There’s good evidence that EPA is better than at improving mood and some evidence that DHA is better at improving cognition, and may even acutely worsen mood.
Without diving into the literature, I don’t think the evidence for the benefits of omega-3 or its subtypes is ‘good’ - at least not in the sources you listed or in a brief look at Wikipedia, a skim of relevant Cochrane’s, and a brief Medline search. The evidence for benefits of supplementation in the general public is poor, and the evidence for benefits in vegetarians/vegans is basically absent.
It’s reasonable for vegetarian/vegans to supplement it, but we should understand that doing so wouldn’t be justified by evidence—it’s just appears to be very low risk and makes some sense on mechanistic grounds.
I think we may not disagree; I was focusing on their impact on mental health in particular, whereas most studies, including the Cochrane one, look only at physiological outcomes. From Examine:
And I combine this with this meta-analysis suggesting that EPA is more responsible for this antidepressant effect.
I haven’t looked into claims around heart health or mortality, so am agnostic there for now
Fair, and I think the literature is really mixed, which you note elsewhere.
For what it’s worth, this recent Cochrane looked at omega-3 supplementation for depression and found a small-to-modest positive effect of Omega-3 supplementation. However, this effect was too small to be clinically significant, and the certainty was ‘low to very low’. Sensitivity analysis according to whether the studies were EPA-only or predominately EPA didn’t change these conclusions, except that the effect size actually got smaller compared to the effect derived from all studies.
Thanks, updating slightly in the direction of “not effective” but not a ton, mostly because I have a pretty high prior on anything that causally reduces systemic inflammation to be effective for depression. It would be quite surprising to me if at least one of the following is true:
Reducing abnormally high systemic inflammation in depressed people doesn’t improve symptoms
EPA supplementation among depressed people doesn’t on average decrease levels of systemic inflammation
EPA supplementation causes depressive symptoms in enough people to offset the effect described in (1) and (2)
Understandable, and thanks for laying your thinking. I think you’re right in that we differ due to our priors. I’m probably more sceptical of mechanistic grounding of claims in medicine, in general. This is partly due to my experience that there’s a poor correlation between how well medical interventions work in reality, and how well they should work given a seemingly strong mechanistic case. It’s probably also due to a scepticism I have in general, which I haven’t really justified.
Thanks for communicating so clearly—it helped me understand where my impressions were coming from, and where we disagree!
And just to clarify, there’s a huge black box in my mind between “inflammation decreases” and “depressive symptoms decrease.” I have no idea what the mechanisms are there!
Thanks, I like these kinds of articles.
Without diving into the literature, I don’t think the evidence for the benefits of omega-3 or its subtypes is ‘good’ - at least not in the sources you listed or in a brief look at Wikipedia, a skim of relevant Cochrane’s, and a brief Medline search. The evidence for benefits of supplementation in the general public is poor, and the evidence for benefits in vegetarians/vegans is basically absent.
It’s reasonable for vegetarian/vegans to supplement it, but we should understand that doing so wouldn’t be justified by evidence—it’s just appears to be very low risk and makes some sense on mechanistic grounds.
I think we may not disagree; I was focusing on their impact on mental health in particular, whereas most studies, including the Cochrane one, look only at physiological outcomes. From Examine:
And I combine this with this meta-analysis suggesting that EPA is more responsible for this antidepressant effect.
I haven’t looked into claims around heart health or mortality, so am agnostic there for now
Fair, and I think the literature is really mixed, which you note elsewhere.
For what it’s worth, this recent Cochrane looked at omega-3 supplementation for depression and found a small-to-modest positive effect of Omega-3 supplementation. However, this effect was too small to be clinically significant, and the certainty was ‘low to very low’. Sensitivity analysis according to whether the studies were EPA-only or predominately EPA didn’t change these conclusions, except that the effect size actually got smaller compared to the effect derived from all studies.
Thanks, updating slightly in the direction of “not effective” but not a ton, mostly because I have a pretty high prior on anything that causally reduces systemic inflammation to be effective for depression. It would be quite surprising to me if at least one of the following is true:
Reducing abnormally high systemic inflammation in depressed people doesn’t improve symptoms
EPA supplementation among depressed people doesn’t on average decrease levels of systemic inflammation
EPA supplementation causes depressive symptoms in enough people to offset the effect described in (1) and (2)
Understandable, and thanks for laying your thinking. I think you’re right in that we differ due to our priors. I’m probably more sceptical of mechanistic grounding of claims in medicine, in general. This is partly due to my experience that there’s a poor correlation between how well medical interventions work in reality, and how well they should work given a seemingly strong mechanistic case. It’s probably also due to a scepticism I have in general, which I haven’t really justified.
Thanks for communicating so clearly—it helped me understand where my impressions were coming from, and where we disagree!
You’re welcome, and likewise!
And just to clarify, there’s a huge black box in my mind between “inflammation decreases” and “depressive symptoms decrease.” I have no idea what the mechanisms are there!