At talks to the Society for Growing Australian Plant meetings I have listened to speakers talk about animals, birds and insects being attracted to particular plants, even to some plants in one area but not to the same plant in a nearby area. What attracts them? Or, even more interestingly, what caused them to not feed from those they choose not to use. People tend to think of their food from plants as being completely safe. Most plants not eaten are poisonous, or so low in nutritional content for humans, they are irrelevant. But there are plants thought to be safe which do cause adverse reactions. I have spent the last thirty years doing diet detective work investigating diet for children and adults with attention, hyperactivity and behaviour problems, physical symptoms such as eczema, diarrhoea, as well as migraine and irritable bowel syndrome. This talk will consider these issues especially with regard to what may be the substances in plants that are suspect.
In 1975 an allergist called Ben Feingold caused a great controversy when he said that additives and other chemicals caused Hyperactivity. His diet did not exclude only additive colour, flavour and a few preservatives, it also excluded substances called salicylates, whether medicinal, such as aspirin, or naturally occurring in spices, mint, and all acidic fruit especially tomato.
The reaction to food was not allergy, where an immunological reaction occurs to a protein, often animal derived, such as to milk or shellfish, or plant derived such as to wheat, peanut, tree nuts, seeds or soy beans.
The exact mechanism occurring in what is called food chemical intolerance in not known, but it is pharmacological. The suspect chemicals are small molecular compounds with a ring in their chemical structure. So it is reasonable to propose that a rash or other symptom is like an adverse reaction to a medication whereby the vast majority of people have the expected change with the medication, but some individuals have an adverse, or unpleasant, reaction.
Initially all news was about the effect on hyperactive children, but the scientific literature showed that a low salicylate diet was also being used by dermatologists for such conditions such as psoriasis, a type of skin rash.
However, other conditions improved on the diet.
A typical story was that all family members went on the diet and where the diet decreased hyperactive symptoms, in one child, the families also reported with surprise, a decrease in symptoms in other children or in themselves. Symptoms often reported were eczema, headaches, tummy aches, bed wetting, carsickness, nightmares or limb pains.
Not only were the symptoms of those on the diet changing, but the diet itself wasn’t exactly right for everyone. Once families excluded the additives and salicylates, they noticed other problem foods. Since Feingold excluded chocolate because of additives I recommended they make home-made cakes with cocoa powder, but in some this caused reactions. Another reaction that involved plants was perfumed flowers. Families reported a return of symptoms when jasmine, mock orange or other strongly perfumed plants were in bloom. They also reported reactions when incense was used. This was as well as non food strong smells, such as diesel fuel, fresh paint, felt pens and some perfumes.
You can see why I called what the families and I were doing “Diet Detective Work”. Other surprises occurred. Families reported behavioural changes, and worsening of the symptoms reported improving above, to the foods commonly implicated in allergy – milk, eggs, wheat, peanut, or soy. So there was an immunological part to the mechanism. Another interesting finding that involved plants was that symptoms often got worse when other family members who had seasonal hay fever or asthma got worse. Patient numbers were also up during spring when pollen loads were high, or during westerly winds. I realised that we were dealing with what I call a “Total Body Load” of suspect foods and environmental factors that affected where each person’s threshold was. A Brisbane allergist reported that allergies were worse when lemon scented gums were out in early November, and also in July when lemon scented tea-trees were out.
Meanwhile patients on the low chemical diet were gradually testing low risk foods to see if they could expand the diet as much as possible without exceeding their threshold. I found that if they painted their house or it was spring time some families had to reduce the suspect foods they had been tolerating to cope with the new load.
One problem was that Feingold had based the salicylate content in excluded foods on analysis done in 1922!!
Dr Joan Woodhill, the earliest Australian dietitian to work in the area, added new exclusions. I was working in central Queensland, often dealing with fruit that had not been analysed. Families experimented with guava, rosella jam, mango, quince, lychees, persimmon, and custard apples, all of which were fairly low risk. It was interesting that if a child used one of these each day it caused less of a reaction than if he had the same one over several days.
