A small study with 14 subjects showed that eating one meal high in saturated fat (89.6%) can impair the ability of high-density lipoproteins (HDLs), the “good” cholesterol, to ward off inflammation of the blood vessels, which is thought to be a key event in vascular disease. It can also impair the ability of blood vessels to react normally to stress.

On another occasion, the study group ate a meal that included 75% polyunsaturated. They found that HDL collected six hours after the saturated fat meal was less effective in blocking expression of molecules associated with inflammation than HDL collected six hours after the polyunsaturated meal. What’s more, HDL collected six hours after the polyunsaturated meal was more effective in inhibiting inflammation-related molecules than HDL collected during a period of fasting.

Some observations: This was a small study. They did not test a monounsaturated fat version of the meal, which is unfortunate, since polyunsaturated fats are more highly prone to oxidation than either of the other 2 which can accelerate processes sensitive to oxidation like aging. Conclusion: My advice has always been to include monounsaturated fat in your diet and avoid both saturated and polyunsaturated fats.

Study: Dr. David S. Celermajer from The Heart Research Institute in Sydney, Australia published in the Journal of the American College of Cardiology.