#418: Should We Consume a Direct Source of DHA?

In Podcasts by Danny Lennon7 Comments

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Today's Topic in Focus:  DHA - Yay or Nay?

In this episode Danny and Alan discuss the debate around whether a direct source of the long-chain omega-3 fatty acid DHA should be recommended. Many people do not consume the marine foods (primarily fatty fish) that contain DHA, and higher DHA intakes, DHA status, and omega-3 indices are predictive of certain health outcomes.

But the essential omega-3 fatty acid alpha-linolenic acid (ALA) can be consumed from plant sources. So do those who do not consume direct sources of DHA have lower DHA status? Does this matter? And if so, then what pragmatic conclusions can we come to? All of this is covered in this episode.

Studies Referenced:
  1. Baker et al., 2016 - Metabolism and functional effects of plant-derived omega-3 fatty acids in humans
  2. Rosell et al., 2005 - Long-chain n–3 polyunsaturated fatty acids in plasma in British meat-eating, vegetarian, and vegan men
  3. Barceló-Coblijn et al., 2008 - Flaxseed oil and fish-oil capsule consumption alters human red blood cell n-3 fatty acid composition: a multiple-dosing trial comparing 2 sources of n-3 fatty acid#
  4. Geppert et al., 2005 - Docosahexaenoic acid supplementation in vegetarians effectively increases omega-3 index: a randomized trial
  5. Witte et al., 2014 - Long-chain omega-3 fatty acids improve brain function and structure in older adults
  6. Arturburn et al., 2006 - Distribution, interconversion, and dose response of n-3 fatty acids in humans
  7. Stark et al., 2016 - Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults
  8. Schwartz et al., 2009 - Modification of dietary polyunsaturated fatty acids via complementary food enhances n-3 long-chain polyunsaturated fatty acid synthesis in healthy infants: a double blinded randomised controlled trial
  9. Gracious et al., 2010 - Randomized, placebo-controlled trial of flax oil in pediatric bipolar disorder
  10. Sarter et al., 2015 - Blood docosahexaenoic acid and eicosapentaenoic acid in vegans: Associations with age and gender and effects of an algal-derived omega-3 fatty acid supplement
  11. Tan et al., 2012 - Red blood cell omega-3 fatty acid levels and markers of accelerated brain aging
  12. Pan et al., 2012 - α-Linolenic acid and risk of cardiovascular disease: a systematic review and meta-analysis
  13. Harris et al., 2021 - Blood n-3 fatty acid levels and total and cause-specific mortality from 17 prospective studies
  14. Cunnane, 2000 - Hunter-gatherer diets—a shore-based perspective
  15. Fleming & Kris-Etherton, 2014 - The Evidence for α-Linolenic Acid and Cardiovascular Disease Benefits: Comparisons with Eicosapentaenoic Acid and Docosahexaenoic Acid
  16. Flock et al., 2013 - Determinants of Erythrocyte Omega‐3 Fatty Acid Content in Response to Fish Oil Supplementation: A Dose–Response Randomized Controlled Trial
  17. Kornsteiner et al., 2008 - Very Low n–3 Long-Chain Polyunsaturated Fatty Acid Status in Austrian Vegetarians and Vegans
  18. Greupner et al., 2018 - Effects of a 12-week high-α-linolenic acid intervention on EPA and DHA concentrations in red blood cells and plasma oxylipin pattern in subjects with a low EPA and DHA status
  19. Brenna et al., 2009 - alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans
  20. Martinez, 2002 - Tissue levels of polyunsaturated fatty acids during early human development
  21. Kar et al., 2016 - Effects of omega-3 fatty acids in prevention of early preterm delivery: a systematic review and meta-analysis of randomized studies
  22. Cheatham et al., 2006 - N-3 fatty acids and cognitive and visual acuity development: methodologic and conceptual considerations
  23. Fokkema et al., 2000 - Short-term supplementation of low-dose gamma-linolenic acid (GLA), alpha-linolenic acid (ALA), or GLA plus ALA does not augment LCP omega 3 status of Dutch vegans to an appreciable extent
  24. Johnson et al., 2008 - Cognitive findings of an exploratory trial of docosahexaenoic acid and lutein supplementation in older women
  25. Dangour et al., 2010 - Effect of 2-y n-3 long-chain polyunsaturated fatty acid supplementation on cognitive function in older people: a randomized, double-blind, controlled trial


  1. Thank you for a great podcast. I really appreciate all the work you do. Any thoughts on the interaction between things like fish oil/krill oil and thyroid medications? It would seem as if they’re contraindicated and would love to know the data behind the relationship. If you’ve already answered this somewhere, no need to answer again, please just point me in a direction.
    Thank you again!

    1. Author

      Hi Will,

      Thanks for the kind words. This is not something I’m familiar with the evidence on, so unfortunately give any input. Probably something I’d suggest reaching out to a endocrinologist or pharmacist about.

      1. Thank you. I asked because a family member was taking fish oil and krill oil and it definitely messed with her thyroid levels – she is on thyroid medication. Her doctor told her to stop taking the fish oil and krill oil and her levels stabilized. I’ve looked into it a bit and there does seem to be some sort of connection, but the exact relationship isn’t completely clear. Some say they should never be taken together, others seem to indicate that it’s fine as long as their is a decent time separation. It would seem that anybody taking a thyroid medication like levothyroxine or synthroid should keep a tight eye on his or her levels as it might have a negative effect – and obviously talk with a doctor.
        Thanks again for the time.

  2. Thank you for the really helpful episode! The information was provided in a really useful format and structure!

    Was the reason this episode only focused on DHA because it’s not credited as much as pure ethyl ester forms of EPA? Do you think there may be a synergistic benefit of supplementing combined EPA and DHA together, and if so, has an optimal ratio been studied?

    Dr Bill Harris suggests that for the brain, EPA may have uniquely beneficial anti-inflammatory benefit even if DHA is more abundant than the EPA in the brain. Any thoughts on his research?

    1. Author

      Hey Mayuri,

      Yes, there are benefits to both EPA and DHA, with both having benefits in some areas, while others tend to be more related to either EPA or DHA.

      Also, in the context of diets that don’t contain fish, and thus rely on ALA for an omega-3 source, the conversion to DHA will be even lower than the conversion to EPA.

  3. Danny have you done a podcast on vitamin k2 , we seem to be hearing alot about its benefits, but what are the draw backs ,does it work ,is it safe , l have heard iin some people it makes there blood pressure go up . W hat is the truth . Steve C

    1. Author

      Hi Steve,

      We discussed vitamin K2 in the context of bone health, in our bone health episode. We may address other health impacts in future episodes.

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