Part I: a Primer on Oleic Acid (OA)
A large body of evidence shows that daily consumption of EVOO confers numerous health benefits, including a significantly reduced risk of cardiovascular disease (CVD).
Factors that contribute to CVD include cholesterol, inflammation, blood vessel function, insulin resistance, and high blood pressure (hypertension). The protective effects of EVOO are attributed to its bioactive components, oleic acid (OA) and more than 30 polyphenols.
In this concise review, we’ll look closely at the mechanisms by which OA works in the body to modify and improve these factors.
What is OA? Oleic acid is a monounsaturated fatty acid (MUFA) that makes up approximately 70 to 80 percent of EVOO by volume. MUFAs and PUFAs (polyunsaturated fatty acids) are the key components of liquid fats, such as vegetable oils and the fats in fish.
Lowers “bad” cholesterol and blood lipid levels: OA lowers LDL or “bad” cholesterol by increasing the amount of LDL that is removed from the blood by the liver and reducing the amount that is produced. In scientific terms, OA increases hepatic LDL receptor activity. Similarly, OA helps lower triglyceride levels by stimulating the liver to increase the breakdown and removal of the proteins that produce triglycerides.
Helps regulate blood pressure: After eating, we experience what is termed the postprandial reflex—a rise in blood triglycerides and increase in blood pressure. When OA enters cell membranes, signals are sent from the intestines to the blood vessels to release vasodilators, which relax the blood vessels, and to block the release of vasoconstrictors, which tighten the blood vessels and raise blood pressure.
Protects the blood vessel lining: Damage to the blood vessel lining (the endothelium) is a major risk factor for CVD. By stimulating the release of vasodilators, OA helps protect the endothelium. OA
also blocks signals from inflammatory proteins that are released with the postprandial reflex, reducing oxidative stress (which can lead to cell damage) and helping prevent atherosclerosis (buildup of cholesterol plaques in the arteries).
Increases insulin sensitivity: In a study of patients with obesity, OA was shown to up-regulate—increase the activity of—a gene that increases insulin sensitivity. OA also reduces insulin resistance in vascular smooth muscle cells, which make up the blood vessel walls.
Studies continue to reveal the ways in which OA exerts its multiple health-promoting effects. In 2018, the FDA determined that evidence supported a qualified health claim that the daily consumption of 20g daily of high-OA oil (EVOO or other high-oleic oil) may reduce the risk of coronary heart disease.
Stay tuned for part II, in which we’ll explore how the polyphenols in EVOO exert powerful protective effects against CVD.
References: 1. Lu Y, Zhao J, Xin Q, et al. Food Science and Human Wellness. 2024;13:529-540. 2. Pirahanchi Y, Sinawe H, Dimri M. Biochemistry, LDL Cholesterol (National Library of Medicine, 2023). 3. Zheng C, Khoo C, Furtado J, Ikekawi K, Sacks FM. Am J Clin Nutr. 2008;88(2):279-281. 4. US Food and Drug Administration. Constituent Update, November 19, 2018. https://www.fda.gov/food/cfsan-constituent-updates/fda-completes-review-qualified-health-claim-petition-oleic-acid-and-risk-coronary-heart-disease.