Hydrogenated and trans fats
        May cause: Dyslexia, dyspraxia, learning
  difficulties, autism.
        Where they are found: Cakes, pastries,
  biscuits, bread, margarine,
  snacks (such as popcorn), commercially fried foods
  including some French fries and hamburgers.
        What they do: Unlike the liquid omega-3 fatty
  acids lacking in most children's diets, these solid man-made fats have
  been shown in animal studies to make the brain membrane less fluid
  and there is good evidence that they alter the signaling ability of
  neurotransmitters or chemical   messengers.

  Some scientists believe the wrong kinds  of fat in the diet may   be a factor in dyslexia, dyspraxia (the inability to
  plan and execute   actions, including communication), autism and ADHD -
  though few studies  support this. 'Children are replacing essential fats
  that would make their bodies and brains work properly with ones that are
  clogging up the   machinery,' says Dr Alex Richardson. Hydrogenated
  fats often contain trans fats, acknowledged by the FSA and others to raise
  'bad' cholesterol and increase the risk of heart disease. In 1993, Flora
  reduced the hydrogenated fat content of its margarine from 21 per cent to 1
  per cent (the label says 'virtually trans fat free'); others have been slow
  to follow.
 
  Refined carbohydrates
        May cause: Irritability, depression,
  antisocial behaviour, aggression, low IQ, reduced sense of smell and taste (affecting appreciation of healthy food).
        Where they are found: Products made from
  processed white flour (white  bread and pasta), cereals, crisps and snacks.
        What they do: It isn't so much what they do as
  what they don't. A diet   high in refined carbs is likely to be low in
  selenium (a deficiency linked to irritability and depression), chromium (essential
  for blood-sugar  control), zinc, iron and B vitamins. Deficiency in
  the last three was  implicated in a 14-year study concluded last year,
  examining the links  between childhood diet and antisocial behaviour as
  teenagers. Compared to those with a healthy diet, malnourished children
  showed a 51 per cent rise in aggression at 17. According to Professor Adrian
  Raine of the University of Southern California, 'Poor nutrition
  characterised by zinc, iron, vitamin B and protein deficiencies leads to low IQ, which
  leads to later antisocial behaviour. These are all nutrients linked to brain
  development.' Similar conclusions were drawn from a 2002  study of young
  offenders at Aylesbury  prison, whose diet was supplemented with vitamins
  and essential fatty acids.  Antisocial behaviour fell by 35 per cent. In a study
  at the Massachusetts  Institute of Technology, children who ate the most
  refined carbs had IQs 25  points lower than those who ate the least.
 
  Added sugars
        May cause: Mood swings, hyperactivity, poor concentration.
        Where they are found: Sugary drinks, sweets,
  coated breakfast cereals,  chocolate (in which sugar is often number two in the
  ingredients, after milk).
        What they do: As a fast-acting carbohydrate,
  sugar is claimed by some to boost blood-sugar levels and create a surge of
  energy and an upbeat mood - though the sugar industry (see main story) denies
  any link between sugar and 'hyperactivity or any other type of "bad
  behaviour" or learning difficulties.' However, its 'empty calories'
  contribute nothing in terms of nutrition. 'If children slurp cans of surgary drinks
  on the way to school,' says Dr Richardson, 'it puts them on an artificial
  high in terms of brain function, but that stimulates the release of too
  much insulin which causes blood-sugar levels to plummet. In a short time,
  their   brains are in a fog. They can't concentrate, they're irritable and find
  it hard to hold on to stable emotional reactions.' So far, evidence has
  been largely anecdotal: many parents, teachers, nutritionists and some
  scientists insist there is a link.
 
  Chemical additives
        May cause: Hyperactivity, tantrums.
        Where they are found: Crisps, snacks, sweets
  and drinks, particularly those with an orange or yellow colour. About 40 per
  cent of products aimed at children contain chemical additives, according to
  the Food Commission (which lobbies for a healthier diet for children).
  Among those claimed to influence behaviour are sunset yellow (E110),
  carmazoine (E122), ponceau 4R (E124) and the preservative sodium benzoate (E211).
  MSG, a flavour enhancer in snacks, is another. 'Glutamate is a brain
  stimulant in the way it's given,' argues nutritionist Patrick Holford,
  'because it enhances sensory perception by making things taste better. Some
  children react badly to it.' The FSA, while agreeing to commission more research,
  says the evidence 'is inconclusive and remains an area of scientific
  uncertainty.'
        What they do: Though described as 'sketchy'
  by the British Nutrition Foundation and others, a Southampton University
  study in 2002 found that a quarter of three-year-olds consuming E-additives in
  a drink showed signs of hyperactivity and tantrums. (The study, finally
  published in 2004, is described by Dr Alex Richardson as 'sound, conducted
  by serious researchers, as impeccably as you could do a study of that
  kind'.) On the Food  Commission's dedicated website www.foodcomm.org.uk/parentsjury
  dozens of  parents have since posted anecdotal evidence of behaviour changes in children who consumed E-additives. All such additives are tested for  safety and approved for use
  in Britain.
 
