Can Diet Help Stop Depression and Violence?
The best way to curb aggression in prisons? Longer jail terms, maybe, or stricter security measures? How about more sports and exercise? Try fish oil. How can children enhance their learning abilities at school? A well-balanced diet and safe, stimulating classrooms are essential, but fish oil can provide an important extra boost. Is there a simple, natural way to improve mood and ward off depression? Yoga and meditation are great, but -- you guessed it -- fish oil can also help do the trick.
A diet rich in vitamins, minerals and fatty acids like omega-3 is the basis for physical well-being. Everybody knows that. But research increasingly suggests that these same ingredients are crucial to psychological health too. And that's a fact a lot of people seem to find hard to swallow.
The relationship between nutrition and aggression is a case in point. In 2002, Bernard Gesch, a physiologist at Oxford University, investigated the effects of nutritional supplements on inmates in British prisons. Working with 231 detainees for four months, Gesch gave half the group of men, ages 18 to 21, multivitamin, mineral and fatty-acid supplements with meals. The other half received placebos.
During the study, Gesch observed that minor infractions of prison rules fell by 26 percent among men given the supplements, while rule-breaking behaviour in the placebo group barely budged. The research showed more dramatic results for aggressive behaviour. Incidents of violence among the group taking supplements dropped 37 percent, while the behaviour of the other prisoners did not change.
Gesch's findings were recently replicated in the Netherlands, where researchers at Radboud University in Nijmegen conducted a similar study for the Dutch National Agency of Correctional Institutions. Of the 221 inmates, ages 18 to 25, who participated in the Dutch study, 116 were given daily supplements containing vitamins, minerals and omega-3 for one to three months. The other 105 received placebos. Reports of violence and aggression declined by 34 percent among the group given supplements; at the s;ame time, such reports among the placebo group rose 13 percent.
Gesch is quick to emphasize that nutritional supplements are not magic bullets against aggression, and that these studies are just "promising evidence" of the link between nutrition and behaviour. "It is not suggested that nutrition is the only explanation of antisocial behaviour," he says, "only that it might form a significant part."
But Gesch is just as quick to emphasize that there is no down side to better nutrition, and in prisons in particular, the cost of an improved diet would be a fraction of the cost of other ways of addressing the problem of violence among inmates.
Still, the menu in British prisons hasn't changed in the five years since Gesch published his results, even though the former chief inspector of prisons in the UK, Lord Ramsbotham, told the British newspaper The Guardian last year 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."
Yet the effect of nutrition on psychological health and behaviour is still controversial, at least in part because it is so hard to study. Our moods, emotions and actions are influenced by so many factors: everything from our genes to our communities to our personal relationships. How can the role of diet be isolated among all these competing influences? That's exactly why Gesch conducted his study in prisons. In a prison, there are far fewer variables, since all detainees have the same routine. Do the results of the inmate trials reach beyond the prison walls? Gesch thinks so: "If it works in prisons, it should work in the community and the society at large. If it works in the UK and in the Netherlands, it should work in the rest of the world."
Another place improved nutrition seems to be working is in the city of Durham in northeastern England. There, Alex Richardson, a physiologist at Oxford University, conducted a study at 12 local primary schools. The research examined 117 children ages 5 to 12, all of whom were of average ability but were underachieving.
Instructors suspected dyspraxia, a condition that interferes with co-ordination and motor skills and is thought to affect at least 5 percent of British children. Possible signs of dyspraxia may include having trouble tying shoelaces or maintaining balance, for example. The condition frequently overlaps with dyslexia and attention deficit hyperactive disorder (ADHD), and is part of a range of conditions that include autistic-spectrum disorders.
Half the group of children in Richardson's study was given an omega-3 supplement for three months; the other half received an olive oil placebo. The results: Children given the omega-3 supplements did substantially better at school than those in the control group. When it came to spelling, for example, the omega-3 group performed twice as well as expected, whereas the control group continued to fall behind.
Richardson came to the study of nutrition through neurology. Her interest was sparked by the rapid rise of conditions like ADHD, autism, dyslexia and dyspraxia. The incidence of these disorders has increased fourfold in the past 15 to 20 years. "These disorders overlap considerably," she says, "but a real solution is rarely offered. A dyslexic child is assigned a special teacher. A kid with dyspraxia is sent to a physical therapist. One with ADHD is prescribed Ritalin. And you've got to learn to live with autism."
But as Richardson writes in They Are What You Feed Them: "There is always something that can be done. Don't ever believe it if anyone tells you otherwise." One of the things that can be done, according to Richardson, is to boost your child's intake of omega-3.
Of course, Omega-3 is not the only answer to ADHD, autism, dyslexia, dyspraxia or other psychological or behavioural disorders, which also include Alzheimer's disease. Studies like Richardson's suggest, however, that it may play an important role in stimulating the brain, keeping it healthy and helping it ward off debilitating conditions.
And it looks like we need all the help we can get. Behavioural dysfuntions like ADHD are currently the fastest-growing type of disorder worldwide. Twenty years ago, no one had even heard of ADHD. Today, everyone knows a kid who is taking Ritalin.
The World Health Organization (WHO) estimates that the number of people with psychological disorders will double by 2020 -- and that around that time, depression will surpass heart and vascular disease as the No. 1 most preventable cause of death. The WHO adds that psychological disorders account for four of the 10 most common causes of disability and that a quarter of the general population will be affected by them at some point in their lives.
