Researchers compared how two cooking oils affect your body’s chemistry. They studied 47 healthy adults who ate either cottonseed oil or olive oil for 4 weeks, then measured changes in their blood. While both oils created similar overall metabolic effects, cottonseed oil produced higher levels of certain immune-regulating compounds. This suggests that cottonseed oil, despite containing more of a type of fat that can cause inflammation, may actually work similarly to olive oil in keeping people healthy. The findings challenge the assumption that cottonseed oil is less healthy than olive oil.

The Quick Take

  • What they studied: Whether eating cottonseed oil or olive oil for 4 weeks causes different changes in blood chemistry and immune system markers in healthy people
  • Who participated: 47 healthy adults were randomly assigned to eat either cottonseed oil or olive oil as part of their regular diet for 4 weeks
  • Key finding: Both oils produced surprisingly similar overall effects on blood chemistry. However, cottonseed oil created higher levels of two specific immune-regulating compounds, suggesting it may affect the immune system differently than olive oil
  • What it means for you: Cottonseed oil appears to be a reasonable cooking oil choice and may not be as unhealthy as previously thought, though olive oil remains a well-established healthy option. More research is needed before making major changes to your cooking oil choices

The Research Details

This was a randomized controlled trial, which is considered one of the strongest types of research. Researchers randomly divided 47 healthy adults into two groups. One group consumed cottonseed oil while the other consumed olive oil for 4 weeks. Before and after the study, researchers took blood samples and analyzed them using advanced laboratory techniques to measure hundreds of different compounds in the blood, including fats and immune-related molecules.

The researchers used three different testing methods to get a complete picture: one method looked at all metabolites (chemical compounds) in the blood without targeting specific ones, another focused specifically on different types of fats, and a third examined special immune-regulating fats called lipid mediators. This multi-method approach allowed them to see both the big picture and specific details of how each oil affected the body.

This research design is important because it allows researchers to directly compare the effects of two different oils in a controlled way. By randomly assigning people to groups and measuring blood chemistry before and after, researchers can be more confident that any differences they find are actually caused by the oil, not by other factors. The use of multiple advanced testing methods ensures they didn’t miss important changes happening in the body.

This study has several strengths: it used a randomized design, included objective laboratory measurements, and employed multiple sophisticated testing methods. However, the study was relatively short (4 weeks), included only healthy adults, and had a modest sample size. The results should be considered preliminary and would benefit from confirmation in larger, longer studies. The study was published in a peer-reviewed journal, meaning other scientists reviewed it before publication.

What the Results Show

When researchers looked at the overall patterns of compounds in the blood, they found that people eating cottonseed oil and people eating olive oil had very similar metabolic profiles. This was surprising because cottonseed oil contains much higher amounts of a type of fat called linoleic acid, which scientists expected might cause more inflammation.

When researchers examined the specific types of fats in the blood, they found clear differences that reflected what people were eating. People eating cottonseed oil had more linoleic acid in their blood, while people eating olive oil had more oleic acid (a different type of fat). This confirmed that the oils were actually being absorbed and used by the body as expected.

The most interesting finding involved special immune-regulating compounds. Two specific compounds—15-deoxy-PGJ2 and prostaglandin F2 alpha—were found in higher amounts in people eating cottonseed oil. These compounds help control inflammation and immune responses in the body. This suggests that cottonseed oil may actually trigger the body to produce more of these protective compounds.

The researchers performed a network analysis, which is like mapping how different compounds in the blood are connected to each other. This analysis revealed two main clusters of changes that appeared to be driven by the dietary intervention. These clusters represented different aspects of how the body responded to each oil, suggesting that cottonseed oil and olive oil trigger somewhat different biological pathways in the body, even though the overall effect on health markers appears similar.

Previous research suggested that cottonseed oil, being high in linoleic acid, might cause more inflammation and negative health effects than olive oil. However, studies in humans had never actually shown that cottonseed oil caused increased inflammation or health problems. This study helps explain why: cottonseed oil appears to trigger the body to produce more of its own anti-inflammatory compounds, which may balance out any pro-inflammatory effects from the linoleic acid. This finding aligns with the puzzling observation that people eating cottonseed oil haven’t shown worse health outcomes in previous studies.

This study has several important limitations. First, it only lasted 4 weeks, which is relatively short for studying long-term health effects. Second, it only included healthy adults, so the results may not apply to people with existing health conditions like heart disease or diabetes. Third, the study had only 47 participants, which is a modest number—larger studies would provide more reliable results. Fourth, researchers only measured blood compounds; they didn’t track actual health outcomes like heart disease or inflammation-related symptoms. Finally, the study didn’t examine how long the effects last after people stop eating the oil.

The Bottom Line

Based on this research, cottonseed oil appears to be a reasonable cooking oil choice for healthy adults and may not be as unhealthy as previously thought. However, olive oil remains a well-established healthy option with decades of research supporting its benefits. If you currently use olive oil, there’s no strong reason to switch to cottonseed oil based on this single study. If you use cottonseed oil, this research suggests you don’t need to worry about it being significantly worse than olive oil. Confidence level: Moderate—this is one study in healthy people over a short time period.

This research is most relevant to healthy adults choosing between cooking oils. People with heart disease, high cholesterol, diabetes, or other metabolic conditions should consult their doctor before making changes to their cooking oils, as this study only included healthy people. The findings don’t apply to children, pregnant women, or people with specific health conditions. If you have concerns about your diet and health, talk to a doctor or registered dietitian.

The changes in blood chemistry happened within 4 weeks, suggesting the body responds relatively quickly to dietary oils. However, this doesn’t mean you’ll notice health benefits or changes in how you feel within 4 weeks. Long-term health benefits from dietary changes typically take months to years to become apparent.

Want to Apply This Research?

  • Track which cooking oil you use daily (cottonseed, olive, or other) and note the amount. Over 4 weeks, monitor any changes in energy levels, digestion, or how you feel. While this study measured blood chemistry, you can track subjective wellness markers that might correlate with dietary changes.
  • If you want to experiment with this research, try using one consistent cooking oil for 4 weeks while keeping other dietary habits the same. Log your choice daily in the app and note any observations about how you feel. This personal experiment mirrors the study design on a smaller scale.
  • Create a 4-week tracking period where you consistently use one oil, then switch to another for comparison. Track energy, digestion, skin condition, and overall wellness. While you won’t be able to measure blood chemistry at home, these subjective markers can help you notice if different oils affect how you feel. Repeat the cycle every few months to see if patterns emerge.

This research is preliminary and should not replace medical advice from your doctor or registered dietitian. While this study suggests cottonseed oil may be comparable to olive oil in healthy adults, it does not prove cottonseed oil is beneficial for treating or preventing any disease. If you have heart disease, high cholesterol, diabetes, or other health conditions, consult your healthcare provider before making significant changes to your cooking oils or diet. This study was conducted in healthy adults over 4 weeks and may not apply to other populations or longer time periods. Individual responses to dietary changes vary, and what works for one person may not work for another.