Is there a connection between omega-3 fatty acids and violence? Does a shortage of essential nutrients cause thuggish behavior? I'm skeptical of any direct causal connection - human behavior just isn't that simple - but I'm still going to eat more fatty fish. The evidence is tantalizing:
The UK prison trial at Aylesbury jail showed that when young men there were fed multivitamins, minerals and essential fatty acids, the number of violent offences they committed in the prison fell by 37%. Although no one is suggesting that poor diet alone can account for complex social problems, the former chief inspector of prisons Lord Ramsbotham says that he is now "absolutely convinced that there is a direct link between diet and antisocial behaviour, both that bad diet causes bad behaviour and that good diet prevents it."
How might such a mechanism actually work in the brain?
Omega-3 DHA is very long and highly flexible. When it is incorporated into the nerve cell membrane it helps make the membrane itself elastic and fluid so that signals pass through it efficiently. But if the wrong fatty acids are incorporated into the membrane, the neurotransmitters can't dock properly. We know from many other studies what happens when the neurotransmitter systems don't work efficiently. Low serotonin levels are known to predict an increased risk of suicide, depression and violent and impulsive behaviour. And dopamine is what controls the reward processes in the brain.
Laboratory tests at NIH have shown that the composition of tissue and in particular of the nerve cell membrane of people in the US is different from that of the Japanese, who eat a diet rich in omega-3 fatty acids from fish. Americans have cell membranes higher in the less flexible omega-6 fatty acids, which appear to have displaced the elastic omega-3 fatty acids found in Japanese nerve cells.
Hibbeln's theory is that because the omega-6 fatty acids compete with the omega-3 fatty acids for the same metabolic pathways, when omega-6 dominates in the diet, we can't convert the omega-3s to DHA and EPA, the longer chain versions we need for the brain. What seems to happen then is that the brain picks up a more rigid omega-6 fatty acid DPA instead of DHA to build the cell membranes - and they don't function so well.
I'm well aware that omega-3's are just the latest nutrional fad, and that feeding violent offenders fish oil isn't a panacea. Nevertheless, it's interesting to realize that the foods we eat actually affect the structure of our brain. We know what Twinkies and junk food do to our waist. What if they also turn our cortex into a mass of ineffectual flab?
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Well, there was the "Twinkie Defense" used by Dan White in 1979. His eating Twinkies and drinking Coke may have increased his depression which led to his killing spree (diminshed capacity). The defense did not say Twinkies caused depression but this is what people came to believe.
Before he ate all those Twinkies and drank Coke, he was fitness fanatic...
David Horrobin's The Madness of Adam and Eve is an interesting read that discusses omega-3's and the evolution of schizophrenia.
The first block-quote mentions also, "multivitamins, minerals". Consumers and prisoners generally experience poor nutrition, which is known to affect cognitive function, directly and indirectly. Omega-3 may be influential, too, but surely it is arbitrary to attribute to it the entire effect.
So now the classic question will be expanded to: "Have you stopped beating your wife now, or do you want another helping of the baked salmon?"
I recently wrote a post summarizing some of the research on omega-3s. The results are by no means conclusive yet, but it does seem promising at this point. http://sharpbrains.wordpress.com/2006/10/19/nutritional-supplements-and…