Omega-3 Index

“Need” is a funny concept.  You don’t need to eat seafood.  You don’t need an appendix or legs, either.

An article about the Omega-3 Index was published in Whole Foods Magazine.  Scanning through the figures, I noticed a few interesting studies.

For example, Association of marine omega-3 fatty acid levels with telomeric aging in patients with coronary heart disease (Farzaneh-Far et al., 2010)

Telomere length is believed to be a biomarker of aging: the shorter your telomeres, the faster you’re aging.  In the study, they measured telomere length in white blood cells and EPA+DHA in whole blood at baseline and again 5 years later.

omega-3 intake and telomerase

Quartile 1: EPA+DHA = 2.3% of the fatty acids in whole blood.

Quartile 2: 3.3%

Quartile 3: 4.3%

Quartile 4: 7.3%

Potential confounders: quartile 4 was comprised of educated rich white old non-smokers with low levels of inflammation, but the statisticians assure us those variables were controlled for… so there’s that.



You might be thinking: Bill-man, I don’t feel like getting my Omega-3 Index tested, how much seafood will put me in that fourth quartile?


omega-3 index


I got dis

Factors influencing EPA+DHA levels in red blood cells in Japan (Itomura et al., 2008)

diet vs RBC EPA and DHA


Salmon is roughly 1-2% EPA+DHA by weight, so a standard ~3 ounce portion has approximately 1-2 grams.  Doing this regularly puts you significantly ahead of the curve.

The impact of age, BMI, and fish intake on the EPA and DHA content of human erythrocytes (Sands et al., 2005)

Omega-3 index in this population: was 4.9% and it increased by ~0.24 units with each additional monthly serving of fatty fish.  Thus, mathematically, to get from 4.9% to 8% would require 13 additional servings per month.  However, biology is not mathematics, and from the figure below it appears that less can do the same.

omega-3 index fish servings per week


>2 servings per week

…and some people just seem “lucky?” 10% without eating seafood?!  Color me skeptical, but these participants specifically were not taking supps…

omega-3 index servings per month nonfried fish

As one who likes to hedge bets, I’d rather assume those people with a high Omega-3 Index are either eating pounds of algae daily or glitches/errors (ie, assume you’re not one of them).



Reminder: why is this important?  

1) Recall the association of Omega-3 Index with telomere length from above.  2) Also, Inverse association between docosahexaenoic acid and mortality in patients on hemodialysis during over 10 years (Terashima et al., 2014).

After adjusting for a plethora of confounding factors, patients with red blood cell phospholipid DHA > 8.1% had a significantly lower risk of all-cause mortality than those with DHA < 7.2%.  No effect of EPA.

many studies report omega-3 fatty acids in different samples (whole blood, white blood cells, red blood cell phospholipids).  I don’t think this matters very much because over time, they equilibrate.


Blood EPA and DHA Independently Predict All-Cause Mortality in Patients with Stable Coronary Heart Disease (Pottala et al., 2010)

27% decreased risk of all-cause mortality in those with total blood levels of EPA+DHA above 3.6% compared to those below it.  3.6%?  According to the data  above, this amounts to about 1 serving/week!

survival probability


Negative finding?  Effects of omega-3 fatty acid supplementation on neurocognitive functioning and mood in deployed U.S. soldiers: a pilot study (Dretsch et al., 2014)

2.5 grams of EPA+DHA per day (Lovaza) for 2 months: “Although the results revealed that omega-3 FAs significantly increased the HS-Omega-3 Index (p = 0.001), there were no significant effects on indices psychological health and neurocognitive functioning by treatment group. Nevertheless, there was a significant inverse correlation between the changes in the HS-Omega-3 Index and daytime sleepiness (r = 0.30, p = 0.009). Short-term treatment with 2.5 g of omega-3 FAs did not alter measures of neurocognition or psychological health, but there was evidence of a relationship between omega-3 levels and daytime sleepiness.”


Not very surprising, given that these are fit, healthy subjects… Omega-3 Index increased from 3.5 to 6.7 in the intervention group, and 3.4 to 4.2 in the control group.  Not huge increases, possibly because it was supps not seafood (N.B. 2.5 grams/d is roughly equivalent in terms of DHA to a big piece of salmon every day; 30 servings per month).

Also, had the participants been old, unhealthy, and mildly cognitively impaired, I strongly suspect neurocognitive outcomes would’ve improved…


DHA supplementation improved both memory and reaction time in young adults: a randomized controlled trial (Stonehouse et al., 2013)


Seafood vs. fish oil supps

Comparison of the effects of fish and fish-oil capsules on the n-3 fatty acid content of blood cells and plasma phospholipids (Harris et al., 2007)

Participants were assigned to get 485 mg EPA+DHA per day, on average, from either 2 servings salmon or tuna per week or from 1-2 capsules per day.

In red blood cell membranes, DHA increased by 50% in the fish group and 46% with supps.  In plasma phospholipids, DHA increased by 64% in the fish group and 60% with supps.  This basically confirms one of the aspects of why seafood is better than supps: greater bioavailability of DHA in seafood.  It’s not a huge difference, but the whole food is also greater than the sum of its parts: seafood comes with additional benefits not found in supps (eg, iodine, selenium, other micronutrients, etc.).


calories proper


Be Sociable, Share!
  • ivor cummins

    Interesting Bill – great read as usual! I did a post on this old chestnut a while back – dunno what you think of these guys study?

    • Bill Lagakos

      excellent post, Ivor! I’ve been curious, will the risk reductions seen with a high Omega-3 Index achieved via seafood be equivalent to those with supps… maybe it’s more than just bioavailability?

  • Raymund Edwards

    This is interesting – A Ray of Hope: DHA Therapy and Nutrition in Peroxisomal Disorders.

    Some very interesting reading about the peroxisome and health and its connection to DHA ( Both synthesis of DHA but also DHA mediating peroxisomal elongation, a prerequisite for peroxisome division )

    Supplements have proven to be miraculous in effect
    BUT only interestingly DHA ethyl esters NOT triglyceride

    ( I suspect it is the slow absorption that builds up over the 24 hours after intake that makes the EE form the one that works )

    links to studies and case histories and research from here

    • Bill Lagakos

      DHA is a relatively potent peroxisome proliferator.

      “BUT only interestingly DHA ethyl esters NOT triglyceride”

      Indeed, interesting.

  • Young Chipotle

    Very interesting. Is there any sort of consensus of a weekly DHA+EPA dosage? Also, how does the omega-3 content of tuna compare with salmon?

    • Bill Lagakos

      tuna has a bit less EPA+DHA than salmon, and according to the studies above, 1 serving every other day (on top of background intake) should put you ahead of the curve

  • Andrea Schüler

    Jack Kruse recently wrote something like: raw seafood is for electron
    loading/mitochondrial healing, cooked seafood is used as fuel like any
    other oil. Oops??? So cooked salmon every day should be useless?