Fish and fish oil consumption do not appear to protect against heart disease, arrhythmias, or sudden death, but why would they increase cancer risk?

Get the preface for Dr. Greger’s brand-new book, How Not to Diet, by subscribing to his free newsletter at

What? Fish oil doesn’t help with heart disease? I was as surprised as you. See: Is Fish Oil Just Snake Oil? (

In terms of PCB contamination, see Food Sources of PCB Chemical Pollutants ( and PCBs in Children’s Fish Oil Supplements ( Our oceans and waterways have become humanity’s sewer; everything eventually flows into the sea. For discussion of all the other industrial contaminants that build up in the aquatic food chain, see:
• Food Sources of Flame Retardant Chemicals (
• Food Sources of Perfluorochemicals (
• Fish and Diabetes (
• Diabetes and Dioxins (
• Pollutants in Salmon and Our Own Fat (
• Dioxins in U.S. Farm-Raised Catfish (
• Dietary Pollutants May Affect Testosterone Levels (
• Flame Retardant Pollutants and Child Development (
• Fish Consumption and Suicide (
• How Long to Detox From Fish Before Pregnancy (

For ways to decrease the risk of prostate cancer and slow its progression, see:
• Ex Vivo Cancer Proliferation Bioassay (
• Prostate Cancer and Organic Milk vs. Almond Milk (
• Flaxseed vs. Prostate Cancer (
• Eggs, Choline, and Cancer (
• Prostate Cancer Survival: The A/V Ratio (

Have a question for Dr. Greger about this video? Leave it in the comment section at and he’ll try to answer it!

Image Credit: Survivor via Pixabay.
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43 replies
  1. Freebase Vegan
    Freebase Vegan says:

    Dr. Greger, there's a troll in here called futurevideo10 spewing blatant misinformation and you'd be wise to block/ban/delete him, or at the very least correct each of his lies. I've no time for that, does anyone really? That's why they should be blocked/banned/deleted. They can use their own pages to spread their animal ag agenda.

  2. AxCYeR
    AxCYeR says:

    A little confused right now. Dr Greger should have pointed out more clearly that it's probably the pollutants that are causing all the bad effects and not EPA, DHA and others themselves. I use "Rx Omega-3" and thought this product was high quality and pretty pure, at least cleaner than all the cheap fish oil stuff you can buy. I should probably focus on getting my Omega-3s from organic high quality flaxseed oil though and just take one fish oil capsule daily for the EPA/DHA. Won't leave it out completely though. I'm avoiding so much other stuff that is definitely bad for us, should be alright.

  3. etmax1
    etmax1 says:

    Hmm I wonder why Japanese have such a high life expectancy then?? A lot of the earlier pro fish oil studies were based on populations that have a lot of fish in their diet??

  4. Anthony Porta
    Anthony Porta says:

    Michael Gregor completely took that study linking prostate cancer and fish oil out of context. He has alot of good information though at times his personal bias toward veganism is reflected in his videos. Gregor if your reading this, contact me so I can help shed some light on why the researchers in that study you looked at were entirely incorrect in publishing it. Dr. A

  5. Tallie Allen
    Tallie Allen says:

    So the take-home message is that omega-3's in and of themselves are putting you at risk for cancer or not?
    This video can cause some serious confusion for people who are dealing with cancer right now!!!

  6. watchtheskies
    watchtheskies says:

    Now I'm confused, Dr Greger it's not clear if you are saying that all long chain Omega 3 DHA EPA supplements are a bad idea?
    so should we stop taking the Algae derived DHA EPA supplement?

  7. Ivan B
    Ivan B says:

    I like the video, but this seems to implicate that dr. Greger is against the omega 3 fats altogether. As much as I like dr. Greger, I will say he tends to cherry-pick some of his studies. And this is not uncommon, its inherent human bias. Because the majority of research in omega 3 fats has been favorable. Many other studies have recommended vegans consume more omega-3 fats but from plant-based sources such as flaxseed, walnuts, chia seeds ext. But also algae omega-3 fats. I understand dr. Gregers position on algae and the potential neurotoxins, but I also believe these neurotoxins are a product of contamination and poor quality control and sourcing. More research needs to be done, but there have been many studies to refute the neurotoxin aspect in regards to spirulina and other algaes. In fact many studies have found benefits and others have done safety evaluations and found no sort of toxins. Which lends some evidence to the fact that it could be contaminated by what's in the water. But I understand dr. Greger taking a conservative stance on this. However, he has not mentioned any neurotoxins being in chlorella, just that it's more expensive then most greens we can get a grocery stores. I will look at all of his other videos on omega-3 fats, but I must say that this is potentially dangerous advice regarding avoidance. The conversion of LA from flaxseed and other sources is very inefficient even with the addition of turmeric. That said, it may be advisable to take a low-level supplement occasionally of algae omega-3 fats, the research certainly has supported it. But more importantly, low levels of these two omega-3 fats, DHA and EPA have been linked with health problems particular cognitive decline and other issues. So yes there needs to be more research, but this needs to speed up a little because this is definitely an important nutritional matter.

