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A study at the University of Iowa conducted by the Brandon Davies Laboratory recently showed that a high-fat, Western diet reduces lifespan, while a diet high in polyunsaturated and omega-3 fatty acids increases cardiac triglyceride uptake and improves insulin sensitivity. The researchers published their in the Journal of Lipid Research.

The incidence of is rising within the global population along with the intake of . Previous research highlighted that age-related changes in body weight, fat distribution, insulin sensitivity and triglyceride metabolism can drive chronic metabolic conditions, including obesity, Type 2 diabetes and hyperlipidemia.

To combat this global health issue, researchers must understand how triglyceride metabolism changes over time.

“We're interested in studying triglyceride metabolism, tracing the journey from the point where triglycerides are consumed, how they enter the bloodstream, and ultimately where they are stored or used for energy.” Kathryn Spitler, lead author and a research associate at UI, said.

The research team explored how different dietary fats influence metabolic health and whether these findings in mice could be relevant for human health.

While there is significant knowledge on triglyceride and fatty acid metabolism in humans, there is a lack of information specifically addressing how aging impacts this process. To close this gap in knowledge, they divided mice into three groups: a control group fed a standard diet, a group fed a high-fat diet rich in saturated fats and a group fed a high-fat diet rich in omega-3 fatty acids, commonly found in fish oil.

“Unlike saturated fats, omega-3 fats are often associated with potential health benefits.” Spitler said. “By comparing these groups, we sought to understand whether the type of fat consumed influences metabolic health during aging.”

In humans, when consuming a high-fat meal, triglyceride levels in the blood rise temporarily and then decrease as the body absorbs the fat. However, with age, the rate at which tissues absorb fat decreases, causing triglyceride levels to remain elevated in the blood for longer after a meal.

“When we eat fatty foods, our digestive tract packages them into these balls of fat called chylomicrons that will circulate throughout our bloodstream. and These circulating chylomicrons provide triglycerides as a source for energy to our highly metabolic tissues or our bodies store triglycerides in adipose tissue,” Spitler said.

They showed that as age increases, tissues absorb fat less efficiently, which can lead to harmful side effects such as increased risk of heart disease, stroke and pancreatitis.

The Davies team also found that mice fed a diet high in fat derived from fish oil, gained weight, but demonstrated increased tolerance to insulin.  These mice showed enhanced cardiac triglyceride uptake, suggesting more efficient fat processing. In contrast, the mice on the Western diet had impaired glucose tolerance and a lower ability to respond to insulin while having higher fat accumulation in non-adipose tissues, which can be linked to metabolic complications.

The researchers’ future directions will explore how omega-3 fats alter cellular signaling involved in insulin tolerance and cardiac triglyceride uptake.

These findings could have important implications for promoting healthier aging in humans, particularly through dietary interventions that emphasize omega-3 fats. Understanding how different fats affect metabolism over time may help prevent age-related diseases like Type 2 diabetes and cardiovascular disease.