Dietary omega-3 polyunsaturated fatty acids as a protective factor of myopia
51 comments
·September 8, 2025nickparker
theologic
Consumer Labs offers as a subscription service testing of various vitamins Including fish oil. They perform a great service, and I think it's economical in terms of determining if what you're buying is really what you want.
Heavy metal contamination is classically not a problem because the fish oil is distilled. My guess is your researcher friend has fallen victim to the marketing of the pharmacological industry-- Although I do want to indicate they do have value, probably not the 500 percent markup that they put on what in essence is a generic product.
Some natural fish oils are not distilled and do have this problem-- These are normally marketed as natural or cod liver oil or something that should hit your radar pretty quick. Your friend's concern about rancidity is clearly a problem And pretty well understood by people for years if you have any familiarity with chemistry. Omega threes get their name from the fact that you have a weird bend on the end of a long carbon molecule. This is susceptible to oxidation. This is true for any Omega 3 molecule regardless of its length Or it's sourcing.
This includes omega-3 "drugs" like Vascepa (pure EPA) and Lovaza (EPA and DHA combination).
Fortunately in testing, they have not found widespread issues with rancidity, although they definitely have found pockets. My normal suggestion to everybody is by a high volume manufacturer that you know is tearing through the product quite rapidly. My top suggestion is Costco. Then make sure you keep your fish oil in the refrigerator, and churn through it on a regular basis.
p1esk
If I eat raw salmon (sashimi) a couple times a week, would I still benefit from consuming fish oil?
johnyzee
Yes. A real, raw source is almost certainly better than a processed and treated source. Bottled fish oil is sometimes rancid. It is also heavily loaded with antioxidants, without which fresh fish oil goes rancid within hours, and which have their own detrimental effects when in excess.
bnycum
I also started taking the Sports Research omega-3 capsules early this year. Seems the consensus for taking any omega-3 is that it's single-source and wild caught which is why I chose that brand. My biggest benefit has been my eyesight with way less floaters.
However I started taking creatine this summer to help with my recovery from running now that I'm older. I will say I feel it's done more for my cognitive function than the omega-3 did.
RankingMember
> biggest benefit has been my eyesight with way less floaters.
Huh, did you also have to get any laser surgery done to get rid of them totally? My research always indicated that once you had floaters, they were basically just there forever and your brain just learned to work around them.
bnycum
No surgery and I don't wear any vision correction, they aren't gone 100% just reduced greatly. I really only ever notice them when going from dark to light. Typically never inside my house under normal light, mainly just outdoors.
My diet does lack seafood overall. While I love salmon my family doesn't. If we eat seafood it's mainly catfish and shrimp though, as we are in Louisiana.
wil421
My eye doc said I had a slight case of blepharitis and that I should use high quality fish oil and eye lid cleaning wipes. The oil would help the membranes or gland in the eye lid, can’t remember which.
mettamage
Playing chess as a baseline thing to know how your cognitive processing is seems like a good idea.
maxboettinger
How much do you take? Evidence-based dosage guidance for supplements is hard to find. Pointers to primary sources with empirically supported dose ranges for common supplements—magnesium, zinc, and multivitamins—appreciated!
theologic
This really is a good use for Perplexity. I suggest a prompt along the lines of "what is the pubmed indications for what somebody should take for omega-3 or n3 pufa for X". This way your pull the primary research and you can have a conversation to your needs.
With that written, generally the literature indicates that somewhere around 1-2G daily of EPA/DHA is in the range of what is fringe mainstream. There is a lot of variance around this and a lot of debate. For example, you'll get a debate about the ability of the body to convert 22 EPA into 24 DHA, so some will push DHA as the preferred source for the body.
adrian_b
The range of 1 to 2 g daily of DHA+EPA has been suggested based on the daily consumption of 2 g or more that is typical for populations like the Japanese, who include a great proportion of marine food in their diet and who appear to derive health benefits from this.
I agree that for now there is no better evidence about which is the optimal daily intake.
Quantities about 10 times less than this might be sufficient to avoid any obvious signs of nutritional deficiency, but are unlikely to be optimal.
The capacity of converting ALA from vegetable oil into DHA and EPA may vary a lot between humans and it is typically lower in males than in females and also lower in older people than in young people.
The less risky choice is to ensure that you eat enough DHA+EPA. Perhaps one does not need 1 to 2 g of DHA+EPA daily, but eating it is unlikely to be harmful, while not eating it carries definite risks.
