The average American gets only 150 mg of EPA+DHA per day — roughly 10–13x below what studies show reduces cardiovascular risk — and the Omega-3 Index (target 8–12% of red blood cell membrane) is the single most actionable biomarker most doctors never order.
2
REDUCE-IT showed a 25% reduction in cardiovascular events with 4 g/day of pure EPA in statin-treated patients with elevated triglycerides, dwarfing the effect of any other add-on lipid agent tested in a generation.
3
EPA and DHA have distinct but complementary roles: EPA is anti-platelet and pro-resolving via resolvins; DHA is the dominant structural fatty acid in brain and cardiac membranes and more potently lowers triglycerides and raises HDL — take both.
4
ALA (flaxseed, chia) is an essential omega-3 but almost none converts to EPA or DHA; it cannot substitute for fish or fish oil supplementation regardless of dose.
Protocols
Concrete recipes — what, when, how much, and why
7 items
Target Omega-3 Index of 8–12% — test before supplementing, then retest in 4 months
WhatOrder an Omega-3 Index test (RBC EPA + DHA as % of total fatty acids) to establish your baseline. Adjust fish intake and/or supplementation dose to reach 8–12%. Retest at ~4 months to see the new steady state.
WhenAt baseline before any supplementation changes; annually thereafter or after any significant dietary change.
Dose4 months to reach new steady state after any intake change (RBC lifespan). Retest every 12 months for maintenance monitoring.
For whomEveryone, but especially patients with cardiovascular risk, depression, or metabolic syndrome. Particularly important before claiming any supplementation protocol is 'working.'
WhyThe Omega-3 Index is a stable, tissue-level biomarker — analogous to HbA1c — that reflects ~3–4 months of average omega-3 status. Average American is at 4–5%; the 8–12% target range is associated with lowest cardiovascular risk and is achievable with supplementation.
CaveatsPlasma omega-3 tests exist but are less stable than RBC measurements and use different reference ranges — do not mix testing methods when tracking over time.
Harris founded OmegaQuant (omegaquant.com) specifically to make this test accessible at $50 direct-to-consumer via a home fingerstick kit. The test is the same assay used by research labs including collaborators at True Health Diagnostics and Boston Heart. He notes that in his research database of ~3,500 people, even those eating three oily fish meals per week AND supplementing only had a 50% chance of reaching 8% — emphasizing how variable individual absorption and incorporation are. Attia was at ~10–11% (EPA 2.2% + DHA 8%) at time of recording.
Mechanism
Red blood cell membranes are assembled in bone marrow from circulating fatty acids — the composition reflects dietary intake and metabolic incorporation over the 120-day RBC lifespan. EPA and DHA compete with omega-6 fatty acids for membrane positions; higher circulating EPA+DHA results in more anti-inflammatory, pro-resolving membrane composition.
our target is 8 to 12 percent just that's a range we think is the healthy range average American is around 5% maybe four or five percent
Also said
“it takes about four months after you make a change your mega three intake to see it a new steady state”— Defines the retesting interval — key for protocol compliance and managing patient expectations.
Therapeutic-dose EPA for cardiovascular risk reduction: 4 g/day icosapent ethyl (Vascepa) for statin-treated patients with residual hypertriglyceridemia
WhatPrescribe icosapent ethyl (Vascepa) 2 g twice daily (4 g total) in patients on a statin with triglycerides 150–500 mg/dL and established CVD or high-risk features (e.g., diabetes).
WhenOngoing, indefinitely, as part of a statin-plus strategy for residual cardiovascular risk reduction.
Dose4 g/day (2 g BID with meals). REDUCE-IT ran ~5 years; benefit appeared and was sustained.
For whomStatin-treated patients with triglycerides 150–500 mg/dL plus CVD history or high-risk features. Harris notes the dose was chosen at 4 g partly for practicality (the company could get better triglyceride lowering at higher doses but compliance would suffer).
WhyREDUCE-IT demonstrated 25% relative risk reduction in cardiovascular events in exactly this population. No other tested add-on therapy has achieved this magnitude of benefit post-statin. Mechanism likely involves EPA's anti-platelet effects, pro-resolution lipid mediators (resolvins), and improved heart rate variability — not primarily triglyceride lowering.
CaveatsTake with food — ethyl ester form absorbs poorly on empty stomach. Monitor for minor bleeding time prolongation (no major excess bleeding seen in REDUCE-IT, but antiplatelet effect is real). The FDA-approved indication is for triglycerides >500 mg/dL (pancreatitis prevention); the 150–500 range is the REDUCE-IT indication and is now also FDA-approved.
