EPA vs DHA: Which One Actually Works?
Why your fish oil bottle may be lying to you about your real dose.
What this episode covers
- Most people who take omega-3 supplements never reach the level shown to support heart, brain, and eye health.
- The fix is to measure your Omega-3 Index in blood, not guess from doses on a bottle.
- Plant-based ALA converts inefficiently to EPA and DHA in most people, making marine sources a more reliable way to increase long-chain omega-3 levels.
Why it matters
If your dose is too low, you may be paying for protection you do not actually have. Knowing your real level shifts the question from 'am I taking enough' to 'I am at 8 percent.'
What stands out
- Most people think 'fish oil' on the bottle means 'omega-3'; the only number that matters is grams of EPA plus DHA, which is often a fraction of the front-label number (label inspection).
- Large meta-analyses have not found convincing evidence that routine omega-3 supplementation meaningfully increases clinically significant bleeding, even among people taking common anticoagulants, although individual surgical decisions should still follow medical advice.
- Most people assume DHA matters most for the brain; for depressive symptoms, EPA-dominant products perform better in pooled trials (meta-analysis of RCTs).
Best-supported action
The single highest-leverage move from this episode, anchored in the strongest evidence the speaker presents.
Eat oily fish (salmon, sardines, mackerel) two to three times per week as the foundational omega-3 move — most people who get adequate marine omega-3 from food reach acceptable Omega-3 Index levels without testing or supplements. If you do not eat fish, discuss with your doctor whether an EPA plus DHA supplement or a baseline Omega-3 Index test is appropriate for your situation.
Where to start
Small low-friction starters covering the main moves from this episode.
- Eat fatty fish more often as part of a balanced diet.
- Read the back label of your supplements, not the front.
- Ask your doctor whether a basic omega-3 test makes sense for you.
Other supported actions
Further actions discussed in this episode, ordered from strongest to weakest evidence. This is one expert's view, the full topic compares and ranks across experts.
- Eat SMASH fish (salmon, mackerel, anchovies, sardines, herring) two or three times per week as the foundational omega-3 source.Moderate evidence
- If you use omega-3 supplements, check the back label for grams of EPA plus DHA per serving rather than the front-label total fish oil milligrams.Strong evidence
- If you do not eat fish regularly and want to know your status, discuss with your doctor whether an Omega-3 Index test and a targeted EPA plus DHA supplement (often around 1500 mg combined per day for 3 to 4 months before re-testing) is appropriate for your situation.Moderate evidence
Full context, impact ratings, and timing — available in related topics
Questions to take to your doctor
- Would an Omega-3 Index test make sense for me before I commit to a daily dose?
- At my current cardiovascular risk, would 1500 mg of combined EPA and DHA daily be reasonable?
- Should I keep taking omega-3 around my next scheduled surgery, or stop?
Full doctor prep with ranked questions available in the full topic page
Context
Researcher focused on the omega-3 index biomarker, with substantial peer-reviewed publication output over four decades. Strongest on the biology and dose-response of marine omega-3s (EPA and DHA); takes a contested position on omega-6 (linoleic acid) as protective, where evidence is observational and mainstream nutrition interpretation differs. Commercial interest: co-founded OmegaQuant, the lab that sells the omega-3 index test.
This conversation is based on dose-response research and meta-analysis but does not prove omega-3 prevents specific outcomes in any individual. Individual response varies by absorption, baseline diet, and genetics. This does not mean you should change or stop your current supplements or medications on your own.
Where people go wrong
- Treating 'omega-3' on the front of a bottle as the dose you are getting.You may be taking less than half the amount actually needed for the health effects you want.
- Stopping omega-3 a few days before surgery 'to be safe.'Tissue levels turn over slowly, so stopping a few days early changes nothing meaningfully.
What to expect over time
- Weeks 1 to 4Body absorbs the new dose; blood levels begin to shift but red blood cells still reflect the old level.
- Months 3 to 4Red blood cells have largely turned over; a re-test shows your new steady-state Omega-3 Index.
- Ongoing maintenanceIf the level is in the 8 to 12 percent range, hold dose; if not, adjust and re-test in 3 months.