Key Takeaways (expand)
- Oleic acid is a long-chain monounsaturated fatty acid that’s the most widely distributed fat in nature.
- Oleic acid makes up about half of the fatty acid content of the adipose tissue in our bodies.
- Oleic acid serves as a structural component of a number of biological compounds—including cholesterol esters and cell membrane phospholipids.
- Via its presence in cell membranes, oleic acid can directly impact cellular function by improving the cell’s antioxidant status, altering membrane fluidity, modulating gene expression involved in cytokine production, and reducing the production of inflammatory agents called eicosanoids.
- Small amounts of oleic acid can be enzymatically produced from a saturated fatty acid called stearic acid.
- Oleic acid causes a rise in circulating levels oleoylethanolamide—an oleic acid derivative that serves as an agonist of peroxisome proliferator-activated receptor α (PPAR-α), an important nuclear receptor involved in lipid metabolism.
- Oleic acid has notable benefits for cardiovascular health, including reducing cardiovascular risk factors like blood cholesterol and triglyceride levels, blood pressure, inflammation, blood coagulation, and oxidative stress, while also improving blood sugar regulation.
- Research links higher oleic acid intake to better cardiovascular outcomes and lower risk of coronary heart disease.
- Oleic acid also exhibits anti-cancer properties—inhibiting the proliferation, progression, and/or metastasis of several cancer types in vitro, and being linked to lower colorectal cancer risk observationally.
- Anti-cancer mechanisms of oleic acid are likely related to its effects on cell cycle arrest, calcium signaling pathways involved in cancer proliferation, the over-expression of oncogenes, and the Akt/mTOR pathway.
- Oleic acid has anti-inflammatory and immune-modulatory properties—including reducing the inflammatory effects of other fats, influencing immune cell proliferation, modulating the production of reactive oxygen species, and inhibiting the expression of several adhesion molecules.
- Oleic acid may benefit body weight regulation, with studies showing that oleic acid-enriched diets lead to greater decreases in central obesity, abdominal fat, body weight, and food intake.
- The oleic acid derivative oleoylethanolamide has likewise been shown to reduce hunger, spontaneous food intake, and liver fat accumulation; in fact, it has an overall protective effect against non-alcoholic fatty liver disease.
- Some evidence suggests oleic acid can increase markers related to tissue repair and promote faster wound healing.
- Oleic acid may also help protect against diabetes and insulin resistance, due to increasing insulin sensitivity, promoting the survival of pancreatic beta-cells, influencing the insulin signaling pathway, and regulating genes related to the PI3K pathway.
- Oleic acid may also help protect against diabetic retinopathy, and reduce the risk of atherosclerosis among diabetics.
- Because oleic acid is non-essential, there’s no deficiency diseases associated with inadequate intake; however, consuming low levels of oleic acid and high levels of more inflammatory fats (such as palmitic acid) may increase the risk of cardiovascular disease and diabetes.
- The best sources of oleic acid are plant oils and high-fat plant foods (such as olives, avocados, peanuts, sunflower seeds, and their oils), as well as some animal fats—especially turkey fat, chicken fat, and lard.
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Oleic acid is a long-chain monounsaturated fatty acid, and the most widely distributed fatty acid in nature! In fact, it’s present in at least small amounts in virtually all oils, and comprises about half of the fatty acid content of the adipose (fat) tissue in our bodies. And while omega-3 and omega-6 fats might be the most famous of the omegas, oleic is technically an omega-9 fatty acid—meaning its molecular structure has a final carbon-carbon double bond in the omega-9 position (that is, the ninth bond from the methyl end of the fatty acid). The word “oleic” comes from the Latin word oleum, which translates to “oil.”
Oleic acid plays an important role in cellular function due to its presence in phospholipids in cell membranes. Along with its well-established benefits for cardiovascular health, it may also help fight inflammation, protect against cancer, influence immune function, and even have anti-diabetes effects.
Many high-fat plant foods and vegetable oils are good sources of oleic acid, including olives and olive oil, avocado and avocado oil, palm oil, canola oil, peanuts and peanut oil, sunflower seeds and sunflower oil, pecans, macadamia nuts, sesame seeds, sesame oil, grape seed oil, soybean oil, and cocoa butter. Some animal fats are also rich in oleic acid—especially turkey fat, chicken fat, and lard (as well as fatty cuts of poultry meat or pork).
