Lab Reference Library / Arachidonic Acid / EPA Ratio Inflammation & Cardiovascular

Arachidonic Acid / EPA Ratio

Q: Can diet change the AA/EPA ratio?

Yes. It is one of the most diet-responsive biomarkers in functional medicine. Increasing EPA through fatty fish or fish oil supplementation while reducing omega-6 seed oils and processed foods typically produces significant ratio improvement within 8 to 12 weeks.

AA/EPA

Reference range, optimal functional medicine levels, and why the AA/EPA ratio is the most clinically actionable measure of your body's inflammatory balance and how diet changes it dramatically.

Most Searched Inflammation Marker

Standard Range 3 – 15

FM Optimal 1.5 – 3

Fasting Required Preferred

Units Ratio

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Category: Inflammation & Cardiovascular | Also known as: AA:EPA Ratio, Omega-6/Omega-3 Ratio | Sample: Whole blood or plasma (fasting preferred)

1. What This Test Measures

The Arachidonic Acid to EPA Ratio (AA/EPA ratio) measures the balance between two critical polyunsaturated fatty acids that compete for the same cellular machinery:

Arachidonic Acid (AA) an omega-6 fatty acid that serves as the primary precursor to pro-inflammatory eicosanoids (prostaglandins, thromboxanes, and leukotrienes). AA is abundant in the modern Western diet through meat, eggs, and processed foods.
Eicosapentaenoic Acid (EPA) an omega-3 fatty acid that produces anti-inflammatory and inflammation-resolving eicosanoids. EPA competes directly with AA for the same enzymatic pathways, effectively reducing AA's pro-inflammatory output.

The ratio is calculated simply: AA divided by EPA. A higher ratio means pro-inflammatory forces dominate. A lower ratio reflects anti-inflammatory balance. Because these fatty acids are incorporated directly into cell membranes throughout the body, the AA/EPA ratio reflects the inflammatory potential of virtually every cell, making it one of the most mechanistically direct inflammation markers available in clinical practice.

The average American has an AA/EPA ratio of 15 to 25, reflecting the extreme omega-6 dominance of the modern Western diet. By contrast, populations with low cardiovascular disease rates traditional Japanese and Mediterranean populations typically have ratios of 1.5 to 4.

2. Why This Test Matters

Chronic low-grade inflammation is now recognized as a core driver of virtually every major chronic disease: cardiovascular disease, type 2 diabetes, neurodegenerative disease, autoimmune disease, and cancer. The AA/EPA ratio provides a direct, measurable window into that inflammatory state at the cellular level.

Cardiovascular disease: High AA/EPA ratios are associated with increased platelet aggregation, arterial vasoconstriction, endothelial dysfunction, and elevated hs-CRP all direct contributors to atherosclerosis and cardiac events.
Metabolic syndrome: Omega-6 dominance promotes insulin resistance and inflammatory adipokine production. Correcting the AA/EPA ratio improves insulin sensitivity alongside reducing inflammation.
Autoimmune disease: AA-derived eicosanoids amplify immune activation. Lowering the AA/EPA ratio is a foundational intervention in autoimmune management, shifting the immune system away from pro-inflammatory signaling.
Neuroinflammation and cognitive decline: EPA and DHA are critical structural components of neural cell membranes. Low EPA relative to AA is strongly associated with depression, anxiety, cognitive decline, and increased Alzheimer's disease risk.
Cancer biology: Elevated AA/EPA promotes tumor-promoting inflammatory signaling. Omega-3 supplementation has demonstrated anti-proliferative and anti-angiogenic effects in multiple cancer types.
Treatment monitoring: Because the ratio is highly responsive to dietary and supplement interventions, it is an ideal biomarker for monitoring the effectiveness of anti-inflammatory protocols. Retesting at 8 to 12 weeks after intervention provides clear objective feedback.

3. Standard Lab Reference Range

Test	Standard Range	Notes
AA/EPA Ratio	3 to 15	Reflects the general population average in Western countries

The standard range reflects Western population averages a population with epidemic rates of cardiovascular and inflammatory disease. A ratio of 12 is "normal" by conventional standards but represents a strongly pro-inflammatory cellular environment by functional medicine criteria.

4. Optimal Functional Medicine Range

AA/EPA Ratio	Functional Interpretation
1.5 to 3	Optimal excellent anti-inflammatory fatty acid balance
3 to 6	Mild inflammatory tendency dietary optimization indicated
6 to 10	Moderate inflammatory state EPA/DHA supplementation recommended
10 to 15	High inflammatory load comprehensive intervention required
Above 15	Significant chronic pro-inflammatory state clinical evaluation of inflammatory drivers required

Traditional Japanese populations among the lowest cardiovascular disease rates in the world typically have AA/EPA ratios of 1.5 to 2.5, achieved through high fish consumption. This population data provides strong support for the functional medicine optimal target.

