A 2026 randomized controlled trial of 90 healthy adults found that interesterified fats—newer alternatives to trans fats—produced similar effects on inflammation markers as traditional palm oil over eight weeks. According to Gram Research analysis, all three fats tested showed no significant differences in interleukin-6, tumor necrosis factor-alpha, visfatin, or C-reactive protein levels, suggesting interesterified fats may be a reasonable replacement for trans fats in processed foods.
Researchers tested whether new types of processed fats could be safer alternatives to trans fats, which are known to harm health. They compared three different fats in a controlled study with 90 healthy adults over eight weeks. According to Gram Research analysis, all three fats had similar effects on inflammation markers in the blood—meaning the newer processed fats didn’t cause more inflammation than traditional palm oil. This suggests that interesterified fats, which are used to replace trans fats in many foods, may be a reasonable alternative, though more long-term research is still needed.
Key Statistics
A 2026 randomized controlled trial of 90 healthy adults found that chemically interesterified fats rich in palmitic and stearic acids produced no significant differences in interleukin-6 (IL-6) levels compared to native palm olein over eight weeks.
Research published in the European Journal of Nutrition in 2026 showed that interesterified fats had comparable effects on tumor necrosis factor-alpha (TNF-α), visfatin, and high-sensitivity C-reactive protein (hsCRP) as traditional palm oil in healthy adults.
An eight-week feeding intervention trial with 90 participants found that all three tested fats—native palm olein, interesterified fat rich in palmitic acid, and interesterified fat rich in stearic acid—produced similar inflammatory responses in the blood.
The Quick Take
- What they studied: Whether new types of processed fats (called interesterified fats) cause inflammation in the body, compared to traditional palm oil
- Who participated: 90 healthy adults who ate specific test fats mixed into snacks for eight weeks
- Key finding: All three types of fat tested produced similar levels of inflammation markers in the blood, with no significant differences between them
- What it means for you: If you eat processed foods containing interesterified fats, they appear to have similar effects on your body’s inflammation as palm oil. However, this was a short-term study, so long-term effects remain unclear
The Research Details
This was a double-blind, parallel feeding intervention trial, which is a gold-standard research design. Researchers gave 90 healthy adults 50 grams of one of three different fats daily for eight weeks—incorporated into snacks eaten at breakfast and afternoon tea. The three fats tested were: native palm olein (traditional palm oil), chemically interesterified fat rich in palmitic acid, and chemically interesterified fat rich in stearic acid. Blood samples were collected at the start, and at weeks zero, six, and eight to measure inflammation markers.
The study was ‘double-blind,’ meaning neither the participants nor the researchers knew which fat each person was eating until the study ended. This prevents bias from affecting the results. The researchers measured four specific inflammation markers in the blood: interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), visfatin, and high-sensitivity C-reactive protein (hsCRP). These markers show how much inflammation is happening in the body.
This research design is important because it controls for many factors that could affect results. By giving people specific amounts of fat in controlled snacks, researchers knew exactly what each person was eating. The double-blind approach prevents expectations from influencing results. Measuring inflammation markers directly in the blood gives objective data about how these fats affect the body.
This study has several strengths: it used a randomized controlled design, included a reasonable sample size of 90 people, and measured multiple inflammation markers. However, the study only lasted eight weeks, which is relatively short for understanding long-term health effects. The study also only included healthy adults, so results may not apply to people with existing health conditions. Additionally, the study measured only inflammation markers—not other health outcomes like heart disease or weight changes.
What the Results Show
The main finding was that all three fats produced similar effects on inflammation markers. There were no statistically significant differences in interleukin-6 (IL-6) levels between the three fat groups. Tumor necrosis factor-alpha (TNF-α) levels also showed no significant differences. Visfatin and high-sensitivity C-reactive protein (hsCRP)—two other important inflammation markers—similarly showed no meaningful differences between the groups.
This means that the newer interesterified fats (which are designed to replace trans fats) didn’t cause more inflammation than traditional palm oil during the eight-week study period. The researchers concluded that these three fats appear to have comparable effects on the selected inflammatory markers they measured.
While the study didn’t report other secondary outcomes in detail, the consistency of results across all four inflammation markers tested strengthens the main finding. The fact that both types of interesterified fats (one rich in palmitic acid and one rich in stearic acid) showed similar results to palm oil suggests that the chemical processing method itself may not significantly impact these particular inflammation markers.
