Omega-3 Fatty Acids (EPA/DHA)
Omega-3 EPA and DHA reduce cardiovascular risk, inflammation, and support brain function. Triglyceride form vs ethyl ester, EPA:DHA ratios for different goals, and how to test your omega-3 index.
What EPA and DHA Do
EPA (Eicosapentaenoic Acid) is a 20-carbon omega-3 fatty acid with primarily anti-inflammatory effects. It competes with arachidonic acid (an omega-6 precursor to inflammatory eicosanoids) for COX-2 and LOX enzymes, generating instead anti-inflammatory and pro-resolving lipid mediators. EPA is the primary active compound for cardiovascular risk reduction and mood disorders.
DHA (Docosahexaenoic Acid) is a 22-carbon omega-3 that is structurally concentrated in cell membranes, brain grey matter (~40% of brain polyunsaturated fats), retina (~60% of retinal polyunsaturated fats), and testes. DHA is critical for neural signalling efficiency, cognitive function, and visual health. It is particularly essential during pregnancy for fetal brain development.
Forms — Why Triglyceride Form Matters
Fish oil omega-3 comes in several chemical forms that dramatically affect absorption:
- Ethyl Ester (EE): The cheapest and most common form — made by chemically reacting fish oil with ethanol. Has lower bioavailability than natural forms and must be consumed with fat. Prone to rancidity. Most budget fish oils in India are EE form.
- Natural Triglyceride (TG): How omega-3 exists naturally in fish. Better absorbed than EE but typically has lower EPA+DHA concentration.
- Re-esterified Triglyceride (rTG): The best form — EPA/DHA is concentrated (like EE) then re-attached to a glycerol backbone (like natural TG). Approximately 70% more bioavailable than ethyl ester. Look for "rTG" or "re-esterified triglyceride" on labels.
- Phospholipid form (krill oil): Highly bioavailable and may cross the blood-brain barrier more effectively for DHA, but provides lower absolute EPA+DHA per gram at a much higher price.
Always check the EPA + DHA content on the supplement facts panel, not the total "fish oil" or "omega-3" amount. A 1000mg fish oil capsule may contain only 300mg combined EPA+DHA. Target 1–3g combined EPA+DHA per day, not total fish oil dose. Take with your largest fat-containing meal for maximum absorption.
EPA:DHA Ratio & Form Guide by Goal
| Goal | Preferred Ratio | Daily EPA+DHA Target | Notes |
|---|---|---|---|
| General health / prevention | Equal EPA:DHA (1:1) | 1–2g | Standard starting point |
| Cardiovascular risk reduction | Higher EPA (3:1 or EPA-only) | 2–4g | REDUCE-IT trial used 4g EPA alone |
| Depression / mood | Higher EPA (≥2:1 EPA:DHA) | 1–2g EPA specifically | Meta-analysis supports EPA for depression |
| Cognitive function / brain | Higher DHA | 1–2g DHA | DHA is the structural brain fat |
| Pregnancy / infant brain | Higher DHA (2:1 DHA:EPA) | 200–400mg DHA minimum | Algae-based preferred in pregnancy |
| Inflammation / hsCRP | Higher EPA | 2–3g | EPA → anti-inflammatory resolvins |
ALA from Plant Sources — Insufficient
Many vegetarians rely on flaxseed oil, walnuts, and chia seeds as omega-3 sources. These contain ALA (alpha-linolenic acid), which the body theoretically converts to EPA and DHA. However, conversion efficiency is very low:
- ALA → EPA: approximately 5–10% conversion efficiency
- ALA → DHA: less than 1% conversion efficiency
This means plant-based ALA is inadequate as a primary omega-3 source for most people. Vegetarians should supplement with algae-based DHA/EPA — this is the original source of omega-3 in the food chain (fish get their omega-3 from the algae they eat). Algae oil supplements are effective and available in India.
The Omega-3 Index — How to Test
The Omega-3 Index measures EPA+DHA as a percentage of total red blood cell fatty acid content. It reflects omega-3 status over the past 3–4 months (RBC lifespan). Target: above 8%.
- Above 8%: Optimal — associated with lowest cardiovascular risk in the Harris & Shearer risk model
- 6–8%: Intermediate — some protection, room to improve
- Below 4%: High risk — most Indians without regular fish consumption test in this range
The test is available at select labs in India (Apollo Diagnostics, Dr Lal PathLabs via speciality request). If unavailable locally, some labs offer postal finger-prick tests. Supplement at 2g/day for 3 months, then retest.
Rancidity & Quality Control
Omega-3 fatty acids are highly unsaturated and prone to oxidation (rancidity). Consuming rancid fish oil may negate benefits and cause harm. To check quality:
- Cut open a capsule — fresh oil should have a mild, neutral smell. Rancid oil smells strongly fishy or rotten.
- Check expiry date — always purchase products well within date
- Store in the refrigerator — particularly important in India's warm climate
- Look for third-party testing certifications (IFOS, USP, or NSF)
India Context
India has the world's largest vegetarian population — approximately 30–40% of Indians are vegetarian and many more are low fish consumers. This creates widespread EPA and DHA deficiency, contributing to the high cardiovascular disease burden. South Asia already has disproportionate cardiovascular risk; low omega-3 status compounds this significantly.
For fish-eating Indians, fresh inland river fish tends to be lower in omega-3 than cold-water marine fish (salmon, mackerel, sardines). Farmed freshwater fish like rohu and catla have lower EPA+DHA than wild-caught marine species.
Frequently Asked Questions
What is the best omega-3 supplement in India?
Look for rTG (re-esterified triglyceride) form for maximum absorption. Check the supplement facts for combined EPA+DHA content per serving — you need 1–3g daily. Reliable options available in India include Nordic Naturals, Viva Naturals, and OmegaVia. Check capsules aren't rancid by smell. Algae-based options suit vegetarians.
What is the difference between EPA and DHA?
EPA is primarily anti-inflammatory — it generates pro-resolving lipid mediators and is most relevant for cardiovascular health and mood. DHA is structural — it is a key component of brain grey matter and cell membranes, most important for brain function and pregnancy. For general health, equal ratios work. For specific goals, prioritise the relevant fraction.
How do I know if my omega-3 intake is adequate?
Test your Omega-3 Index (EPA+DHA % of RBC fatty acids). Target above 8%. Most Indians without regular fatty fish intake test at 2–4%, which is associated with significantly elevated cardiovascular and cognitive risk. Supplement 2g EPA+DHA daily for 3 months, then retest to confirm you've reached target range.
Can vegetarians get enough omega-3 in India?
Not from plant sources alone. ALA from flaxseed and walnuts converts to EPA at only 5–10% and to DHA at less than 1%. Vegetarians need algae-based DHA/EPA supplements — this is the original source of omega-3 in the food chain. 250–500mg daily algae DHA+EPA is effective and widely available.