Food and mood

Sarah Wellard investigates the latest evidence on how diet,
additives and pesticides affect young people’s behaviour.

It may not be just young people’s physical health that is
at risk from a diet that is high in saturated fats, sugar and salt
and low in essential nutrients. There is growing evidence that, for
some children, behaviour and learning capacity are being
compromised as well.

Research published last year in the British Journal of
on the benefits for young offenders of taking
dietary supplements provides compelling evidence of links between
inadequate diet and violent behaviour. Two hundred and thirty young
offenders took part in a random controlled trial over 18 months,
with half the participants receiving supplements of vitamins,
minerals and essential fatty acids and half receiving placebos
(dummy capsules which looked identical to those containing the
supplements). The group taking the supplement committed 40 per cent
fewer violent offences than the control group on the placebo, and
there was a 25 per cent reduction in offending.

A striking feature of the study is that although balanced meals
were available within the institution, prisoners’ food
diaries revealed that they were choosing unhealthy options and
supplementing the meals with sugary drinks and snacks. The
nutritional supplements were aimed merely at correcting the
inadequacy of participants’ diets. Research by the
Consumers’ Association found alarming parallels in the diets
of children eating school meals. Although healthy options were
listed on the menu, children’s food diaries showed that they
too reject the fruit and vegetables on offer and opt for fatty and
sugary foods instead.

So can we conclude that similar results would be found if the
participants had been children and young people living with their
families? Bernard Gesch, author of the study and senior research
scientist in physiology at Oxford University, points out that
nutrients are crucial ingredients in the biochemical processes that
produce brain neurotransmitters like serotonin and dopamine which
are known to affect mood. He adds: “The study did take place in a
prison regime but since every one of us needs these nutrients there
is every reason to think it may also reduce offending in the
community where poor diets are consumed. We tend to forget that
humans are physical as well as psychological beings and putting
poor fuel into the brain seems significantly to affect social

Gesch’s research does not explore whether all or just some
of the dietary supplements are linked with a reduction in offending
behaviour. And it does not indicate whether we are all predisposed
towards bad behaviour from a nutritionally poor diet, or whether
some people are more at risk.

Another area of research, into links between diet and some of
the behavioural and learning problems associated with dyslexia,
dyspraxia and attention deficit hyperactivity disorder (ADHD), may
provide part of the answer.

Dr Alexandra Richardson, senior research fellow in physiology at
Imperial College School of Medicine and at Oxford University, found
benefits for children with information processing difficulties of
taking omega 3 supplements, the fatty acid found most commonly in
oily fish such as mackerel, sardines and salmon. She says: “These
fatty acids are utterly crucial to human health and especially to
the brain but they have just about disappeared from our diets.” She
believes that a wide range of conditions where brain and behaviour
are involved can be improved with fish oils. “Depression is an
omega 3 depletion syndrome. Controlled trials show that symptoms
can be reduced by treatment with the omega 3 fatty acid EPA.”

Richardson is currently collating the findings of her latest
study, with 120 dyspraxic children in Durham, who are taking either
a fatty acid supplement or a placebo. So far the results are very
promising. However, she does not suggest that all children with
ADHD, dyslexia or dyspraxia will benefit from fatty acid
supplements, and emphasises that dietary or metabolic deficiency is
only one factor in these complex conditions.

Food additives are another area of concern in the diet and
behaviour debate. For decades parents of small children, and
especially parents of children with ADHD, have been concerned that
some additives may be triggering, or at least contributing to poor
concentration, over-activity and mood swings.

The Food Standard Agency (FSA), the government’s food
watchdog, commissioned its own research into the effects of certain
additives on children’s behaviour, but the study was deemed
by experts to be methodologically flawed. A spokesperson for the
commission explains: “There were problems in the way the research
was set up. It didn’t separate the effects of known
stimulants such as caffeine and sugar with the possible effects of
food additives.” The FSA is now commissioning new research.

Kath Dalmeny, research officer at the Food Commission, an
independent food campaigning organisation, believes the Food
Standards Agency should issue advice now to food manufacturers to
avoid using certain additives. She says that the suspect additives
are often used in poor quality foods to make them appear more
palatable. “Take fruit-flavoured drinks. They often contain a lot
of additives aimed at mimicking natural products. A drink may
contain 5 per cent fruit and manufacturers add vitamin C to market
it as a healthy product, but the rest is sugar, water and
additives. Not only may additives be contributing to family
disharmony, but they are masking poor ingredients which deprive
children of valuable nutrients.”

Foods containing high levels of additives tend to be consumed by
poorer families who are less able to afford higher quality,
healthier alternatives. Dalmeny says: “It’s easy to tell
people to read the labels, but not everyone knows that these
additives are suspect. How many people actually know that E102 is
tartrazine [one of the suspect additives]? Understanding food
labels can be quite technical and some of the additives appear in
unexpected places – like tartrazine in tinned mushy peas.

So what food can be eaten that does not cause harm to consumers?
Even those children who do eat a healthy balanced diet may be at
risk from pesticide residues in fruit and vegetables. Sandra Bell,
food and farming campaigner at Friends of the Earth explains:
“There is concern about the impact of OPs (organophosphate
pesticides). They are known to affect the central nervous system
and scientists have suggested that behavioural problems in children
could be linked to OP exposure. The most vulnerable time is for the
fetus during pregnancy but young children may also be at risk.”

One organophosphate, chlorpyrifos, has been banned in the US
because of concerns that it may be linked to brain damage, but it
is still used by European farmers. Causal links between exposure to
chemicals and toxic effects for children are notoriously difficult
to prove and so far the British government has been unwilling to
accept that there may be a risk from long-term exposure to low
levels of organophosphates.

Bell adds: “New regulations are being brought in on processed
baby foods – they must not contain any pesticide residues. But
unless they are buying organic food parents giving their children
fresh fruit and vegetables do not have that guarantee.” Some
supermarkets, such as Waitrose, Marks & Spencer and Co-op, are
looking to supply produce without organophosphates, and Friends of
the Earth and other campaigners want to see tighter controls on the
use of pesticides introduced across the European Union.

For the majority of British children, who are consuming less
than half the recommended five portions of fruit and vegetables a
day, concerns about pesticide residues may seem academic. It is
clear, however, that it is high time we put food and diet much
higher up the agenda.

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