Harris is careful to note that the cardiovascular benefit in REDUCE-IT was not driven by the 15% triglyceride reduction seen in the trial. He and Attia both emphasize that patients with normal triglycerides should not infer they will get the same event reduction — there is no trial in that population at this dose. The VITAL trial, using one-fifth the dose in a healthy population, did show 20% MI reduction, suggesting dose-dependent benefit even below REDUCE-IT's level.
Mechanism
EPA is converted to E-series resolvins and protectins that terminate inflammatory cascades. EPA also competes with arachidonic acid for cyclooxygenase and 5-lipoxygenase, producing thromboxane A3 (weakly pro-platelet) instead of thromboxane A2 (strongly pro-platelet), reducing platelet aggregation. Additionally, EPA incorporation into cardiac cell membranes improves autonomic tone (heart rate variability).
it showed a 25% reduction in risk for overall cardiovascular events over about a four or five year period... and it worked great and it worked with virtually no side effects and you can take it with any other medications
Supplementation protocol for general population: target 2–4 g/day EPA+DHA from high-quality fish oil taken with food
WhatChoose a high-quality, concentrated fish oil supplement (Carlson's or Nordic Naturals as examples of reputable brands). Read the label for actual EPA+DHA content — a 1,000 mg capsule may contain only 300 mg EPA+DHA; a concentrated product may have 800–850 mg per capsule. Dose to deliver 2–4 g EPA+DHA daily. Take with the largest meal of the day.
WhenDaily, with food. If fasting in the morning, take at dinner.
DoseOngoing. 2 g/day is a reasonable maintenance target for healthy adults; 4 g/day for those with known cardiovascular risk or elevated triglycerides.
For whomGeneral population not eating at least 2–3 servings of oily fish per week. Particularly important for people with cardiovascular risk, those with depression or mood issues, and anyone not meeting fish intake recommendations.
WhyThe average American gets only ~150 mg/day EPA+DHA from diet; reaching 8–12% Omega-3 Index typically requires supplementation. Ethyl ester forms (most concentrated supplements) absorb poorly without food; taking with a fat-containing meal substantially improves bioavailability.
CaveatsVerify label: '1000 mg fish oil' is NOT the same as '1000 mg EPA+DHA.' Most standard capsules contain 30–35% EPA+DHA; concentrated products may contain 60–85%. For 4 g/day EPA+DHA, you may need 5–6 standard capsules but only 4–5 concentrated capsules.
Attia recommends Carlson's and Nordic Naturals based on a New York Times analysis by Anahad O'Connor that evaluated brands for GMP compliance, label accuracy, and contaminant levels. Harris notes consumer reports testing has generally found commercial omega-3 products accurate on EPA+DHA content and free of meaningful environmental pollutants. The line between pharmaceutical-grade EPA+DHA drugs and high-quality dietary supplements is blurring: a highly concentrated supplement may be chemically indistinguishable from Lovaza. Harris: 'I don't think there's a substantial difference at all in quality there's a lot of omega-3 supplement companies that make very high quality stuff.'
I don't think there's a substantial difference at all in quality there's a lot of omega-3 supplement companies that make very high quality stuff that they just aren't going to the trouble of going through an FDA approval to get it treated and developed as a drug but it's the same chemistry
Also said
“if you take an ethyl ester of omega-3 on an empty stomach the absorption is quite low almost none as opposed to taking it with food which improves the absorption quite a bit”— The single most actionable tip for supplementation compliance — take with food, especially fat-containing meals.
Fish intake protocol: prioritize oily small fish; albacore tuna is acceptable; avoid the high-mercury four
WhatEat oily fish (salmon, sardines, herring, mackerel) as primary EPA+DHA food sources. Albacore tuna is a practical high-EPA+DHA option with acceptable mercury for most adults. Avoid tilefish, swordfish, king mackerel, and shark (high mercury, especially relevant in pregnancy and for children).
WhenAim for 2–3 servings of oily fish per week; this is the dietary baseline that, combined with supplementation, gives a 50/50 chance of reaching an 8% Omega-3 Index.
DosePer serving: ~1–2 g EPA+DHA from a typical 4 oz serving of salmon; Okinawans historically consuming ~1.5–2 g/day EPA+DHA had markedly lower cardiovascular disease.
For whomGeneral population. Pregnant and lactating women: avoid the high-mercury four absolutely; consume salmon, sardines, herring freely.
WhyOily fish provide EPA+DHA in a triglyceride form (better absorbed than ethyl esters) alongside protein, vitamin D, and selenium. The mercury concern is overstated for most edible fish — the four high-mercury fish account for virtually all meaningful exposure.
CaveatsIndividual mercury clearance varies dramatically — Attia notes patients eating tuna 3x/week with mercury below 10 mcg/L alongside patients eating tuna twice a month hitting the upper limit. Monitoring mercury levels periodically is warranted for high tuna consumers.
