August 2, 2023 – A preferred ingredient within the American weight-reduction plan is linked to ulcerative colitis, a form of inflammatory bowel disease characterised by a chronically inflamed colon. The ingredient is soybean oil, which may be very common in processed foods. In fact, per capita consumption of soybean oil within the United States increased by greater than 1,000 times within the twentieth century.
In a study from the University of California Riverside and UC Davis showed that mice fed a weight-reduction plan high in soybean oil were at higher risk of developing colitis.
The likely offender? Linoleic acid, an omega-6 fatty acid that makes as much as 60% of soybean oil.
Small amounts of linoleic acid help maintain the body's water balance, but Americans stand up to 10% of their every day energy from linoleic acid, although they only need 1 to 2%, researchers say.
The findings are based on earlier Research links a weight-reduction plan high in linoleic acid to inflammatory bowel disease (IBD) in humans. (Previous Research In mice, high consumption of the oil was also related to obesity and Diabetes in rodents.)
For the brand new study, the researchers wanted to research in additional detail what effects linoleic acid has on the intestines.
How linoleic acid can promote inflammation
In mice, the soybean oil weight-reduction plan disrupted the ratio of omega-3 to omega-6 fatty acids within the gut. This led to a decrease in endocannabinoids, lipid-based Molecules that help to dam Inflammation.
Enzymes that metabolize fatty acids are “shared between two metabolic pathways,” said study co-author Frances Sladek, PhD, a professor of cell biology at UC Riverside. “When you flood the system with linoleic acid, you have fewer enzymes available to convert omega-3s into good endocannabinoids.”
The endocannabinoid system is linked to “visceral pain” within the gut, said Punyanganie de Silva, MD, MPH, an assistant professor at Brigham & Women's Hospital who was not involved within the study. But the connection between the endocannabinoid system and inflammation shouldn’t be fully understood.
“This is one of the first papers to address the link between linoleic acid and the endocannabinoid system,” said de Silva.[The researchers] suggest a possible recent mechanism by which linoleic acid may increase inflammation” – namely, through its effect on the endocannabinoid system.
Changes within the intestinal microbiome
The intestinal microbiome of the mice also showed an increased amount of adherent invasive E. colia form of bacteria that grows using linoleic acid as a carbon source. A “very close relative” of those bacteria was associated with IBD in humans, said Sladek.
Using a technique called MetabolomicsThe researchers examined 3,000 metabolites in each the intestinal cells of the mice and within the bacteria. In each cases, the endocannabinoids decreased.
“We were actually quite surprised. I didn't realize that bacteria produce endocannabinoids,” said Sladek.
Helpful bacteria, corresponding to the probiotic Lactobacillus species, died. The mice also had increased oxylipin levels, which Obesity in mice and colitis in humans.
A weight-reduction plan high in linoleic acid can result in a leaky gut
Linoleic acid binds to a protein called HNF-4α. Disrupting the expression of this protein can weaken the intestinal barrier, allowing toxins to enter the body – higher often known as “leaky gut.” Mice fed soybean oil had lower protein levels and a more porous intestinal barrier, increasing the danger of inflammation and colitis.
“The HNF-4α protein remains transmissible from mouse to human, so whatever is happening to it in the mouse gut, there is a very high probability that a similar effect will be seen in humans,” said study co-author Poonamjot Deol, PhD, a research associate at UC Riverside.
Nevertheless, de Silva urges “caution in interpreting these results” because “this is still an experimental phenomenon and these results need to be reproduced in clinical studies, as humans have a far more diverse microbiome and more variable environmental influences than in these very controlled studies on mouse models.”
De Silva says cooking with olive oil “can help improve the omega-3 to omega-6 ratio” and recommends eating a varied weight-reduction plan that features omega-3 fats, corresponding to those from flaxseeds and walnuts, and minimal amounts of processed foods and saturated fats.
In the long run, endocannabinoids will likely be studied as a “potential therapy to treat IBD symptoms,” Deol said. She hopes to learn much more about how linoleic acid affects the endocannabinoid system.