The link between food and behaviour

John Hoffman sorts through the latest research

EDITOR’S NOTE: Caroline Connell, Today’s Parent‘s Editor-in-Chief, brought this story to our attention. Originally published in February 2005, this topic has once again made headlines in newspapers around the world.

According to findings published on September 6, 2007 in a respected British medical journal, researchers have confirmed for the first time that benzoate (a common preservative found in fruit drinks, soft drinks, jam, etc.) mixed with artifical food colouring have been linked to hyperactivity in children. Scientists report that fruit drinks containing benzoate with higher levels of food colouring had “significantly adverse” effects on preschool-aged children, and increased hyperactivity in school-aged children (namely 8- and 9-year-olds).

We offer the history of the numerous food additives/hyperactivity studies that have been conducted over the last 35 years, as well as tips for parents on how to spot a problem with your child, ways to detect culprit foods and alter diets, and resources and related reading that can answer your questions.

Lisa, Todaysparent.com
Patrick* seemed “off” when he got home from school — out of sorts and irritable. When it was time to go to jazz dance lessons, the five-year-old balked. At the lesson, which Patrick usually enjoyed, he was unco-operative and soon wound up in such a rage that the teacher called his dad to come and get him. Within five minutes of getting home, Patrick was asleep. When he woke up an hour later, his shirt and hair were soaked with sweat. Otherwise, he was fine.

What’s happening here? A child with low tolerance for frustration, perhaps short on sleep and having a bad day? That’s not what Patrick’s mom and dad think. They believe his behaviour that day stemmed directly from some jelly beans he had eaten at school. “When he eats certain kinds of candies, his ears go beet red, his body temperature seems to rise, he gets all flushed and sweaty, and he becomes defiant and difficult to deal with,” says Jane Morton*, a mother of two from Fredericton.

The notion that food can cause, or at least contribute to, behaviour problems is not news. California allergist Benjamin Feingold generated headlines and controversy in 1973 when he suggested that reactions to food additives — artificial colours and flavours — caused much of what was then called hyperactivity. Since then, Feingold’s theory has been studied and mainly dismissed by mainstream doctors and allergists. But the idea has never gone away. And now a small but mounting number of studies seem to support the observations of parents like Morton, suggesting that reaction to food can affect the behaviour of some children. The questions are: Which kids, which foods and how much?

*Name changed by request.
Tracking the Behaviour
The most recent — and probably best — study was done by researchers from the University of Southampton and St. Mary’s Hospital in England. They found that certain artificial food colourings and preservatives affected not just kids with suspected behaviour problems or food sensitivities, but even some “normal” children.

For four weeks, 277 three-year-olds ate a diet free of artificial colours and a preservative called sodium benzoate. At specified intervals children were “challenged”: given a specially prepared fruit drink. Half the time it was laced with additives (four food colourings and sodium benzoate). Parents, who didn’t know which drink was which, reported reduced hyperactivity on the additive-free diet and increased hyperactivity in the period after the challenge with either fruit drink. However, the reported increase in hyperactivity was greater after the additive-laden drink. The differences were modest, though significant enough that researchers concluded there was “a generalized adverse effect of artificial food colour and benzoate preservatives.”

This study is significant because of its size and because it drew children from a general pool — in this case, all three-year-olds living on the Isle of Wight. Previous studies had been small — 20 or fewer kids — and most involved kids already identified as having behaviour problems and/or food reactions. In the Isle of Wight study, children’s behaviour tended to improve on the additive-free regime, whether or not they had ADHD or allergies; however the improvements, though noticeable, were not life transforming.

That’s what Morton has observed about Patrick after several years of a diet that excludes most store-bought processed foods, dairy, eggs, canned tomato products and oranges, among other things. (After Feingold’s initial reports, the thinking on foods that may adversely affect certain kids expanded beyond additives to include some whole foods with known allergenic properties, such as tomatoes, wheat and dairy.) “The diet has helped, but it has not been a magic solution,” Morton says. Ditto, more or less, for Elizabeth and Colin Poitras of Calgary, when they eliminated artificial colours and flavours from their five-year-old son’s diet for 30 days, on the advice of their paediatrician. On day 28, Colin said to Elizabeth, “Do you see a difference in Ethan’s behaviour?” Neither was certain. However, two days after they reintroduced the eliminated foods, the decline was striking. “Instead of just talking back, Ethan was back to shouting and waving his arms around as he did so,” says Elizabeth. They quickly resumed the restricted diet and, a year later, believe that it has helped. Meanwhile Ethan has been diagnosed with ADHD and has started a trial of medication.
Searching for the Connection
The link between food and hyperactive or otherwise negative behaviour is difficult to prove. First, it’s about trying to show that one tricky-to-diagnose and often misunderstood condition (food allergy or intolerance) causes or worsens another condition (ADHD) which is similarly fraught with controversy and possibilities for misdiagnosis. Second, those who believe in the food-behaviour connection have yet to pin down a biological mechanism to explain how it works.

One controversial theory is espoused by physician Michael Lyon of Coquitlam, BC, author of Is Your Child’s Brain Starving? It focuses on a condition called “leaky gut.” Lyon explains that the small intestine (gut) is designed to allow fully digested food molecules to pass through its wall into the bloodstream. With leaky gut (which can stem from a number of possible causes including bad diet or overuse of antibiotics), an excess of biologically active molecules that would normally be screened out get through and enter the bloodstream. “Antibodies become bound to these food molecules and they can build up to form immune complexes,” says Lyon. These immune complexes, he says, can cause behaviour or learning problems.

