Are Omega-6s Healthy or Unhealthy in a Keto Acids Context?
We recently documented the health benefits of consuming sufficient omega-3 fatty acids. Often, researchers discuss omega-3 fatty acids in the context of their counterpart, omega-6 fatty acids. Outlets like Authority Nutrition suggest that consuming too many omega-6 fatty acids can lead to health issues ranging from inflammation to heart disease. Others emphasize the importance of maintaining a proper ratio of omega-6 to omega-3 fatty acids.
But what’s the real story behind this controversial fatty acid? And is there any credibility to the idea of consuming the proper ratio? Below, we explore the science, its impact on health, and how much you should truly be consuming.
Biochemistry of Omega-6 Fatty Acids
Omega-6 fatty acids, like their “sister” molecule omega-3 fatty acids, are polyunsaturated fats. This means they consist of a three-carbon molecule called glycerol attached to three chains of carbon and hydrogen atoms known as fatty acids.
Since they are polyunsaturated, at least one of these three fatty acid chains has more than one double bond between carbon atoms. In contrast, monounsaturated fats have only one double bond between carbon atoms in their fatty acid chains, and saturated fats have no double bonds between carbon atoms in the fatty acid chain.
By definition, all omega-6 fatty acids contain a double bond between the 6th and 7th carbon atoms from the right of the carbon chain. Omega-3 fatty acids also have this bond, plus an additional one between the 3rd and 4th carbon atoms from the right.
Omega-6 fatty acids are most commonly found in one of three forms in the human body. The first, linoleic acid (LA), is 18 carbon atoms long and has two double bonds: one between the 6th and 7th carbon atoms from the right and another between the 9th and 10th. Its omega-3 counterpart, alpha-linolenic acid (ALA), is nearly identical but also has a double bond between the 3rd and 4th carbon atoms from the right.
The second form, gamma-linolenic acid (GLA), is almost identical to LA but has an extra double bond between the 12th and 13th carbon atoms from the right. It can be obtained directly from certain foods or converted from LA.
The third omega-6 fatty acid, arachidonic acid (AA), contains 20 carbon atoms and four carbon-carbon double bonds. Like LA, the first is between the 6th and 7th carbon atoms from the right, the second between the 9th and 10th, and the other two between the 12th/13th and 15th/16th.
AA is usually derived from GLA (which comes from LA) and can be found directly in some food sources. Omega-6 fatty acids also occur in nature in several other forms ranging from 18 to 24 carbon atoms in length.
Omega-3 and omega-6 fatty acids are typically referred to as essential fatty acids. This means the body requires them for critical functions but cannot produce them, so humans must obtain them through food or supplements. Fortunately, many dietary sources contain LA.
The best sources are plant-based oils, including (from highest to lowest): safflower, sunflower, soybean, corn, and cottonseed. LA is also found in whole grain bread, animal fat, and cereals. GLA is usually produced from ingested LA but can be directly consumed from plant-based oils like black currant seed oil, borage oil, and evening primrose oil. AA is not essential as the body produces it naturally, but it can become essential if LA is deficient or the conversion from LA to AA is impaired. Dietary sources of AA include red meat, eggs, dairy, and certain fungi.
The Importance of Omega-6 Fatty Acids
Omega-6 fatty acids are crucial for several bodily functions. Together with omega-3s, they support cellular growth, brain function, bone health, and stimulate hair and skin growth.
The American Heart Association recommends that 5-10% of daily calories come from omega-6 fatty acids. Most Americans meet this through common dietary sources like vegetable oils, but often lack sufficient omega-3 intake.
Omega-6 fatty acids in the form of GLA may offer particular benefits. Preliminary research suggests GLA supplements could help manage conditions like osteoporosis, high blood pressure (when combined with omega-3s), diabetic retinopathy symptoms, premenstrual syndrome (PMS), and reduce pain and swelling in rheumatoid arthritis. The conversion of GLA to DGLA is promoted by nutrients like zinc, vitamins C, B3, and B6, and magnesium.
