According to the study, a connection has been established between calorie-restricted diets and improved brain function. Although prior studies with animals have shown memory improvement, this is the first study that has shown how calorie restriction can influence memory function in humans.
The study included 50 participants aged 50 to 72, split into three groups. Members of one group were asked to decrease their calorie intake by 30 percent while eating foods they would normally consume but in smaller portions. The second group was not asked to decrease calorie intake, but instructed to boost the amount of healthy, unsaturated fat consumed by 20 percent. The third group was asked to make no dietary changes at all.
After 90 days, study participants were given tests requiring the memorization of words to measure levels of memory function. Although two of the groups showed no difference in memory scores, the group who lowered their calorie intake had an average of a 20 percent improvement in memory performance.
According to one of the researchers, Dr. Agnes Flöel, the lower calorie intake group experienced a decline in insulin levels and less signs of inflammation. This could explain the better memory scores as their brain cells were kept in better health. These participants also lost from four to seven pounds. Dr. Flöel explained how lower insulin levels could increase the sensitivity of receptors within the brain that, in turn, improve insulin signals and allow memories to be retained for a longer period of time. She also described how inflammation is believed to promote aggregation of toxic proteins and promote insulin resistance that suggests a decrease in inflammation would help brain function.
The researchers noted that they were surprised to find that participants in the unsaturated fat group experienced no improvement in memory. They suspect that this may have been due to the fact that most of the group members did not consume foods rich in omega-3 fatty acids. Hence, they are conducting a larger study requiring the unsaturated fat group to eat a lot of omega-3 fats.
Details for the study:
Witte AV et al Caloric restriction improves memory in elderly humans PNAS January 27, 2009 vol. 106 no. 4 1255-1260
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