Arachidonic acid optimal range and reference range
Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026
Sera's bands for Arachidonic acid:
- Optimal 10 – 15 %; sufficient 8 – 20 %; out of range below 8 or above 20 %.
Evidence grade: Published reference interval. A band that primarily reflects a published adult laboratory or population reference interval. It is not necessarily applicable to every assay or laboratory.
At Sera's last range review a change to this band was proposed and held, because the evidence for it was thin, so the band is unchanged. The note below says where it matches published intervals and where it does not.
All units
| Unit | Optimal | Sufficient | Out of range |
|---|---|---|---|
| % | 10 – 15 | 8 – 20 | below 8 or above 20 |
What the evidence says
Bands reflect population distributions rather than an outcome-linked target. Functional interpretation depends on the AA:EPA balance rather than on AA alone — this is a necessary membrane component whose eicosanoids include resolving as well as inflammatory ones. A high AA with a low DGLA suggests an accelerated delta-5 desaturase step, which insulin drives. No published reference interval exists for red cell arachidonic acid as a percentage. Cohort means are 14 to 17% in Western populations, so with the optimal band ending at 15% the average Western result reads Sufficient; a pooled analysis of 30 cohorts found higher arachidonic acid was not associated with higher cardiovascular risk.
Assay: Results differ meaningfully between platforms and methods. Compare against the interval printed by the issuing laboratory before acting on a borderline value.
Sources
- Red Blood Cell Fatty Acid Patterns from 7 countries: Focus on the Omega-3 Index — Schuchardt JP, Cerrato M, Ceseri M, et al. — Prostaglandins, Leukotrienes and Essential Fatty Acids, 2022 · Peer-reviewed publicationMean red cell arachidonic acid measured by one method: 14 to 17% in the United States, Canada, Germany, Spain and Italy (13.9 to 16.8%), about 12% in Japan, Korea and Alaska. Sera's optimal upper edge of 15% cuts through the middle of the Western means; the sufficient band of 8 to 20% contains all of them.
- Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality — Marklund M, Wu JHY, Imamura F, et al. (CHARGE Fatty Acids and Outcomes Research Consortium) — Circulation, 2019 · Peer-reviewed publicationPooled analysis of 30 cohorts, 68,659 people: arachidonic acid levels were not associated with higher cardiovascular risk, and the highest fifth had a hazard ratio of 0.92 for total cardiovascular disease against the lowest. Mixed blood fractions; no threshold. No outcome basis for marking a higher AA down.
What AA (C20:4 n-6, RBC) measures
Arachidonic acid. A long-chain omega-6 fatty acid and the substrate for the inflammatory eicosanoids, measured as a share of red blood cell membrane fatty acids.
Not simply undesirable — it is a normal and necessary membrane component, and the eicosanoids it yields include resolving as well as inflammatory ones. What matters is its balance against EPA, which is what the AA:EPA ratio reports.