The Biological Roles of Oleic Acid
As a monounsaturated fat, oleic acid has one double bond between two carbon atoms in its hydrocarbon chain—hence “mono,” or one. This distinguishes oleic acid from polyunsaturated fats (which have multiple double bonds) and saturated fats (which have no double bonds). And because double bonds are vulnerable to oxidation, this molecular structure makes oleic acid less stable than saturated fats, but more stable than polyunsaturated ones.
Oleic acid serves as a component of many important biological compounds, including cholesterol esters and the phospholipids in cell membranes. Its presence in phospholipids is particularly important: once incorporated into cell membranes, oleic acid can directly and indirectly impact cellular function, including by altering membrane fluidity (which impacts signal transduction and membrane-protein interactions), improving antioxidant status (since oleic acid is less prone to lipid peroxidation and reactive oxygen species production than polyunsaturated fatty acids), decreasing the arachidonic acid content of cell membrane phospholipids (arachidonic acid being a precursor for inflammatory agents called eicosanoids), and modulating gene expression that regulates cytokine production.
Oleic acid can be produced from another fatty acid, stearic acid—a saturated fat found in meat, cocoa butter, shea butter, and a variety of other plant and animal fats. This biosynthesis occurs via an enzyme called stearoyl-CoA 9-desaturase, which helps dehydrogenate stearic acid to form its monounsaturated derivative, oleic acid. Only about 9 – 14% of stearic acid undergoes this conversion, though!
Oleic acid intake causes an increase in circulating levels of one of its derivatives, oleoylethanolamide—a high-affinity agonist of peroxisome proliferator-activated receptor α(PPAR-α), an important nuclear receptor involved in lipid metabolism. By increasing the substrate availability for oleoylethanolamide synthesis, oleic acid contributes to a number of different metabolic effects.
Oleic Acid in Health and Disease
Consumption of oleic-acid rich foods (such as olives, avocados and their oils) is associated with diverse health benefits, including reduced risk of cardiovascular disease, type 2 diabetes, obesity, and some forms of cancer in addition to immune health benefits, reducing inflammation and improving wound healing.
Interestingly, the major trans fatty acid in the Western diet, elaidic acid, is a trans isomer of oleic acid. This means its molecular structure has the same side groups, but placed on the opposite side of the double bond. In stark contrast to oleic acid, elaidic acid has a number of detrimental health effects—including increasing the risk of cardiovascular disease, worsening blood lipid profiles, and even increasing the progression of metastatic cancer.
Oleic Acid and Cardiovascular Disease
Oleic acid is most famous for its benefits for cardiovascular health. Much of the research here was initially sparked by observations that olive oil, and Mediterranean diets that use it liberally, are associated with significantly lower rates of cardiovascular disease. From there, subsequent studies identified the oleic acid component of olive oil as responsible for many of those heart-health benefits (the polyphenols in this oil being another cardiovascular boon!).
In general, epidemiological studies have linked higher monounsaturated fat intake, particularly in the form of oleic acid, to better cardiovascular outcomes and lower risk of coronary heart disease. Additional research shows that oleic acid can specifically improve cardiovascular risk factors like blood cholesterol and triglyceride levels, blood coagulation (clotting), blood sugar regulation, inflammation, and oxidative stress. Likewise, studies show that the oleic acid component is responsible for the hypotensive (blood pressure-lowering) effects of olive oil!
Oleic Acid and Cancer
Although less well-publicized than its role in cardiovascular health, oleic acid also has some promising anti-cancer effects. For example, a case-control study found that even after adjusting for important confounders (including age, sleep, smoking, alcohol, biological sex, and BMI), oleic acid consumption was associated with a significantly reduced risk of colorectal cancer. And, in vitro experiments show that oleic acid can inhibit the proliferation, progression, and/or metastasis of several types of cancer cells, including tongue cancer and liver cancer.
Although the exact mechanisms behind these anti-cancer effects are still being studied, so far we know that oleic acid can block the Akt/mTOR pathway (in turn inducing apoptosis and autophagy), induce cell cycle arrest, suppress the over-expression of certain oncogenes (mutated genes with cancer-causing abilities), and modulate intracellular calcium signaling pathways involved in cancer proliferation. More research is needed here to better understand oleic acid’s role in different types of cancer, especially in humans!
Oleic Acid and Immunity
Oleic acid may also have some anti-inflammatory and immune-modulatory properties. A meta-analysis of 31 randomized controlled trials concluded that oleic acid supplementation significantly lowers C-reactive protein (although it has no apparent effect on other markers of inflammation). And, experiments have illuminated a variety of ways oleic acid can influence immune function and inflammation, including inhibiting the expression of vascular cell adhesion molecule-1 (VCAM-1), reducing the inflammatory effects of other fats (particularly long-chain fatty acids), inhibiting leukocyte migration (an important step in the inflammatory response), inhibiting intercellular adhesion molecule 1 (ICAM-1) (which is involved in inflammatory processes and the T-cell mediated host defense system), modulating the production of reactive oxygen species, and influencing T cell and natural killer cell proliferation.
