Ockham’s Razor, ABC Radio National
Sunday at 8.45am, repeated Mondays at 2.15pm
Food - What's smell got to do with it?
Sunday 16 May 2004
If bitterness is a warning via taste, is flavour a warning via smell?
Robyn Williams: Do you remember the Feingold diet? You’d have to be getting on a bit if you do, because it became famous 30 years ago. Dr Feingold from America constructed an elimination diet so that children hideously sensitive to added chemicals in foods, or even naturally occurring ones, could find out what was bad for them and made them hyperactive, as we called it then.
Well dietitians have moved on They even talk of supertasters these days. Joan Breakey from Brisbane has been trying to tease out what’s sensible and what isn’t for the patients she looks after, and she’s found a lot of it has to do with smell.
Joan Breakey: In any normal group there are those who I would describe as having a constitution of iron. They’re not worried by any aspect of food. Then there are the normal people, the people who are seen as fussy. They notice stale foods, strong flavours and even the difference between different brands of favoured foods. Food sensitive people are particularly sensitive to small changes of flavour and smell in food. I am advancing the idea that a big part of what food sensitive people are most sensitive to is flavour.
This idea took some time to develop.
In the 1970s the Feingold diet exclusions included artificial colours and flavours, some preservatives and salicylates. Smells such as paint and petrol were also implicated. Chocolate became an early addition to the exclusions. My diet responding patients were often very fussy about taste, texture and temperature; children would often reject over-ripe bananas, and potatoes or cheese if it tasted mouldy to them. I became wary of mould and recommended that fruit be trialled early or mid-season, not late season. Through what I now call diet detective work, I learned that mild flavoured, good quality fruit was better tolerated. Food sensitive children seemed to either love or hate certain smells. One child would be excited by the smell of petrol, while another would be nauseous.
I trialled a colour and preservative free nature identical mango flavoured bubbly drink. The children reacted, showing artificial flavour was a problem. I learned that additive flavour was used in doses ten times that of colour. So I began emphasising flavour more.
After trials of liked smells, parents reported children having happy-high behaviour, distractibility and sleep problems. Disliked smells were so described as they were usually known to produce adverse symptoms. I often asked patients how they felt when they had to cope with high doses of perfumes. We all presume that our experience with regard to smells is the same as others, but food sensitive people notice smells much more. Individual variation of tolerance in the population does need to be recognised. A perfume that produces migraine in one patient may be liked by another.
In the 1980s new data on salicylates in foods became available. This provided much needed security about the chemical content of food. Meanwhile, the suspect substances broadened to include all additive colours, flavours, most preservatives, salicylates, natural and added monosodium glutamate, and various amines, in addition to chocolate. Additive colours and flavours caused the most reactions; and chocolate and tomato sauce were reported to cause reactions in over 80%. Paint and petrol smells were reported a problem in nearly as many.
Around this time I developed the concept of The Total Body Load, which was a combination of all the factors that seemed to aggravate the underlying symptoms. These factors included the natural and additive food chemicals, smells, stress, contact dyes, infections, allergy foods and inhalants. There was individual variation in the importance of the various factors, and liked suspect foods and smells were better tolerated than disliked ones.
One day it occurred to me that one common factor in most excluded foods was flavour, additive flavour, tangy fruit, herbs, spices, teas, peppermints, chocolate, aged and matured foods, and flavour enhancers. All foods high in flavour were suspect. Additive colour and benzoate preservatives are aromatic in chemical structure. Some preservatives and allergens are not covered by this convenient classification, but flavour does cover the main culprits. It includes the high amine smell in ripe bananas, the mouldy smells in foods, and the flavour component in additives, as well as smells and perfumes in the environment.
It is fascinating that people who are food sensitive are sensitive in that it can cause adverse reactions in their body, but also sensitive insofar as they are discerning or discriminating, often seen by others as fussy. It is as if those who are more sensitive or fussy should be that way, to minimise adverse reactions. Hence, after their initial elimination diet and main food challenges, I found that marginal foods that were fresh, high quality, and with only a mild bouquet would be tolerated.
