And Why Is It Important?
What is the omega-6:3 ratio?
In nutrition, we look at the omega-6:3 ratio to assess whether a diet is too high or low in omega-6s and whether it provides enough omega-3s.
Humans evolved on a diet with an omega-6 to the omega-3 ratio of approximately 1:1 (2).
In our modern Western diet, the average ratio of omega-6 to omega-3 has increased from 1:1 to as much as 30:1 (3).
A ratio of 30:1 indicates we are ingesting 30 times more omega-6s than omega-3s and 30 times more than is necessary for optimal health!
Essentially, our modern diets are too high in the inflammatory omega-6 fats and too low in the healthier omega-3 fats.
What are omega-6 fats?
Omega-6 polyunsaturated fatty acids (PUFAs) are essential fatty acids that must be obtained from the diet.
They cannot be made by humans because our bodies lack the necessary enzymes (1).
Food sources of omega-6 fats are vegetable oils (i.e. safflower oil, sunflower oil, corn oil, canola or rapeseed oil, soybean oil), sunflower seeds, nuts, beans, seeds, and grains.
We need some omega-6s in our diets.
However, as we’ll discuss below, the modern American diet is too high in omega-6 fats. These fats are inflammatory and contribute to multiple health problems. Read on for more details.
What are omega-3 fats?
Omega-3 fatty acids, like omega-6s, are also polyunsaturated fatty acids that are essential for the body and must come from the diet.
The difference between omega-6 fatty acids and omega-3 fatty acids is the chemical make-up of each molecule.
It is related to how many double bonds and carbons are on each PUFA molecule.
Food sources are fatty fish (wild salmon, herring, mackerel, and sardines; also check out our article “What is the Healthiest Seafood?”), high-quality fish oil, flaxseed oil, flaxseeds, walnuts, and chia seeds.
The primary health-promoting omega-3 fats that people know are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These are primarily found in fish and fish oil.
Omega-3 fats are anti-inflammatory, are essential for good brain health, and have many other positive effects on overall health.
We typically do not get enough omega-3 fats in the modern diet.
As an aside, omega-9 is another type of fatty acid.
Their chemical structure is slightly different again from omega-6s and omega-3s.
They are not considered essential because the body can make omega-9s (unlike omega-6s and omega-3s). Omega-9 fats are primarily found in olive oil, macadamias, and other nuts.
Omega-9 is also anti-inflammatory and good for overall health.
What is the ideal ratio?
The ideal ratio is 1:1, or as close to that as possible. Our genes evolved hundreds of thousands of years ago.
This is a process that happens very slowly over time.
During evolution, our genes were programmed to have a 1:1 omega-6 to omega-3 ratio (4).
So, for optimal health and to best suit our bodies, a ratio of 1:1 is the ideal.
Anything around 5:1 or below still conveys health benefits.
Why is this ratio important?
Excess omega-6 fats in the diet contribute to a multitude of health problems.
They create low-grade inflammation, oxidative stress (from free radicals) and atherosclerosis (the buildup of plaque on arteries).
Omega-6s contribute to the creation of more pro-inflammatory molecules in the body.
In contrast, omega-3s can reduce inflammation caused by omega-6s (5).
A very high omega-6 to omega-3 ratio promotes inflammation and disease, such as cardiovascular disease, cancer, and other inflammatory and autoimmune diseases.
Higher omega-3 intake has an anti-inflammatory and suppressive influence against these types of chronic disease.
In various studies, lower omega-6 to omega-3 ratios of between about 2.5:1 to 5:1 reduced risks and improved outcomes of multiple diseases, including cardiovascular disease, breast cancer, asthma, rheumatoid arthritis, and colorectal cancer (6).
In one study, supplementing with fish oil (i.e., omega-3 fats) led to a significant shift in cholesterol makeup to larger HDL (“good” cholesterol) particles (vs. LDL, “bad” cholesterol).
Fish oil was found to be anti-inflammatory and to prevent the early onset of heart disease (7).
Being deficient in omega-3 fats is associated with insulin resistance and metabolic syndrome, brain function, and non-alcoholic fatty liver disease (NAFLD) (8).
One study looked at children with epilepsy and found that they had lower levels of omega-3 and higher levels of omega-6 fatty acids and an abnormal (high) ratio of omega-6 to omega-3 compared to non-epileptic children (9).
Children with asthma have worse asthma severity and lung function, and higher systemic inflammation due to a higher omega-6 level in their diet.
Omega-3 was found to be protective and reduce the effects of indoor pollution in children with asthma (10).
Omega-3 fats have a therapeutic influence against some cancers and can improve the effect and tolerability of chemotherapy.
This is because omega-3s can suppress inflammation.
Conversely, omega-6 fats can encourage the progression of some cancers (11).
Omega-3 fats are anti-depressive.
Depression is linked to inflammation in the brain.
Omega-3s are anti-inflammatory and are vital for brain health, which makes them effective both in preventing and treating depression (12).
How to optimize your omega-6:3 ratio through diet
The first step to maintaining a healthy omega-6 to omega-3 ratio is to cut out the highest sources of poor-quality omega-6 fats from your diet.
Eliminate omega-6 vegetable oils such as safflower oil, sunflower oil, corn oil, canola or rapeseed oil, soybean oil, and any other vegetable oil you come across.
This will knock out most of the omega-6 fats in most people’s diets.
Be wary that restaurants, fast food, and take-out meals often contain these poor-quality inflammatory oils, so you will need to keep eating out to a minimum.
Nuts can be high in omega-6s but still offer many health benefits (read more about nuts and your health in our article “The World’s Healthiest Nuts!”).
To increase your anti-inflammatory omega-3 fats and support brain health, eat lots of fatty fish like wild salmon, herring, anchovies, mackerel and sardines.
Be aware that farmed salmon is high in omega-6 fats due to the poor-quality feed the fish are given.
If you want the good omega-3 fats, eat wild salmon.
Walnuts, flaxseeds, and chia seeds are also good (vegetarian) sources of omega-3s.
By eliminating vegetable oils from your diet and enjoying foods high in omega-3 fats, you will help to keep your omega-6:3 ratio low, reap the health benefits of lower inflammation, and combat chronic diseases!