ARBOR CLINICAL NUTRITION UPDATES ©
This week we consider two interesting studies that looked at whether taking whether broad-spectrum nutritional supplements improves aggressive and antisocial behaviour.
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Arbor Clinical Nutrition Updates
NUTRITION RESEARCH REVIEW
Study 1: Misbehaviour in young adult prisoners
Supplements of vitamin and minerals together with essential fatty acids resulted in significantly fewer disciplinary offences amongst young adults in prison, according to recently published English trial.
Subjects: 231 young adult prisoners.
Method: Randomised, double-blind, placebo-controlled trial. Subjects were given either placebo or active supplementation. Active supplementation consisted of a commercially available product containing a wide range of vitamins and minerals (including trace elements such as selenium, chromium and manganese) at doses roughly equivalent to recommended dietary intake (RDI), together with a commercial omega:3 fatty acid supplement.
A seven day dietary record was taken and psychological testing performed at the outset. The length of each study remaining on the trial was variable, as their stay in the prison was obviously based on their legal situation !
Results:A total of 172 subjects remained in the trial for at least 2 weeks. The pre-intervention dietary intake, disciplinary offence record and psychological test scores were similar in the placebo and active intervention groups.
Those subjects taking supplements for at least 21 days had a 35% reduction in the number of disciplinary offences compared with pre-supplementation baseline (from 16.0 to 10.4 incidents per 1000 person-days, 95% CI 16.3-53.9%, p < 0.001), whereas the placebo group did not (6.7% reduction, 95% CI: -15.3-+28.7%). The largest reduction of offences seen in the active group was in relation to the more serious incidents, including violence.
Reference: Br J Psychiatry 2002 Jul;181:22-8
Study 2: Delinquency in schoolchildren
Subjects: Schoolchildren (aged 6-12 years) from "working class," primarily Hispanic, elementary schools.
Method: Randomised, placebo-controlled, double-blind trial. 468 children were given either supplements or placebo by their teachers, as part of a wider study looking at the impact of supplements on intelligence.
From this lager group, 80 children were shown to have been disciplined during an 8 month period (September to April inclusive). These 80 children formed the analysis group.
Supplements were multi vitamin and minerals at levels equal to 50% of the U.S. daily recommended allowance. Both supplements and placebo were taken for 4 months. The primary outcome measure was a notation of delinquency (whether violent or non-violent) in the school records.
Results: The frequency of disciplinary incidents was much less in the disciplined children taking supplements than in those on placebo (mean of 1.0 incidents c.f. 1.9) . This was a reduction of 47% (95% confidence interval, 29% to 65%, p< 0.03).
Reference: J Altern Complement Med 2000 Feb;6(1):7-17
The question of whether poor diet can be a direct cause of aggressive, antisocial or violent behaviour is controversial. Certainly some parents may have the impression that `junk food' (whowever they may define it) causes `bad behaviour' in their children. But whether there are some specific elements of diet, nutritional imbalance or deficiency that directly cause aggression remains the subject of much debate.
This is part of a broader question of how diet affects mood and mental performance, for example in relation to hyperactivity in children. That broader question is more than we can cover here, but is one we will be returning to in a later issue.
Despite the enormous potential implications of link between diet and aggression, there is surprisingly little good research available on the subject. The two studies summarised in this issue are therefore a valuable contribution to our knowledge, particularly as they are both randomised, placebo-controlled trials based in `real world' situations.
Because the supplements used in these trials covered a very broad spectrum of nutrients, they give little clue as to what specific nutrients may have been involved in the improvements that were seen. But those improvements were of sufficient magnitude to make a big difference in society, were they to be more confirmed by subsequent studies. This new data confirms several previous trial reports involving broad spectrum vitamin and mineral supplements and essential fatty acids (ref. 1,2).
We are still at a very early stage of our understanding on this topic, and do not even really know which paticular nutrients or aspects of diet should be tested in such trials.
Previous mainly observational studies have reported links between aggression or violence and a wide variety of nutrients, low tryptophan affecting serotonin metabolism (ref. 2), elevated copper:zinc ratio (ref.3), decreased omega:3 fatty acid levels (ref.4), hypoglycaemic responses in a glucose tolerance test (ref. 5) and low serum cholesterol levels (ref.6). Positive results from a randomised trial of essential fatty acid supplementation on aggressive (ref.7), which may prove to be a promising line of enquiry. However, all these observational studies are prone to significant confounding from social and demographic factors, (for example the link between cholesterol and violence is confounded by age)
One difficulty in establishing the connection may well be that there is a lot of individual variation in people's behavioural response to nutritional imbalances, or that some of the links are very specific to the individual, for example an allergic or other adverse reaction to a specific foods.
It would be ideal if all institutions - including schools and prisons - served consistently nutritious and affordable food, but even that may not guarantee that such problems would be avoided. The subjects in the first study, for example, had below recommended dietary intakes for many nutrients, despite the prison diet providing levels which met the RDI.
WHAT DOES IT MEAN FOR THE CLINICIAN?
There is some quite good evidence that poor diet is linked causally with aggessive behaviour. It is too early to know exactly to whom this applies and what elements of nutrition are involved, but research on these questions has the potential to yield powerful benefits for individuals and society.
1. Journal of Nutritional and Environmental Medicine. 1997;
2. J Clin Invest 1996 Feb 15;97(4):1129-33
3. Psychopharmacology (Berl) 2001 Oct;157(4):395-400
4. Physiol Behav 1997 Aug;62(2):327-9
5. Physiol Behav 1996 Apr-May;59(4-5):915-20
6. Neuropsychobiology 1982;8(1):30-4
7. J Psychiatr Res 2000 Jul-Oct;34(4-5):301-9.
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