Can too much fatty food harm young brains?

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Eating a very high-fat diet early in life may disrupt development of the prefrontal cortex in young brains, according to new research in mice.

Scientists compared the brains of juvenile and adult mice fed either an extremely high-fat diet or a more typical diet. The fat-rich diet contained high levels of saturated fats.

After just four weeks, young mice fed the high-fat diet showed signs of impaired cognitive function. Problems materialized even before the mice started to gain weight.

While their metabolic systems were severely disrupted and they became obese, there were no comparable changes in the behavior of mature mice fed a high-fat diet over an extended period of time.

“Even so, this does not rule out the possibility that a high-fat diet may also be harmful for the brains of adult mice,” says Urs Meyer, former group leader of the Laboratory for Physiology and Behavior at ETH Zurich and now a professor at the University of Zurich.

One of the key factors in the development of these cognitive problems may be age. The prefrontal cortex, which is responsible for the executive functions of the human brain, is particularly vulnerable, as it takes longer to mature than other structures in the mammalian brain.

The results of the mice study are readily translatable to humans, says Meyer. “As in humans, the prefrontal cortex in mice matures mainly during adolescence.”

The executive functions attributed to this area of the brain, which include memory, planning, attention, impulse control and social behavior, are similar for both mice and humans. Also, the neuronal structures affected by fatty foods are identical.

Meyer points out, however, that the extremely high-fat diet—mice received more than 60 percent of their calories in the form of fats—was not typical of the amount consumed by most people over an extended period. “Only very few children and adolescents consume high-fat diets so excessively,” explains Meyer.

Such an exaggerated level of fat was deliberately chosen to allow the researchers to clearly demonstrate the effect of fatty foods on the maturation of the brain and to provide evidence for the underlying principle.

The study didn’t address the maximum amount of fat a diet can include to avoid subsequent damage to the maturing prefrontal cortex, Meyer says. “Anyone eating fast food once a week is unlikely to be at risk.”

Source: ETH Zurich