  8. Jon Topham
    Jon Topham says:

    low quality video! you missed the part in the prostate cancer paper where omega 3s were from the diet not supplementation! this is key because purity can be found in fish oil supplements

  9. Netinspired
    Netinspired says:

    the researchers who first concluded that fish oil is good for you because of omega-3s must be a bunch of nuts. the source is always important and fish is pretty far connected as far as homo sapiens is concerned. I mean we are originally a tropical being and should explore our physiological source for omega-3s which would come from greens and nuts. also the best way to imbibe these healthy fats is to consume the WHOLE food and not a highly processed source like fish oil which could definitely be carcinogenic given its tendency to rancidity like a whole bunch of market promoted unsaturated refined oils which have also been knocked off the health pedestal in recent years. go back a few years and weren't sunflower, soy, corn oil et al supposed to be very healthy because of their being highly unsaturated? well fish oil just joined their ranks of discredited, over hyped, slickly marketed SNAKE OILS.

  10. In Young Kim
    In Young Kim says:

    Look around!
    Under the name of religion, what human have been doing against each other. Acceptance, rather than rigidity is the key to peace but our ego and arrogance hinder to grow.

  11. sgtsnakeeyes11
    sgtsnakeeyes11 says:

    here goes dr greger grasping at straws again to spin the vegan narrative this time that fish aren't unhealthy despite mountains of evidence suggesting otherwise that he conveniently omits.

  12. Captain Planet
    Captain Planet says:

    i think the trick is always to take of little of everything and not to much of 1 thing.Evertday I consume 1 tbsp of ground flax, 1 tbsp chia seeds, 1 fish oils capsule (they recommend 3 on tub i have) and when i'm a millionaire i start consuming 1 algae based dha/epa oil a day. mix it up. little of each #variety

  13. Oblivion 1
    Oblivion 1 says:

    On a video you made I saw one of the sources you linked talking about prostate cancer and there is a line saying that men who ate salmon had no assoication with prostate cancer.

  14. Bramble Q123
    Bramble Q123 says:

    "I know of no reason why you shouldn’t resume taking your fish oil supplements. The study in question, from the Fred Hutchinson Cancer Research Center in Seattle, Wash., made headlines and snagged lots of sound bites, but much of the news coverage – including that in medical publications – did not accurately reflect the findings. Aside from the sensationalist way it was reported, the study itself has serious shortcomings." __

  15. Mr. S
    Mr. S says:

    THERE ARE COMMMENTS ABOUT CENSORSHIP ON YOUTUBE. I WOULD LIKE TO DO A LITTLE TEST. IS ANYONE HAVING PROBLEMS WATCHING "THE GREATER GOOD – REAL STORIES OF VACCINE INJURY" ?IT IS ABOUT GARDASIL AND THE HOW SOME GIRLS HAVE HAD HORRIBLE DEBILITATING PROBLEMS AFTER GETTING THE VACCINE. by the way amazing video by you Dr. Greger. I stopped eating meat after learning so much with your videos. very scary all the cover up an lies with junk science to confuse the public by certain entities to keep us fat, sick and anxious/depressed. great video by other creator is "transform your mind, change your brain" by dr. Richard j. Davidson. also "mingyur rinpoche~ calming the mind: the practice of awareness meditation". These two videos helped me get off Xanax and feel better than ever.

  16. energy fx
    energy fx says:

    it's not omega -3 which causes cancer ,it's PCB which found in fish oil causes cancer . so take vegan omega-3, like flax seed and it's really reduce the risk of heart stroke if you have taken it for very long period like more than a year.

  17. StrategicMadness
    StrategicMadness says:

    Trouble is there are other studies – what to believe? The DART study, published in 1989, was the first randomized trial to show the efficacy of fish oil on CAD. In the trial, 2033 post-MI patients were randomized to receive 3 types of diets: a diet that was either high in cereal fiber, polyunsaturated fat, or fish oil. The fish oil group consumed 200 to 400 g/wk of fatty fish (2 portions of fish per week) or 0.5 g/d of Maxepa fish oil supplement. At 2 years, the primary end point of all-cause mortality was reduced by 29% in the fish oil group, whereas no improvement was seen in the other dietary advice groups.

    The Lyon Diet Heart Study, performed shortly after the DART study, was a prospective trial of 607 survivors of MI who were randomized to either a Mediterranean diet or a regular Western diet. At a mean follow-up of 27 months, the primary end point of death from cardiovascular causes and nonfatal deaths had a 73% relative risk reduction—a positive effect that continued at follow up assessment at a mean of 46 months.


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