Omega-3 fatty acids are vital fats that play key roles in heart, brain, and metabolic health. While omega-6 fats are energy-providing and plentiful in many diets, most people don’t consume enough omega-3s. Omega-9 fats are nonessential because the body can synthesise them.
Omega-3, omega-6 and omega-9 fatty acids are all important dietary fats.
Each offers health benefits, but achieving the correct balance among them matters. A diet skewed toward one type may contribute to chronic health issues.
Below is an overview of omega-3, -6 and -9 fats, including:
- what they are
- why they matter
- where to obtain them
What are omega-3 fatty acids?
Omega-3s are polyunsaturated fats that the body cannot manufacture.
“Polyunsaturated” describes their chemical configuration: “poly” denotes many and “unsaturated” indicates the presence of double bonds — meaning omega-3s contain multiple double bonds.
The label “omega-3” describes the location of the final double bond, three carbon atoms away from the molecule’s tail end (the “omega” position).
Because the body cannot produce omega-3s, they are classed as essential fats that must be consumed via food.
The American Heart Association (AHA) suggests eating at least two servings of fish weekly, especially oily fish, which are rich in omega-3s.
There are several omega-3 varieties, differing in chain length and structure. The three most common are:
- Eicosapentaenoic acid (EPA): A 20-carbon fatty acid that primarily makes eicosanoids, molecules that can lower inflammation. EPA may also ease depressive symptoms.
- Docosahexaenoic acid (DHA): A 22-carbon fatty acid that constitutes around 8% of brain mass and supports brain growth and function.
- Alpha-linolenic acid (ALA): An 18-carbon fatty acid that can be converted into EPA and DHA, though conversion is limited. ALA seems to benefit cardiovascular, immune, and nervous system health.
Omega-3s are essential components of cell membranes and perform several other functions, including:
- Enhancing heart health. Omega-3s may help regulate cholesterol, triglycerides, and blood pressure (, , , , 10, ).
- Supporting mental well-being. Omega-3 supplements could help treat or prevent depression, Parkinson’s disease, and psychosis in high-risk individuals, though more research is necessary.
- Helping with weight and waist management. Omega-3s may assist in controlling body weight and waist circumference, but additional studies are required.
- Lowering liver fat. Early research indicates omega-3 intake may reduce liver fat deposits (, , 19).
- Supporting infant brain growth. Omega-3s contribute to fetal brain development.
- Combating inflammation. Omega-3s can help manage inflammation linked with some chronic conditions.
Insufficient omega-3 intake relative to omega-6s may promote inflammation and chronic illnesses such as rheumatoid arthritis, diabetes, atherosclerosis, and heart failure.
SummaryOmega-3s are essential fats you must obtain from food. They offer notable benefits for heart, brain, and metabolic health.
What are omega-6 fatty acids?
Omega-6s are also polyunsaturated fatty acids, but their final double bond sits six carbons from the omega end.
Like omega-3s, omega-6s are essential and must be consumed through diet.
They primarily serve as an energy source. The most common omega-6 is linoleic acid, which the body can elongate into longer omega-6s like arachidonic acid (AA).
AA, like EPA, generates eicosanoids. However, AA-derived eicosanoids tend to be more pro-inflammatory.
Pro-inflammatory eicosanoids are important for immune responses, but excessive production can raise the risk of inflammation-related diseases.
A healthy omega-6 to omega-3 ratio is believed to lie between 1:1 and 4:1 (, ), yet typical Western diets may reach ratios of roughly 15:1 to nearly 17:1 (32).
Can omega-6 be helpful?
Certain omega-6 fatty acids have demonstrated therapeutic promise for chronic symptoms.
Gamma-linolenic acid (GLA) is an omega-6 found in particular oils, such as:
- evening primrose oil
- borage oil
Much of dietary GLA is converted to dihomo-gamma-linolenic acid (DGLA) in the body.
Evidence suggests GLA and DGLA may confer health advantages; for instance, GLA might ease symptoms of inflammatory disorders, though further research is needed.
One study concluded that supplements of another omega-6 — conjugated linoleic acid (CLA) — might help reduce body fat in humans.
SummaryOmega-6s are essential energy-providing fats. Nonetheless, it’s beneficial to consume more omega-3s relative to omega-6s.
What are omega-9 fatty acids?
