The Omega-6 to Omega-3 Ratio: What Research Does and Does Not Support
The omega-6 to omega-3 ratio is often quoted as a health target. Here is what reviews and trials we read found, what they did not, and why absolute amounts matter.
Content last updated . This page has not been medically reviewed.
The omega-6 to omega-3 ratio is a number comparing how much of two families of fats you take in or carry in your blood. It sounds tidy, but the reviews we read did not find good human trial evidence that aiming for a particular ratio improves health. One review concluded that the ratio is "of little value" on theoretical and evidential grounds. [1] This page explains why, what the research does show, and what we could not verify.
For background on the fats themselves, see Omega Fatty Acids Explained, omega-6 fatty acids and what omega-3 does in the body.
Where the ratio idea comes from
Omega-3 and omega-6 fats are both essential, meaning the body must get them from food. [2] NHS describes them as the two main types of polyunsaturated fat. [3] Researchers noticed that the two families compete for some of the same enzymes, and that the substances made from them can push inflammation, blood vessel behavior and platelet stickiness in different directions. [1] That led to the idea that the balance, not just the amounts, might matter.
Why a ratio can mislead
A ratio hides the amounts behind it. As a hypothetical example, a 10 to 1 ratio could come from 10 units of omega-6 and 1 of omega-3, or from 20 and 2. These are very different diets. A 2018 critical appraisal said this "apparently simple metric" has theoretical and practical difficulties that have caused misunderstandings, and suggested focusing on EPA and DHA levels instead. [4]
What the research found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Is the ratio a good guide to heart risk? | A 2006 review found few human experimental and clinical trial data supporting it. [1] | Expert review; limited |
| Does eating more omega-6 raise heart risk? | A Cochrane review of 19 trials (6461 adults, 1 to 8 years) found low-quality evidence of little or no difference in deaths or cardiovascular events. [5] | Low quality |
| Are higher blood levels of linoleic acid (the main omega-6) linked to harm? | A pooled analysis of 30 observational studies found higher levels were linked to lower risks of total cardiovascular disease, cardiovascular death and ischemic stroke. [6] | Observational; cannot prove cause |
| Did one older trial swapping saturated fat for omega-6 do harm? | In the Sydney Diet Heart Study (men aged 30 to 59 with a recent coronary event, safflower oil in place of saturated fat), the intervention group had higher death rates than controls. [7] | Single small trial from 1966 to 1973; mixed with the rest |
| Is the ratio linked to dementia? | A 2013 review found limited evidence for an association between the ratio, cognitive decline and dementia. [8] | Mostly observational; limited |
Together these do not support a simple "lower omega-6" message. They also do not show that high omega-6 intake is harmless in every situation. Differences in who was studied and what omega-6 replaced (saturated fat, other fats) make comparisons hard.
What official intake tables say
Health Canada lists separate Adequate Intakes (AIs) for linoleic acid and alpha-linolenic acid (ALA), not a ratio. For adults aged 19 to 30 and 31 to 50, the AI is 17 g per day of linoleic acid and 1.6 g per day of ALA for men, and 12 g and 1.1 g for women. In pregnancy it is 13 g and 1.4 g. [9] (Health Canada table, page dated 2025-11-19.) No upper limit was set for either, and the table adds that missing data do not mean high intakes are tolerated. [9] We could not read the NIH Office of Dietary Supplements or EFSA pages, so we do not quote their figures.
Frequently asked questions
What is the omega-6 to omega-3 ratio?
It compares the amount of omega-6 fats with omega-3 fats, in the diet or in blood. It is a number, not a measure of health by itself. [4]
Is there an ideal ratio?
In the sources we read, no trial-based ideal was established; one review called the ratio of little value for judging heart risk. [1]
Should I cut omega-6 to improve my ratio?
The Cochrane review found low-quality evidence that raising omega-6 made little or no difference to deaths or cardiovascular events, and did not show harm from it. [5] Ask a clinician or dietitian about your own diet.
What could I measure instead?
A 2018 paper proposed the Omega-3 Index, the share of EPA and DHA in red blood cells. [4] See Omega-3 deficiency and testing for its limits.
Do eating more fish and plant omega-3 foods change the ratio?
They add omega-3, which changes the ratio arithmetic. NHS advises at least 2 portions of fish a week, one of them oily. [10] See oily fish.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: "limited" means few or low-quality studies; "mixed" means results point different ways; "insufficient" means too little to judge.
Limits and who should ask a clinician
- Almost none of this research tested a target ratio directly. Proper evidence not found: we looked in PubMed and the NHS and NCCIH pages for trials that assigned people to a ratio and measured health outcomes, and found none.
- Omega-3 fish oil supplements are a separate matter, with their own cautions: see Omega-3 safety and interactions and medication interactions.
- People who take blood thinners, are pregnant or breastfeeding, have liver or kidney disease, or have surgery planned should talk to a clinician or pharmacist before adding an oil or supplement.
References
- The omega-6/omega-3 ratio and cardiovascular disease risk: uses and abuses. Curr Atheroscler Rep 2006. Read 2026-10-22.
- Essential fatty acid deficiency in 2015: the impact of novel intravenous lipid emulsions. PubMed record. JPEN J Parenter Enteral Nutr 2015. Read 2026-10-22.
- NHS, Different fats in food. United Kingdom; page last reviewed 14 April 2023. Read 2026-10-22.
- The omega-6:omega-3 ratio: a critical appraisal and possible successor. Prostaglandins Leukot Essent Fatty Acids 2018. Read 2026-10-22.
- Omega-6 fats for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev 2018. Read 2026-10-22.
- Biomarkers of dietary omega-6 fatty acids and incident cardiovascular disease and mortality. Circulation 2019. Read 2026-10-22.
- Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: recovered data from the Sydney Diet Heart Study and updated meta-analysis. BMJ 2013. Read 2026-10-22.
- The omega-6/omega-3 ratio and dementia or cognitive decline: a systematic review on human studies and biological evidence. J Nutr Gerontol Geriatr 2013. Read 2026-10-22.
- Health Canada, Dietary reference intakes tables: reference values for macronutrients. Page dated 2025-11-19. Read 2026-10-22.
- NHS, Fish and shellfish. United Kingdom. Read 2026-10-22.