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Comment by davidhollander | Hacker News Reader

> increased IQ in children because of the presence of Omega-3 Fatty Acids. Did you know though that both Flaxseed and Walnuts are both better

The fatty acid in both Flaxseed and Walnuts you are referring to is alpha Linolic acid (ALA), whereas fish contains Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA). Out of these, only DHA is found in the brain. If DHA is not present in the diet, ALA can be converted into it, but only at an extremely low rate of efficiency [1]

The only reliable vegan source of DHA I am aware of is certain types of algae. Additionally, by consuming extremely large quantities of nuts you will typically be overloading your copper to zinc ratio.

[1] http://dx.doi.org/10.1186%2F1476-511X-8-33 "Are all n-3 polyunsaturated fatty acids created equal?"

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ALA is adequately converted to DHA, you didn't read the article you linked. Studies on rats are far from conclusive... but then why claim it's a human-health fact?

"While there is discrepancy in ALA conversion rates in rats, these studies imply that dietary ALA could sufficiently supply the brain with DHA in the absence of exogenous DHA intake."

This is consistent with all other research I've read, debunking this myth has become a hobby.

>you didn't read the article you linked

Is this a joke? The article specifically states:

>It is not enough to assume that ALA exerts effects through conversion to EPA and DHA, as the process is highly inefficient in humans.

>with higher levels of ALA, no net rise in the level of circulating DHA occurred [2,3]. For example, feeding 10.7 g/d of ALA from flaxseed oil for 4 weeks failed to increase low DHA levels in breast milk of lactating women [4]. Some estimate that only 5–10% and 2–5% of ALA in healthy adults is converted to EPA and DHA, respectively [5], while others suggest that humans convert less than 5% of ALA to EPA or DHA [6]. The International Society for the Study of Fatty Acids and Lipids (ISSFAL) recently released an official statement on the conversion efficiency of ALA to DHA. They concluded that the conversion of ALA to DHA is on the order of 1% in infants"

Now let's examine the actual context of your quote:

>"While there is discrepancy in ALA conversion rates in rats, these studies imply that dietary ALA could sufficiently supply the brain with DHA in the absence of exogenous DHA intake. It is important to note that the hepatic DHA synthesis rates observed for rats do not extend to humans [44]. The higher rates reflect a more efficient ALA elongation process in mice and rats"

It specifically states that ALA->DHA is only a phenomena that occurs in rats and not humans.

>Studies on rats are far from conclusive... but then why claim it's a human-health fact?

Exactly my point. The human studies clearly state it is not reliably converted, and you are claiming it IS based on a rat study. The whole article I linked is based on the assumption it is NOT, and from the perspective that we should be examining the health benefits of ALA independently from the health benefits of fish oil.

Let me clarify: Inefficient conversion of dietary ALA to DHA is neither correlated nor causative to anything.

My point is that ALA provides adequate, not elevated levels of DHA, and there's no evidence to the contrary.

Now let's examine the actual context of my quote:

> ALA is adequately converted to DHA

I think it's worth mentioning where you make a false statement, directly after citing inefficient conversion rates in humans.

>It specifically states that ALA->DHA is only a phenomena that occurs in rats and not humans.

Which is it, inefficient or non-existent in humans?

This statement: >It is not enough to assume that ALA exerts effects through conversion to EPA and DHA, as the process is highly inefficient in humans.

... Says exactly nothing about healthy levels of DHA. It is non sequitur. It skirts the issue, it avoids the topic, the statement tries to make a huge jump in unreasonable unproven logic. This paper shows nothing but the therapeutic effect of DHA/EPA on diseased people.

There is no evidence to suggest inadequate DHA is produced from dietary ALA in otherwise healthy humans. Not in this paper, nor any I've seen.

> Inefficient conversion of dietary ALA to DHA is neither correlated nor causative to anything

It's correlated with being a human, but the significance of very inefficient conversion versus trivial conversion is simply that it prevents us from claiming they are metabolically identical goods.

>Which is it, inefficient or non-existent in humans?

Inefficient. 'ALA->DHA' shorthand was meant to token the previous idea of "efficient endogenous ALA to DHA conversion" and not initialize a new false one.

>no evidence to suggest inadequate DHA

I think you're missing the point by intentionally or unintentionally rephrasing this in terms of avoiding a negative. Let me requote the initial context by jeremymims:

> Just for the record, fish consumption is linked to increased IQ in children because of the presence of Omega-3 Fatty Acids. Did you know though that both Flaxseed and Walnuts are both better, cheaper, and less environmentally damaging sources of Omega 3s than fish?

My primary point is that one cannot rationally assert that the numerous positive IQ benefits scientific literature attributes to consumption of fish and fish oil are somehow equally or better attributable to walnut and flax consumption. The evidence indicates differing methods of action and a need to consider their health benefits independently.

> The evidence indicates differing methods of action and a need to consider their health benefits independently.

Fair enough. I learned a thing or too here, so thanks.

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