A team at the University of California, Riverside reported in the Journal of Lipid Research that a high-fat diet rich in soybean oil caused significant weight gain in most mice studied, while genetically engineered mice on the same diet resisted weight gain. The study links these different outcomes to a liver protein, HNF4α, and to lipid metabolites called oxylipins.
The transgenic animals produced a slightly different form of HNF4α, had far fewer oxylipins in the liver, showed healthier liver tissue and displayed enhanced mitochondrial function. The researchers identified specific oxylipins derived from linoleic acid and from alpha-linolenic acid that were necessary for weight gain in regular mice. Yet transgenic mice on a low-fat diet also had elevated oxylipins without becoming obese, suggesting that oxylipins are important but not alone sufficient; other metabolic factors matter.
Further analysis found much lower levels of two enzyme families that convert linoleic acid into oxylipins in the altered mice. These enzymes are highly conserved across mammals, and their levels can vary with genetics, age, sex, medications, diet and other factors. Notably, only oxylipin levels in the liver, not in blood, correlated with body weight, so common blood tests may miss early changes.
Soybean oil consumption in the US rose five-fold from about 2% to nearly 10% of total calories. Although soybean oil contains no cholesterol and soybeans are a rich plant protein source, the study found soybean oil consumption was associated with higher cholesterol in mice. The team is now studying how oxylipin formation leads to weight gain and whether similar effects occur with other oils high in linoleic acid, such as corn, sunflower and safflower. The researchers have no human trials planned but hope the results will guide future research and inform nutrition policy. Sonia Deol noted this may be a first step toward explaining why some people gain weight more easily, and Frances Sladek recalled earlier work showing soybean oil was more obesogenic than coconut oil.
Difficult words
- oxylipins — molecules made when fats are chemically changed
- transgenic — describing animals with changed genes
- mitochondrial — related to tiny energy structures in cells
- linoleic acid — a common vegetable fatty acid in oils
- alpha-linolenic acid — a plant-based essential fatty acid
- enzyme — a protein that speeds up chemical reactionsenzymes
- obesogenic — tending to cause weight gain
- correlated — show a relationship between two things
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could variation in enzyme levels among people (for example by genetics or age) affect how they respond to diets high in linoleic acid?
- The article says oxylipin levels in liver, not blood, correlated with weight. How might this influence medical tests or early detection of diet effects?
- Transgenic mice had elevated oxylipins on a low-fat diet but did not become obese. What does this suggest about the role of oxylipins and other metabolic factors in weight gain?
Related articles
African leaders urged to fix health financing at UNGA80
At the 80th UN General Assembly in New York, Obinna Ebirim urges African countries to press for fairer donor partnerships and to increase domestic health funding. He highlights staff shortages, weak infrastructure and the National Health Fellows Programme.
Targeting a brain circuit to reduce opioid relapse
Researchers at Washington State University found that lowering activity in a specific brain connection cut heroin-seeking in a preclinical model. The study identifies a pathway between the prelimbic cortex and the paraventricular thalamus and tests two ways to reduce its activity.
Internet use may reduce loneliness for older unpaid caregivers
A US study found that older unpaid caregivers who use the internet more often tend to feel less lonely. Researchers analysed 2019–2020 California survey data from 3,957 caregivers aged 65 and older; about 12% had health problems.
Drug‑resistant Salmonella in children’s food and water in Karamoja
A peer‑reviewed study found drug‑resistant Salmonella in nearly half of food and water consumed by under‑fives in Karamoja. High resistance to azithromycin and other drugs raises health, economic and development concerns.