Harris contextualized fish intake historically: traditional Okinawans eating seafood daily consumed ~1.5–2 g EPA+DHA/day; Greenland Eskimos studied by Dyerberg and Bang in the 1970s were consuming 6–7 g/day from seal blubber, whale meat, and fish. Harris notes that 80% of Eskimo calories were fat (mostly saturated), yet they showed virtually no acute myocardial infarction — the observation that launched systematic omega-3 research. Albacore/white tuna has 2x the EPA+DHA of chunk light tuna but more mercury; Harris argues the omega-3 benefit clearly outweighs the mercury risk for the vast majority of adults.
sardines herring mackerel almost all their oily fish are gonna have high epa levels so simply because they have high oil does it have fat in their flesh and their tissues... the benefits of eating fish even if there's some mercury in it far outweigh the downside of the mercury
Omega-3 index testing timing and methodology
WhatUse a red blood cell (RBC) omega-3 test — not plasma or plasma phospholipid — for longitudinal tracking. Test at baseline, then 4 months after any intake change, then annually for maintenance.
WhenBaseline testing before changing supplementation; 4 months post-change to assess new steady state; annually thereafter.
DoseSingle fingerstick test; $50 direct-to-consumer from OmegaQuant (omegaquant.com). Results in ~1 week.
For whomAnyone supplementing with omega-3s or eating significant fish — particularly patients with cardiovascular risk, depression, or metabolic disease.
WhyRBC membranes turn over in ~120 days and provide a time-averaged measure of omega-3 status that is not acutely altered by last meal. Plasma tests reflect shorter windows and use incompatible reference ranges — comparing an RBC 8–12% target to a plasma result would give a misleadingly low number.
CaveatsDo not use plasma omega-3 tests and attempt to compare to the 8–12% RBC reference range — plasma levels are inherently lower and use a different numerical scale.
Harris has validated RBC omega-3 levels against tissue biopsies from heart transplant patients, showing strong correlation between RBC and cardiac membrane omega-3 content. Similar correlations exist for liver, skeletal muscle, and intestinal tissue. The brain is the outlier — adult brain DHA does not track well with RBC DHA, which Harris attributes to the blood-brain barrier and the relatively stable DHA composition of mature neurons.
red cells correlate with quite a few other tissues in terms of the omega-3 levels so they are a good reflection of other tissues... it's the only one that's the least reflective of is the brain at least in the adult
Use EPA-dominant formulations for mood and depression; take both EPA and DHA for cardiovascular endpoints
WhatFor patients with depressive symptoms or mood concerns, prefer EPA-dominant omega-3 products (EPA:DHA ratio > 2:1). For cardiovascular risk reduction without depression, EPA+DHA combination products are appropriate and supported by the most data (VITAL, REDUCE-IT equivalent data for the population). Do not self-select DHA-only for 'brain health' — the evidence does not support it.
WhenOngoing supplementation decision at initiation.
Dose2–4 g/day total for cardiovascular; studies for depression used varied doses but consistently EPA-dominant.
For whomPatients with elevated cardiovascular risk get EPA+DHA. Patients with mood/depression concerns get EPA-dominant products.
WhyMeta-analyses of omega-3 depression trials show benefit only for EPA-rich products. High-DHA products tested for depression are consistently neutral. EPA likely acts via anti-inflammatory effects in brain vasculature rather than direct neuronal incorporation.
Harris: 'the products that seem to work to actually have an effect on depressive symptoms are ones that are richer in EPA and the DHA.' The counterintuitive paradox: the brain is ~85% DHA (of total EPA+DHA in cell membranes) and virtually EPA-free, yet EPA is the active omega-3 for mood. Harris hypothesizes EPA's resolvins and anti-inflammatory action in the cerebral vasculature — not neuronal DHA replacement — drives the clinical signal. In fish, EPA and DHA naturally co-occur in roughly 40:60 ratios; the EPA-dominant formulations are man-made concentrations. Harris's overall guidance: 'I think that's the best thing to do is to get both of them at this point for any condition all conditions.'
the products that seem to work to actually have an effect on depressive symptoms are ones that are richer in EPA and the DHA and you know when so you look at a meta-analysis like a compilation of lots of different studies the positive ones are the ones that are richer in EPA but there's no EPA in the brain
High-dose triglyceride lowering: 4–6 g/day EPA+DHA for severe hypertriglyceridemia (>500 mg/dL)
WhatFor patients with triglycerides >500 mg/dL at risk of pancreatitis, prescribe 4 g/day EPA+DHA (Lovaza or generic equivalent) — the FDA-approved dose for this indication. Higher doses (6+ g/day) lower triglycerides further but are impractical due to pill burden.
Dose4 g/day ongoing (FDA-approved). Harris's original studies used 18–25 g/day but those were research doses not practical for clinical use.
