The careful analysis of the natural chemical salicylate, carried out by Dr Anne Swain for the RPAH diet, was groundbreaking research and was used as a guide in 1985. However, the amounts she found present did not correlate as expected with tolerance in patients. The reaction-causing chemicals may be salicylates or compounds somewhat similar to salicylate in their chemical structure. Even if we did know what the suspect compounds that cause reactions in food sensitive people are, they, and there may be several, may vary so much in plant foods that it is not possible to have tables that are meaningful when planning diets. After over 40 years of my career specializing only on food sensitivity I propose the hypothesis that flavouring compounds in the suspect foods are an important contribution to adverse reactions.
This is a complex issue. Fortunately we know from clinical practice research, not analytical research, which foods are best to minimise with diet investigation.
The Diet Detective Method, which is based on reported tolerances on over 1100 patients closely followed up, and 3000 more whose reactions were used to refine the work presented in my books. All the research findings of the many others working in this area were considered. [See my Review Article https://foodintolerancepro.com/category/evidence-base/the-role-of-diet-and-behaviour-in-childhood/ ]
Over many years my work has showed some important findings. Wherever only suspect artificial additives were excluded families did not get as much benefit and symptoms would still, frustratingly, increase and decrease. Foods thought to be high in salicylates do need to be considered. Foods high in herbs, spices and concentrated tomato continue to be reported as causing reactions. Chocolate was reported as causing reactions often and by the late 1990s all the various amines, and monosodium glutamate (MSG) and other glutamates, were excluded. As well carob and vanilla flavours (allowed on the low salicylate diet), were reported as causing reactions. This also shows reactions were not just a placebo effect as no early diet excluded them. My position that tolerance is related to strength and quality of flavour was strengthened over time and is shown in the careful amounts advised in the Baseline Diet for the Low Chemical diet investigation.
How can you use flavor knowledge to help diet investigation? You can begin with the Baseline diet of the Diet Detective Method, or the RPAH Elimination Diet so you get a baseline position to do challenges from. You need to note something important. Some of the excluded foods are foods you do not like anyway so excluding them makes sense to you. But some are foods you like, including ones you like very much and cannot see yourself living without. These include tea, mints, tomato dishes or tasty Thai, Asian or Mexican meals. But I do not need you to investigate foods you do not like anyway. I need you to also investigate highly flavoured foods you have not thought cause reactions. The reason you do not suspect them is because you feel good after eating them and any adverse reaction you get will probably not occur for 24 hours.
After your four-week Baseline diet you can do the main challenges to give you the big picture. Then you can use your sense of taste and smell. Most food sensitive people have a good, even very good, sense of smell and taste. If a fruit or veg or a meal taste “strong or wrong” to you then it is probably high in some food chemicals you would be better minimising. Salicylate content is said by researchers to match the amount of tart and bitter flavours. So you can assume that if you think some food tastes tart or bitter to you it probably is best excluded for a while, but if you like that flavour do test that food at another time.
Additive colours, flavours and benzoate have a similar structure to aspirin, and to natural salicylates. These compounds and amines are reported to be metabolized by particular enzymes, so it makes sense that they are grouped together in this diet. The important idea I am suggesting you consider is that natural flavours are also similar and may be the missing chemicals that explain the finer points of this elimination diet. Glutamates, including MSG, are flavour enhancers, so it makes sense that some people react to them. Then it gets tricky chemically, as different food-sensitive people vary in just which of these suspect chemicals they individually react to. My hypothesis is that food sensitive people have their own particular biochemical pathways to metabolise or “detox” the various suspect chemicals, including flavours. This means that there is individual variation in what foods are tolerated. In the future pharmacologist and toxicologists may be able to explain what is happening, but it will still not mean there are easy tables of suspect chemicals to follow. Fortunately that does not stop you can learning how to best test foods for your individual self using what others have found from my books. In Chapter 3 of Are You Food Sensitive? there is an important summary of how to think about salicylates, amines, monosodium glutamate, and natural flavours. In Chapter 3 of Tolerating Troublesome Foods there is lots of important ideas on why food tolerance can change and one of these is factors in the food, and flavour is an important factor.
The Best Guess Food Guide of over 300 foods is provided in Chapter 5 in Tolerating Troublesome Foods, 2014 edition. It is based on reported tolerance in thousands of food sensitive people. It provides a guide that allows you to test foods to give you a diet with the most variety of foods that suits you individually. See www.foodintolerancepro.com to learn more.