12 February 2007

Diet & your brain: aggression

Aggression has many causes, including psychological stresses, political pressures and hormonal factors. However, research indicates that dietary factors may also play a role.


Nutrients and aggression
In this series on “The Influence of Diet on the Brain & Nervous System”, we have already discussed dietary factors that can influence appetite, and the role of inositol in bulimia and psychiatric conditions, such as panic disorders, depression and obsessive compulsion. This article will consider how diet can potentially influence aggression.

The Aggressive Age
We live in an aggressive world if the War in Iraq and clashes in other parts of the globe are anything to go by.

Aggression has many causes, including psychological stresses, political pressures and hormonal factors, such as testosterone. In individual human beings aggression can manifest as antisocial behaviour, road rage, physical assault, including murder, and many other actions that cause harm to fellow humans. Recent research has indicated that dietary factors may well play a role in calming aggression.

Teenage offenders
Aggression is not necessarily age-related, but it is a fact that the teenage years are often fraught with aggressive behaviour, particularly in young men. A sad consequence of this teenage rage and lack of control, is the fact that many young offenders land up in jail or in correctional facilities. While such youngsters are incarcerated, they often vent their rage and frustration on fellow inmates. Such behaviour is usually punished by strict discipline and loss of privileges.

Researchers in the UK recently conducted a study with 231 young adult prisoners who were randomly chosen to either receive placebo (inactive substance), or a vitamin and mineral supplement together with omega-3 fatty acids. The vitamin and mineral supplement also contained trace elements such as selenium, chromium and manganese. All the nutrients in the supplement were included at levels of more or less the Recommended Daily Dietary Allowance (RDA).

At the start of the trial, the young participants were given psychological tests to measure aggression and their usual dietary intake was determined. The disciplinary offence records of each prisoner before and during the trial were compared.

Promising results
The results of this British study showed that young offenders who received vitamin, mineral, trace element and omega-3 supplementation, had 35% fewer disciplinary offences than those subjects who were receiving placebo. Interestingly the greatest improvement in antisocial behaviour was found for really serious offences such as physical violence.

Aggression in schoolchildren
Not all young offenders are put in jail. Many schoolchildren, particularly in economically deprived populations, also exhibit rage, antisocial behaviour, aggression and general ‘bad behaviour’. In a second study conducted in the USA, researchers gave 80 schoolchildren aged six to 12 years, vitamin and mineral supplements, or placebo, in an attempt to decrease delinquency.

These supplements provided approximately 50% of the RDA of the different nutrients for a study period of four months.

Once again, the results of the American study indicated that vitamin and mineral supplements can reduce aggressive behaviour. The study group receiving supplements were 47% less likely to exhibit delinquent behaviour than those receiving placebo.

Diet and Aggression
Although there have been indications in the past that a poor or inadequate diet lacking essential nutrients can cause aggressive behaviour, research in this field has to date been rather limited. The results of these two studies which produced dramatic decreases of 35% in aggression in teenage offenders, and of 47% in delinquent schoolchildren, are therefore most encouraging.

Because the subjects in both studies took supplements, which contained a wide variety of vitamins, minerals, trace elements, and omega-3 (in the UK study), we still don’t know at this stage which of the nutrients had this positive effect. Experts theorise that low tryptophan levels may influence serotonin levels in the brain, or that an imbalance in the copper-zinc ratio, or a deficiency in omega-3 fatty acids, may contribute to violence and aggression. There are also some indications that hypoglycaemia or low blood sugar levels can trigger outbursts. A great deal of additional research remains to be done in this important field to try and pinpoint more accurately those nutrients that can calm rage and prevent antisocial behaviour.

At the present moment, the best approach to controlling aggression in children and teenagers, is to make quite sure that they are eating a balanced diet and do not suffer from hypoglycaemia. To achieve this, they need to eat regular meals and healthy snacks, avoid junk food and get plenty of exercise. If you are struggling with a really rebellious teenager or an impossible family member who flares up at the slightest provocation and tends to violence, it may be a good idea to give them a complete vitamin and mineral supplements, as well as Salmon oil capsules for omega-3.

If you have any diet queries, post a question or message on The Message Board. I am here to assist you with your Diet and Food Choices, so let’s interact. (Dr I V van Heerden, Registered Dietician)

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