One common type of fat may increase diabetes risk, while another helps fight it

A new review suggests that the type of fat you eat may affect your risk of developing type 2 diabetes.

Saturated fats rich in palmitic acid – the most common saturated fatty acid in U.S. foods – appear to make it harder for the body to respond to insulin.

Meanwhile, monounsaturated fats rich in oleic acid — such as those found in olive oil — may help protect against insulin resistance, the review concluded.

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"Palmitic acid is found in meats, dairy products, cocoa butter and in the form of palm oil in foods, including margarine, cereal, sweets, baked goods and fast foods," Tanya Freirich, a registered dietitian nutritionist in Charlotte, North Carolina, told Fox News Digital. She was not involved in the review. 

"Oleic acid, on the other hand, is in higher concentration in foods like olive oil, canola oil, nuts, sunflower seeds, eggs, olive, avocados and also in meats (beef, chicken, pork), milk, cheese and pasta."

The review, which was published in the journal Trends in Endocrinology & Metabolism, was led by researchers from the University of Barcelona and the CIBER Area for Diabetes and Associated Metabolic Diseases (CIBERDEM) in Spain.

The findings suggest that fat quality may be more important than total fat quantity when it comes to metabolic health and diabetes risk.

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This appears to support the idea that diets rich in monounsaturated fats, such as the Mediterranean diet, may contribute to lower rates of type 2 diabetes.

"Palmitic acid promotes several molecular processes that impair insulin action," study investigator Dr. Manuel Vázquez-Carrera, from the Department of Pharmacology, Toxicology and Therapeutic Chemistry at the University of Barcelona, told Fox News Digital. 

Too much palmitic acid can cause harmful fat byproducts to build up in the body, which can impair the body's ability to respond to insulin, he warned. This makes it harder to control blood sugar and increases the risk of insulin resistance and type 2 diabetes.

"It also promotes inflammation, oxidative stress, mitochondrial dysfunction and cellular stress responses, which contribute to insulin resistance and β-cell dysfunction," Vázquez-Carrera added.

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By contrast, oleic acid – a hallmark of the Mediterranean diet – does not have these harmful effects, according to the researcher.

"In fact, oleic acid can counteract many of the detrimental effects triggered by palmitic acid, by promoting the storage of fatty acids in relatively inert triglycerides, preserving mitochondrial function and reducing inflammation," he said.

Freirich confirmed that the review is consistent with previous research supporting the use of olive oil in the diet for metabolic benefits.

"Also confirming previous research, the consumption of saturated fats is associated with some negative metabolic changes," she told Fox News Digital.

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Given the complexity of foods and diets, there is an overlap between foods that contain both types of fatty acids, the nutritionist noted. 

"Palmitic acid and oleic acid can both be found in olive oil, baked goods and fast foods, in differing amounts," she said. "All sources of fat in our diet contain a mix of saturated and unsaturated fatty acids."

Vázquez-Carrera noted that these findings come from a review of numerous experimental, clinical and epidemiological studies rather than a single clinical trial.

"One important limitation is that much of the mechanistic evidence comes from cell culture and animal studies," he said. 

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"Although these studies provide valuable insights into how specific fatty acids affect insulin signaling, further human intervention studies are needed to confirm the extent to which these mechanisms operate in everyday dietary settings."

In addition, many of the human studies in the review relied on self-reported dietary intake, which can introduce inaccuracies. 

"Another challenge is that people consume foods containing complex mixtures of fatty acids and bioactive compounds rather than isolated fatty acids," Vázquez-Carrera added. "Therefore, it remains difficult to fully disentangle the specific contribution of individual fatty acids in free-living populations."

The review’s findings appear to support current dietary recommendations that emphasize replacing part of the saturated fat intake with unsaturated fats, according to Vázquez-Carrera.

"This means favoring dietary patterns rich in foods such as extra-virgin olive oil, nuts, seeds, legumes, vegetables, fruits and fish, while limiting excessive consumption of foods rich in saturated fats, especially highly processed foods," he advised.

The review does not suggest that a single nutrient alone determines diabetes risk, the researcher pointed out.

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"Rather, maintaining a healthy body weight, engaging in regular physical activity and following an overall healthy dietary pattern, such as the Mediterranean diet, remain fundamental strategies for preventing insulin resistance and type 2 diabetes."

Type 2 diabetes develops over many years, with genetics, lifestyle and environmental factors all playing a role, Vázquez-Carrera noted.

"Future research should move beyond simply classifying fats as ‘good’ or ‘bad’ and instead focus on understanding how specific fatty acids, their dietary sources and their interactions within whole dietary patterns affect metabolic health," he said.

Improving the quality of dietary fat intake could prove to be an effective strategy for reducing type 2 diabetes risk, according to the researcher.

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"A simple takeaway for consumers is to swap out foods high in saturated fat more often with foods rich in heart-healthy fats, like olive oil, nuts and avocados, to better support blood sugar and metabolic health," advised New Jersey-based registered dietitian Erin Palinski-Wade, who was also not involved in the review.

Anyone at a higher risk for type 2 diabetes should consult a healthcare provider for personalized guidance on nutrition, exercise and other preventive measures, experts say.