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Whether or not oils such palm, canola, rape or soyabean are unhealthy is a matter of sometimes furious debate. But evidence is piling up that eating processed food and snacks - which invariably are made using such seed oils - is almost certainly unhealthy, as is reusing oil that has already deep-fried food, a common practice in homes and restaurants. A team of scientists in India and the US carried out tests on rats and found that animals given food cooked in reheated sesame or sunflower oil "showed increased oxidative stress and inflammation in the liver" as well as "significant damage in the colon." They said the findings suggest long-term consumption of reused oils could be a cause of "increased neurodegeneration." The work, which was presented at the annual meeting of the American Society for Biochemistry and Molecular Biology, found that eating the reheated oil disrupts the "bidirectional communication network between the liver, gut and brain," an axis which "plays a crucial role in regulating various physiological functions." "Deep frying food not only adds calories; reusing the same oil for frying, a common practice in both homes and restaurants, removes many of the oil's natural antioxidants and health benefits," they warned, discussing the better-known effects of eating too much deep-fried food, which often entails consuming too much reused oil in turn. Not only does the reused oil lack the natural health benefits contained in the first time it was used, it can in turn "contain harmful components such as acrylamide, trans fat, peroxides and polar compounds," the University of Illinois and Central University of Tamil Nadu team warned. Multiple studies have been published showing the ill-effects of too much seed oil-laden processed food, which has been linked to increasing prevalence of obesity and diabetes. A recent French experiment even concluded that eating it has an immediate and negative impact on facial attractiveness, while last month another study found a link between overdoing the snacking and diminished mental health. Still other work suggests that the effects of processed food have not been separated from other usual suspects behind ill-health, such as lack of exercise, smoking and drinking alcohol.