Janice Joneja, an immunologist, dietitian and author in Kamloops, BC, sees it differently. Joneja, who ran the Allergy Nutrition Research Program at Vancouver Hospital and Health Sciences Centre for 12 years, agrees that leaky gut may play a role, but she views histamine as the prime suspect. Most of us have heard of histamine, usually with respect to allergic reactions. Some research has found that in certain individuals, foods can sometimes cause a non-allergy-related release of histamine which has a pharmacological (drug-like) effect. “Histamine is a neurotransmitter that is known to cross the blood-brain barrier, and I think this may go towards explaining some of the food-behaviour connection for some children,” she says. The authors of the Isle of Wight study also suggested that a non-allergy response to histamine was the most likely explanation for the effect of food additives on behaviour.

In the end, the biological explanation matters little to parents who are struggling to manage difficult behaviour. What matters to Amanda Bryson* of Moose Jaw, Sask., is the difference she saw when, following the advice of a naturopath, she eliminated pork, eggs and most prepared foods — “basically anything in a box or a can” — from her 2½-year-old daughter’s diet. “When we eliminated these foods, she went from being a nasty, obstinate, horrid toddler to a normal child who occasionally got upset.” Once the family relaxed their standards and went to A&W. “When I asked Camilla if she was finished, she flung her plate across the room,” Bryson says. “She hadn’t done anything like that in months. It’s possible I’ve eliminated more than we need to, but I’m afraid to reintroduce these foods. I don’t want to go back to where we were.”

*Name changed by request.
Experimenting with Diet
Cutting out foods with artificial colours and flavours, the first-line approach recommended by Lyon, should mean a healthier diet with no, or at least considerably less, junk food and fried fast foods. That seems like a no-lose proposition for parents concerned about their kids’ health as well as behaviour. Mind you, all parents we spoke to talked of a long, difficult learning curve of label reading, searches for cookies or crackers that their child could handle and the inevitable slip-ups.

Parents should proceed with more care, Joneja cautions, if they wish to explore the idea that specific, normally nutritious foods, such as milk, cheese, egg, wheat, peanuts, tomatoes and citrus fruits, are contributing to behaviour problems. “If you take out a lot of foods — all dairy, for example — you have to find substitutes that provide equivalent nutrition value,” she says. She recalls one 14-year-old boy she saw in her clinical practice whose parents had removed many foods from his diet without proper follow-up. “He was tiny and fragile looking. I would have guessed he was about 10. I discovered that there were only six or eight foods in his diet.”

Finding sound advice in this area is a problem. “We just don’t have enough scientific data to guide our way,” says Joneja. Family doctors don’t usually have time to devote to elimination diets. “We have tests that are of some help, but we don’t have a simple test that can always reliably identify food allergies and intolerances,” Joneja adds.

Bryson, a registered nurse, took her child to a naturopath because she couldn’t get the input she needed from her family doctor, even though she was not entirely comfortable with the naturopath’s diagnostic techniques. For example, he diagnosed food allergies (as he called them) by holding a little vial of food against Camilla’s chest while Bryson touched her shoulder, then the naturopath pushed down on Bryson’s arm. If her arm became weak, that indicated “allergy” to the food in the vial. Even though it seemed like voodoo to Bryson, it did implicate certain foods, such as oats, that she had already concluded were causing problems for Camilla. “I still don’t know what to make of some of it,” she says.

Here’s another concern: Hyperfocusing on food as the sole source of a child’s behaviour problems could make parents blind to other issues, such as mental health or development problems, learning disabilities or even a parent-child relationship problem. Plus, Joneja adds, “I don’t think we want to give children the message that food is a bad guy either.”

Still, when a child’s behaviour is making life miserable for him and the family, and when standard behaviour fixes don’t seem to work, diet is a legitimate line of inquiry. Says Joneja: “I believe that a limited-time trial on a diet that is free from additives, diagnosed allergens and, in some cases, common allergens, is a reasonable thing to do before opting for medication.” But, she adds, it’s essential that parents seek professional advice to ensure that the child’s diet is nutritionally adequate and that he is properly assessed for other problems. And keep your expectations modest. “If the diet changes help, medication may not be necessary,” says Joneja. “If they don’t work, nothing is lost. But I think families need options.”

Meanwhile, Jane Morton will be keeping Patrick well away from jelly beans.

Resources
Dealing with Food Allergies: A Practical Guide to Detecting Culprit Foods and Eating a Healthy, Enjoyable Diet by Janice Vickerstaff Joneja, Bull Publishing 2003.

Is Your Child’s Brain Starving? by Michael R. Lyon, Mind Publishing 2002.

Allergy or Intolerance?
People often use the following terms in different ways or interchangeably. To help clear up the confusion:

Food allergy: An immune system response triggered by a food.

Food intolerance: A reaction to a food caused not by the immune system but by the way the body metabolizes (processes) the food.

Food sensitivity: A vague term with no clearly defined clinical meaning; sometimes used generically when people are unsure what is causing the reaction to a food.

Elimination Diets
The only sure way to diagnose a food allergy or intolerance is via an elimination diet. The idea is to remove a number of suspect foods from a diet for four to six weeks. If the symptoms don’t disappear, then they are most likely not caused by food. If they do disappear, foods are reintroduced one at a time to see which specific foods are causing the problem. Although there is much disagreement about food allergies and reactions among various types of practitioners, virtually all agree that an elimination diet is the only sure way to confirm food allergies, intolerances and sensitivities.

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