Soybean oil linked to weight gain in mice ^{CEFR B1}

Researchers at the University of California, Riverside published a study in the Journal of Lipid Research showing that most mice fed a high-fat diet rich in soybean oil gained significant weight. A separate group of genetically engineered (transgenic) mice on the same diet did not gain weight, which focused attention on a liver protein called HNF4α.

The engineered animals produced a slightly different form of HNF4α. They had far fewer oxylipins, healthier livers and improved mitochondrial function despite eating the same soybean oil diet as regular mice. The team identified specific oxylipins derived from linoleic acid and from alpha-linolenic acid that were necessary for weight gain in regular mice.

However, transgenic mice on a low-fat diet also showed elevated oxylipins without becoming obese, so oxylipins alone are not sufficient to cause weight gain. The researchers found much lower levels of two enzyme families that convert linoleic acid into oxylipins; these enzymes are conserved across mammals and can vary with genetics, diet and other factors. Only liver oxylipin levels, not blood levels, correlated with body weight.

The authors note soybean oil consumption has risen sharply and that they saw higher cholesterol in mice. They plan further research but have no human trials planned now.