Omega-3, omega-6, and omega-9 fatty acids are all important dietary fats.
They all have health benefits, but it’s important to get the right balance between them. An imbalance in your diet may contribute to a number of chronic diseases.
Here’s a guide to omega-3, -6 and -9 fatty acids, including:
- what they are
- why you need them
- where you can get them
Omega-3 fatty acids are polyunsaturated fats, a type of fat your body can’t make.
The term “polyunsaturated” refers to their chemical structure, as “poly” means many and “unsaturated” refers to double bonds. Together they mean that omega-3 fatty acids have many double bonds.
“Omega-3” refers to the position of the final double bond in the chemical structure, which is three carbon atoms from the “omega,” or tail end of the molecular chain.
Since the human body can’t produce omega-3s, these fats are referred to as “essential fats,” meaning that you have to get them from your diet.
The American Heart Association (AHA) recommends eating at least two portions of fish per week, particularly oily fish, which is rich in omega-3 fatty acids (1).
There are many types of omega-3 fats, which differ based on their chemical shape and size. Here are the three most common:
- Eicosapentaenoic acid (EPA): This 20-carbon fatty acid’s main function is to produce chemicals called eicosanoids, which help reduce inflammation. EPA may also help reduce symptoms of depression (2, 3).
- Docosahexaenoic acid (DHA): A 22-carbon fatty acid, DHA makes up about 8% of brain weight and contributes to brain development and function (4).
- Alpha-linolenic acid (ALA): This 18-carbon fatty acid can be converted into EPA and DHA, although the process is not very efficient. ALA appears to benefit the heart, immune system, and nervous system (5).
Omega-3 fats are a crucial part of human cell membranes. They also have other important functions, including:
- Improving heart health. Omega-3 fatty acids may help manage cholesterol, triglyceride, and blood pressure levels (6, 7, 8, 9, 10, 11).
- Supporting mental health. Omega-3 supplements may help manage or prevent depression, Parkinson’s disease, and psychosis in those at risk. However, more research is needed (12, 13, 14).
- Reducing weight and waist size. Omega-3 fats may help people manage their weight and waist circumference but more studies are needed (15, 16).
- Decreasing liver fat. Initial research suggests that consuming omega-3s may help decrease the amount of fat in your liver (17, 18, 19).
- Supporting infant brain development. Omega-3s support brain development in a fetus (20, 21).
- Fighting inflammation. Omega-3 fats may help manage inflammation that occurs with some chronic diseases (22, 23).
A low intake of omega-3 fatty acids compared with omega-6s may contribute to inflammation and chronic diseases, such as rheumatoid arthritis, diabetes, atherosclerosis, and heart failure (24, 25).
Omega-3 fats are essential fats that you must get from your diet. They have important benefits for your heart, brain, and metabolism.
Like omega-3s, omega-6 fatty acids are polyunsaturated fatty acids. However, the last double bond is six carbons from the omega end of the fatty acid molecule.
Omega-6 fatty acids are also essential, so you need to obtain them from your diet.
They mainly provide energy. The most common omega-6 fat is linoleic acid, which the body can convert to longer omega-6 fats such as arachidonic acid (AA) (26).
Like EPA, AA produces eicosanoids. However, the eicosanoids that AA produces are more pro-inflammatory (27, 28).
Pro-inflammatory eicosanoids play a key role in the immune system. However, when the body produces too many, they can increase the risk of inflammation and inflammatory disease (29).
A healthy ratio of omega-6 to omega-3 fatty acids appears to be between 1-to-1 and 4-to-1 (30, 31), but studies suggest that people who follow a typical Western diet may consume a ratio of between 15-to-1 and almost 17-to-1 (32).
Can Omega-6 be beneficial?
Some omega-6 fatty acids have shown benefits in treating symptoms of chronic disease.
Gamma-linolenic acid (GLA) is an omega-6 fatty acid found in certain oils, such as:
- evening primrose oil
- borage oil
When consumed, much of it is converted to another fatty acid called dihomo-gamma-linolenic acid (DGLA).
Research suggests that GLA and DGLA may have some health benefits. For example, GLA may help reduce symptoms of inflammatory conditions. However, more research is needed (33).
The authors of one study concluded that taking supplements of another form of omega-6 — conjugated linoleic acid (CLA) — may help reduce fat mass in humans (34).
Omega-6 fats are essential fats that provide energy for the body. However, people should eat more omega-3s than omega-6s.
Omega-9 fatty acids are monounsaturated, meaning they only have one double bond.
It’s located nine carbons from the omega end of the fatty acid molecule.
Oleic acid is the most common omega-9 fatty acid and the most common monounsaturated fatty acid in the diet (35).
Omega-9 fatty acids aren’t strictly “essential,” as the body can produce them.
However, consuming foods rich in omega-9 fatty acids instead of other types of fat may have health benefits.
A 2015 study found that feeding mice diets high in monounsaturated fat improved insulin sensitivity and decreased inflammation (36).