Diet could well play a central role in all this. The quality -- and quantity -- of the food we eat has increased dramatically over the past century or so. But we are eating more and more processed foods, which contain less and less of the essential minerals, vitamins and fatty acids that appear to be so crucial for mental health. Tomato juice, for example, contains 64 percent less vitamin C, 49 percent less carotene and 17 percent less niacin than a fresh tomato.
Gesch says we "seem to have made unprecedented changes to human diets in recent years with little or no systematic evaluation of the effects on our brain or behaviour." He wants to reverse "high-calorie malnutrition" by encouraging nutritionists, physicians and educators to concentrate not just on calorie intake but on the consumption of nutritional components like vitamins, minerals and fatty acids as well.
In our distant evolutionary past, we all had much more varied diets. Research among native tribes in remote areas suggests that our hunter-gatherer forebears consumed between 100 and 150 different types of plants during the course of a year.
Nowadays, our grain consumption is heavily dominated by wheat. Soy oil accounts for more than 80 percent of the fat Americans consume. Health authorities recommend a minimum of 400 grams (14 ounces) of vegetables and fruit each day, but lots of people don't even come close to that. And even those who do eat lots of fruit and vegetables often don't get the full nutritional benefit because intensive farming has depleted the soil of key minerals.
So what's a consumer to do? Eat fish. Working with the U.S. National Institutes of Health (NIH), American physician and psychiatrist Joseph Hibbeln compared data on fish consumption with figures on depression and murder in a large number of countries around the world. Fish are a rich and ready source of omega-3. In countries in which fish consumption is low, Hibbeln found the likelihood of suffering from depression was up to 50 times greater than in countries where it is high.
Some 6.5 percent of New Zealanders suffers from severe depression; these citizens also eat very little fish. In Japan, where fish consumption is high, 0.1 percent of the population suffers from depression. Manic depression (bipolar disorder) is rare in Iceland, which has the highest per capita fish consumption in the world, but is quite common in Brazil and Germany, where people don't eat as much fish. Hibbeln also found that, on average, the risk of being murdered is 30 times greater in countries where fish consumption is low compared to countries where it is high.
Cultural and other factors certainly influence these statistics, but the comparisons are nevertheless illustrative. Overall, in subsequent trials, Hibbeln found that depressive and aggressive feelings diminished by about 50 percent after taking fish-oil capsules for two to four weeks.
Based on this and other research, the WHO concluded in a report last year: "Certain dietary choices, including fish consumption, balanced intake of micronutrients and a good nutritional status overall, also have been associated with reduced rates of violent behaviour."
How can something like omega-3 have such an impact on behaviour and psychological health? Communication between the nerve cells in the brain depends on the circulation of neurotransmitters, such as serotonin and dopamine. Low serotonin levels are associated with an increased risk of suicide, depression and violent behaviour.
Omega-3, a long, flexible molecule, appears to facilitate the circulation of neurotransmitters like serotonin in the brain, thus boosting communication among nerve cells. And nerve cells that talk a lot with each other make new connections in the brain, a process crucial for learning. Less flexible fatty acids than omega-3, though, do not as efficiently support the chatter.
Hibbeln's work has shown that the brain tissue of Americans is different from that of the Japanese. American cell membranes contain much higher levels of the less flexible omega-6 fatty acids; Japanese cell membranes are significantly richer in omega-3. Processed foods happen to be rich in omega-6, and Americans eat a lot of them. These omega-6 fatty acids seem to have displaced the omega-3 fatty acids found so abundantly in fish, of which the Japanese are so fond.
Other studies have found that depressed patients and children with ADHD and autism are deficient in omega-3. So some scientists speculate that this change in the fatty acids contained within our brains could be causing the modern rise in psychological disorders.
Although more and more research underlines the importance of nutrition for psychological wellness, these findings have not been widely translated into action. "Politicians, policymakers and business leaders keep asking for more research involving thousands of people, like the trials done for every new drug," Richardson complains. "But I say, We have done the uncontrolled experiments now [in the general population] for quite some time." Pharmaceutical firms have few incentives to organize their own studies, since omega-3 is derived primarily from fish oil -- and you can't patent fish.
This frustrates many scientists in the field. "Do we want to wait for more studies that confirm these findings, or do we want to do something today about the level of crime and aggression in our societies?" asks Stephen Schoenthaler, a sociologist at California State University at Stanislaus, in Turlock, California, who has studied the link between food and behaviour for the past 25 years and led several studies among prisoners and schoolchildren showing the social benefits of a healthier diet.
It's not all good news, though. Consumers should watch out for manufacturers that make exaggerated claims about these nutritional supplements. "Never use supplements as a substitute for a good diet," counsels Richardson. "The key thing that most people seem to have forgotten is that food is not just fuel, it is nourishment. Food is not just a source of energy that one can consume on the run. A healthy diet needs to provide a minimum of essential nutrients in a dosage recommended for daily use."
A multivitamin and mineral supplement is a good "insurance policy," Richardson says, and 500 mg of omega-3 every day is not a bad idea either. But buyer beware: Not all supplements are good supplements, so seek the advice of a qualified professional before deciding which supplement, if any, is right for you.
It almost sounds too good to be true, but research is beginning to confirm that vitamins, minerals and fatty acids can reduce aggression and improve psychological well-being. That could be a simple recipe for a more peaceful world.