Omega-6 to Omega-3 Ratio: What Does It Mean and What's Optimal?

Fat intake was once vilified, but we now know that fats, especially healthy fats, play a significant role in satiety, hormone health, heart health, and cognitive function. [1] One metric that’s been used as a standard to determine whether a person is getting the right types of fat in the right amount in their diet is the omega-6 (n-6) to omega-3 (n-3) ratio (sometimes called n6:n3 ratio). Today, those following a Western diet—characterized by a high intake of saturated fats, refined carbohydrates, and processed foods—consume far more omega-6 than omega-3 fatty acids. 

While both are essential fatty acids, each has different effects on the body's inflammatory response and cardiovascular health. Several researchers have hypothesized for decades that the n-6:n-3 ratio of an overall diet plays a large role in health and disease risk. However, recent evidence suggests that this metric may not be as useful as once thought. [1] 

Here’s everything you need to know about the omega-6 to omega-3 fatty acid ratio, how it influences inflammation in the Western diet and important considerations for cardiovascular health.

Omega-6 and omega-3 polyunsaturated fatty acids

Fats can either be classified as saturated or unsaturated. Polyunsaturated fats are a class of unsaturated fats and are characterized by their two or more double bonds. 

Omega-6 and omega-3 polyunsaturated fatty acids (PUFAs) are the only two types of fatty acids that the human body is unable to produce. [1] Both must come from the diet and are therefore termed “essential fatty acids." 

Both omega-6 and omega-3 fatty acids are important components of cell membranes and act as precursors to other substances in the body, including those involved in blood pressure regulation and the inflammatory response. [2, 3] 

Omega-3 fatty acids—eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)—are found predominantly in fatty fish (i.e. salmon, herring, and mackerel), walnuts, chia seeds, and flaxseeds, and are well known for their cardio-protective effects on the body. They help lower triglycerides, promote blood flow and cardiac and vascular function, and control thrombosis and inflammation. [2]  

Linoleic Acid (LA)—an omega-6 fatty acid found primarily in vegetable oils, along with some nuts and seeds—can also be beneficial for heart health when eaten in moderation and in place of saturated fats. [2, 3] LA acts mainly through lowering LDL-cholesterol. However, for several decades, the belief was that omega-6 fatty acid intake should be reduced to improve the ratio of omega-6 to omega-3s. [1]



What is the omega-6 to omega-3 ratio?

Although it is important to consume both omega-6 and omega-3 fatty acids, too much or too little of one of the two can affect how the other functions in the body. [5]

Omega-6s are not inherently bad for you. In fact, they can improve cardiovascular health when coming from whole foods such as nuts and seeds. [2, 6] But, when omega-6 intake from refined vegetable oils is high, they can promote inflammation and oxidative stress, both of which can lead to poor heart health outcomes if accompanied by low omega-3 consumption. [7, 8]

Therefore, the n-6:n-3 ratio helps determine if there is a proper balance between the two to ensure optimal health outcomes.

Recommended daily intake of omega-3 and 6

Despite varying conclusions in the literature, in general, the ideal n-6:n-3 fatty acid ratio is 4:1. This means that you should aim to eat 1 gram of omega-3 for every 4 grams of omega-6. [2, 4, 5] 

The Dietary Guidelines for Americans 2020-2025 recommends that adults consume 1.1-1.6 grams of omega-3s per day.

Following the 4:1 ratio, that would be up to 6.4 grams a day of omega-6s. Monounsaturated and saturated fats would comprise the remainder of a person's daily fat intake intake. 

How did the typical Western diet skew this ratio in omega-6’s favor? 

