Science - September 2, 2004

Heart takes little notice of oily fish

The fatty acids in fish have little influence on the heart rhythm, at least not in healthy people and not in people who only have mild heart rhythm disturbances. Anouk Geelen devoted her PhD research to the matter in the sub-department of Human Nutrition.

Oily fish is good for the heart. Researchers believe that this is because the fatty acids in them regulate the heart rhythm. In order to test this theory, Geelen gave healthy people high doses of fish fatty acids in capsules and then looked at whether their hearts beat more efficiently. There was no difference. When she repeated the experiment on a group of people with mild heart rhythm disturbances she discovered that the fish fatty acids did not reduce the number of rhythm disturbances. What they did do was to make the heart beat a little slower.

Geelen is not prepared to say that fish fatty acids do not work. ‘There are still a number of big experiments running,’ she says. ‘Only when they are completed will we be able to say something about fish fatty acids.’ Nevertheless, the PhD student is not frustrated by her lack of results after four years. ‘That’s how it goes in the sciences,’ she adds. ‘Each research project is one piece of a bigger puzzle, and when you put a lot of pieces next to each other you get the bigger picture. And it’s still not certain whether we will have the bigger picture even when the big experiments are finished.’ /WK