More evidence for the benefits of eating fish

The British television presenter and lifestyle coach Amanda Hamilton shares her views on health and nutrition.

Given that this world of ours demands immediate solutions to immediate problems, it is perhaps no surprise that the most popular food supplement in the UK and US is - wait for it - fish oil. In Britain alone, annual sales of fish oils are some £110 million (Dh625m). It would be a media-shy person indeed who has not heard of the benefits of fish oil supplements and, more specifically, omega-3 fatty acid-based supplements, in the press.

The benefits trotted out by an often un-sceptical media and a very active nutritional supplements industry range from reducing blood pressure to the controversial claims that they can improve your children's IQ, and prevent or help cure diabetes. I was reading the influential Dr Andrew Weil's online column the other day and a fascinating article on this very subject, which at the very least throws some interesting light on the value of fish oils - and specifically omega-3 fatty acids - to our physical and mental health.

If you visit Japan you'll know that, despite the perennial economic woes and Sisyphean working week, the populace appears remarkably content. In fact, the much put-upon Japanese are - according to World Health Organisation statistics - the nationality least likely to suffer from depression. According to Weil and more specifically highly qualified medical professionals, part of the answer may be the significant role played by the consumption of fish in their diet.

Dr Joseph Hibbeln, a senior clinical investigator at the US's National Institute of Alcohol Abuse & Alcoholism, reports: "The average Japanese citizen eats about 145lb (66kg) of fish annually. The average American eats about 42lb (19kg)." Hibbeln says this might explain why American rates of major depression are around 30 times higher per capita than in Japan. He goes on to argue that "an imbalance between omega-3 fatty acids (which are found in the fatty tissues of fish and, to a lesser extent, in walnuts and flax seeds) and omega-6 fatty acids (most prevalent in vegetable oil, and especially soya oil) in the western diet is a modern nutritional disaster", giving rise to not only to "depression, but also dyslexia, hyperactivity, even a tendency toward violence and murder. Bringing the fats into proper proportion appears to drastically alleviate those conditions." Strong stuff, indeed.

The challenge with western diets is that, according to Hibbeln, "upwards of 20 per cent of all calories in the US-influenced western diet come from soybean oil" and very little from fish oil. "That is much different from 100 years ago." Hibbeln says our human problem with the two fatty acids is that the enzymes that process it are very "promiscuous". In other words, these enzymes will willingly "build cell membranes out of either fat".

Thus, in the case of cell membranes associated with omega-3, we see an association with lessened diabetes, heart disease and depression and - intriguingly - murder and prison violence (he quotes a study in 2002 in the UK where serious offences came down by some 37 per cent in nine months among British prisoners whose diets contained vitamins, minerals and omega-3 oil reduced). The challenge for us busy people, of course, is how to redress the balance. According to Dr Richard Deckelbaum, director of the Institute of Human Nutrition at Columbia University in New York, "the average consumption of omega-3 fatty acids in the US is one-third to one-sixth of what we consider to be recommended levels" and that consumption based on omega6 should be correspondingly lowered.

Of course, even with this well-qualified recommendation, many of us are wary of omega-3 fatty acid-based fish oil because of worries about pollutants such as mercury that may have accumulated in the fish. Both Weil's counsel and my own are threefold. Firstly, seek fish oil supplements based on fish such as wild salmon, sardines and trout that are lower in the food chain. Larger, more carnivorous fish are more likely to contain dangerous levels of toxins.

Secondly, if you are going to use a supplement, only use one with a fivestar rating from International Fish Oil Standards, a Canadian organisation that assesses the purity of commercial fish oil supplements. Lastly, and more straightforward: eat more fresh fish in your diet, and as ever reduce or omit processed foods that have been made with omega-6 fatty acid foodstuffs such as soya and vegetable oils.