However, excessive omega-6 intake can lead to issues like increased inflammation, excessive blood clotting, unnecessary cell growth, and blood vessel constriction. Omega-3 fatty acids generally affect the body differently.
Explaining the Omega-3/Omega-6 Ratio
Omega-3 and omega-6 fatty acids are biochemically similar and compete for the same enzymes. This means these enzymes can bind to either substrate to carry out their reactions. If there’s a good balance between omega-6 and omega-3 fatty acids, this won’t be a problem. Scientists refer to the ratio between these two polyunsaturated fatty acids in the diet as the “omega-6 to omega-3 ratio.”
Because both fatty acids compete for the same enzymes, high levels of omega-6s may counteract some benefits of omega-3s. Some researchers believe this promotes inflammation and blood vessel constriction, negatively affecting health. Both fatty acids also affect gene regulation and are incorporated into cell membranes differently, further highlighting the importance of maintaining a proper omega-6 to omega-3 ratio.
People following a “Western diet,” high in processed meats and vegetable oils, typically consume far more omega-6s than omega-3s. In the past 50 years, the amount of omega-6 fatty acids in American body fat stores has increased from 7% to 23%. While Americans now consume more omega-3 fatty acids than before, the average omega-6/omega-3 ratio has doubled, raising concerns among researchers. A 2002 paper noted that humans evolved on a diet with an omega-6 to omega-3 ratio of about 1, whereas Western diets now have ratios of 15/1-16.7/1.
Given the rising prevalence of chronic conditions like obesity, diabetes, cardiovascular disease, and depression, researchers have investigated whether increased omega-6 consumption is a contributing factor.
The Great Debate: Is the Omega-3/Omega-6 Ratio Important?
Some studies suggest the ratio between omega-6s and omega-3s matters significantly. According to a 2002 review by Simopoulos et al.:
“Excessive omega-6 PUFA and a very high omega-6/omega-3 ratio, common in today’s Western diets, promote many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases, while increased omega-3 PUFA (a low omega-6/omega-3 ratio) has suppressive effects.”
Researchers noted that a ratio of 4:1 or lower was associated with a 70% decline in cardiovascular disease mortality over two years. A ratio below 5:1 had beneficial effects on colorectal cancer and asthma symptoms, and below 3:1 reduced inflammation in rheumatoid arthritis patients. Conversely, a ratio above 10:1 had negative health consequences. Consequently, these researchers concluded that “a lower omega-6/omega-3 fatty acid ratio is more desirable for reducing the risk of many chronic diseases prevalent in Western societies.”
A 2006 meta-analysis examined data from seven randomized trials with 11,275 subjects. It found that diets with mixed omega-3 and omega-6 fatty acids reduced the risk of death from myocardial infarction and coronary heart disease by 22%, while diets with only omega-6 fatty acids increased this risk by 13%. Researchers also noted that substituting omega-6 fatty acids for trans-fats and saturated fats without increasing omega-3 intake led to an overall increased risk of death. They stated that “…advice to specifically increase n-6 PUFA intake, based on mixed n-3/n-6 RCT data, is unlikely to provide the intended benefits, and may actually increase the risks of CHD and death.”
Supporting this, a 2005 study suggested consuming more omega-3s and fewer omega-6s leads to “less intense” action of the inflammatory agent eicosanoids, reducing the chances of developing cardiovascular diseases. Another group of researchers recommended a diet with 6% LA and about 1% omega-6 fatty acids, roughly corresponding to an omega-6/omega-3 ratio of 6:1.
Some research indicates a lower omega-6/omega-3 ratio benefits the body. Researchers provided 22 subjects with a traditional Swedish diet lower in omega-3 fatty acids for 4 weeks, followed by a traditional Mediterranean diet higher in omega-3 fatty acids. They observed a 10% and 15% reduction in leukocytes and platelets, respectively, after the Mediterranean diet. Other key inflammation markers like c-reactive protein remained unchanged. In two trials on 29 subjects with inflammatory bowel disease, administering omega-3 fatty acids lowered the omega-6:omega-3 ratio while reducing inflammation-related symptoms. Another study in older, healthy adults found an inverse correlation between bone mineral density and the omega-6/omega-3 fatty acid ratio.
