▲ 325 points
back
204 comments
Studies like this always seem to cite stats in a way that's pretty inaccessible to me. This is more clear to me:
* 217,122 participants whose data was extracted from the UK biobank database
* Out of those 217,122, 325 got early onset dementia over an average of 8.3 years
* The vast percentage of data came from exactly one blood draw per person between 2006 and 2010 at the beginning of the biobank study
Omega-3 Blood | Hazard Risk | Rate of Incidence | Percent Incidence
Level Quintiles | | Over 8.3 Years | Over 8.3 Years
-------------------|------------------|--------------------|------------------
Q1 (Lowest 20%) | 1.0 | 193 in 100,000 | 0.193%
Q4 (High) | 0.62 | 120 in 100,000 | 0.120%
Q5 (Highest 20%) | 0.60 | 116 in 100,000 | 0.116%The most interesting finding is that the non-DHA effect is much stronger than the DHA effect. This doesn't align with the mechanistic explanation. Either this this is a novel and interesting result, or it's more evidence that we're just measuring wealth and health consciousness.
Observational studies like these are useful for guiding future research, but, on their own, they're essentially useless for informing lifestyle changes.
So you can reduce your dementia incidence risk from Q1 -> Q5 by a whopping 0.08%-points.
But in media you surely will read about a 40% reduction.
*edited: %-points instead of %
This could significantly underestimate the real impact. A single point measurement is perhaps a pretty noisy measure of long term average. If we had lifetime averages, the quintiles would be more purely differentiated by the variable of interest, and the risk would be as well.
Why are Q2 and Q3 missing. My guess is that they show a higher incident rate than Q1. Let me verify that, oh wait I can't. This article is pointless
Besides there is so much noise here. You ate fish before going to the doctor to get your blood drawn in 2006
also keep in mind, P hacking came about as a means to try to prove racial science.
We have been here before many times. Nutritional epidemiology studies have a terrible track record of establishing causal relationships (e.g., Beta-carotene and lung cancer, selenium and prostate cancer, etc all were not replicated when the definitive clinical trials were done). The problem is that statistical models with questionable and often untestable assumptions are used, but the results are reported as if these models were fault-less. The result is overly optimistic estimates of statistical significance and inflated confidence in study findings.
I would disagree with this. While we can always point to examples where epi did not align with RCTs, this doesn’t capture how discordant (or not) this relationship is in the aggregate.
Thing is, we actually have empirics on this, and in reality observational studies comparing intake to intake are concordant in over 90% of cases, so I think we actually have a very strong case for making causal inferences based on replicated epi findings:
> Compared to participants at Q1 of DHA, those at Q5 of non-DHA showed a significant lower risk of EOD. A statistically significant lower risk was observed in Q3, Q4 and Q5 of non-DHA omega-3
If I'm reading this right, if you can't get many fish sources in your diet, it's better to increase the quantity of non-DHA sources (certain seeds, oils and vegetables). But my understanding is non-DHA is not helpful so I may not be understanding correctly
I think it's easy to take algal-based omega-3 supplements. They've gotten pretty good in the last couple years with gummies with a high dose and no algae test. And no fish killed!
> But my understanding is non-DHA is not helpful so I may not be understanding correctly
Alpha-linolenic acid (ALA), the Omega-3 present in most plant sources, can get its chemical structure lenghtened to EPA and DHA in the organism. The problem appears to be, when people get older, the efficiency of this conversion takes a large hit.
> But my understanding is non-DHA is not helpful so I may not be understanding correctly
A lot of the common wisdoms about fish oil and omega-3 were based on early studies that had some too good to be true results. As studies were scaled up to more participants and more rigorous methods many of the amazing early results gave way to less impressive or even null results.
I think it’s a good idea to get a mix of omega-3s in your diet, but given everything I’ve seen I don’t think it’s all that important to start micro optimizing everything with isolated supplements. Consume a mixed variety of sources and try to get some fish in there every once while.
The importance of DHA specifically in this study is a good example of how individual studies don’t tell the whole story. This could be a spurious result that is correlated with something else that leads to elevated DHA in the blood (diet choices). Supplementing isolated DHA could miss whatever the real factor was.
Well the other major omega-3 typically supplemented is EPA. Which also mostly comes from fish sources (and both DHA and EPA come from algae that the fish eat)
ALA is very weakly converted to the other fatty acids but it also has benefits in its own right. It's a pretty interest antioxidant being active in both fat and water
What’s missing from this is how much omega 3 containing food, how often you need to get this protective result.
Do I need to eat fish twice a week? 5 times? Do I need to supplement because there is no way to eat enough fish?
Would love some practical guidance tacked on to this
It's really unclear unfortunately.
The correlative effect is quite clear, i.e people who have high omega 3 levels (eat a lot of fish) have health benefits.
But in random controlled trials Omega 3 supplements have not had convincing effects.
It might be because the supplements aren't very good, or because there's actually something completely different going on, like fish displaces less healthy foods from the diet.
I like to get my omegas from the following sources, no fish needed!
