EATING too much of the trans fats used to prolong the shelf life of foods such as margarine might affect learning and memory, and even damage the brain, claims Ann-Charlotte Granholm of the Medical University of South Carolina in Charleston.
Small amounts of trans fats are found naturally in milk and other foods, but some processed foods have high levels. These trans fats are created by hydrogenation – the process used to solidify oils and prolong shelf life. Products in the US will soon have to list their trans fat content because, like saturated fats, they are thought to raise cholesterol levels.
Granholm put rats on a diet that was 12 per cent fat, giving one group fats rich in trans fats and the other just soybean oil. Most people would not eat so much fat, except those on the Atkins diet, she says.
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When put through a standard maze test, the animals on the trans fat diet learned more slowly and made more errors. They were five times worse at the task. The brains of the animals also showed signs of damage to the hippocampus, a region important for learning and memory.
“Kids in school are fed hydrogenated fats and then asked to learn,” Granholm told the Society for Neuroscience meeting in San Diego last week. “I think this has high relevance.” But other experts cautioned against drawing conclusions from a small animal study.