Soybean oil, one of the most widely consumed cooking oils globally, may contribute to obesity due to its high linoleic acid content, according to new research published in the Journal of Lipid Research. The study raises important questions about the metabolic impact of excessive omega-6 fatty acid intake, particularly in societies where soybean oil is used extensively in home kitchens, restaurants, and ultra-processed foods.
According to the U.S. Soybean Export Council, soybean oil represents 57% of all cooking oils used in the U.S. and 30% of global consumption, making its health effects highly relevant to public nutrition.
What the study found
Researchers at the University of California, Riverside examined transgenic mice engineered to produce an altered form of the liver protein HNF4A, which plays a critical role in liver, pancreas, and gut function. These mice were expected to respond differently to linoleic acid metabolism.
Key findings include:
- Transgenic mice fed a high soybean oil diet gained significantly less weight than normal mice on the same diet.
- They produced lower levels of pro-inflammatory oxylipins, compounds formed from linoleic acid.
- Improved mitochondrial function and overall healthier livers were observed.
- The results suggest that oxylipins derived from linoleic acid drive obesity in regular mice.
Lead researcher Dr. Sonia Poonamjot Deol explained that most humans consume far more linoleic acid than needed, largely due to processed foods and restaurant cooking oils. This may cause excessive oxylipin accumulation, inflammation, and weight gain.
Is soybean oil harmful for humans? Experts weigh in
Experts caution that while the findings are compelling, mouse-model results cannot be directly applied to humans. Dr. Mir Ali, a bariatric surgeon not involved in the study, emphasized the need for human-based research to confirm these mechanisms.
Registered dietitian Monique Richard, MS, RDN, LDN, noted that soybean oil itself is not inherently harmful. Rather, the concern lies in:
- Highly refined processing
- Excessive consumption
- Its dominance in ultra-processed foods
How to reduce soybean oil intake
Dietitians recommend several practical strategies:
- Read ingredient labels: “Vegetable oil” often means soybean oil.
- Choose whole foods over ultra-processed snacks.
- Cook more meals at home to control fat sources.
- Use cooking methods like grilling, roasting, and air-frying to reduce oil use.
- Choose healthier oils such as extra-virgin olive oil, avocado oil, sesame oil, or peanut oil.
- Enjoy whole soy foods like tofu or edamame, which do not carry the same concerns.
Richard emphasizes that “the components of our meals matter to our molecules,” underscoring the importance of balanced dietary choices rather than fear-based avoidance.