Qem
> but you need to buy a fancy brand to avoid rancid oil or heavy metal contamination both of which ~null out the benefits
I didn't know about the rancidity problem, thank you. Knew about the contamination issue. To avoid it, I tried to source oil derived from sources lower in the food chain, either vegan algae oil, or krill oil. But krill oil is super expensive, when compared to fish oil, with lower levels of EPA/DHA per capsule. The problem with algae oil it's that those I've found contain only DHA. Not sure about the relative importance between EPA/DHA, although.
adrian_b
The so-called "algae" are not algae.
"Algae oil" is a marketing term that has been chosen for sounding better, especially to vegans, than "Schizochytrium oil" or "oil from stramenopiles".
Schizochytrium is an organism somewhat similar to a fungus, but which is not a fungus and it is distantly related to brown algae and diatoms (but unlike those, it is not an alga; it never had chloroplasts acquired by symbiosis).
The first cultivated strains of Schizochytrium produced only DHA, but now there are strains that also produce EPA. At least in Europe, you can easily find Schizochytrium oil that contains DHA + EPA in a 2:1 proportion. For most humans, especially for most males, both DHA and EPA are needed, because the capacity of interconversion between them is typically insufficient in comparison with what is needed.
However, even if it has become cheaper in recent years, Schizochytrium oil remains about 3 times more expensive than fish oil, per its fatty acid content. There are also many vendors that try to deceive their customers by selling diluted oil at about the same price as the decent vendors, therefore at a price many times higher per the fatty acid content.
In Europe, in recent years I have preferred Möller's Pure Cod Liver Oil, which is quite tasty, either alone or added to food. Using bottled oil is much better than using capsules. Besides being cheaper and not ingesting garbage capsules, tasting the oil makes certain that it neither is rancid nor has any suspect content. This is also true for Schizochytrium oil. Many decades ago, cod liver oil had a reputation of something that children were forced to eat, despite its bad taste. This is completely untrue nowadays, when the oil is made either immediately after catching or from fish that have been frozen immediately after catching, so the oil has not degraded and it retains a pleasant taste.
If Schizochytrium oil will become cheaper, i.e. with a price not more than double in comparison with pure cod liver oil, then I will switch to it, removing from my diet the only ingredient that is obtained by killing animals.
storus
Omega-3 together with vitamin B2 repolarizes microglia from pro-inflammatory state to healing state, so no wonder your brain got a boost. Now, how can I tell if Omega-3 capsules are rancid?
adrian_b
If you buy bottled oil instead of capsules, you can feel its taste, so you can sense whether it is rancid or it has any other suspect taste.
Good omega-3 oil has a pleasant taste, there is really no need to eat capsules made from chemically-modified cellulose or who knows what other material that is not suitable as food.
The omega-3 oil can be mixed with whatever oil you add to your food, e.g. to a salad.
storus
Yeah, I mean if I open a capsule, I can tell. But without opening it, is there any way to tell it's rancid?
JumpCrisscross
> I play chess a bit like sushi ginger for the mind - purge working memory with a short intense task to context switch
I use it as a stupidity meter. If I play a series of bad bullet games, I’m more cautious about my decision making that day.
da02
Your life sounds amazing. What other discoveries have you found? Do you publish anywhere online? (social media, Youtube, etc.)
whatever1
Compare Chinese and Indian myopia frequencies. One country loves fish the other is mostly vegetarian.
bilsbie
I just can’t imagine how you’d remove healthy user bias from a study like this.
hellojebus
This reminded me of the Knowledge Project podcast with Dr. Rhonda Patrick on certain biomarkers, including omega index as an indicator for longer life span.
https://fs.blog/knowledge-project-podcast/dr-rhonda-patrick/
JumpCrisscross
How much was the highest-quartile group consuming?
simianwords
Hi any trusted review of Nordic Natural's fish oil please?
savorypiano
This should be studied across different populations, not just one which is known for myopia.
FollowingTheDao
I disagree, I think they need to study specific populations for specific diseases associated with different diets. If you study this across population where this doesn’t matter as much then they will say omega-3 has no effect on nearsightedness, which is bad for the population that needs omega-3.
Omega-3 saved me from the fate of my family, dying from a heart attack before I was 50.
And I see this need in my genetics, specifically FADS1 FADS2 polymorphisms that make me need higher chain omega-3 fatty acids like from seafood.
j45
Agree. Omega 3 is well studied.
Things don’t have have to be proven universally for every human, but omega 3 seems pretty universal.
nemo44x
Omega 3 helps manage triglycerides which when high make managing insulin difficult which results in the liver putting more glucose in the blood. This can create poor vision as high glucose damages eyes.