5. Symptoms Associated With Abnormal Levels

High AA/EPA Ratio

Chronic fatigue and low energy
Joint pain, stiffness, and morning aching
Brain fog, depression, and mood instability
Skin conditions: eczema, psoriasis, rosacea
Cardiovascular symptoms: hypertension, elevated triglycerides
Elevated inflammatory markers (hs-CRP, Lp-PLA2)
Autoimmune disease flares
Poor wound healing and slow recovery
Digestive inflammation (IBD, IBS)
Menstrual pain and cramping (prostaglandin excess)

Very Low AA/EPA Ratio

Very low ratios below 1.0 are uncommon and typically reflect very high EPA/DHA supplementation
Extremely low AA can theoretically impair immune activation and platelet function relevant mainly at very high omega-3 doses
Ratios of 1.0 to 1.5 achieved through dietary means are generally considered beneficial, not excessive
Clinical concern for very low AA/EPA is rare and usually not relevant in standard practice

6. What Causes Abnormal Results

Causes of a high AA/EPA ratio (pro-inflammatory)

High omega-6 diet: vegetable seed oils (corn, soybean, sunflower, safflower, canola) are the primary dietary source of linoleic acid, which converts to AA; these oils dominate the processed food supply
Low omega-3 intake: limited fatty fish consumption; avoidance of fish oil supplementation
Processed and ultra-processed food consumption: virtually all processed foods are made with omega-6-dominant oils
Excess dietary AA: conventionally raised meat, poultry, and eggs fed omega-6-rich grain diets have higher AA content than grass-fed or pastured equivalents
Insulin resistance and metabolic syndrome: impairs the conversion of plant-based omega-3 (ALA) to EPA
Chronic stress: cortisol promotes AA release from cell membranes
Alcohol excess: impairs omega-3 metabolism and promotes AA production
Aging: the delta-6 desaturase enzyme required for omega-3 conversion declines with age
Zinc and magnesium deficiency: these minerals are required cofactors for fatty acid desaturase enzymes

7. How to Improve This Marker

Nutrition

Increase fatty fish: wild salmon, sardines, mackerel, anchovies (2 to 3x per week minimum)
Eliminate or drastically reduce seed oils: corn, soybean, sunflower, safflower, canola
Replace with olive oil, avocado oil, and coconut oil for cooking
Choose grass-fed beef and pastured eggs significantly lower in AA than grain-fed
Mediterranean diet pattern the most evidence-based dietary approach for AA/EPA optimization
Add walnuts, flaxseed, and chia (plant omega-3s that partially convert to EPA)
Reduce ultra-processed food consumption (primary source of hidden omega-6 oils)

Lifestyle

Regular exercise improves fatty acid metabolism and reduces systemic inflammation
Stress reduction chronic cortisol elevation promotes AA mobilization from membranes
Improve sleep quality sleep deprivation promotes pro-inflammatory fatty acid signaling
Reduce alcohol impairs omega-3 conversion pathways
Retest at 8 to 12 weeks after dietary and supplement changes to objectively track response

Targeted Support

EPA/DHA fish oil most direct intervention; 2 to 4g per day of combined EPA and DHA produces meaningful ratio improvement within 8 to 12 weeks; higher EPA content preferred over DHA for inflammatory reduction
High-EPA formulations products with EPA:DHA ratio of 3:1 or higher are most effective for lowering the AA/EPA ratio specifically
Algae-based omega-3 vegan alternative with EPA and DHA
Curcumin inhibits AA-derived eicosanoid production independently; synergistic with omega-3s
GLA (gamma-linolenic acid) evening primrose or borage oil; shifts omega-6 metabolism toward anti-inflammatory pathways
Correct zinc and magnesium deficiencies required for desaturase enzyme function

8. Related Lab Tests

The AA/EPA ratio is most informative when interpreted alongside these related markers:

Omega-3 IndexComplementary EPA/DHA Measure

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hs-CRPDownstream Inflammation Marker

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Lp-PLA2Vascular Inflammation Marker

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HomocysteineIndependent Cardiovascular Risk

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Fasting InsulinImpairs Omega-3 Conversion

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RBC MagnesiumDesaturase Enzyme Cofactor

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9. When Testing Is Recommended