  High-GI (glycemic index) foods
        May cause: Mood swings, lethargy, depression.
        Where they are found: Baguettes, bagels,
  pizza, instant white rice,  fries, instant mashed potato.
        What they do: Like sugar, foods at the top of
  the glycaemic index  (which are broken down quickly and converted into
  glucose) create a surge of energy and an elevated mood. When insulin kicks in
  to deal with the sugar 'high', the opposite is felt. High-GI foods are best
  avoided by diabetics. The link with mood is less accepted.
      
 Stimulants
            May cause: Hyperactivity, anxiety,
  cravings, insomnia,   tiredness.
        Where they are found: Fizzy drinks, energy
  drinks, tea, coffee (caffeine).
        What they do: Stimulants alter mood and
  behaviour - but the jury is  out on whether the small amounts in caffeinated
  drinks and food affect kids. In 2003, a study of 200 teens in the US showed that
  those with a high caffeine intake were less mentally alert - a claim
  disputed by the soft drinks industry. Researchers found the average daily
  intake of caffeine was 63mg, equivalent to half a cup of coffee.
  * * *
 
What Your Children Should Eat
  The good mood diet for optimum health
   http://observer.guardian.co.uk/foodmonthly/story/0,,1453545,00.html
 
  Essential fatty acids
        May help: Depression, dyslexia, ADHD,
  dyspraxia, autism.
        Where they are found: Oily fish (salmon,
  sardines, fresh tuna, mackerel), fish-oil supplements, seeds (flax, hemp, sunflower,
  pumpkin) or their cold-pressed oils. Tinned tuna is a poorer source but 'better than
  nothing', says Dr Alex Richardson, a research fellow at the University Laboratory of Physiology, Oxford.
        What they do: These are the building blocks of
  good brain development, similar to the liquid fats - such as DHA and EPA - of which 65
  per cent of the brain is composed. They keep the membrane flexible and allow
  brain cells to signal efficiently. The main group are the omega-3s (found
  in fish and seafood) followed by the omega-6s (seeds). 'We already have
  too much omega-6 in our diet,' Dr Richardson reveals, 'so with children,
  just get loads of omega-3s into them.'
 
  Complex carbohydrates
        May help: Mood swings, extreme behaviour, hyperactivity.
        Where they are found: Porridge oats, oat
  cakes, brown rice, wholegrains (including wholegrain bread and pasta),
  beans, lentils, quinoa and most fruit. 'The ideal good-mood cereal is whole
  oats,' says nutritional therapist Deborah Colson, 'either as muesli or a
  porridge with fresh fruit added for variety. The next best would be wholegrain
  toast with an egg or some nut butter - protein food.' What they do: When
  broken down by the body, these slow-burn carbohydrates produce an even
  dispersal of glucose through the system - without the highs and lows associated
  with refined carbohydrates (such as sugar and white flour).
 
  Tryptophan
        May help: Depression, impulse control,
  appetite, low self-esteem, anxiety.
        Where it is found: Turkey, chicken, meat,
  fish, eggs, nuts (especially walnuts), bananas, avocados, cottage cheese, beans,
  peas, lentils and soya.
        What it does: This 'good mood protein' (an
  amino acid) is converted by the body into serotonin, a hormone that elevates
  mood. Some say the amounts are too small to have an effect, others that
  tryptophan only works on an empty stomach. Eating slow-acting carbs helps the
  body absorb tryptophan and convert it.
 
  Essential minerals
        May help: ADHD, fidgeting, hyperactivity,
  violent and antisocial behaviour, poor attention span, irritability,
  insomnia, lowered IQ.
        Where they are found: Green leafy vegetables,
  nuts and wholegrains for magnesium (ADHD, fidgeting); lean meat, liver, offal
  and tinned oily fish for zinc and iron (nervous system, insulin
  production); dairy produce, canned bony fish, tofu, egg yolk, pulses and figs
  for calcium (nerves, cell membranes, sleep); Brazil nuts, wheatgerm, molasses,
  liver, kidney, sunflower seeds, wholewheat bread for selenium
  (irritability, depression); unrefined grains, mushrooms, prunes, raisins, nuts
  and asparagus for chromium (blood sugar levels).
        What they do: Among other things, they are
  linked to healthy brain development and IQ â€" which influence behaviour.
  Last month, the Government revealed that all 496 schools participating in a
  national healthy eating programme - with an emphasis on nutrition - achieved
  better results in English, maths and science.
 
  Essential vitamins
        May help: Hyperactivity, aggression,
  depression, poor attention, low  IQ.
        Where they are found: Citrus fruits, berries
  and watercress for vitamin C; fresh raw or cooked Brussels sprouts,
  asparagus, spinach, kale, black-eye beans and yeast extract for B vitamins
  (folates), in which most school meals are deficient.
        What they do: According to the Food and Mood
  Project, endorsed by the mental health charity Mind, vitamins C and B are
  'good mood vitamins' essential for emotional and mental health. Studies
  have shown that deficiency in essential vitamins can lead to
  antisocial behaviour.
 
  Low-GI foods
        May help: Mood swings, hyperactivity,
  restlessness, aggression.
        Where they are found: Oats, ryebread,
  pumpernickel, pasta and noodles (ideally wholegrain), yams, carrots, baked beans,
  lentils, dried apricots and other stoned fruits, fruits from temperate
  climates (not exotics).
        What they do: Like complex carbohydrates, they
  release glucose slowly into the bloodstream and do not exert a yo-yo effect
  on mood.