Reducing what you eat by nearly a third may improve memory, according to German researchers.
They introduced the diet to 50 elderly volunteers, then gave them a memory test three months later. The study, reported in the Proceedings of the National Academy of Sciences journal, found significant improvements.However, a dietician said the reduction could harm health unless care was taken. There is growing interest in the potential benefits of calorie restricted diets, after research in animals suggested they might be able to improve lifespan and delay the onset of age-related disease. However, it is still not certain whether this would be the case in humans - and the the levels of "caloric restriction" involved are severe.
The precise mechanism which may deliver these benefits is still being investigated, with theories ranging from a reduction in the production of "free radical" chemicals which can cause damage, to a fall in inflammation which can have the same result.
The researchers from the University of Munster carried out the human study after results in rats suggested that memory could be boosted by a diet containing 30% fewer calories than normal.
The study volunteers, who had an average age of 60, were split into three groups - the first had a balanced diet containing the normal number of calories, the second had a similar diet but with a higher proportion of unsaturated fatty acids, such as those found in olive oil and fish. The final group were given the calorie restricted diet.
After three months, there was no difference in memory scores in the first two groups, but the 50 in the third group performed better.