There’s also some evidence that oleic acid can support wound healing. In animal models, skin wounds treated with oleic acid for five days had significantly faster healing time, and exhibited an elevation of several markers related to tissue repair (including collagen III mRNA, tissue inhibitor matrix metalloproteinase 1 (TIMP1), and matrix metalloproteinase-9 (MMP9)).
Oleic Acid and Obesity
Additionally, oleic acid may offer benefits for body weight regulation and obesity. A review of 28 clinical trials found that on the whole, diets enriched with oleic acid can help decrease abdominal fat, central obesity, food intake, and body weight, while possibly increasing energy expenditure. These effects may be due to oleic acid stimulating AMP-activated protein kinase signaling, in turn regulating energy metabolism in a way that promotes fat oxidation. Some evidence also suggests that oleic acid can reduce the activity of stearoyl-CoA desaturase-1—an enzyme involved in the lipogenesis, or the creation of new fat.
The oleic acid derivative oleoylethanolamide also has important metabolic and weight-regulating effects. Studies show oleoylethanolamide can reduce hunger and spontaneous food consumption, due to activating certain dopamine pathways and increasing the secretion of oxytocin (a hormone that causes satiety signaling in the brain). Likewise, oleoylethanolamide has been shown to activate transport proteins and nuclear receptors involved in fatty acid uptake, beta-oxidation, and lipolysis, including PPAR-α and fatty acid translocase (FAT)/CD36). And, some of these activities can reduce liver fat accumulation specifically.
A systematic review of oleoylethanolamide studies found an overall protective effect against non-alcoholic fatty liver disease, due to its role in regulating a number of biological processes involved in the disease progression (including inflammation, fat metabolism, energy homeostasis, and oxidative stress).
Oleic Acid and Type 2 Diabetes
Oleic acid could even help protect against insulin resistance and diabetes! Studies have variously shown that oleic acid can improve the survival of insulin-secreting beta cells, increase insulin sensitivity, influence the insulin signaling pathway, and help regulate the genes related to the PI3K pathway (which is heavily involved in metabolism and beta-cell activity). Some observational research also shows that oleic acid consumption may be protective against a common diabetes complication, diabetic retinopathy. In one study, people with the highest versus lowest intake of oleic acid had a 52% lower risk of this condition. And, oleic acid (especially compared to linoleic acid) may reduce the risk of atherosclerosis among diabetics, due to producing fewer chylomicron remnant particles after meals.
Some of these anti-diabetic effects are due to the way oleic acid changes the inflammatory activity of certain other fats, such as palmitic acid. In fact, the dietary palmitic acid/oleic acid ratio significantly impacts diabetes risk in humans, and experiments show that incubating palmitic acid-exposed cells with oleate (an ester of oleic acid) prevents the increase in endoplasmic reticulum stress, inflammation, and insulin resistance normally induced by palmitic acid. So, not only does oleic acid independently benefit insulin sensitivity and glucose metabolism; it can also counteract the damaging effects of other fats.
Health Effects of Oleic Acid Deficiency
Because the body can manufacture its own oleic acid from other fats as needed, oleic acid deficiency isn’t clinically recognized. However, consuming low levels of oleic acid and high levels of more inflammatory fats (such as palmitic acid) may have unfavorable effects for disease risk, especially cardiovascular disease and diabetes.
How Much Oleic Acid Do We Need?
As a non-essential fat, no recommended dietary intake exists for oleic acid. In general, consuming 1 to 2 tablespoons of oleic acid-rich oils (such as olive oil or avocado oil) daily may deliver enough of this fatty acid to produce some of the health benefits seen in studies! A good daily goal is 20 grams of monounsaturated fats.
There’s no known toxicity for oleic acid, even in very large quantities, but a laxative effect may occur from very high intakes (50 – 100 g in one sitting).
Best Food Sources of Monounsaturated Fatty Acids
The following foods have high concentrations of monounsaturated fatty acids (the most common of which is oleic acid), containing at least 10 grams per serving, making them our best food sources of this heart-healthy fat!
Good Food Sources of Monounsaturated Fatty Acids
The following foods are also excellent or good sources of monounsaturated fatty acids (the most common of which is oleic acid), containing at least 2 grams (and up to 10 grams) per serving.
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