A comprehensive investigation at the University of California, Riverside has discovered that excessive intake of soybean oil can increase detrimental bacteria in the gut, which could potentially cause colitis and inflammatory bowel disease (IBD). The linoleic acid present in soybean oil was highlighted as the main issue, with the researchers noting that surplus amounts adversely influence the gut microbiome.
The UC Riverside-led study in mice indicates that diets rich in soybean oil reduce endocannabinoids in the gut and can instigate colitis.
An overconsumption of soybean oil has been associated with numerous health problems including obesity, diabetes, and potentially autism, Alzheimer’s disease, anxiety, and depression. Recent research has added ulcerative colitis, a type of inflammatory bowel disease (IBD) characterized by lasting inflammation of the large intestine, to this expanding list.
Researchers from the University of California, Riverside, analyzed the gut of mice consistently fed a soybean oil-rich diet for up to 24 weeks in the lab. They discovered a decrease in beneficial bacteria and an increase in harmful bacteria (particularly, adherent invasive Escherichia coli) — conditions that can induce colitis.
Featured in the photo, from left to right, are Frances Sladek, James Borneman, and Poonamjot Deol. Credit: Stan Lim, UC Riverside
Soybean oil is the most frequently used edible oil in the United States and its use is rapidly expanding in other nations, particularly Brazil, China, and India. In the U.S., the production of soybean took a leap in the 1970s for animal feed use, which subsequently led to the increased production of soybean oil. Soybeans, rich in protein, are economical and easy to cultivate.
“Our research challenges the long-held belief that most chronic illnesses originate from consuming an excess of saturated fats from animal products, and that, inversely, unsaturated fats from plants are invariably healthier,” Poonamjot Deol, an assistant professional researcher in the Department of Microbiology and Plant Pathology and a co-corresponding author on the paper published on July 3 in Gut Microbes, an open-access journal, explained.
Deol clarified that the main concern is the linoleic acid in soybean oil.
“While our bodies require 1-2% of linoleic acid daily, based on the paleo diet, Americans today are getting 8-10% of their energy from linoleic acid daily, most of it from soybean oil,” she said. “An overabundance of linoleic acid has a negative impact on the gut microbiome.”
Soybean oil currently stands as the most consumed cooking oil in the U.S. Credit: Stan Lim, UC Riverside
Deol and her colleagues discovered that a diet high in soybean oil promotes the growth of harmful bacteria such as adherent invasive E. coli in the gut. This bacteria utilizes linoleic acid as a carbon source to fulfill its nutritional needs. Moreover, several beneficial gut bacteria are unable to survive in the presence of linoleic acid and perish, which leads to the proliferation of harmful bacteria. Adherent invasive E. coli has been identified in humans as a cause of IBD.
According to Deol, “The combination of beneficial bacteria dying off and harmful bacteria flourishing makes the gut more susceptible to inflammation and its consequent effects. Furthermore, linoleic acid causes the intestinal epithelial barrier to become permeable.”
The barrier function of the intestinal epithelium plays a crucial role in maintaining a healthy gut; its disruption can lead to increased permeability or leakiness. As a result, toxins can escape from the gut and enter the bloodstream, significantly raising the risk of infections and chronic inflammatory conditions like colitis. The researchers point out that the rise in IBD coincides with the increase in soybean oil consumption in the U.S. and propose a potential link between the two.
Toxicologist Frances M. Sladek, a professor of cell biology and a co-corresponding author on the research paper, reflected on the connection made between heart disease and saturated fats in the late 1950s.
“Following studies that highlighted the detrimental effects of saturated fats, it was presumed that all unsaturated fats were beneficial,” she said. “However, not all unsaturated fats are alike, with some being beneficial for health. For instance, the unsaturated fat in fish oil is renowned for its myriad health benefits. People, therefore, assumed that soybean oil is perfectly safe and healthier to consume than other oils, without actually conducting a direct comparison as we have.”
Sladek emphasized that linoleic acid is an essential fatty acid. The soybean oil used in their experiments contained 19% linoleic acid. The American Heart Association suggests that 5 to 10% of daily calories should come from omega-6 polyunsaturated fatty acids, such as linoleic acid, to maintain heart health. Linoleic acid can be sourced from several seed oils, including safflower and sunflower, as well as from animal fat.
