food chemical content between high and moderate. Based on our list there is a 10-100x difference between high and moderate. And a 10x difference between moderate and low. So even this change is huge.

Another option is that if you have a good understanding of this diet, you can sometimes pinpoint individual causes.

For example, I have had clients find they react strongly to beer and wine but not gin and vodka. That is a clear red flag for food chemicals potentially being relevant which can be worth exploring. But it might not be worth doing the full diet. Small changes might be all that is necessary.


The more knowledge I have gained regarding food chemicals over the years, the more it seems like they are actually relevant for a relatively large portion of the population.

But that still leads back to the two main questions:

  1. How useful is the RPAH elimination diet?
  2. When should it be used?

From my perspective, the research is not necessarily overwhelmingly positive. This post from Diet vs Disease does a great job analysing the science.

There is research supporting it, but it is not like it solves all the problems listed earlier with a massive success rate. And there could be components included in it that are not necessary.

But if food chemicals are the issue, the RPAH elimination diet is a great cover-all solution to identify what the cause is.

Personally, even though I think it is relevant for a lot of people, I do not use it super frequently in practice. I only use it with a few clients here and there.

For people who get serious symptoms that they have had no luck in solving, it is likely worth a shot. If symptoms are mild and/or you have not investigated other options first, it is probably an option I would not utilise since it is such a difficult process. The trade-off is not always worth it.

By Aidan Muir

Aidan is a Brisbane based dietitian who prides himself on staying up-to-date with evidence-based approaches to dietetic intervention. He has long been interested in all things nutrition, particularly the effects of different dietary approaches on body composition and sports performance. Due to this passion, he has built up an extensive knowledge base and experience in multiple areas of nutrition and is able to help clients with a variety of conditions. One of Aidan’s main strengths is his ability to adapt plans based on the client's desires. By having such a thorough understanding of optimal nutrition for different situations he is able to develop detailed meal plans and guidance for clients that can contribute to improving the clients overall quality of life and performance. He offers services both in-person and online.