For whomPatients with triglycerides >500 mg/dL. Triglycerides 200–500 represent 'garden variety' hypertriglyceridemia where the REDUCE-IT protocol is more relevant.
WhyHigh-dose omega-3 lowers triglycerides dramatically in hypertriglyceridemia — Harris's original work showed patients with triglycerides of 2,000 mg/dL dropping to 250. The effect is dose-dependent. This is the oldest and most established indication for pharmaceutical omega-3.
CaveatsAt 4–6 g/day in hypertriglyceridemic patients, LDL-C and ApoB may rise 15–25 mg/dL. This is the same patient population in whom this LDL rise was originally documented. Considered acceptable given the pancreatitis prevention and cardiovascular benefit.
Harris's first study gave subjects 25 g/day EPA+DHA through salmon consumption and pure salmon oil drinking — intended as a 'never need to study this again if it doesn't work' design. Triglycerides dropped dramatically while total cholesterol fell modestly. The later 1985 New England Journal paper using 18–20 g/day in isolated hypertriglyceridemia showed massive triglyceride reduction ('instead of their triglycerides being 2,000 they were down to 250') and was published alongside two other omega-3 papers that same week — the moment that put omega-3 fatty acids 'in lights on the map.'
we found they giving them fish oil just just knock the socks out of their truck instead of their triglycerides being 2,000 they were down to 250 it was a huge effect
What's new
Personal practice updates, fresh positions, predictions
8 items
REDUCE-IT: pure EPA at 4 g/day cuts cardiovascular events 25% on top of statins
~mid episode
The REDUCE-IT trial randomized ~8,000 statin-treated patients with triglycerides 150–500 mg/dL and prior CVD or diabetes to 4 g/day of icosapent ethyl (Vascepa) vs. mineral oil placebo. Over ~5 years, the EPA arm showed a 25% relative risk reduction in a composite of cardiovascular endpoints including MI and need for revascularization — the largest event-reduction seen for any add-on therapy after a statin in this era.
Why this matters: Fifteen years of negative trials for post-statin add-on drugs; pure EPA succeeded where niacin, fibrates, and others failed. The magnitude rivals PCSK9 inhibitors despite a completely different mechanism and a far cheaper intervention.
Background
The Japanese JELIS trial (2007) used the same molecule (epadil / EPA ethyl ester) and showed benefit in a Japanese cohort. Amarin replicated it at much larger scale in a Western population.
Bill Harris notes the triglyceride reduction in REDUCE-IT was only about 15% — far less than what the original high-dose fish oil studies produced — suggesting the cardiovascular benefit is not primarily mediated by triglyceride lowering. Proposed mechanisms include EPA's conversion to resolvins (anti-inflammatory pro-resolution lipid mediators), antiplatelet effects analogous to low-dose aspirin without the GI toxicity, and improved heart-rate variability reflecting better autonomic tone. Attia emphasizes that the event reduction exceeded what was seen in Fourier and Odyssey (PCSK9 inhibitor trials) despite REDUCE-IT being in a somewhat different population, calling the result 'really quite amazing.'
it showed a 25% reduction in risk for overall cardiovascular events over about a four or five year period which is not that long and it was effective across you know myocardial infarction need for angioplasty a variety of different cardiovascular unfortunate outcomes so it was a big hit
Also said
“it was really for the last 15 years we've been searching for other lipid lowering drugs that or other other drugs that will improve the outcomes over statins... this one pure EPA worked and it worked great and it worked with virtually no side effects”— Frames REDUCE-IT in the context of a 15-year drought of post-statin add-on trials — makes the result historically significant.
“it's not enough whatever role inflammation and it's such a a slippery word that's thrown around so much but EPA definitely gives rise to molecules that are pro of resolution of inflammation so inflammation starts the EPA will will shut it down to whatever extent a cardiovascular event is precipitated by an inflammatory event the omega-3 EPA could could participate in that”— Harris's mechanistic account for why pure EPA could reduce events beyond any triglyceride-lowering pathway.
The Omega-3 Index: 8–12% is the healthy target; average American is at 4–5%
~later half
Harris developed the Omega-3 Index — EPA + DHA expressed as percent of red blood cell membrane fatty acids — as the clinically meaningful biomarker. The target range of 8–12% represents roughly 2x the current US average and is associated with the lowest cardiovascular risk in population studies. Most physicians never order it.
Why this matters: Unlike plasma levels (which fluctuate with last meal), the RBC membrane reflects 3–4 months of average intake — a stable, tissue-level snapshot analogous to HbA1c for glucose. At $50 direct-to-consumer from OmegaQuant, there is almost no barrier to testing.
Background
Harris founded OmegaQuant after a decade of academic omega-3 research specifically to make this test accessible. Red cell EPA+DHA correlates well with omega-3 levels in cardiac, liver, skeletal muscle, and intestinal tissue — but not well with brain.