There was something happening whereby, what was being found generally, that the overall load mattered, was one part of the story. As well the person was worse off if they had too much of one particular plant food.
Some research reported that different varieties of tomatoes contained different amounts of salicylate, so it was presumed that different varieties of other fruit did too. I noted that under-ripe or just ripe fruit was better tolerated, and that over-ripe, late season, or out of season fruit, were less well tolerated. In addition, if fruit was reported to smell or taste a bit “musky” or “mouldy” it was less well tolerated.
As well as Feingold causing a controversy, a psychiatrist in England said that wheat and all cereals were causing severe behavioural changes, so he recommended a cave man diet high in meats with no cereals.
As research developed other foods that contained amines, not only chocolate, strong cheeses and red wines, were implicated. These included banana, pawpaw, avocado, oranges, pineapple, figs, broccoli, mushrooms and tomato. The careful approach for dietitians was to exclude any food reported to contain any of these from the initial elimination diet. Since I had always relied on what patients reported reactions to I did not want to be that strict. The experience with over-ripe and out of season fruit pointed to some change in the fruit. With patients testing food I realised that tolerance, especially of bananas and broccoli, changed greatly from just –ripe to over-ripe, and that foods such as pawpaw, avocado, and spinach were tolerated if the flavour was mild.
The other natural chemical which caused reactions was MSG, naturally present in a seaweed, tomato and mushrooms, and, of course, soy sauce.
I had found that food sensitive people were often considered fussy by others, the children were usually very fussy eaters, and they all noticed smells more than the general population. I realised that if I encouraged them to notice the smell of food they wanted to test for tolerance it helped. If the test food smelled “too ripe” “mouldy” or “strong” to them then tolerance was reduced. This also, fortunately for them, meant they could, once established on the diet, occasionally have a very good wine, a very mild beer, wear a very good perfume, use a very mild honey, or have a cup of mild tea. One lady had such a good sense of taste and that she could identify the leather in Leatherwood honey, even though the tree only has that name as the wood smells of leather when it is cut down.
I researched literature on amines and learnt that most increase with ageing or ripening reflecting what was happening clinically.
In 1980 an analysis of salicylate in Australian foods was published by RPAH dietitian Dr Ann Swain. The figures were very useful but they did not correspond exactly to patient reports of tolerance. Other analysis did not confirm the findings, but they still have a role.
In UK researchers used a “Few Foods” diet and reintroduced foods one at a time. Many plant foods caused hyperactivity reactions. Frequency of particular reactions did not follow the salicylate analysis. Plants can have an indirect effect. A child who is allergic to corn reacted to eggs from chickens fed corn. After flood rains reactions to milk increased, but then they subsided over time. After some research I realised that the cows had been eating new plants after flood rains and the flavours had been secreted into the milk. Just as breast feeding infants can react after their mother has curry, mint or teas, so can those who drink cow’s milk react to plants the cows have eaten.
I noticed that smell, or flavour mattered. Foods high in flavour such as spice, peppermint, teas, tangy fruit, concentrated tomato products, almonds, mushrooms, over ripe bananas, ripe broccoli, vinegar, sauces, aged foods, and MSG which is called a ‘flavour enhancer’ [ as well as artificial flavour], are all implicated. Fortunately, or was evolution, those who are most aware of flavour and smell are included in those most likely to be food sensitive. Once they have learnt the appropriate elimination diet they can gradually trial foods using their better-then-average sense of smell and taste.
An understanding of the effect of diet needs to include the diet itself, the symptoms that are affected by diet, just who is susceptible and the possible mechanism. These are described in my books, especially “Are You Food Sensitive?”
If birds, bats, bees and other flying things can choose one tree over another to feed from, and sensitive humans have higher tolerance for milder, better quality flavour and smell then it makes sense that animals do too. Flavour and smell matter to all species!
Australian plants are a pleasure. However do remember that there are people who can react either allergenically, or pharmacologically especially to those with a perfume.