Arachidonic Acid / EPA Ratio
Here’s what it reflects — and what to do about it.
Longetic pulls together every lab and record you’ve had, follows how Arachidonic Acid / EPA Ratio changes over time, and explains what’s shifting — so you walk into your next appointment prepared, with reminders for retests along the way.
What is Arachidonic Acid / EPA Ratio?
Compares an omega-6 (arachidonic acid) with an omega-3 (EPA) in cell membranes, reflecting pro- and anti-inflammatory fat balance.
This ratio measures the relative proportion of arachidonic acid, an omega-6 fatty acid, to EPA, an omega-3 fatty acid, within cell membranes, and is used as an indicator of dietary fat intake patterns and membrane fatty-acid composition. It relates to cardiovascular and cellular health because a diet with proportionally more omega-6 relative to omega-3 fats has been studied in relation to inflammatory balance, while diets richer in omega-3s from oily fish tend to lower this ratio. Clinicians and researchers may consider this ratio alongside the broader omega-3 index and omega-6/omega-3 ratio to build a picture of overall fatty-acid balance. It does not diagnose any condition on its own and reflects dietary intake patterns that can shift over weeks to months with changes in diet.
Lifestyle factors that influence this marker
- Include oily fish such as salmon, mackerel, sardines, or trout regularly as a dietary source of omega-3 fats
- Reduce reliance on highly processed foods and refined vegetable oils high in omega-6 fats
- Consider omega-3-rich plant sources such as walnuts, chia, and flaxseed
- Balance overall dietary fat intake rather than eliminating any single fat source
- Engage in regular physical activity as part of overall cardiovascular health
- Avoid smoking, which is linked to broader inflammatory and cardiovascular effects
Tests often checked alongside this
- EPA (Eicosapentaenoic Acid) — the denominator and a key omega-3 fatty acid
- Omega-6: Arachidonic Acid — the numerator
- Omega-6/Omega-3 Ratio — a related overall fatty-acid balance marker
- HS-Omega-3-Index — reflects overall omega-3 status in membranes
How this can show up in how you look and feel
- Persistently elevated values are not themselves associated with specific symptoms
- A diet low in oily fish and high in processed vegetable oils may be associated with a higher ratio
What can affect this marker
- Diet composition, particularly intake of oily fish versus processed vegetable oils
- Overall omega-6 and omega-3 fat intake patterns
- Alcohol intake and smoking status
- Certain health conditions affecting fat metabolism
What to track over time
- Trend over repeated testing alongside dietary changes
- Whether the ratio shifts after increasing oily fish or omega-3 intake
- How it relates to the broader omega-6/omega-3 ratio over time
What to ask your doctor
- What does this ratio suggest about my dietary fat balance?
- Would increasing oily fish or omega-3 intake likely help improve this ratio?
- How does this relate to my overall omega-3 index?
- Should this be retested after dietary changes?
This glossary entry is for informational purposes only and is not a substitute for professional medical advice. Read our Terms of Use.
References
About our sources
Official sources
Government health agencies, national institutes, and intergovernmental bodies whose guidelines carry regulatory or policy weight.
Clinical / professional
Medical societies, specialty colleges, and professional associations whose consensus statements reflect clinical practice standards.
Peer-reviewed research
Original research articles and systematic reviews published in indexed journals and verified through PubMed or DOI.