We've all heard about omega-3 fatty acids and even omega-6 fatty acids. But what about omega-9 fatty acids? Chances are you've never even heard of these fatty acids unless you've happened to spy them lurking on the nutrition facts label of your flaxseed oil supplement. So if no one ever really talks about omega-9 fatty acids, what exactly are they? And do we even need them? Read on to find out.
Omega Fatty Acids: The Basics
To get a better understanding of exactly what omega-9 fatty acids are, it's helpful to understand a little bit about all the omega fatty acids. Because even though omega-3, omega-6, and omega-9 fatty acids are related, there are some important differences between them.
For one thing, omega-3 and omega-6 fatty acids are polyunsaturated fatty acids (PUFAs). This means that the carbon atoms that make up the fatty acid chain are linked by multiple double bonds.
Unlike saturated fats, which are found in foodstuffs like coconut oil, palm oil, and animal fats, unsaturated fats like omega-3 and omega-6 fatty acids lose hydrogen atoms with every double bond—thus, they're not "saturated" with hydrogen atoms. These double bonds also give the chain flexibility and allow it to bend, which is why polyunsaturated fats are liquid at room temperature.
Every fatty acid chain has an omega, or methyl, end and an alpha, or acid, end. On the omega end of the chain lies a methyl group, and on the alpha end carboxylic acid. And each omega fatty acid gets its numerical designation based on how many carbon atoms away the first double bond is from the omega end.
When it comes to omega-3 fatty acids, there are actually 11 different types, but only 3 of them are considered crucial for overall health.
- Eicosapentaenoic acid (EPA): This marine-based omega-3 is used by the body to create signaling molecules, including eicosanoids. Good sources of EPA are fatty fish like salmon, sardines, mackerel, and herring as well as fish oil products.
- Docosahexaenoic acid (DHA): Like EPA, DHA is a marine-based omega-3 fatty acid and is an important component of cell membranes.
- Alpha-linolenic acid (ALA): This plant-based omega-3 is (somewhat inefficiently) converted in the body into EPA and DHA. ALA is found in substantial quantities in foods like walnuts, hemp seed oil, flaxseed oil, chia seed oil, and canola oil.
Like omega-3 fatty acids, there are 11 types of omega-6 fatty acids, but only a few are known to be important to overall health, including:
- Linoleic acid (LA): Found mostly in plant-based foods, including vegetable oils like sunflower oil, safflower oil, corn oil, and soybean oil, as well as flaxseeds and pumpkin seeds, LA is converted in the body into signaling molecules like arachidonic acid.
- Gamma-linolenic acid (GLA): Used in the formation of signaling molecules, including eicosanoids, GLA can be found in evening primrose oil, hemp oil, borage oil, and chia seed oil.
It's also important to remember that omega-3 and 6 fatty acids are considered essential fatty acids, which means the body can't make them on its own, so they have to be obtained from dietary sources.
By contrast, omega-9 fatty acids are considered nonessential fatty acids because the body can manufacture them on its own using other unsaturated fats.
So does that mean we don't need them?
The Skinny on Omega-9 Fatty Acids
Aside from being classified as nonessential fatty acids, omega-9 fatty acids are different from the other omega fatty acids in one other respect: they're made up of both polyunsaturated and monounsaturated fatty acids.
There are also eight omega-9 fatty acids:
- Hypogeic acid
- Oleic acid
- Elaidic acid
- Gondoic acid
- Mead acid
- Erucic acid
- Nervonic acid
- Ximenic acid
While very little is known about hypogeic acid, which is a component of human breast milk; elaidic acid, which is found in large quantities in hydrogenated vegetable oils; gondoic acid, which is a monounsaturated fatty acid found mostly in jojoba oil; and ximenic acid, which plays a role as a human metabolite, the other four omega-9 fatty acids have been better studied.
