By Dr. Ruairi Robertson
Omega-3, omega-6 and omega-9 fatty acids are all important dietary fats.
Interestingly, each one has a number of health benefits for your body.
However, it’s important to get the right balance of omega-3, -6 and -9 fatty acids in your diet. An imbalance may contribute to a number of chronic diseases.
Here is a guide to omega-3, -6 and -9 fatty acids, including what they are, why you need them and where you can get them.
What Are Omega-3 Fatty Acids?
Omega-3 fatty acids are polyunsaturated fats, a type of fat your body can’t make.
Their name comes from 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 World Health Organization (WHO) recommends eating at least two portions of oily fish per week, which is rich in the omega-3s EPA and DHA (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 also helps reduce symptoms of depression (2, 3).
- Docosahexaenoic acid (DHA): A 22-carbon fatty acid, DHA makes up about 8 percent of brain weight and is extremely important for normal 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 is mainly used by the body for energy (5).
Omega-3 fats are a crucial part of human cell membranes. They also have a number of other important functions, including:
- Improving heart health: Omega-3 fatty acids can increase “good” HDL cholesterol. They can also reduce triglycerides, blood pressure and the formation of arterial plaques (6, 7, 8, 9, 10).
- Supporting mental health: Taking omega-3s can reduce symptoms of depression, schizophrenia and bipolar disorder. It can also reduce the risk of psychotic disorders for those who are at risk (11, 12, 13, 14, 15).
- Reducing weight and waist size: Omega-3 fats play an important role in weight management and can help reduce waist circumference (16, 17).
- Decreasing liver fat: Consuming omega-3s in your diet can help decrease the amount of fat in your liver (18, 19, 20).
- Supporting infant brain development: Omega-3s are extremely important for brain development in babies (4, 21).
- Fighting inflammation: Omega-3 fats are anti-inflammatory, meaning they can reduce the inflammation in your body that can contribute to a number of chronic diseases (22, 23, 24).
- Preventing dementia: People who eat more fish, which is high in omega-3 fats, tend to have a slower decline in brain function in old age. Omega-3s may also help improve memory in older people (25, 26).
- Promoting bone health: People with higher omega-3 intake and blood levels tend to have better bone mineral density (27, 28).
- Preventing asthma: Omega-3 intake can help reduce symptoms of asthma, especially in early life (29, 30, 31).
Unfortunately, the Western diet does not contain enough omega-3s. A deficiency may contribute to chronic diseases like obesity, diabetes and heart disease (32).
Summary: Omega-3 fats are essential fats that you must get from your diet. They have important benefits for your heart, brain and metabolism.
What Are Omega-6 Fatty Acids?
Like omega-3 fatty acids, omega-6 fatty acids are polyunsaturated fatty acids.
The only difference is that 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.
These fats are primarily used for energy. The most common omega-6 fat is linoleic acid, which can be converted into longer omega-6 fats such as arachidonic acid (ARA) (33).
Like EPA, ARA is used to produce eicosanoids. However, the eicosanoids produced by ARA are more pro-inflammatory (34, 35).
Pro-inflammatory eicosanoids are important chemicals in the immune system. However, when too many of them are produced, they can increase inflammation and inflammatory disease (36).
Although omega-6 fats are essential, the modern Western diet contains far more omega-6 fatty acids than necessary (37).
The recommended ratio of omega-6 to omega-3 fatty acids in the diet is 4:1 or less. However, the Western diet has a ratio between 10:1 and 50:1.
Therefore, although omega-6 fats are essential in the right quantities, most people in the developed world should aim to reduce their omega-6 intake (37).
Nevertheless, 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 and borage oil. When consumed, much of it is converted to another fatty acid called dihomo-gamma-linolenic acid (DGLA).
One study showed that taking a high dose of GLA supplements significantly reduced a number of symptoms of rheumatoid arthritis (38).
Another interesting study found that taking GLA supplements in addition to a breast cancer drug was more effective at treating breast cancer than the drug alone (39).
Conjugated linoleic acid (CLA) is another form of omega-6 fat that has some health benefits. For example, one large study found that taking 3.2 grams of CLA supplements per day effectively reduced body fat mass in humans (40).