Key Takeaways: Some research suggests that a lower omega-6/omega-3 ratio (6:1 and below) in the blood may help reduce the risk of complications related to the cardiovascular and immune systems.
Putting it in Perspective: How Much Does the Omega-6/Omega-3 Ratio Really Matter?
Evidence suggests that while it’s important to consume adequate amounts of omega-3 and omega-6 fatty acids, the actual ratio between them isn’t the strongest indicator of risk for certain chronic conditions. In the study by Wijendran et al., researchers suggested an ideal omega-6 to omega-3 ratio of 6:1. However, they emphasized that “the absolute mass of essential fatty acids consumed, rather than their n-6/n-3 ratio, should be the first consideration when contemplating lifelong dietary habits affecting cardiovascular benefit from their intake.”
This supports the notion that while monitoring the omega-6/omega-3 ratio is important, it’s more critical to ensure proper intake of each essential fatty acid.
Another study indicates that consuming adequate amounts of omega-6 and omega-3 fatty acids is more important than achieving the correct ratio. In a 6-month randomized, parallel trial with 258 subjects aged 45-70, researchers provided diets with 6% energy from essential fatty acids but varying ratios. They concluded that “decreasing the n-6:n-3 ratio does not influence insulin sensitivity or lipase activities in older subjects,” though increased omega-3 intake led to favorable changes in LDL particle size. However, they couldn’t determine if this was due to the ratio or adequate intake of both fatty acids. Thus, they recommended omega-3 fatty acid intake of 0.7% energy or 1 gram per day for optimal health.
Another study assessing the same group found that lowering the omega-6/omega-3 ratio didn’t affect fibrinogen, activated factor XII, and factor VII levels, which increase ischemic heart disease risk. Researchers noted that a lower ratio temporarily reduced triglycerides but didn’t result in long-term decreases or improvements in other cardiovascular fitness indicators.
Finally, a 2009 American Heart Association report underscored the importance of adequate omega-6 fatty acid intake. They stated that data from randomized trials, case-control and cohort studies, and long-term animal feeding experiments indicate that consuming at least 5% to 10% of energy from omega-6 PUFAs reduces CHD risk relative to lower intakes. They remarked that “to reduce omega-6 PUFA intakes from their current levels would be more likely to increase than to decrease risk for CHD.”
Key Takeaways: Some research indicates that the omega-6/omega-3 ratio is a weak indicator of overall health. Additionally, this research emphasizes the importance of consuming the recommended daily amounts of omega-3 and omega-6 fatty acids rather than fixating on the precise ratio between the two.
How Much Should You Truly Be Getting?
Research on the importance of the omega-6/omega-3 ratio is mixed. Some high-quality studies suggest a higher ratio (above 10:1) may increase the risk of negative health conditions related to heart health and inflammation. Other credible research finds a weak association between this ratio and chronic diseases. Furthermore, a recent analysis by the American Heart Association emphasizes the importance of consuming at least 5-10% of daily calories from omega-6 fatty acids.
How can we use this conflicting research to guide dietary choices? We can extract two important key takeaways:
- It is critical to meet your daily requirement of omega-3 fatty acids. The American Heart Association recommends an average of 1000 mg per day.
- Some foods high in omega-6s but low in omega-3 fatty acids, such as safflower oil, chips, and processed meat, are nutritionally-poor and should be avoided on most diets, including the ketogenic diet.
The best way to get your servings of omega-3 fatty acids is to eat two 3 ounce servings of fatty fish such as mackerel, sardines, and salmon per week. It is also important to note that some foods high in omega-6 fatty acids, such as walnuts and Brazilian nuts, are also high in omega-3 fatty acids and have other nutritional benefits.
More research needs to be done to show the clinical significance of omega-6 fatty acids and the omega-6 to omega-3 ratio. But for now, science shows that it’s more important you get the proper amount of omega-3 and omega-6 fatty acids from nutrient-rich sources such as nuts, dairy, and lean meats.
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