The imbalance between omega-6 and omega-3 fatty acids in the modern Western diet may be fueling a host of chronic inflammatory conditions.
Key Facts:
- The ratio of omega-6 to omega-3 fatty acids has increased from 4:1 to as high as 20:1 over the past century.
- High omega-6 intake and low omega-3 promotes inflammation, while omega-3s resolve inflammation.
- Omega-6s are abundant in vegetable oils like soybean and corn oil; omega-3s are highest in fatty fish.
- Omega imbalance has been linked to rheumatoid arthritis, inflammatory bowel disease, allergies, asthma and more.
Source: Missouri Medicine 2021
Balancing Act Between Pro- & Anti-Inflammatory Fats
Inflammation is a crucial part of the body’s immune response.
Short term inflammation helps fight infections and heal injuries.
However, chronic low-grade inflammation is now believed to be a major driver of many modern inflammatory diseases.
The key to controlling inflammation lies in our diet, specifically in the balance between two classes of essential fatty acids: omega-6 and omega-3.
Omega-6 and omega-3 fatty acids are polyunsaturated fats that the body cannot produce on its own.
They must be obtained through the diet.
The most common omega-6 fat is linoleic acid, found in high amounts in vegetable oils like soybean, corn, and safflower.
Omega-3s include: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), which are abundant in fatty fish, fish oil, flaxseed, and algae.
While both omega-6 and omega-3 fats are essential for health, they have competing roles.
Omega-6s tend to be pro-inflammatory and promote allergic responses, while omega-3s are anti-inflammatory and resolve inflammation.
Chronic inflammation results when these fats fall out of balance.
Modern Diet Imbalance: 20:1 Omega-6 to Omega-3
For most of human evolution, the ratio of omega-6 to omega-3 fatty acids in the diet was estimated to be around 4:1 or less.
However, in the typical Western diet today, the ratio has climbed to an estimated 20:1 in favor of omega-6 fatty acids.
This shift occurred largely over the past century with the advent of modern vegetable oil production and food processing.
Consumption of linoleic acid has more than doubled in the United States over the past 50 years, thanks to the widespread use of omega-6 rich oils like soybean, corn, and safflower in processed foods, fast foods, and restaurant fare.
At the same time, intake of omega-3s has declined.
According to research, this growing imbalance between such high omega-6 and low omega-3 intake encourages a “pro-inflammatory, pro-allergic, pro-thrombotic state.”
In other words, it primes the body for chronic low-grade inflammation and related diseases.
Omega-6s: Drivers of Inflammation
Omega-6 fatty acids, particularly linoleic acid, are converted in the body to inflammatory compounds like prostaglandins and leukotrienes.
Studies suggest linoleic acid may activate inflammatory genes, compounding its health impacts.
Oxidized omega-6s have been found to activate NF-kB, an inflammatory signaling molecule.
They also boost the production of inflammatory cytokines like tumor necrosis factor alpha (TNF-a), interleukin 1-beta (IL-1B), and interleukin 6 (IL-6).
Conversely, omega-3s derived from fish and fish oil, especially EPA and DHA, have well-established anti-inflammatory properties.
They inhibit pro-inflammatory signaling molecules like NF-kB. Omega-3s also increase levels of inflammation-resolving mediators like resolvins and protectins.
Thus, adequate omega-3 intake helps counterbalance excessive omega-6s and resolve inflammation.
But with modern omega-6 intake outpacing omega-3s by 5- to 20-fold, this balance has been thrown out of whack.
Omega Imbalance Linked to Chronic Diseases
A large body of research has linked high omega-6 intake, low omega-3 intake, and the growing imbalance between these two fats to a host of chronic inflammatory diseases.
Rheumatoid Arthritis
Rheumatoid arthritis is an autoimmune condition characterized by painful joint inflammation.
Multiple clinical trials indicate omega-3 fatty acids can reduce symptoms like joint tenderness and swelling in rheumatoid arthritis patients.
Fish oil may also lower inflammatory markers like TNF-a.
Research suggests the omega-3 DHA is particularly beneficial, reducing inflammatory signaling molecules and prostaglandins.
One study found that swapping linoleic acid for DHA reduced leukotriene B4, a driver of inflammation, by 60-75%.
Inflammatory Bowel Diseases
Inflammatory bowel diseases like Crohn’s and ulcerative colitis involve chronic intestinal inflammation.
