Regular portions of fish may help keep dementia at bay in people with a big hereditary risk of the disease. The result underlines the importance of current Dutch government advice to eat fish once a week, writes Ondine van de Rest, a researcher at Human Nutrition, in the journal JAMA.
Fish market in South-Korea. Photo: Hoks
More and more people in the Netherlands are suffering from Alzheimer’s disease and other forms of dementia. This is a growing health problem even in rising economies such as China. There are still big gaps in our knowledge about Alzheimer’s and there has been little success in tests of potential medicines in recent years. Prevention seems to be the only fruitful approach: increasing welfare, education level and health levels mean that Dutch seniors are only getting Alzheimer’s at an advanced age.
Eating fish is a promising preventive measure. Together with colleagues in Chicago, Ondine van de Rest studied a group of 544 seniors who have been monitored since 1997. They filled in questionnaires about their eating habits. The brains of 286 deceased persons were studied for signs of dementia such as the scars of mini strokes and accumulations of damaging proteins. The brains were also examined for concentrations of heavy metals often found in fish, such as mercury.
The old people who had consumed relatively large amounts of fish turned out to have incurred significantly less damage to their brains. However, this only applied to people with the gene that raises the chances of Alzheimer’s. ‘That is puzzling,’ says Ondine van de Rest, ‘and it is hard to explain it.’ Of the participants 25 percent had this gene and they in particular were the ones who had less brain damage the more fish they had eaten. Van de Rest is eager to do further research on this link in future.
Van de Rest found another reassuring result as well. Elderly people who ate a lot of fish had more mercury in their brains, but this had no harmful effects. So people who eat fish once a week, as recommended by the Dutch health council, need not worry. Van de Rest did emphasize, however, that children and pregnant women should probably be more cautious.