In a study of ~3,500 people who submitted blood to OmegaQuant and reported their fish and supplement habits, Harris found that the 50th percentile for an 8% index required eating three oily fish meals per week AND taking a supplement. Some people eating one fish meal per week with no supplement nonetheless reached 8% — indicating strong genetic variability in absorption and incorporation. Attia notes he personally tested at about 10% (EPA ~2.2% + DHA ~8%). The time constant for RBC turnover means changes in omega-3 intake take ~4 months to reach a new steady state — important for re-testing intervals.
we think and what we call the omega-3 index which is EPA plus DHA in red cell membranes our target is 8 to 12 percent just that's a range we think is the healthy range average American is around 5% maybe four or five percent
Also said
“I just think we need to see more doctors measuring omega-3 status because it means a lot low omega-3 means something... I really want to encourage people to make the assessment of omega-3 status in their patients as important as measuring cholesterol”— Harris's bottom-line clinical call to action: treat omega-3 testing as a standard-of-care biomarker.
“the group that has the 50/50 chance of an eight percent omega-3 index we're eating free reported eating three oily fish meals a week and taking a supplement”— Quantifies what it actually takes to hit the target — diet alone is usually insufficient without supplementation.
ALA conversion to EPA is negligible — flaxseed oil cannot substitute for fish oil
~mid episode
When people have given radiolabeled ALA and measured how much converts to EPA in vivo, the answer is less than 1%. Even feeding 12 grams of ALA can only raise RBC EPA from ~1% to ~2%. ALA is an essential fatty acid with its own value, but it is not a meaningful precursor for the long-chain omega-3s that drive cardiovascular and other benefits.
Why this matters: A very common misconception — vegetarians and vegans relying on flaxseed or chia for omega-3 coverage are not reaching physiologically relevant EPA or DHA levels. Algal oil DHA/EPA is the only plant-based fix.
Background
The enzyme competition for delta-6-desaturase between the omega-6 (LA → ARA) and omega-3 (ALA → EPA) pathways means conversion efficiency is inherently low, especially in a high omega-6 background diet.
Harris has directly tested this: 'when people have tried giving 12 grams of ala not just flaxseed oil is straight la yeah you don't even get — it might take an EPA level of 1% in a red cell and maybe drive it to 2%.' The same logic applies to LA→ARA: arachidonic acid is tightly controlled and does not respond to LA intake, which partly explains why eating more vegetable oils does not meaningfully raise inflammatory arachidonic acid levels despite popular concern.
when people have tried giving 12 grams of ala not just flaxseed oil is straight la yeah you don't even get me might take an EPA level of 1% in a red cell and maybe drive it to 2%
Also said
“it's never when people have tried giving 12 grams of ala... it doesn't work and ala itself... I have no problem with ala I just have a problem with it being a substitute for fish oils or omega-3 long-chain omega-3 because it doesn't”— Harris's explicit verdict: ALA has value but cannot substitute for preformed EPA+DHA.
High-dose EPA raises LDL-C and ApoB in hypertriglyceridemic patients — mechanism is DHA-mediated LDL receptor slowdown
~early-mid episode
When high-dose omega-3 (6 g/day of EPA+DHA) was given to people with elevated triglycerides without changing background diet, LDL cholesterol rose from ~120 to 140–150 mg/dL and ApoB increased. More recent mechanistic work points to DHA specifically slowing LDL receptor activity — reducing clearance of LDL particles from circulation.
Why this matters: This finding triggered FDA warning letters to fish oil supplement companies marketing cholesterol-lowering claims and caused a 'gut punch' for the industry. It also underpins the debate about whether EPA-only products (REDUCE-IT) are superior to EPA+DHA products for cardiovascular outcomes.
Background
Harris's 1985 New England Journal paper was one of the first to show this effect. Earlier studies had used extremely high doses (18–25 g/day) with full dietary control; the LDL rise appeared when just adding omega-3 capsules on top of a normal background diet.
Harris clarifies the LDL rise is specifically observed in patients with elevated triglycerides (type 4 and 2b hyperlipidemias), not necessarily in normolipidemic people. The proposed mechanism: DHA in cell membranes alters LDL receptor kinetics, reducing hepatic clearance. Attia raises the confounder of metabolic syndrome — most hypertriglyceridemic subjects in 1985 were likely insulin resistant, which itself impairs LDL clearance. Harris acknowledges they weren't thinking about metabolic syndrome at the time.