- hemp hearts (complete protein, goes best with oatmeal for breakfast, on salads, or in soups for an extra bit of nutty / fatty flavor)
- pumpkin seeds (also good source of iron, iirc)
- algae-based supplement (currently taking an omega3 + vit D + vit K combo capsule from nordic naturals)
What's also interesting that some recent studies show eating eggs every day actually is harmful, most likely due to the Omega3 to Omega6 ratio.
So here we go again. First it was cholesterol, which was then rebutted, so people (myself included) started eating eggs every day. And now this. You can't win!
https://blog.ncase.me/on-depression/ - I think this is explained in a better and simpler way
Note that EOD is both rare (of all dementia cases) and highly inheritable.
This looks like a pretty weak correlation in a study that doesn't control for any other variables.
Which is not nothing but concluding anything about causality is a stretch.
I bet this is due to omega 3 reducing inflammation and oxidative stress
I wonder how much of this is Omega-3 in the diet, or if there are processes that could deplete levels in the blood.
Abstract says blood levels objectively reflect dietary intake.
I suspect the positive effects of consuming nutritious forms of fish-centric meals has as much to do with what you're _not_ eating in those meals as contents like omega-3s.
There's a bunch of less harmful stuff you can fill your diet with that just by virtue of displacing terrible things has positive effects.
Yeah. In many cases these correlations wind up being a measure of home cooking.
Wouldn't Omega-3 and vitamin B2 together be a great prophylaxis for most neuro-degenerative conditions due to repolarizing microglia?
I would recommend it to elderly family members, but they have atrial fibrillation, and I heard omega 3 can exacerbate it?
It's seemingly dose dependent. Low omega 3 can seems to have the same mechanistic effect. As for what the dose should be? No clue, personally, and it depends on your heavily diet since even one fishy meal could provide as much as most supplements do. Personally, I don't eat much fish, so I'm comfortable with a supplement. If I ate even one piece of salmon in a day I'd skip the supplement that day.
If I had afib I'd talk to a doctor about it before taking it and probably would stay well under 1G on any day I don't eat fish and skip it entirely on a day that I do.
Not a dr, not a health professional, not anyone you should listen to perhaps at all, but this is my understanding.
There’s a good pod on this exact subject with nutrition scientists: https://sigmanutrition.com/episode538/
The TL;DR (IIRC) is that we tend to only see this in trials where atrial fib is a tertiary endpoint so there’s not really compelling data to suggest AF is a risk.
But give it a listen and see what you think, it was a while ago I listened to it and I’m not qualified to give actual advice!
Omega-3 good, Omega-6 bad has been known for many years.
For example, Scott Alexander wrote in 2014 on his blog Slate Star Codex about how Omega-3 lowers crime rates and Omega-6 increases crime rates. And he links to some cool RCTs where you can check the methodology yourself.
https://slatestarcodex.com/2014/02/18/proposed-biological-ex...
Eat your fish!
There is zero evidence in that article, or anywhere else that I’ve seen for that matter, that omega 6 is harmful. The evidence provided there would perhaps suggest that omega 3s are beneficial, but that’s about it.
It always amazes me a little how people somehow figure out the good thing to do probably just by simple pattern recognition. The benefits of fish oil are know for a long time yet not we're not marketed with concrete explanation.
I’d love it if we could ban single-study health papers from HN. Meta analysis or bust.
Highly underrated
is it enough to eat a can of sardines everyday?
The levels of n3s we usually see associated with benefits tend to be the equivalent of 1-2 servings of fish per week.
Are vegan sources of omega 3 worth it or am I fucked
Just use an algae-based omega-3 supplement. Eating algae is how fish build up omega-3 levels in their bodies anyway.
Should be, that's where the fish get it from.
Just get an omega 3 supplement that has a good amount of DHA and EPA. There’s not as much evidence to support it as there is to support eating fish, but that’s more due to a dearth of research on the subject than because the evidence suggests it has no effect.
Unfortunately it tends to be more expensive. I have recs if you’re in the UK but not much use otherwise!
Or eat mussels. Yes I am aware that this is not vegan, but it is hard to think that they would be a lot more conscious than plants, and they are sustainable and clean up the water.
I consider myself vegan (although I guess I'm technically not then) but eat mussels, they contain almost everything missing in a vegan diet.
very worth it! seven years here with no negative health effects noticed; plus, you’re saving animal lives and helping sustain the planet.
natural sources for omega FAs include hemp hearts and pumpkin seeds.
Not sure where you are located, but here in the UK supermarkets (eg Tesco) sell vegan omega 3/6/9 capsules.
Seaweed :)
Cool! But isn‘t that already common wisdom and the basis for the omega3 fanboy culture?
It's difficult if not impossible to increase your intake of omega-3 without increasing your intake of omega-6 even more. I am not sure that's worth it.
Studies also show you do NOT need DHA and DHA can be detrimental, you want pure EPA or very high EPA to DHA ratio
if you want the purest Omega3 EPA without all the contaminants that are in OTC supplement nonsense (they are completely unregulated and untested by batch)
ask your doctor for a script of generic VASCEPA
CostPlusDrugs has the cheapest generic Vascepa that I've found
The dose is usually two pills a day but trust me on this, start with one for a long time, it takes your GI a long time to handle it without bathroom urgency