I could be here for a long time, and I will probably add to this as I get more time, but, for now, here are the most salient points and supporting research.
Firstly, the latest position paper on vegetarian and vegan diets (considered the gold standard on plant-based nutritional guidance) stated the following in their 2025 update:
A) Omega-3 ALA appears to biosynthesise to omega-3 DHA in key tissues, and may be sufficient to maintain DHA (the isotope analysis University of Toronto research that underpins Ahiflower was cited).
B) LCPUFA supplementation (i.e. EPA and DHA) may cause adverse health outcomes in some people, it mentions mental and cardiovascular health problems specifically
C) According to the balance of evidence, ALA sources should be prioritised at this point in time
D) Conversion from ALA to LCPFUAs may be impaired in some people due to dietary and genetic factors.
Given all of these factors, it makes the most sense that the highest natural combined omega-3 ALA+SDA source makes the most sense, since omega-3 SDA overcomes the issues that some people may face with ALA due to their diet or genetic makeup, whilst bypassing the risks of adverse health outcomes from LCPUFA supplementation.
Secondly, DHA has a negative feedback inhibition, so when we take in preformed DHA (i.e. fish or an algae supplement), we inhibit the body’s natural omega-3 metabolism pathway.
Thirdly, DHA consumption blunts the cardio-protective benefits of EPA (EPA is readily raised in the blood from plant-based omegas, particularly those with high omega-3 SDA levels whereas DHA is not!) Just linking one study for now but I have multiple to back up this point.
Fourthly, the trials showing DHA supplementation benefits aren’t performed on vegan populations who are sufficient in plant-based omega-3; they tend to intentionally find omega-3 deficient populations when putting the studies together- if they were performed in a vegan population who were consuming sufficient ALA (or ALA+SDA) and were still showing great benefit, then we’d have something to talk about.
Fifth, a healthy human brain only needs 2.4-3.8mg per day of DHA to maintain its structure and function; this is a FRACTION of the amount that we take in algae supplements. It’s also a fraction of the amount we’d be making from ALA, even at incredibly low conversion rates.
Sixth, if you’re a vegan adamantly arguing for the necessity of taking algae then you’re essentially arguing against a plant-based diet being natural to our bodies, since B12 is easily explained (we used to get it from soil residue and water), but I don’t see anybody naturally drawn to going and scooping up pond scum to eat.
Seventh, neurological challenges related to insufficient DHA are likely due instead to low vitamin B12 intake, which reduces the uptake of DHA into brain tissue due to impaired methylation. Elevated homocysteine levels are strongly linked to dementia. Anti-inflammatory compounds such as curcumin also help DHA uptake in the brain tissue.
Eighth, people are widely erroneously under the impression that so long as they take sufficient algae DHA they can forget about their plant-based omega-3s now. DHA does not retroconvert at any meaningful amount to the other omega-3s, and so you are neglecting a wide range of beneficial omega-3s with their own health properties and oxylipins, whilst down-regulating your body’s natural metabolism pathway. To me this is simply a lose-lose situation, one that is unnecessary and probably doing more harm than good.
Take Home Message: Focus on B12, exercise, sufficient omega-3 ALA+SDA and a wide variety of healthy plant foods packed fully of phytonutrients and you’ll likely fare exceptionally well for brain health on a plant-based diet!
P.S. Whilst much of the research regarding brain tissue samples were sadly performed on rodents, a lot of preliminary research was conducted to justify applicability of findings to humans.
P.P.S. If you want to look deeper into these topics deeper, I highly recommend Geoff Palmer’s lecture for the T Colin Campbell Institute.
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