Major changes in food technology and modern agriculture over the last 100 years have led to increased production of vegetable oils high in omega-6 fatty acids. Today, the typical Western diet is approximately 5 to 15 times higher in omega-6s than omega-3s. [5] This is primarily due to the increased consumption of omega-6-rich seed oils, such as soybean, corn, and safflower oil, the latter two having an n6:n3 ratio of approximately 60:1 and 77:1, respectively. [4] 

And you may be eating more of these oils than you think. Processed vegetable oils are often hidden in commonly consumed foods like:

• Salad dressing
• Mayonnaise
• Bread
• Cereals
• Fried foods
• Pre-packaged baked goods

High consumption of these refined vegetable oils can promote inflammation, which largely accounts for the rationale behind recommendations to improve your n-6:n-3 ratio by reducing omega-6 fatty acid intake. [4] 

Furthermore, no controlled human studies have analyzed the effects of omega-6 fatty acids on heart disease. [7] Though some animal studies link inflammation to seed oils high in omega-6s, controlled studies show that linoleic acid, the most common omega-6 fatty acid, does not significantly increase levels of inflammatory markers. [4, 6, 7]

The problem with relying on the n-6:n-3  ratio as a metric for healthy fat intake

The exploration of fatty acid status and health outcomes like heart disease, stroke, diabetes, and aging has gained increased interest in recent years. There are three omega-3 fatty acids, alpha-linolenic acid, EPA, and DHA, and seven omega-6s found in the blood. This makes fatty acid analysis much more complex than more straightforward biomarkers like glucose or cholesterol, which involve single biomarkers. [1]

Omega-3 fatty acid status has been expressed in a variety of different ways in research and clinical medicine, making it difficult to determine an optimal omega-3 status. [2] Using the n-6:n-3 ratio to predict health outcomes has inherent weaknesses:

• Two very different consumption matters, namely a high intake of both omega-6 and omega-3 intake, and a low intake of both types, would yield similar n-6:n-3 ratios. 
• The ratio implies all omega-3s are good and all omega-6s are bad.
• The ratio doesn’t consider the variety of dietary fatty acid food sources.

Despite its weaknesses, research does indicate that an optimal n-6:n-3 fatty acid ratio within a healthy diet positively impacts inflammation and other biological processes. However, there is no solid agreement on what that ratio should be. [4]

It is well known that a diet too high in omega-6 fatty acids from processed vegetable oils can increase inflammation, which is why it is recommended to aim for an n-6:n-3 ratio of 4:1 as a guide. However, emphasis should be placed on improving overall dietary patterns rather than reducing omega-6 fatty acid intake. [3]

How can you optimize your intake of healthy fats? 

In recent years, researchers have found more evidence that, in particular, a low omega-3 intake is the primary driver of poor heart health outcomes. [6, 7]

The best way to promote health is to get adequate levels of omega-3, either through fish and seafood consumption or supplementation (like with fish oils). This will automatically skew your n-6:n-3 ratio in a more favorable direction. [1, 2, 7] Limiting inflammatory omega-6s from seed oils in processed foods is still recommended, but omega-6s from whole food sources are still beneficial and should not be avoided.

Connecting to InsideTracker

InsideTracker measures biomarkers that can be altered by consuming foods with a high n-6:n-3 fatty acid ratio, like LDL cholesterol, HDL cholesterol, total cholesterol, triglycerides, and hsCRP, to name a few.

InsideTracker plots your blood biomarker data in relation to the optimal zone for you based on your sex, ethnicity, activity level, and age. And, if your specific biomarker levels are unoptimized, InsideTracker provides science-backed recommendations on how to improve.

When you purchase InsideTracker’s Ultimate Plan and have unoptimized lipid markers, you may see recommendations for omega-3-rich foods. Omega-3-rich foods like fatty fish, nuts, seeds, and olive oil are well-researched foods that when incorporated, can improve your lipid markers.

Additionally, if you select “Heart health” as your InsideTracker goal, recommendations that will help you improve or maintain a healthy heart and blood vessels will show a higher impact for you.

References:

[1] https://doi.org/10.1016/j.plefa.2018.03.003

[2] https://doi.org/10.3390/nu13072421

[3] https://doi.org/10.1038/s41569-019-0206-1

[4] http://dx.doi.org/10.1136/openhrt-2018-000946

[5] https://doi.org/10.1016/j.plipres.2016.07.002

[6] https://doi.org/10.1161/CIRCULATIONAHA.108.191627

[7] https://doi.org/10.1016/j.jand.2012.03.029

[8] http://dx.doi.org/10.1136/openhrt-2018-000898