Trans fats, which were previously used to harden oils, are known to increase inflammation and harm heart health. This study suggests that interesterified fats—the newer alternative—don’t appear to have the same inflammatory effects as trans fats, at least in the short term. However, research on interesterified fats is still limited compared to research on trans fats and other dietary fats. This study adds to the growing body of evidence that interesterified fats may be a safer alternative to trans fats, though they’re not necessarily ‘healthy’ fats.
The study lasted only eight weeks, which is too short to determine long-term health effects. The study only included healthy adults, so results may not apply to people with obesity, diabetes, or heart disease. The study measured only inflammation markers—it didn’t measure other important health outcomes like cholesterol levels, blood sugar, or actual disease risk. Additionally, the study used margarine (a processed food) as the delivery method, which contains other ingredients beyond just the test fats. Finally, the study didn’t measure whether these fats affected other aspects of health or inflammation in different ways.
The Bottom Line
Based on this research, interesterified fats appear to have similar short-term effects on inflammation as palm oil. However, this doesn’t mean you should actively seek out foods with interesterified fats—it simply means they may not be worse than some alternatives. The best approach remains eating mostly whole foods (fruits, vegetables, whole grains, lean proteins) and limiting processed foods in general. If you do eat processed foods, interesterified fats appear to be a reasonable alternative to trans fats. Confidence level: Moderate (based on an eight-week study in healthy adults).
This research is most relevant to food manufacturers deciding which fats to use in processed foods, and to people concerned about inflammation from processed foods. If you have heart disease, diabetes, or other health conditions, consult your doctor about your fat intake. If you’re generally healthy and eat mostly whole foods, this research suggests you don’t need to worry specifically about interesterified fats in occasional processed foods.
This study measured inflammation markers over eight weeks, so any effects would appear within that timeframe. However, the long-term effects of eating these fats for months or years remain unknown. Real-world health benefits (or harms) from dietary changes typically take weeks to months to become noticeable.
Frequently Asked Questions
Are interesterified fats healthier than trans fats?
Research suggests interesterified fats don’t increase inflammation markers like trans fats do. A 2026 study found they had similar effects to palm oil. However, ‘healthier’ is relative—whole foods remain the best choice for overall health.
What are interesterified fats and why are they used?
Interesterified fats are oils that have been chemically rearranged to make them solid at room temperature. Food manufacturers use them to replace trans fats in processed foods like margarine, baked goods, and snacks.
Do interesterified fats cause inflammation in the body?
An eight-week study of 90 healthy adults found no significant increase in inflammation markers from interesterified fats compared to palm oil. However, long-term effects beyond eight weeks remain unclear.
Should I avoid foods with interesterified fats?
You don’t need to specifically avoid them based on this research. However, limiting all processed foods is still the best approach. If choosing between trans fats and interesterified fats, the research suggests interesterified fats may be the safer option.
How long does it take to see health effects from changing fat intake?
This study measured changes over eight weeks. Real-world health improvements from dietary changes typically appear within 4-12 weeks, though individual responses vary based on overall diet and lifestyle.
Want to Apply This Research?
- Track your processed food intake weekly, noting which products contain interesterified fats versus other fat types. Rate your energy levels and any inflammation symptoms (joint pain, bloating) on a 1-10 scale to monitor personal response.
- When shopping, compare nutrition labels on processed foods and choose products with interesterified fats over trans fats when possible. However, prioritize reducing overall processed food consumption rather than optimizing between fat types.
- Monitor general inflammation indicators over 8-12 weeks: track energy levels, joint comfort, digestion, and skin condition. If reducing processed foods overall, note improvements in these areas. Remember that many factors beyond fat type affect inflammation.
This research summary is for educational purposes only and should not replace professional medical advice. The study measured only short-term inflammation markers in healthy adults over eight weeks—it did not measure long-term health outcomes or effects in people with existing health conditions. If you have heart disease, diabetes, obesity, or other health concerns, consult your healthcare provider about your dietary fat intake. Individual responses to dietary fats vary based on genetics, overall diet, and lifestyle factors. This summary reflects the study’s findings but does not constitute medical advice or a recommendation to consume interesterified fats.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.