LDL cholesterol the bad cholesterol started to go up that was one of the downsides of the Omega 3 story because all of a sudden we published this it gets a lot of press American Heart Association and the fish oil companies that were just starting to advertise their product as cholesterol-lowering... FDA sends out all these letters to these companies and say you can't you're false advertising
Also said
“more recent studies have suggested that there is actually in effect primarily of the DHA component on LDL receptor activity it actually can slow down the action of LDL receptors so the LDL receptors are not removing LDL particles from the blood as fast as they used to be so the blood levels go up”— The mechanism explanation — DHA slows LDL receptor kinetics, which is a clearance effect, not a production effect.
VITAL trial: 850 mg EPA+DHA showed 20% reduction in MIs despite a null primary composite endpoint
~later episode
VITAL randomized ~20,000 healthy Americans (primary prevention) to one Lovaza capsule (~850 mg EPA+DHA) vs. placebo. The primary composite cardiovascular endpoint was neutral, but a prespecified analysis of myocardial infarctions showed a ~20% reduction, and in people eating fewer than 1.5 fish meals per week, the primary composite endpoint was significantly reduced.
Why this matters: The study was widely reported as 'fish oil doesn't work' but buried the MI finding and the fish-intake subgroup. For Harris, the meaningful take is that even sub-therapeutic doses (one-fifth of REDUCE-IT's dose) in low-risk people hint at benefit — and the composite endpoint diluted a real signal.
Background
VITAL was designed roughly a decade before it reported, when 1 g of Lovaza was the approved dose. It was a true primary prevention trial — the first large one for omega-3.
Harris: 'if you exclude the composite metric and you just look at the CHD metric... there was a nine or ten percent reduction in risk for heart disease.' The dose (850 mg) was one-fifth of REDUCE-IT's 4 g dose in a much lower-risk population. Harris and Attia agree the headline 'fish oil doesn't work' was incorrect and that VITAL actually provides some of the strongest primary-prevention evidence for low-dose EPA+DHA — particularly for the population most deficient in fish intake.
it was a heart attacks were significantly you know 20% reduction in heart attacks and 20% reduction in fatal heart attacks were one of the findings I mean that's impressive for 850 milligrams a day it's amazing to me that you can even do that
Also said
“if you look at people who report eating less than 1.5 fish meals a week there was a significant stat on the primary endpoint of cardiovascular disease both taking just one capsule Lovaza there was some really positive stuff in this study but it was buried in the press headlines as fish oil don't work”— The subgroup where the benefit was clearest: people with low baseline fish intake, suggesting those most deficient benefit most.
Ethyl ester fish oils require food for absorption; free fatty acid forms do not
~late episode
Ethyl ester omega-3s (the form of Vascepa, Lovaza, and most concentrated supplements) require enzymatic conversion in the gut and absorb poorly on an empty stomach — a major practical issue for people who skip breakfast or do time-restricted eating. Free fatty acid formulations absorb without enzymatic processing but were only in clinical trials (Epanova/Omtryg) at time of recording.
Why this matters: A commonly missed clinical nuance: taking a fish oil capsule in the morning on an empty stomach may deliver very little EPA/DHA. Taking it with the largest meal of the day substantially improves absorption.
Harris: 'if you take an ethyl ester of omega-3 on an empty stomach the absorption is quite low almost none as opposed to taking it with food which improves the absorption quite a bit.' Attia's workaround: take fish oil capsules at dinner. The STRENGTH trial (Epanova — free fatty acid EPA+DHA, ~4 g) was expected to report ~2020 with a primarily similar design to REDUCE-IT; Harris predicted it would be equally or more successful given the superior bioavailability.
if you take an ethyl ester of omega-3 on an empty stomach the absorption is quite low almost none as opposed to taking it with food which improves the absorption quite a bit but a triglyceride based oil or a free fatty acid more to the point free fatty acid doesn't require any enzymatic conversion to get absorbed at all
EPA is the active omega-3 for depression, not DHA — despite the brain being DHA-rich
~mid episode
The brain and retina contain almost no EPA and are dominated by DHA. Yet meta-analyses of omega-3 trials for depression consistently show that products richer in EPA are effective while DHA-dominant products are not. Harris hypothesizes EPA is exerting anti-inflammatory effects in the brain's vasculature or signaling, not by directly incorporating into neurons.
Why this matters: Refutes the intuitive assumption that 'feed the brain DHA.' The mechanism for EPA's antidepressant-adjacent effect is unknown but empirically robust across multiple studies — a counterintuitive finding with practical dosing implications.
