A high-fat diet is associated with various genetic changes, which increase the risk of obesity and colon cancer, for example, while negatively affecting the immune system and brain function.
In a new study by experts at the University of California, Riverside, the effects of three high-fat diets, which differed only in their fatty acid composition, on gene expression in the intestine were examined.
The results can be read in the English-language journal “Scientific Reports”.
Mice consumed different high-fat diets
In the research, mice were fed three different forms of diet over a period of 24 weeks. In each of these diets, at least 40 percent of the calories consumed came from fats. The team then examined the intestinal flora and also possible genetic changes in all parts of the animals’ intestines.
One group of mice consumed a diet containing saturated fats from coconut oil and another group consumed monounsaturated modified soybean oil. The third group of mice consumed an unmodified soybean oil high in polyunsaturated fats, according to the team.
High-fat diet alters gene expression
When comparing the effects of these diets with a low-fat diet, the researchers found changes in gene expression in all three groups. This is the process in which genetic information is converted into a functional product, such as a protein, the experts explain.
It is often claimed that a plant-based diet is healthy. However, this does not apply to a high-fat plant-based diet, reports study author Professor Frances Sladek.
High-fat diets change intestinal bacteria
In the new study, the team documented numerous effects of a high-fat diet. For example, major changes were found in genes related to fat metabolism and the composition of intestinal bacteria.
This was demonstrated, among other things, by an increase in pathogenic E. Coli bacteria and a simultaneous reduction in so-called Bacteroides, a genus of bacteria that is known to protect the body from pathogens. Changes in genes that regulate susceptibility to infectious diseases were also identified.
“We saw that the pattern recognition genes that recognize infectious bacteria were affected. We saw that genes that signal cytokines, which help the body control inflammation, were affected,” reports the professor in a press release.
A diet high in fat promotes harmful intestinal bacteria
This makes it clear that high-fat diets affect the host’s immune system genes while creating an environment in which harmful gut bacteria can thrive.
The team had previously found in other research that there was a link between soybean oil intake and obesity and diabetes, both of which are important risk factors for COVID-19.
The current study now shows that all three high-fat diets examined increase the expression of ACE2 and other so-called host proteins that are used by COVID spike proteins to enter the body.
Link between high-fat diets and cancer
The team also found that a high-fat diet increased signs of stem cells in the colon, which Professor Sladek says can be a precursor to cancer. In terms of effects on gene expression, coconut oil and then unmodified soybean oil were associated with the most such changes.
What role do polyunsaturated fatty acids play?
The differences between the two soybean oils examined suggest that the polyunsaturated fatty acids in unmodified soybean oil, especially linoleic acid, play a role in changing gene expression, the researchers explain.
According to the team, mice that were fed soybean oil in the study showed more pronounced negative changes in their microbiome, the experts add.
Negative effects of soybean oil
In previous years, the research group had already found that soybean oil caused obesity, diabetes, insulin resistance and fatty liver disease in mice. Additionally, it has been shown that soybean oil can affect genes in the brain that are linked to diseases such as autism, Alzheimer’s, anxiety and depression.
However, the team specifically points out that these results only apply to soybean oil, and not to other soy products, such as tofu or soybeans themselves.
Diet should not include too many high-fat foods
The results make it clear how important it is to pay attention to a balanced and healthy diet that does not include too many high-fat foods.
In general, however, there seem to be big differences in how different fatty acids affect health, intestinal flora and also genes, with coconut oil and soybean oil seeming to bring about particularly strong changes. (as)