The Royal Prince Alfred Hospital (RPAH) diet, frequently and sometimes confusingly referred to as the 'Prince Alfred diet', is a diagnostic and therapeutic elimination diet designed to identify food chemical sensitivities. It is not a lifestyle diet for the general public but a clinical tool used under the supervision of a healthcare professional, typically a dietitian, to pinpoint triggers for persistent symptoms. Also known by the acronym FAILSAFE (Free of Additives and Low in Salicylates, Amines and Flavour Enhancers), this diet focuses on natural food chemicals that can cause adverse reactions in sensitive individuals, as opposed to true allergies.
The RPAH Diet: A Three-Phase Protocol
The diagnostic process of the RPAH diet is highly structured and comprises three distinct steps. It requires discipline and guidance to ensure accuracy and nutritional adequacy.
- Phase 1: The Elimination Diet. This initial phase is highly restrictive and typically lasts for two to six weeks. The goal is to remove all major food chemical sources—salicylates, amines, glutamates, and certain food additives—from the diet. Other potential irritants like gluten and dairy might also be eliminated based on the individual's symptom history. The aim is to achieve a symptom-free baseline for at least five consecutive days. While some people may experience a temporary worsening of symptoms (known as 'withdrawals') before improvement, it is crucial to stay on track during this period.
- Phase 2: Food Challenges. Once a symptom-free baseline is established, the challenging phase begins. Food groups containing the eliminated chemicals are reintroduced one by one, in specific doses, to observe any potential reactions. Each food chemical group (e.g., salicylates, then amines) is tested individually over a short period. This systematic process helps identify which specific food chemicals are causing the adverse effects. Symptom-tracking is vital during this phase to accurately pinpoint triggers.
- Phase 3: The Modified Low-Chemical Diet. Following the challenges, the individual and their dietitian work to create a personalized, modified diet. This plan restricts only the identified trigger chemicals while reintroducing all other previously eliminated 'safe' foods. The final step is to find an individual's 'threshold' for the problematic chemicals—the amount they can consume without triggering symptoms. This is not a permanent, complete avoidance diet but a managed approach to minimize symptom flare-ups.
Targeted Food Chemicals and Additives
The RPAH diet primarily focuses on four groups of compounds known to cause issues for some sensitive individuals. These are different from the allergens targeted by traditional allergy testing or the fermentable carbohydrates addressed by the low-FODMAP diet.
- Salicylates: These are natural chemicals found in a wide variety of fruits, vegetables, herbs, spices, and some medications. High levels are found in items like berries, tomatoes, honey, and some nuts.
- Amines: Biogenic amines, including histamine and tyramine, are found in aged, fermented, or processed foods. Examples include aged cheeses, chocolate, wine, and cured meats.
- Glutamates: Both naturally occurring and artificially added glutamates (such as MSG) can trigger reactions. High natural levels are found in tomatoes, mushrooms, and aged cheeses.
- Food Additives: Artificial food colors, preservatives (e.g., benzoates, sulphites), and flavor enhancers are targeted. These are often found in processed and packaged foods.
RPAH vs. Low-FODMAP Diet
Confusion sometimes arises between the RPAH and low-FODMAP diets, as both are elimination protocols. However, they target entirely different compounds and are used for different purposes.
| Feature | RPAH (FAILSAFE) Diet | Low-FODMAP Diet |
|---|---|---|
| Primary Target | Food chemical intolerances (salicylates, amines, glutamates, additives). | Intolerances to fermentable carbohydrates (FODMAPs). |
| Symptoms Addressed | Wide-ranging, including digestive issues, eczema, hives, headaches, and behavioural issues in children. | Primarily digestive symptoms like bloating, gas, pain, and altered bowel habits, particularly in people with IBS. |
| Mechanism | Sensitivity to bioactive food chemicals accumulating in the body. | Poor absorption of short-chain carbohydrates in the small intestine. |
| First-Line Choice | Often considered after other causes, such as IBS, have been ruled out. | Generally the first dietary intervention recommended for managing IBS symptoms. |
Is the RPAH Diet Right for You?
The RPAH diet is a rigorous process and should only be undertaken with professional guidance from a trained dietitian to avoid nutritional deficiencies and ensure accuracy. While some anecdotal evidence suggests its effectiveness, particularly for chronic hives and certain behavioral issues, robust, large-scale randomized controlled trials (RCTs) are limited. For individuals with unexplained chronic symptoms who have ruled out other conditions and allergies, it can be a valuable diagnostic tool.
Conclusion
The Royal Prince Alfred Hospital diet, or the FAILSAFE diet, is a highly specific elimination protocol for diagnosing food chemical intolerances. It is a systematic, three-phased approach that should be supervised by a healthcare professional. By removing salicylates, amines, glutamates, and specific additives, it aims to identify triggers for chronic, unexplained symptoms. While challenging, the personalized knowledge gained from the RPAH diet can lead to significant improvements in quality of life for sensitive individuals. For more information on this diagnostic process, see the RPAH Allergy Unit's resources.