Oleic acid is a monounsaturated omega-9 fatty acid. Not only is it the most well-known omega-9, it's also the most abundant fatty acid in nature. Oleic acid is found in a number of sources, including animal fats, peanut oil, avocados, macadamia nuts, and olive oil. In fact, it's the triglycerides of oleic acid that make of the majority of the fats found in olive oil. Oleic acid also makes up the majority of the fatty acids in fat tissue.
Mead acid is a polyunsaturated omega-9 fatty acid that's known to play a number of roles in the body. When there's a deficiency of essential fatty acids, mead acid helps maintain the structural integrity of cell membranes. In fact, elevated levels of mead acid in the blood are an indication that an essential fatty acid deficiency is present. Mead acid is also found in large amounts in cartilage.
Erucic acid is a long-chain monounsaturated omega-9 fatty acid. Erucic acid is found mainly in members of the Brassica family, including canola, mustard, broccoli, and Brussels sprouts. It's also one of the main ingredients (along with oleic acid) in Lorenzo's oil—a treatment for adrenoleukodystrophy (ALD) developed in the 1980s by the parents of a son who had been diagnosed with the neurodegenerative disease.
Nervonic acid is a monounsaturated omega-9 fatty acid that plays an important role in brain development and myelin sheath production. Nervonic acid is found in foods like canola oil, salmon, and flaxseeds.
Now that we've covered the more technical aspects of omega-9 fatty acids, what about the health benefits? Is it worth your while to seek out dietary sources of these fatty acids?
Health Benefits of Omega-9 Fatty Acids
Because omega-9 fatty acids are found in high concentrations in olive oil, cruciferous vegetables, and avocados, you might be thinking to yourself that there must be something to these fatty acids.
And you'd be right.
Immune System Health
A meta-analysis published in the journal Nutrición Hospitalaria found that oleic acid acts as an anti-inflammatory, and that a diet rich in this omega-9 fatty acid may have a beneficial effect on inflammatory diseases like arthritis, diabetes, heart disease, asthma, and autoimmune conditions.
Likewise, an interesting study published in the journal Rehabilitation Nursing found that rheumatoid arthritis patients who applied olive oil topically to painful joints experienced significant decreases in both pain and swelling.
And a study published in the Pakistan Journal of Medical Sciences found that septic patients who were supplemented with a combination of omega-3 and omega-9 fatty acids exhibited decreased inflammatory markers and improved biochemical parameters.
Similarly, a study published in the journal PLoS One found that oleic acid decreased levels of free radicals, prevented kidney and liver injury, and improved survival in septic mice.
Endocrine and Heart Health
Elevated levels of triglycerides and cholesterol are known risk factors in the development of cardiovascular disease. What's more, the risk of heart disease is further increased in people with diabetes. However, a number of studies have found that diets rich in monounsaturated fatty acids are associated with a lower risk of both cardiovascular disease and diabetes.
For example, a study published in the American Journal of Clinical Nutrition found that patients with diabetes who ate a diet high in monounsaturated fatty acids experienced significant decreases in both triglycerides and very low-density lipoprotein (VLDL)—a harmful form of cholesterol related to low-density lipoprotein (LDL). In fact, researchers found that MUFA-rich diets resulted in decreases of 19% and 22%, respectively. Plus, levels of high-density lipoprotein (HDL), the so-called good cholesterol, increased. And all benefits were seen without any associated increases in weight.
Another study published in the journal Diabetes found that mice who ate a high-fat diet that emphasized monounsaturated fatty acids had improved insulin sensitivity and markers of fat tissue. These same findings were noted in human study participants as well.
A study published in the European Review for Medical and Pharmacological Sciences found that obese patients with and without nonalcoholic fatty liver disease who were given reduced-calorie diets rich in both monounsaturated and polyunsaturated fatty acids experienced decreases in systolic blood pressure, cholesterol, blood sugar, and liver enzyme levels.
And a study published in the World Journal of Gastroenterology noted that supplemental olive oil decreased the buildup of triglycerides in the livers of rats with nonalcoholic fatty liver disease.
