from Hacker News

Omega-3 is inversely related to risk of early-onset dementia

by brandonb on 2/8/26, 4:47 PM with 184 comments

  • by djoldman on 2/8/26, 5:54 PM

    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%

  • by drgo on 2/9/26, 12:20 AM

    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.

  • by deeth_starr_v on 2/8/26, 5:23 PM

    > 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

  • by engelo_b on 2/8/26, 6:16 PM

    from an actuarial perspective, these longitudinal studies on dementia are huge. early-onset is basically the hardest risk to price for long-term care because the tail of the claim is so long and expensive. finding a solid inverse correlation like this is the kind of thing that eventually shifts premium modeling for an entire generation.

  • by MarkMarine on 2/8/26, 5:53 PM

    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

  • by dur-randir on 2/8/26, 7:05 PM

    Note that EOD is both rare (of all dementia cases) and highly inheritable.

  • by raffa667 on 2/8/26, 6:11 PM

    https://blog.ncase.me/on-depression/ - I think this is explained in a better and simpler way

  • by hmontazeri on 2/8/26, 5:21 PM

    I bet this is due to omega 3 reducing inflammation and oxidative stress

  • by HPsquared on 2/8/26, 5:06 PM

    I wonder how much of this is Omega-3 in the diet, or if there are processes that could deplete levels in the blood.

  • by shiandow on 2/8/26, 10:35 PM

    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.

  • by storus on 2/8/26, 8:21 PM

    Wouldn't Omega-3 and vitamin B2 together be a great prophylaxis for most neuro-degenerative conditions due to repolarizing microglia?

  • by unsupp0rted on 2/8/26, 5:32 PM

    I would recommend it to elderly family members, but they have atrial fibrillation, and I heard omega 3 can exacerbate it?

  • by purplehat_ on 2/8/26, 8:15 PM

    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!

  • by firemelt on 2/9/26, 10:27 AM

    is it enough to eat a can of sardines everyday?

  • by akashnagar on 2/8/26, 6:35 PM

    Highly underrated

  • by pengaru on 2/8/26, 6:00 PM

    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.

  • by hsuduebc2 on 2/8/26, 11:45 PM

    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.

  • by 46493168 on 2/8/26, 5:55 PM

    Are vegan sources of omega 3 worth it or am I fucked

  • by DonThomasitos on 2/8/26, 5:06 PM

    Cool! But isn‘t that already common wisdom and the basis for the omega3 fanboy culture?

  • by ck2 on 2/8/26, 6:32 PM

    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

    https://pmc.ncbi.nlm.nih.gov/articles/PMC5282870/

    https://www.youtube.com/watch?v=3uoQUM30Ess

  • by midtake on 2/8/26, 6:13 PM

    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.