January 27, 2009
Study Suggests Low-Calorie Diet Can Boost Memory
German researchers suggest that reducing what you eat by nearly a third may improve memory.
The study showed significant improvements in 50 elderly volunteers who were given a special low-calorie diet and were then administered memory tests.
Dieticians warned, however, that the reduction in calories could harm health without special supervision.
Research in animals has suggested calorie restricted diets might be able to improve lifespan and delay the onset of age-related disease.
A team 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.
But scientists are unsure as to whether this would translate to humans, and the levels of "caloric restriction" involved are severe.
Several theories abound over the success of the mechanism, ranging from a reduction in the production of "free radical" chemicals that can cause damage, to a fall in inflammation, which can have the same result.
For the study, volunteers with an average age of 60 were split into three groups.
The first group was given 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 calorie-restricted diet was administered to the third group.
Three months later, the first two groups showed no difference in memory scores, but the 50 in the third group performed better. The calories-restricted group also showed other signs of physical improvement including decreased levels of insulin and fewer signs of inflammation.
These changes could explain the better memory scores by keeping brain cells in better health, researchers said.
"To our knowledge, the current results provide first experimental evidence in humans that caloric restriction improves memory in the elderly. The present findings may help to develop new prevention and treatment strategies for maintaining cognitive health into old age," the researchers wrote.
Expert supervision was taken to make sure that the volunteers, despite eating a restricted diet in terms of calories, carried on eating the right amount of vitamins and other nutrients.
"The drop in insulin levels are one plausible reason why mental performance might improve," said Dr. Leigh Gibson from Roehampton University.
He said the hormone was known to act on parts of the brain related to memory, and the higher levels found in people with poorly controlled type II diabetes had been directly linked to worse memory and cognitive function.
People, particularly those already at normal or low weight, should be "extremely careful" about attempting such a diet, according to spokesman for the British Dietetic Association.
"There is other evidence that, far from enhancing memory, dieting or removing meals can interfere with memory and brain function," she told BBC news.
She stated that a 30 percent drop in calories is a significant one for someone who is not overweight, and should not be undertaken lightly.
"It could even be dangerous if the person is already underweight."
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