Wonder if this is related.
fortran77
I hate to sound like one of those "Do Your Own Research" types, but as far as I can tell, there are only a few supplements that have repeatedly shown _some_ benefits in peer-reviewed replicated studies for general health:
Vitamin D, Omega 3, and possibly Magnesium and Creatine.
So I stopped taking a daily multivitamin and I just take modest doeses of these 4 supplemements every day.
yalok
Summary from GPT (wow, not sure about avoiding cheese & milk - sounds risky for calcium/bones health):
Omega-3 fats seem to protect against myopia, while saturated fats seem to increase the risk. Other nutrients didn’t show clear effects.
Foods rich in omega-3 (protective foods) • Fatty fish: salmon, mackerel, sardines, tuna, herring, anchovies • Seafood: oysters, mussels • Plant sources: flaxseeds, chia seeds, walnuts, hemp seeds • Oils: flaxseed oil, canola oil, soybean oil • Fortified foods: some eggs, dairy, or juices enriched with omega-3
Foods high in saturated fats (risk foods) • Fatty meats: beef, lamb, pork, processed meats (sausages, bacon) • Dairy: butter, cheese, cream, whole milk, ice cream • Baked goods: pastries, cookies, cakes made with butter or shortening • Fast foods: fried chicken, burgers, pizza • Coconut and palm oil products (though plant-based, they’re high in saturated fats)
So the takeaway is: More fish, nuts, and seeds may help protect children’s eyes, while too many fatty meats, butter, and fried foods may raise the risk of myopia.
angiolillo
> wow, not sure about avoiding cheese & milk - sounds risky for calcium/bones health
The importance of dairy is overblown, especially in the US where the dairy industry funds a lot of school nutrition initiatives. I helped out around a cousin's dairy farm as a kid but eventually discovered that I'm part of the ~2/3rds of the world population that doesn't digest dairy well.
You'll get calcium as long as you eat some white/navy beans, tofu, kale, okra, collards, broccoli raab, chia, or even "calcium fortified" foods.
alphazard
There has historically been a lot of flawed research about saturated fat. Sugar and fat together is always fattening, and being obese comes with a lot of risk.
> Summary from GPT
This whole post is filled with bad implicit advice. No one should stop eating meat to make their eyesight better. No one should add canola oil to their diet as a source of Omega 3.
adrian_b
Yeah, also soybean oil would be as useless as canola oil.
Among vegetable oils, flaxseed oil is the best source of ALA, while also walnut oil and hemp oil have decent amounts.
However many humans, especially many men, have a too low capacity for elongating ALA into DHA and EPA, so they may remain deficient in omega-3 fatty acids even when eating decent amounts of ALA from flaxseed oil or the like.
Because you normally do not know your own biosynthetic abilities, it is less risky to eat fish oil or Schizochytrium oil, instead of flaxseed oil.
AstroBen
> not sure about avoiding cheese & milk - sounds risky for calcium/bones health
Non-fat dairy. Greek yogurt + walnuts + berries
j45
Low/no-fat cheeses are available too.
The kitchen is a pharmacy.
rsync
"... wow, not sure about avoiding cheese & milk - sounds risky for calcium/bones health ..."
A disappointing level of knowledge and sophistication in this late, 21st century era.
Your bone health is almost entirely correlated to the load bearing exercise and gravity stress that you put on your musculoskeletal system.
Fine optimizations to your diet (just like fine optimizations everywhere in life) are only sensible after you've taken care of the big, macro factors.
privatelypublic
Milk/cheese is hardly the best/only source of calcium.
FollowingTheDao
Although high omega-3 with saturated fats may protect against the effect of only a diet high and saturated fats.
If I was not on my phone, I would look up the studies on this. :)
I have a fun omega-3 anecdata point going right now. A friend of mine researches the stuff in mouse models and told me it's extremely beneficial, but you need to buy a fancy brand to avoid rancid oil or heavy metal contamination both of which ~null out the benefits. She recommended Sports Research.
I bought some and started taking it and my 1:1 bullet chess ELO jumped from 850 to ~1070 over the next couple weeks.
I play chess a bit like sushi ginger for the mind - purge working memory with a short intense task to context switch. I intentionally don't study openings or anything so I can use it as a benchmark for mental horsepower with a reasonably slow drift in the baseline from 'actually learning chess'.
My friend says this effect is way too big to actually attribute to the vitamins and it has to be placebo etc but I'm thoroughly enjoying the idea that omega-3 Nick would win 3/4 bullet matches against deficient Nick.
https://www.chess.com/member/nickparkerprint/stats/bullet?da...