The same study found that humans who ate high monounsaturated fat diets had less inflammation and better insulin sensitivity than those who ate diets high in saturated fat.
Omega-9 fats are nonessential fats that the body can produce. Replacing some saturated fats with omega-9 fats may benefit your health.
You can easily obtain omega-3, -6, and -9 fatty acids from your diet, but you need the right balance of each. The typical Western diet contains more omega-6 fats than necessary and not enough omega-3 fats.
Here’s a list of foods that are high in omega-3, -6, and -9 fatty acids.
Foods high in omega-3 fats
Oily fish is the best source of omega-3s EPA and DHA. Other marine sources include algal oils. ALA mainly comes from nuts and seeds.
There are no official standards for daily omega-3 intake, but various organizations offer guidelines. Most experts recommend an intake of 250–300 milligrams per day (37).
According to the Food and Nutrition Board of the U.S. Institute of Medicine, the adequate intake of ALA omega-3s per day is 1.6 grams for adult males and 1.1 grams for adult females aged 19 years and over (38).
Here are the amounts and types of omega-3s in one serving of the following foods:
- salmon: 4.0 grams EPA and DHA
- mackerel: 3.0 grams EPA and DHA
- sardines: 2.2 grams EPA and DHA
- anchovies: 1.0 grams EPA and DHA
- chia seeds: 4.9 grams ALA
- walnuts: 2.5 grams ALA
- flaxseeds: 2.3 grams ALA
Foods high in omega-6 fats
High levels of omega-6 fats are present in refined vegetable oils and foods cooked in vegetable oils.
Nuts and seeds also contain significant amounts of omega-6 fatty acids.
According to the Food and Nutrition Board of the U.S. Institute of Medicine, the adequate intake of omega-6s per day is 17 grams for males and 12 grams for females ages 19–50 years (39).
Here are the amounts of omega-6s in 100 grams (3.5 ounces) of the following foods:
- soybean oil: 50 grams
- corn oil: 49 grams
- mayonnaise: 39 grams
- walnuts: 37 grams
- sunflower seeds: 34 grams
- almonds: 12 grams
- cashew nuts: 8 grams
Foods high in omega-9 fats
Omega-9 fats are common in:
- vegetable and seed oils
There are no adequate intake recommendations for omega-9s since they’re nonessential.
Here are the amounts of omega-9s in 100 grams of the following foods:
- olive oil: 83 grams
- cashew nut oil: 73 grams
- almond oil: 70 grams
- avocado oil: 60 grams
- peanut oil: 47 grams
- almonds: 30 grams
- cashews: 24 grams
- walnuts: 9 grams
The best sources of omega-3s are oily fish, whereas omega-6s and omega-9s are present in plant oils, nuts, and seeds.
Combined omega-3-6-9 supplements usually provide each of these fatty acids in suitable proportions, such as 2-to-1-to-1 for omega-3:6:9.
Such oils can help increase your intake of omega-3 fats and enhance your balance of fatty acids so that the ratio of omega-6 to omega-3 is less than 4-to-1.
However, most people already get enough omega-6 from their diet, and the body produces omega-9. For this reason, most people do not need to supplement with these fats.
Instead, it’s best to focus on getting a good balance of omega-3, -6, and -9 fatty acids from your diet.
Ways of doing this include eating at least two portions of oily fish per week and using olive oil for cooking and in salad dressings.
In addition, try to limit omega-6 intake by limiting your consumption of other vegetable oils and fried foods that have been cooked in refined vegetable oils.
People who do not get enough omega-3 from their diet may benefit from an omega-3 supplement rather than a combined omega-3-6-9 supplement.
Combined omega-3-6-9 supplements provide optimal ratios of fatty acids. However, they likely provide no additional benefits compared with omega-3 supplements.
Much like other oils, polyunsaturated fatty acids are easily oxidized when exposed to heat and light.
Therefore, when buying an omega-3-6-9 supplement, choose one that’s cold pressed. This means the oil has been extracted with limited heat, minimizing the oxidization that can damage the fatty acid molecules.
To ensure you’re taking a supplement that isn’t oxidized, choose one that contains an antioxidant such as vitamin E.
Additionally, select a supplement with the highest omega-3 content — ideally more than 0.3 grams per serving.
Furthermore, since EPA and DHA have more health benefits than ALA, choose a supplement that uses fish oil or algal oil, rather than flaxseed oil.
Choose an omega-3 supplement instead of a combined omega-3-6-9 supplement. If you’re buying a combined supplement, choose one with a high concentration of EPA and DHA.
Combined omega-3-6-9 supplements are popular, but they generally provide no additional benefit over taking omega-3 alone.
Omega-6s are essential in certain quantities, but they’re present in many foods. People who follow a Western diet may already consume too many.
Additionally, the body can produce omega-9 fats, and they’re easily obtained in the diet. So you don’t need to take them in supplement form.
Therefore, although combined supplements contain optimal omega 3-6-9 ratios, taking just omega-3s will likely provide you with the most health benefits.