Summary: Omega-6 fats are essential fats that are an important source of energy for the body. However, the Western diet contains too many.
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What Are Omega-9 Fatty Acids?
Omega-9 fatty acids are monounsaturated, meaning they only have one double bond.
It is 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.
Omega-9 fatty acids aren’t strictly “essential,” meaning they can be produced by the body. In fact, omega-9 fats are the most abundant fats in most cells in the body.
However, consuming foods rich in omega-9 fatty acids instead of other types of fat may have a number of beneficial health effects.
One large study found that high-monounsaturated fat diets could reduce plasma triglycerides by 19 percent and “bad” very-low-density-lipoprotein (VLDL) cholesterol by 22 percent in patients with diabetes (41).
Another study found that feeding mice diets high in monounsaturated fat improved insulin sensitivity and decreased inflammation (42).
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 (42).
Summary: Omega-9 fats are non-essential fats, since they can be produced by the body. Diets that replace some saturated fats with omega-9 fats may have benefits for metabolic health.
Which Foods Contain These Fats?
You can easily obtain omega-3, -6 and -9 fatty acids from your diet.
However, it is important to get the right balance of each. The Western diet contains far more omega-6 fats than necessary and not enough omega-3 fats.
Here is a list of foods that are high in omega-3, -6 and -9 fatty acids.
Foods High in Omega-3 Fats
The best source of omega-3 EPA and DHA is oily fish.
However, you can also obtain these omega-3s from other marine sources, such as algal oils. ALA, on the other hand, is mainly obtained from nuts and seeds.
There are no official standards for daily omega-3 intake, but various organizations offer guidelines.
According to the Food and Nutrition Board of the US Institute of Medicine, the adequate intake of omega-3s per day is 1.6 grams for men and 1.1 grams for women, for adults 19 years and over (43).
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
Omega-6 fats are found in large amounts 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 US Institute of Medicine, the adequate intake of omega-6s per day is 17 grams for men and 12 grams for women, for adults from 19–50 years old (43).
Here are the amounts of omega-6s in 100 grams (3.5 oz) 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
As you can see, it is very easy to get more than enough omega-6s through your diet.
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Foods High in Omega-9 Fats
Omega-9 fats are also common in vegetable and seed oils, as well as nuts and seeds.
There are no adequate intake recommendations for omega-9s, since they are non-essential.
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
Summary: The best sources of omega-3s are oily fish, whereas omega-6s and omega-9s are found in plant oils, nuts and seeds.
Should You Take an Omega-3-6-9 Supplement?
Combined omega-3-6-9 supplements usually provide each of these fatty acids in suitable proportions, such as 2:1:1 for omega-3:6:9.
Such oils can help increase your intake of omega-3 fats, which should be consumed more in the Western diet.
In addition, these oils provide a healthy balance of fatty acids so that the balance of omega-6 to omega-3 is less than 4:1.
However, since most people already consume too many omega-6s and omega-9s are produced by the body, there is no general need to supplement with these fats.
Therefore, it is best to focus your diet on getting a good balance of omega-3, -6 and -9 fatty acids. This should involve eating at least two portions of oily fish per week and using olive oil for cooking and in salad dressing.
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.
If you do not get enough omega-3s in your diet, it is best to take an omega-3 supplement alone rather than a combined omega-3-6-9 supplement.
Summary: Combined omega-3-6-9 supplements provide optimal ratios of fatty acids, but likely provide no additional benefits to omega-3 supplements.
How to Choose an Omega 3-6-9 Supplement
Much like other oils, polyunsaturated fatty acids are easily oxidized when exposed to heat and light.
Therefore, if you’re buying an omega-3-6-9 supplement, choose one that is 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 are choosing a supplement that isn’t oxidized, choose one that contains an antioxidant such as vitamin E.
Additionally, choose 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.
Summary: 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.
The Bottom Line
Although combined omega-3-6-9 supplements have become very popular, they generally provide no additional benefit over taking omega-3 alone.
Omega-6s are essential in certain quantities, but they are in many foods and people following a Western diet already consume too many of them.
Additionally, omega-9 fats can be produced by the body and are 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.
Reposted with permission from our media associate Authority Nutrition.