In the ‘90s, with increased emphasis on amines in food, the strong flavoured chocolate, mature cheese and aged wine, remained high risk, but canned fish, ham, browned meats, bananas, avocado and broccoli were well tolerated as long as they were very fresh, with a mild flavour.
About this time, several researchers reported on a group of people called supertasters. They were highly sensitive to certain tastes, especially bitter and hot, spicy foods. And specifically, to the taste of 6-n-propylthiouracil (PROP), which to a supertaster tastes bitter, mild to a taster and without taste at all to a non-taster. Sweet taste is also enhanced.
The ability to be a supertaster is inherited. Anatomically supertasters have more nerve endings in their tongues. Interestingly, they also have more pain and touch nerve endings there. They notice pepper, alcohol and fizzy drinks more, and are better at perceiving fat in food.
One research group investigated the role of smell in those living near livestock farms. They report that disliked smells impair mood, that people are more depressed, more anxious when they smell unpleasant odours. This is particularly interesting as the most commonly improved symptom on a low flavour (low additive and low natural chemicals) diet is mood.
How does this research apply to my work? I believe that food sensitive people are supertasters, and that they form a new sub-group who are also supersmellers. They often describe foods as strong, and often throw out food that smells stale to them. They often comment on how hot spices are, or how sickly sweet some foods are. They are also often very aware of smells, such as paint or petrol, and strong perfumes, particularly in perfume departments in large department stories. Many food sensitive children are fussy about foods, noticing the smell, taste or feel of the food. Once they are taught to use what they have often presumed was being fussy, to help understand their food tolerance, food sensitive people become surprisingly good at judging what they can handle. In the late 1990s I reviewed the literature on amines in food, as they are particularly important in food sensitive people with migraine, tummy aches and irritable bowel syndrome. Findings included a wide variability in the amount of amines in food. It seems that the amount of amines present is highly dependent upon the amount of aging, ripening, maturing or staleing. There are amines developed on purpose, such as aged meat, matured cheese and wine, and there are unintentional amines developed as food becomes stale. The names given to some of the staleing amines, ‘putrazine’ and ‘cadaverine’, speak volumes about the role of smell. This research has reinforced what I was finding clinically. Food sensitive people should be very wary of any food they think is poor quality, smells strong or stale to them, at the particular time they are assessing it. In doing this they also incorporate the idea of how robust or fragile they feel, depending on the total body load of factors they react to.
It is possible that the mechanism of food sensitivity is the slower or abnormal metabolism that sensitive individuals have for the suspect aromatic compounds. This would explain why food-sensitive people are reported to have bad breath and high body odour, which are alleviated by diet therapy using what is in fact a low aroma diet.
Where can the idea of sensitivity to flavours and smells be used? It is helpful in being aware that super sensitive people really appreciate being understood. The presence of the sensitivity is an indication that diet investigation for suspected food intolerance should occur, especially if other indicators, such as an atopic history, or a history of migraine, irritable bowel syndrome or mouth ulcers, are also present. Diet can decrease the aggravation of underlying problems whether these are physical allergic symptoms, migraine or irritable bowel syndrome, attention deficit disorder, attention deficit hyperactivity disorder or mood problems.
There is a wide variation in flavour awareness in the population, from those with a constitution of iron to normal people, to gourmets and supertasters, and food sensitive people who are also supersmellers. In flavour we have a useful grouping of the most important suspect foods investigated in food sensitive people. Furthermore, many of them are supersensitive to smells, and so can learn to use flavour as a test of the most likely tolerance of food.
In those with a constitution of iron, there are no food rules; in normal and gourmet people, the rule is: Smell your food, it is a guide to likes and dislikes, and therefore enjoyment of food. In supersensitive people the rule becomes: Smell your food, it might be making you ill.
Robyn Williams: But you can try to avoid the problem by using your nose. Joan Breakey practices around Brisbane.
Next week we leap ahead to the future with David Singleton. He’s been there. How to live in a city 20 or 30 years from now? How will you get to work? Or will it come to you?
I’m Robyn Williams.
Guests on this program:
Joan Breakey Website
Presenter: Robyn Williams
Producer: Brigitte Seega