A study published in the journal Clinical and Experimental Allergy found that intake of monounsaturated fatty acids was inversely associated with asthma risk.
Likewise, a study published in the European Respiratory Journal noted that asthmatic males who ate a diet rich in monounsaturated fatty acids had a lower incidence of neutrophilic airway inflammation.
A study published in the journal Immunobiology noted that oleic acid's anti-inflammatory properties may make it useful in the treatment of wounds.
A long-term cross-sectional study published in the journal PLoS One found that a higher intake of olive oil was associated with a lower risk of severe skin photoaging.
Another study published in the British Journal of Nutrition found that a higher intake of total fat, including monounsaturated fat, was significantly associated with an increase in skin elasticity.
And a study published in the Journal of Translational Medicine found that patients with psoriasis who adhered to a Mediterranean diet and increased consumption of extra-virgin olive oil experienced significant improvement in symptoms. What's more, higher extra-virgin olive oil consumption was inversely associated with blood levels of C-reactive protein (CRP)—an important inflammatory marker.
Brain and Nervous System Health
We mentioned earlier that omega-9 fatty acids play an important role in nervous system health, and numerous studies have borne this out.
For example, a study published in the journal Biochimica et Biophysica Acta Biomembranes noted that omega-9 fatty acids offer protection against the pain and overactive reflexes often seen as a side effect of peripheral nerve damage. They were also noted to improve sensorimotor function following injury to the spinal cord.
A study published in the journal Diabetes found that mice supplemented with monounsaturated fatty acids experienced improved glucose metabolism, brain activity, and sleep behavior. What's more, the same study noted those same effects in human participants.
Similarly, a study published in the journal Metabolism involving young women who were supplemented with alternating high saturated fat and high monounsaturated fat diets noted that the high saturated fat diet was associated with increased inflammatory markers and concomitant changes in brain activation.
A mouse study published in the Annals of Clinical and Translational Neurology found that extra-virgin olive oil reduces the buildup of tau protein in the brain, improves synaptic integrity, and protects against memory impairments and neuroinflammation. These findings led researchers to speculate that extra-virgin olive oil could be effective in "preventing or halting" Alzheimer's disease.
And a meta-analysis published in the Journal of Stroke and Cerebrovascular Diseases noted that higher intake of monounsaturated fatty acids was associated with a decreased risk of hemorrhagic stroke.
Another study published in the journal International Immunopharmacology noted that erucic acid, which can be converted in the body to nervonic acid, may act as a remyelinating and anti-inflammatory agent—properties that could make erucic acid useful in the treatment of demyelinating diseases like multiple sclerosis and Alzheimer's disease.
Finally, a study published in the American Journal of Clinical Nutrition found that participants who ate a diet rich in oleic acid experienced increased levels of daily physical activity, enhanced resting metabolic rate, and improvements in mood, especially with regard to feelings of anger and hostility.
Should You Supplement with Omega-9 Fatty Acids?
As you can see from the studies listed above, just because the body can produce its own omega-9 fatty acids doesn't mean it can't use a little extra dietary help now and then.
In fact, most—if not all—of the diseases associated with the typical Western diet may be helped by eating more foods rich in omega-9 fatty acids.
However, it's important to remember that omega-9 fatty acids are available in a wide range of foods, and not all of them are particularly healthy.
So if you decide to add more of these nonessential fatty acids to your diet, be sure to choose healthy sources, such as:
- Olive oil
- Hemp seeds
- Chia seeds
- Macadamia nuts
- Flax seeds
And don't forget to include a healthy ratio of omega-3 and 6 fatty acids too. The body requires all three for overall health, so eating a well-balanced diet that includes omega-3, 6, and 9 fatty acids will ensure you're getting the health benefits of all these important fats.
And, as noted earlier, omega-3, 6, and 9 fatty acids are found together in many foods, including flax seeds, chia seeds, and hemp seeds, which means you can easily get all the fatty acids you need by increasing your consumption of these sources.