Cardiovascular disease risk assessment especially when hs-CRP or other inflammatory markers are elevated
Autoimmune disease to assess inflammatory fatty acid burden and guide omega-3 dosing
Metabolic syndrome or insulin resistance
Chronic joint pain, inflammatory skin conditions, or IBD
Depression, anxiety, or cognitive concerns omega-3 status is directly relevant to neurological inflammatory balance
Monitoring response to omega-3 supplementation or dietary change (retest at 8 to 12 weeks)
Any individual consuming a Western diet as part of a comprehensive inflammatory risk assessment
Athletes and individuals with high physical stress omega-3 status significantly impacts recovery and inflammation resolution

10. Clinical Perspective

Clinical Perspective

The AA/EPA ratio is one of my favorite tests to order because it is both highly informative and highly correctable and most patients have never heard of it. The typical new patient at The Lamkin Clinic comes in with a ratio between 12 and 20. They have been eating the standard American diet loaded with seed oils, very little fish, and wondering why they feel inflamed, achy, and fatigued. When we explain that their cellular membranes are essentially marinating in pro-inflammatory fatty acids and show them the number, it becomes a very concrete motivator for dietary change. When we retest at 12 weeks after optimizing their fish oil and reducing seed oils, the ratio often drops to 4 or 5 and they almost always report feeling meaningfully better before we even retest. It is one of the clearest examples of labs-drive-lifestyle in functional medicine.

Brian Lamkin, DO | Founder, The Lamkin Clinic | Edmond, Oklahoma

11. Frequently Asked Questions

What does the AA/EPA ratio measure?

The AA/EPA ratio measures the balance between arachidonic acid (AA), a pro-inflammatory omega-6 fatty acid, and eicosapentaenoic acid (EPA), an anti-inflammatory omega-3 fatty acid. Because these fatty acids are incorporated directly into cell membranes, the ratio reflects the inflammatory potential of virtually every cell in the body. A higher number means more pro-inflammatory; a lower number means better anti-inflammatory balance.

What is the optimal AA/EPA ratio?

In functional medicine, a ratio between 1.5 and 3 is considered optimal, reflecting the range seen in populations with low cardiovascular and inflammatory disease rates particularly traditional Japanese populations. Ratios between 3 and 6 indicate mild inflammatory tendency. Above 6 represents elevated inflammatory risk. The average American ratio of 15 to 25 reflects the omega-6 dominance of the Western diet.

What does a high AA/EPA ratio mean?

A high ratio indicates that pro-inflammatory omega-6 fatty acids significantly outnumber anti-inflammatory omega-3 fatty acids in cell membranes, creating a systemic pro-inflammatory cellular environment. This is associated with increased cardiovascular disease risk, metabolic syndrome, autoimmune disease activity, neuroinflammation, depression, and accelerated biological aging.

Can diet change the AA/EPA ratio?

Yes it is one of the most diet-responsive biomarkers in functional medicine. Increasing EPA through fatty fish or fish oil supplementation, while reducing omega-6 seed oils and processed foods, typically produces significant ratio improvement within 8 to 12 weeks. This makes it an excellent monitoring tool for anti-inflammatory interventions.

Does fish oil lower the AA/EPA ratio?

Yes, directly and reliably. EPA supplementation increases EPA concentration in cell membranes and competitively inhibits AA's access to inflammatory enzymes, lowering the ratio on both ends simultaneously. Doses of 2 to 4g EPA/DHA daily produce meaningful improvement within 8 to 12 weeks. High-EPA formulations with an EPA:DHA ratio of 3:1 or greater are most effective for ratio reduction specifically.

What is the difference between the AA/EPA ratio and the omega-3 index?

The AA/EPA ratio measures inflammatory balance by comparing omega-6 to omega-3 directly it is a relative measure. The omega-3 index measures the absolute percentage of EPA and DHA in red blood cell membranes it is an absolute sufficiency measure. Both are useful and complementary. The AA/EPA ratio is more sensitive to dietary omega-6 load; the omega-3 index better reflects long-term omega-3 tissue status. At The Lamkin Clinic we frequently order both together for a complete picture.

Content authored and clinically reviewed by Brian Lamkin, DO, founder of The Lamkin Clinic in Edmond, Oklahoma. Brian Lamkin, DO has 25+ years of experience in functional and regenerative medicine. This page reflects current functional medicine practice standards and is updated as new clinical evidence becomes available.

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The AA/EPA ratio is one of the most actionable inflammation markers in functional medicine. Schedule a consultation to include it in your panel and get a clear picture of your inflammatory status.

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Medical Disclaimer: This content is provided for educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Lab interpretation should always be performed in clinical context by a qualified healthcare provider. Reference ranges and optimal targets may vary based on individual patient history, clinical presentation, and laboratory methodology. Schedule a consultation to discuss your specific results with Dr. Lamkin.