New research suggests that the fats in olive oil may lead to greater weight gain than those in other sources.
The study, recently published Reports, found that the main fatty component in olive oil, oleic acid, may promote the growth of new fat cells.
Oleic acid is a type of monounsaturated fat, sometimes called omega-9. A major source of oleic acid is olive oil, but the fatty acid is also found in other oils – including rapeseed (canola) oil and sunflower oil – as well as foods such as nuts, meats, cheese, eggs and avocado.
“You can think of the fat cells as an army,” said study co-author Dr Michael Rudolph, assistant professor of biochemistry and physiology at the University of Oklahoma. “When you give oleic acid, it initially increases the number of ‘fat cell soldiers’ in the army, which creates a larger capacity to store excess dietary nutrients.
“Over time, if the excess nutrients overtake the number of fat cells, obesity can occur, which can then lead to cardiovascular disease or diabetes if not controlled.”
Scientists at the universities of Oklahoma, Yale and New York fed a variety of high-fat diets to mice, using coconut oil, peanut oil, milk, lard and soybean oil.
They found that high levels of oleic acid changed the activity of two proteins – called AKT2 and LXR – which in turn resulted in the faster growth of precursor cells, which form new fat cells. This was not the case with the other fats.
But Rudolph said the solution was not to abandon olive oil altogether.
“I think the take-home message is moderation and to consume fats from a variety of different sources,” he said. “Relatively balanced levels of oleic acid seem to be beneficial, but higher and prolonged levels may be detrimental. If someone is at risk for heart disease, high levels of oleic acid may not be a good idea.”
However, in small amounts, oleic acid is associated with good health. Previous research has linked it, often via olive oil, with longevity, healthy ageing, lower levels of inflammation, and lower risk of obesity and heart disease.
It is also important to note that this study was only carried out on mice, so its findings may not directly translate to the effect of oleic acid on humans.
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