Medical researchers from the University of Hong Kong (HKUMed) have found that oleic acid (OA) – the kind found in olive oil – boosts γδ-T cells (or delta gamma T cells). The team made the discovery while investigating how different dietary fatty acids could influence this small subset of T cells that act as rapid-response soldiers against infection and tumor growth.

These immune cells are also known to become dysfunctional in people with obesity or those who have a diet high in saturated fats.

The researcher isolated human γδ-T cells and grew them in culture, then exposed a set of them to OA, and another to palmitic acid (PA), which is commonly found in palm oil, meat and dairy products. They then assessed cell survival, metabolic activity and tumor-killing ability. The OA-treated cells were not just viable but showed indications of their metabolism running at full strength, their mitochondria stayed stable, their signaling was balanced and their tumor-killing machinery was intact.

"Our research suggests that dietary fatty acid supplementation, particularly with foods rich in OA, such as olive oil and avocados, could enhance γδ-T cell immunosurveillance, leading to more effective cancer treatments," said lead author Tu Wenwei, a professor in the Department of Paediatrics and Adolescent Medicine at HKUMed.

However, cells exposed to PA suffered metabolic failure and inflammatory self-destruction. Essentially, their energy machinery broke down and they died in a way that made the surrounding immune system environment even more hostile. So if OA can bolster and strengthen T cell responses to tumors, PA essentially did the opposite.

"The results indicate that cancer patients should avoid PA and consider OA supplementation in their diets to improve clinical outcomes of γδ-T cell-based cancer therapies," said Tu.

While these findings were demonstrated in mice models and cell cultures, it strengthens a growing argument in immunometabolism – how nutrients shape immune behavior – that certain natural fats have widespread benefits for cell health. And, conversely, some might do more harm than good. Saturated fatty acids – like PA – tend to promote inflammation and oxidative stress, while unsaturated fats like OA support cleaner energy production and longer cell survival.