Science - June 24, 2010

Healthy food if you're lucky

Diet determines whether genes do their job. Not everyone benefits equally from healthy food.

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Studies of healthy food should allow for the genetic make-up of the people in the experiment. This is the conclusion of Edith Feskens, professor of Nutrition and Metabolic Syndrome. Feskens and her team studied the relationship between the level of cholesterol in the blood and three variants of the FADS gene (a gene involved in the metabolism of fat) in 3,500 people. 
The relationship could not be demonstrated when the experimental subjects had a diet with few omega-3 and omega-6 fatty acids.  However, there did turn out to be a relationship if the diet contained a large amount of such fatty acids: the experimental subjects with one particular variant of the FADS gene turned out to benefit from a diet rich in fatty acids as they had a reduced level of cholesterol. The subjects with the other variants turned out not to be susceptible to the cholesterol-reducing effect of omega-3 and omega-6 fatty acids. In other words, the diet determines whether this specific gene has an effect. The results have been published in the online edition of The American Journal of Clinical Nutrition.  

Contradictory
It is known that unsaturated fatty acids such as omega-3 and omega-6 fatty acids are good for your heart and vascular system. These fatty acids are to be found in fish and vegetable oil, and have the effect of reducing cholesterol levels. 'Even so, healthy food does not always seem to work and research results are sometimes rather contradictory', says Feskens. 'This is probably because researchers still do not allow sufficiently for the genetic susceptibility of the experimental subjects.' 

Chances
The influence the FADS gene has on the cholesterol-reducing effect of omega-3 and omega-6 fatty acids does not mean that some people should just forget about eating fish. 'It is still too soon to make dietary recommendations and we don't want to encourage fatalism', says Feskens. 'Some people can benefit more from a healthy diet than others but you will always have chances, even if your genes are not optimal.'
The results for the variants of the FADS gene should be put into perspective, Feskens feels. 'We have a lot of genes that play a part in the metabolism of fat', explains the professor. 'People who don't have the right FAD variant may still have other genes that ensure unsaturated fatty acids have a cholesterol-reducing effect.'

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