“Every animal has to obtain linoleic acid from its diet,” Sladek stated. “No animal can synthesize it. While a small amount of it is needed by the body, this does not imply that having it in abundance is beneficial. For instance, linoleic acid is necessary for proper functioning of several membranes in the body, such as those in the brain. If our diet consisted solely of saturated fats, our cell membranes would become too rigid and malfunction. Future research is required to determine the safe daily consumption limit for linoleic acid.”
According to Sladek and Deol, olive oil, which contains less linoleic acid, is a healthier oil to consume.
“Olive oil, a staple in the Mediterranean diet, is known for its health benefits, including a lower obesity rate. We have now found that unlike soybean oil, it does not increase the susceptibility of mice to colitis,” Sladek stated.
Chart demonstrating the consumption of edible oils in the U.S. for 2017/18. Credit: USDA
James Borneman, a professor of microbiology and plant pathology at UCR and a co-corresponding author on the paper, is a specialist in gut microbiome. He has collaborated with several groups at UCR on various research projects, including those investigating how gut microbes hinder weight loss in obese individuals. For the current study, he joined forces with Deol and Sladek to investigate the gut microbes of mice fed a high soybean oil diet.
“Adherent invasive E. coli contributes to IBD in humans, and finding this E. coli in these mice is concerning,” he noted. “While it can sometimes be unclear how mouse-based research translates to humans, in this study the connection is fairly clear.”
The research team was also surprised to find a decrease in endocannabinoids (cannabis-like molecules produced naturally by the body to regulate various physiological processes) in the gut of mice fed a high soybean oil diet. At the same time, there was an increase in oxylipins, oxygenated polyunsaturated fatty acids that regulate inflammation.
“Oxylipins in the liver have been previously found to correlate with obesity,” Deol explained. “Certain oxylipins have also been identified as bioactive in colitis studies. The crux of our current study is that a diet enriched
Table of Contents
Frequently Asked Questions (FAQs) about Soybean Oil Consumption Effects
What are the negative impacts of consuming high amounts of soybean oil?
Consuming high amounts of soybean oil can lead to an increase in harmful bacteria in the gut, potentially causing inflammatory conditions like colitis and Inflammatory Bowel Disease (IBD). This oil has also been linked to health issues such as obesity, diabetes, autism, Alzheimer’s disease, anxiety, and depression. The excessive linoleic acid in soybean oil is identified as the main concern, as it negatively affects the gut microbiome.
What happens when the gut microbiome is negatively affected by soybean oil?
When the gut microbiome is negatively affected by soybean oil, beneficial bacteria decrease, and harmful bacteria increase. This change in bacterial composition can lead to conditions like colitis. The harmful bacteria, adherent invasive E. coli, uses linoleic acid to meet its nutritional demands. The growth of this bacteria can cause Inflammatory Bowel Disease (IBD) in humans.
What’s the role of linoleic acid in our diet, and why is its excess harmful?
Linoleic acid is an essential fatty acid necessary for our bodies in small amounts (1-2% daily). However, an excess of it, mostly consumed through soybean oil, can negatively impact the gut microbiome, encouraging the growth of harmful bacteria. It can make the intestinal epithelial barrier porous, which can lead to increased permeability or leakiness, potentially resulting in infections and chronic inflammatory conditions.
Are there healthier alternatives to soybean oil?
Yes, oils with lower amounts of linoleic acid, such as olive oil, are healthier alternatives to soybean oil. Other healthy options include coconut oil and avocado oil. However, corn oil is not a recommended substitute as it contains the same amount of linoleic acid as soybean oil.
Why is soybean oil consumption so high in the U.S.?
Soybean oil is the most commonly used edible oil in the United States because it is relatively inexpensive. It’s also a byproduct of soybean production, which increased in the 1970s for use as animal feed. Its widespread use in processed foods and restaurants contributes to its high consumption.
More about Soybean Oil Consumption Effects
- Health Effects of Dietary Fats
- Impact of Dietary Fats on Gut Microbiota and its Consequences for Health
- Inflammatory Bowel Disease (IBD)
- Benefits and Risks of a High-fat Diet
- Understanding the Soybean Oil Consumption in the U.S.
4 comments
Wow this is eye-opening! Guess I’ll be switching to olive oil in my kitchen then.
Just shows why we need to stay clear of processed foods, folks! Go for natural, organic stuff – good for you and the planet!
So, all this time I thought I was doing my body a favor, and now it’s wrecking my gut? Great just great!
Really? Soybean oil is that bad? and here i was thinking it was healthier option… goes to show, you can’t trust everything on the shelves.