Omega-9s are monounsaturated fats, each containing a single double bond.
That double bond is positioned nine carbons from the omega end of the molecule.
Oleic acid is the predominant omega-9 and the most common monounsaturated fat in food.
Omega-9s are not strictly essential because the body can manufacture them.
Still, replacing other fats with omega-9-rich foods may offer health advantages.
A 2015 study in mice showed diets high in monounsaturated fats improved insulin sensitivity and reduced inflammation (36).
That study also found people consuming high-monounsaturated diets experienced lower inflammation and better insulin sensitivity versus those eating diets high in saturated fat.
SummaryOmega-9s are nonessential since the body can make them. Swapping some saturated fats for omega-9s may be beneficial.
Which foods contain these fats?
You can get omega-3, -6, and -9 fats easily from food, but balance is key. The standard Western diet tends to supply too much omega-6 and too little omega-3.
Below are foods rich in omega-3, -6 and -9 fatty acids.
Foods rich in omega-3 fats
Oily fish are the top sources of EPA and DHA. Algal oils are another marine source. ALA is abundant in nuts and seeds.
No official daily omega-3 standard exists, but many organisations recommend about 250–300 milligrams daily.
The U.S. Institute of Medicine’s Food and Nutrition Board suggests an adequate intake of ALA of 1.6 grams per day for adult men and 1.1 grams per day for adult women aged 19 and older.
The following shows omega-3 amounts and types in a single serving of these 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
Refined vegetable oils and foods fried in these oils are rich in omega-6 fats.
Nuts and seeds also supply sizable amounts of omega-6s.
The Food and Nutrition Board of the U.S. Institute of Medicine recommends an adequate intake of omega-6s of 17 grams per day for men and 12 grams per day for women aged 19–50 years (39).
Below are omega-6 contents per 100 grams (3.5 ounces) of common 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-9s are plentiful in:
- vegetable and seed oils
- nuts
- seeds
There are no recommended intake values for omega-9s because they are nonessential.
Here are omega-9 amounts per 100 grams of several 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
SummaryOily fish are the best omega-3 sources, while omega-6s and omega-9s are abundant in plant oils, nuts, and seeds.
Should you take an omega-3-6-9 supplement?
Combined omega-3-6-9 supplements typically provide these fats in balanced ratios, for example 2:1:1 for omega-3:6:9.
Such blends can boost omega-3 intake and help improve the overall fatty acid ratio so omega-6 to omega-3 drops below 4:1.
However, most people already obtain ample omega-6 from food, and the body makes omega-9. Thus, many people do not need supplements for these fats.
It’s generally better to aim for a healthy dietary balance of omega-3, -6 and -9, for instance by eating two servings of oily fish weekly and using olive oil for cooking and dressings.
Also try to lower omega-6 consumption by reducing intake of refined vegetable oils and fried foods prepared in those oils.
Individuals lacking sufficient omega-3 from food may benefit more from a dedicated omega-3 supplement rather than a combined omega-3-6-9 product.
SummaryCombined omega-3-6-9 supplements supply balanced fatty acid ratios, but they likely offer no extra advantage over omega-3-only supplements.
How to choose an omega 3-6-9 supplement
Polyunsaturated fats are prone to oxidation when exposed to heat and light.
When selecting an omega-3-6-9 supplement, pick one that is cold-pressed; this extraction method limits heat exposure and helps prevent oxidation of the fatty acids.
To minimise the chance of taking an oxidised product, choose supplements that include an antioxidant such as vitamin E.
Also opt for a supplement with a high omega-3 concentration — preferably more than 0.3 grams per serving.
Since EPA and DHA deliver more documented health benefits than ALA, prefer supplements using fish oil or algal oil rather than flaxseed oil.
SummaryPrefer an omega-3 supplement over a combined 3-6-9 formula. If choosing a combined supplement, select one with a strong EPA and DHA content.
The bottom line
Although omega-3-6-9 supplements are common, they typically give no greater benefit than taking omega-3s alone.
Omega-6s are essential in moderation but are widespread in many foods; people consuming a Western diet often have excess intake.
The body can synthesise omega-9s, and they are readily available in foods, so supplementation is usually unnecessary.
Therefore, while combined supplements offer balanced ratios, focusing on omega-3s will probably deliver the most health advantages.
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