Harris: 'the positive ones are the ones that are richer in EPA but there's no EPA in the brain... what's happening is EPA is probably providing some unique and anti-inflammatory effects in in the brain circulation that's affecting... the expression of depressive symptoms.' He cautions against concluding EPA is the 'heart omega-3' and DHA the 'brain omega-3' — both appear in all fish together and likely work synergistically. His practical recommendation remains to take both, not to self-select one based on simplified organ-target reasoning.
the products that seem to work to actually have an effect on depressive symptoms are ones that are richer in EPA and the DHA and you know when so you look at a meta-analysis like a compilation of lots of different studies the positive ones are the ones that are richer in EPA but there's no EPA in the brain
Linoleic acid (omega-6) is protective, not harmful — large meta-analyses refute the omega-6 demonization narrative
~later episode
Population studies involving thousands of people tracked for 5–30 years show that higher blood levels of linoleic acid (LA, the main dietary omega-6) are associated with lower risk of heart disease, MI, and type 2 diabetes. Arachidonic acid (ARA) levels are entirely neutral — they neither cause nor prevent those outcomes.
Why this matters: Directly challenges the popular narrative that seed oils are inflammatory and dangerous. Harris argues the omega-6 to omega-3 ratio framework is misleading because it presupposes omega-6 is bad — when the data consistently show LA is protective.
Background
Barry Sears, Bill Lands, and Artemis Simopoulos popularized the omega-6/omega-3 ratio concern. Harris disagrees with the framework, noting it conflates LA (the dominant omega-6 we eat) with ARA (the inflammatory-pathway end product) when only LA levels, not ARA levels, predict outcomes.
Harris: 'a very clear signal that the higher the level of linoleic acid meaning the more you eat — that's the only way you can raise it — is by eating more — the higher the level of linoleic acid the blood the lower the risk of heart disease the lower the risk of myocardial infarction the lower the risk of diabetes.' He is blunt: 'I don't like about AAA EPA ratio or omega-6 to omega-3 is it distracts people from the real problem which is the lack of epa and DHA — it lets them run and say okay well I can fix my ratio by eating less omega-6 and not eating more omega-3 — that doesn't help.'
a very clear signal that the higher the level of linoleic acid meaning the more you eat that's the only way you can raise it is by eating more the higher the level of linoleic acid the blood the lower the risk of heart disease the lower the risk of myocardial infarction the lower the risk of diabetes
Also said
“I don't like about AAA EPA ratio or omega-6 to omega-3 is it distracts people from the real problem which is the lack of epa and DHA it lets them run and say okay well I can fix my ratio by eating less than mega six and not eating more omega-3 that doesn't help”— Harris's core argument for why the ratio framing is counterproductive — it encourages the wrong behavioral change.
Recommendations
Products, supplements, and tools mentioned in the episode
3 items
Vascepa (icosapent ethyl) — pure EPA ethyl ester, 4 g/day
Supplement
The only FDA-approved pure EPA pharmaceutical, validated in REDUCE-IT (25% cardiovascular event reduction). Indicated for statin-treated patients with triglycerides 150–500 mg/dL plus CVD or diabetes.
Harris notes the product is 'essentially the same thing' as Japan's epadil (approved 1980s) — icosapent ethyl, EPA as an ethyl ester. The drug is manufactured by Amarin. The key clinical nuance: it must be taken with food for adequate absorption, as ethyl esters require enzymatic conversion in the gut that is facilitated by co-ingested dietary fat.
vs alternatives
Lovaza (EPA+DHA at 85%) is the alternative pharmaceutical and is now generic; it covers both EPA and DHA. The REDUCE-IT result is specific to pure EPA — no EPA+DHA combination drug has been tested at equivalent dose in an equivalent population. Harris notes the upcoming STRENGTH trial (Epanova, free fatty acid EPA+DHA) would provide the comparison.
the product was called vicita like vascular EPA the ASC EPA a company that makes the drugs called Ameren and the way the study was done they gave four grams a day of this EPA... four grams a day versus the four grams of a mineral oil placebo
Two consistently highly-rated fish oil brands for purity, accurate labeling, and EPA+DHA concentration. Attia recommends based on Anahad O'Connor's New York Times analysis of brand quality.
Harris confirms that consumer-reports-style testing of supplements has generally found commercial fish oil products accurate on EPA+DHA content and free of meaningful contaminants. The key label-reading skill: look for actual EPA+DHA grams, not total fish oil milligrams. A 1,000 mg capsule of standard fish oil may contain only 300 mg EPA+DHA; a concentrated product may have 800+ mg. To reach 2 g/day EPA+DHA from a standard product you may need 6–7 capsules; from a highly concentrated product, just 2–3. Carlson's makes an 'EPA Gems' product that is heavily skewed toward EPA (roughly 75–80% EPA of the omega-3 content) — the closest OTC approximation of a pure EPA product.
vs alternatives
Krill oil has EPA and DHA in phospholipid form (theoretically better absorbed) but is much more expensive per gram of EPA+DHA and the evidence base is far smaller than fish oil. Algal oil provides DHA (and sometimes EPA) and is the only plant-based option for vegans/vegetarians — Harris would endorse it as preferable to ALA sources like flaxseed, though the EPA+DHA concentration per capsule is typically lower than fish oil.
