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DHA - On Further Thoughts...

 

I recently posted this video where I stated I have grown uneasy about recommending routine DHA supplementation for vegans. I said that I had become unsure what possible adverse effects the supplement might be facilitating & until I learned more about this subject, I would use this calendar year to optimize my ALA intake with daily ground flaxseeds & an otherwise ALA-rich diet. I plan to reassess the state of testing methods & see which test, if any, could give me meaningful information about my DHA status. I'm not saying that DHA supplements are evil nor that people who take them or advocate their use are wrong or that I have closed the door on their use. I’m saying that, at this time, the science is not mature enough to permit me to feel comfortable giving advice on DHA supplementation.

It was not unexpected that such a video would cause distress in my friend & colleague, Dr Joel Fuhrman, a passionate advocate of DHA for vegans as a preventative against dementia, which he reports having seen frequently in his practice. I call your attention to the following article that kindled my concerns (1) that demonstrated that the elevation in EPA levels commonly seen with DHA supplementation is not, as widely believed, from “backfilling,” wherein 22-carbon atom DHA somehow turns back into 20-carbon-atom EPA. On the contrary, this study shows that the elevation of EPA demonstrated here is the result of DHA inhibiting EPA clearance from the blood, thus, producing EPA accumulation in the tissues. This concerns me greatly, as it is a red flag saying to me, “If swallowing pre-formed DHA is backing up EPA metabolism, what else is it doing?” 

 

I also found evidence confirming that taking DHA supplements increases cell permeability & it makes me wonder if that increases permeability to carcinogens. (2) 

These concerns were enough for me to question if I really know what I am doing as I tell people to take DHA on a daily basis & until I can be confident that my advice is doing no harm, including making the cells more permeable to carcinogens, I have, for now, decided to hold off on my recommendation to take supplemental DHA. If people want to continue taking it, I can understand why that would seem reasonable, as there is evidence supporting that stance, as well.  

I know Dr Fuhrman’s condemnation of me as a physician has been very vehement. It will not dim my friendship with or appreciation of Dr Fuhrman as a man of character & a fine doctor who has the best interest of his patients at heart. (Likewise with my friends & colleagues Dr Joel Kahn & Dr Michael Greger who probably also will disagree with my clinical decision at this time. They are all respected & cherished lights in the field of plant-based nutrition & my appreciation for them remains undimmed.) 

As I said at the beginning, I am choosing to not take DHA supplements for the rest of this calendar year & to optimize my own DHA production to see what I learn about the subject but have not closed my mind on the subject. As time unfolds & the research studies are done, if I find solid scientific evidence to alleviate my concerns & to support its use, I may consider it appropriate, once again. The science will tell the story & dictate my decisions.

I appreciate all, including Dr Fuhrman, who is helping me find my way to the truth about this important, complex & subtle subject.

Michael Klaper, M.D.

 

(1) Compound-specific isotope analysis reveals no retro conversion of DHA to EPA but the substantial conversion of EPA to DHA following supplementation: a randomized control trial.

https://www.ncbi.nlm.nih.gov/pubmed/31204771

(2)  Stillwell W, Wassall SR. Docosahexaenoic acid: membrane properties of a unique fatty acid. Chem Phys Lipids. 2003;126(1):1–27.

Hossain Z, Kurihara H, Hosokawa M, Takahashi K. Docosahexaenoic acid and eicosapentaenoic acid-enriched phosphatidylcholine liposomes enhance the permeability, transportation and uptake of phospholipids in Caco-2 cells. Mol Cell Biochem. 2006;285(1-2):155–163.

Stillwell W, Ehringer W, Jenski LJ. Docosahexaenoic acid increases the permeability of lipid vesicles and tumor cells. Lipids. 1993;28(2):103–108. doi:10.1007/bf02535772