Studies show linoleic acid may stimulate inflammation in intestinal cells.
Oxidized linoleic acid has been found to boost IL-8, a chemokine that recruits inflammatory cells.
In Crohn’s patients, linoleic acid increases COX-2 and IL-8.
Conversely, fish oil may dampen inflammation in IBD patients by lowering inflammatory cytokines like TNF-a, IL-1B, and IL-6.
Thus, limiting linoleic acid intake while increasing anti-inflammatory omega-3s may benefit those with IBD.
Allergies & Asthma
Research links the rise in allergic disorders to increased omega-6 consumption.
The omega-6 arachidonic acid gives rise to inflammatory leukotrienes involved in allergies and asthma.
Omega-3s counteract this response by reducing inflammatory mediators and boosting specialized pro-resolving mediators.
Clinical trials confirm pregnant women who take omega-3 supplements reduce their children’s risk of food allergies, eczema, and sensitization by up to 66-91%.
Observational studies also associate higher maternal fish intake with significantly lower rates of childhood allergies and asthma.
While large trials are still needed, preliminary evidence suggests omega-3 supplements may reduce airway inflammation and asthma severity scores in children.
But optimal therapeutic doses still need to be defined.
Autoimmune Diseases
Higher omega-6 and lower omega-3 intake may contribute to inappropriate immune reactions against the body’s own tissues in autoimmune diseases like type 1 diabetes, multiple sclerosis, and lupus.
Animal studies indicate omega-3 fatty acids may help prevent and treat certain autoimmune conditions.
For example, fish oil lowered disease incidence and severity in mouse models of lupus and MS.
Some human trials show benefit as well. Multiple studies found fish oil improved symptoms and reduced inflammation in lupus patients.
Small trials suggest omega-3s may benefit MS patients too. Larger clinical trials are still needed to confirm effects.
Metabolic Syndrome
Metabolic syndrome refers to a cluster of conditions that raise heart disease risk, including obesity, high blood pressure, high blood sugar, and abnormal cholesterol levels.
Human and animal research indicates omega-3 fatty acids help reduce risk factors for metabolic syndrome.
For example, fish oil lowers elevated triglycerides, a type of fat in the blood.
Omega-3s may also improve insulin sensitivity. Additionally, populations consuming high omega-3 diets have lower obesity rates.
However, clinical trial evidence has been mixed overall regarding omega-3s for metabolic syndrome. Larger, longer term trials are warranted to clarify their therapeutic role.
The Case for More Omega-3s, Less Omega-6s
The totality of evidence suggests that restoring a healthier 4:1 omega-6 to omega-3 balance may help rein in chronic inflammation and related diseases.
There are two main strategies for achieving this:
1. Increase Omega-3 Intake
Boosting omega-3 EPA and DHA intake through fatty fish or supplements counteracts excessive omega-6s.
Fish oil capsules are a convenient option.
The American Heart Association recommends 1 gram per day of combined EPA/DHA for general health.
Therapeutic doses of 2-5 grams may be optimal for inflammatory conditions.
Whole food sources like salmon, sardines, herring, trout, and mackerel are rich in omega-3s.
Aim for at least two 3-4 ounce servings of fatty fish per week. Ground flaxseed, walnuts, and chia seeds also provide ALA.
2. Limit Omega-6 Intake
Cutting back on refined omega-6 vegetable oils can help reduce the dietary omega-6 load.
Limit fried foods, packaged snacks, and other processed items made with soybean, corn, safflower, sunflower, and cottonseed oils. Use olive or avocado oil for cooking instead.
Focus on whole food sources of omega-6s like nuts, seeds, avocados, and leafy greens, rather than processed oils.
Maintain an overall healthy diet and lifestyle to control inflammation.
Achieving Balance Against Chronic Disease
In summary, strong scientific evidence indicates that restoring balance between omega-6 and omega-3 fatty acids may help overcome chronic inflammation and reduce the modern burden of inflammatory diseases.
Further clinical research is still needed to continue elucidating the therapeutic role of omega fats & optimal ratios for human health.
However, current data suggests that upping omega-3s while limiting excess omega-6 intakes provides an accessible nutritional strategy for protecting long-term health.
References
- Paper: The importance of maintaining a low omega-6/omega-3 ratio for reducing the risk of autoimmune diseases, asthma, and allergies
- Authors: James J. DiNicolantonio (PharmD) & James O’Keefe (MD)