New York, Jan 4 : High-fat diets affect genes linked not only to obesity, colon cancer and irritable bowels, but also to the immune system, brain function, according to a study in mouse models. Researchers at the University of California - Riverside fed mice three different diets over the course of 24 weeks where at least 40 per cent of the calories came from fat. Then, they looked not only at the microbiome, but also at genetic changes in all four parts of the intestines. One group of mice ate a diet based on saturated fat from coconut oil, another got a monounsaturated, modified soybean oil, and a third got an unmodified soybean oil high in polyunsaturated fat. Compared to a low-fat control diet, all three groups experienced concerning changes in gene expression, the process that turns genetic information into a functional product, such as a protein. "Word on the street is that plant-based diets are better for you, and in many cases that's true. However, a diet high in fat, even from a plant, is one case where it's just not true," said Frances Sladek, a cell biology professor at the varsity. The study, reported in a paper in the journal Scientific Reports, documents the many impacts of high-fat diets. It showed major changes in genes related to fat metabolism and the composition of gut bacteria, as well as changes in genes regulating susceptibility to infectious diseases. "We saw pattern recognition genes, ones that recognise infectious bacteria, take a hit. We saw cytokine signalling genes take a hit, which help the body control inflammation," Sladek said. "So, it's a double whammy. These diets impair immune system genes in the host, and they also create an environment in which harmful gut bacteria can thrive." The study also showed that all three high-fat diets increase the expression of ACE2 and other host proteins that are used by Covid spike proteins to enter the body. In addition, the team observed that high-fat food increased signs of stem cells in the colon. "You'd think that would be a good thing, but actually they can be precursors to cancer," Sladek said. The researchers hope the study will cause people to closely examine their eating habits. /IANS