I don't think there's a substantial difference at all in quality there's a lot of omega-3 supplement companies that make very high quality stuff that they just aren't going to the trouble of going through an FDA approval
Take fish oil with the largest fat-containing meal of the day (not on empty stomach)
Practice
Ethyl ester omega-3 supplements (the form of Vascepa, Lovaza, and most concentrated OTC products) require enzymatic conversion in the gut. This process is dramatically better in the presence of dietary fat. Taking fish oil in the morning on an empty stomach — especially while fasting — may result in near-zero absorption.
Attia's personal protocol: takes fish oil at dinner because he skips breakfast. Harris confirms the science: triglyceride-based and free-fatty-acid omega-3 formulations absorb without food, but ethyl esters do not. The only free-fatty-acid prescription omega-3 at time of recording was Epanova (in clinical trials); free fatty acid formulations will become more available as more trials complete. The practical upshot: even expensive, high-quality fish oil taken at the wrong time provides minimal benefit.
I sort of take my fish oil at night as close to dinner as possible
Also said
“if you take an ethyl ester of omega-3 on an empty stomach the absorption is quite low almost none as opposed to taking it with food which improves the absorption quite a bit but a triglyceride based oil or a free fatty acid more to the point free fatty acid doesn't require any enzymatic conversion to get absorbed at all”— The mechanism of why timing matters — ethyl esters require enzymatic processing that is enzyme-stimulated by dietary fat.
OmegaQuant Omega-3 Index Test ($50 direct-to-consumer)
Tool Sponsored · disclosed
Home fingerstick RBC omega-3 test providing EPA+DHA as percent of red blood cell membrane fatty acids. Target 8–12%. Ships a kit; patient self-collects; results in ~1 week.
DisclosureBill Harris is the founder and CEO of OmegaQuant — explicit commercial conflict disclosed by Attia in the intro.
Harris founded OmegaQuant after his academic research career specifically to democratize access to omega-3 testing — the same assay used in major clinical trials and by research collaborators. The $50 price point and home collection eliminate all access barriers. Attia's endorsement: 'there are few things in medicine where you can spend 50 bucks and get the single most important piece of data to inform a supplementation decision.' The test can also be used to verify label accuracy of fish oil products by testing before and after 4 months of supplementation.
vs alternatives
Quest Diagnostics offers a plasma phospholipid omega-3 panel; Boston Heart and True Health Diagnostics offer plasma tests. All are directionally comparable but use different reference ranges — the 8–12% target is specific to the RBC test. Never compare a plasma result to the RBC reference range.
it's a finger stick test I got it so they don't even need to go into a lab no no they just do it at home it's send it to us... for $50 a patient can basically receive a kit from you that they take into... a blood test not a saliva test
Lines worth pulling out — contrarian, specific, or perfectly phrased
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our target is 8 to 12 percent just that's a range we think is the healthy range average American is around 5% maybe four or five percent
The single most actionable number from the episode — defines both the target and the gap for the average person.
it showed a 25% reduction in risk for overall cardiovascular events over about a four or five year period which is not that long and it was effective across you know myocardial infarction need for angioplasty a variety of different cardiovascular unfortunate outcomes so it was a big hit
The headline REDUCE-IT result in Harris's own words — the strongest cardiovascular event-reduction data for any add-on lipid therapy in a generation.
the products that seem to work to actually have an effect on depressive symptoms are ones that are richer in EPA and the DHA and you know when so you look at a meta-analysis like a compilation of lots of different studies the positive ones are the ones that are richer in EPA but there's no EPA in the brain
One of the most counterintuitive findings in the entire omega-3 field — the molecule that works for brain symptoms barely appears in brain tissue.
I just think we need to see more doctors measuring omega-3 status because it means a lot low omega-3 means something... I really want to encourage people to make the assessment of omega-3 status in their patients as important as measuring cholesterol
Harris's clinical call-to-action: treat the Omega-3 Index like you treat LDL — measure it, act on it, retest.
a very clear signal that the higher the level of linoleic acid meaning the more you eat that's the only way you can raise it is by eating more the higher the level of linoleic acid the blood the lower the risk of heart disease the lower the risk of myocardial infarction the lower the risk of diabetes
Directly refutes the popular 'seed oils cause inflammation' narrative with the largest prospective epidemiological evidence available.
if you take an ethyl ester of omega-3 on an empty stomach the absorption is quite low almost none as opposed to taking it with food which improves the absorption quite a bit
Critical practical detail missed by most supplement users — time your fish oil with food or you may be absorbing very little.
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Educational summary of the cited expert source — not medical advice. Open the source recording linked above and consult a qualified physician before acting on any protocol.
