Doctor's Note

This is the first of a 3-part video series on the role industrial pollutants may play in our diabetes epidemic. Stay tuned for Diabetes and Dioxins and Pollutants in Salmon and Our Own Fat.

More on the changing views surrounding fish oil supplements in Is Fish Oil Just Snake Oil?

Other foods associated with diabetes risk include processed meat and eggs. See Bacon, Eggs, and Gestational Diabetes During Pregnancy and Eggs and Diabetes, while Indian gooseberries and flaxseeds may help (Amla Versus Diabetes and Flaxseed vs. Diabetes).

Other videos on how polluted our oceans now are include:

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  • Joevegan

    Thank you Dr. Greger and staff. I’ve been eating a WFPB diet for almost 3 years now and your work helps me to make prudent choices.

    • Thea

      Joevegan: Thanks for your note. It’s so nice to hear when the site has helped people. Good luck to you.

  • DGH

    I would like to echo my appreciation. The main reason I do not consume fish is for ethical reasons; our civilization has declared a full-scale war on fish species in the oceans.

    My understanding though from the literature is that consumption of oily fish and in particular the omega-3 PUFA present in oily fish (salmon, tuna, etc) actually lowers the risk of atherosclerotic coronary artery disease. This would be contrary to the effects on diabetes incidence. How does one reconcile these differences?

    I suppose the DART and DART-2 trials, particularly their long-term follow-up reports, did definitively show no benefit of recommending avid fish consumption for preventing heart attacks or death.

  • magicoyote

    Dr Greger, how about contamination risk in products like algae- derived omega 3 supplements? Is it a concern as well?

    • Thea

      magicoyote: I’m not a definitive source for this question, but it is my understanding that algea-derived DHA and EPA pills (as of now) come from algea grown in a controlled tank in a factory – not gathered from wild sources. So, to my thinking, assuming they started off with pure materials, contamination risk would be almost non-existent.

      • magicoyote

        wow, I had no idea! but that makes sense, thanks! and thanks for your amazing work. This is the best website on the internet for real information I can trust!

  • robert

    I wonder, are you beginning to question the recommendation to supplement the vegan diet with omega 3’s derived from algae? This is something that has long been marketed and recommended by Dr. Fuhrman. If I take this oil at the recommended dose I get some rather impressively colored bruises. I have the notion that my blood should stay in my veins, so I have stopped this practice.

  • Kitsy Hahn

    ” A recent study found that the insulin producing cells in the pancreas
    don’t appear to work as well in people who eat two or more servings of
    fish a week.”

    What’s that they say about change being the only thing permanent? It was only a matter of time before the “eat two or more servings of fish a week” advice got skewered too. Other foods have had their turn. But then, fish did receive a lot more than a mere 15 minutes worth of fame.

    • mike at the river

      Questions of contamination aside, do algae based DHA/EPA supplements affect the B cells (insulin producing cells) in the pancreas?

      • Kitsy Hahn

        Hey dude, you talkin’ to me? :-)

      • Darryl

        To my knowledge, there aren’t any studies on algal DHA/EPA and insulin resistance, metabolic syndrome, diabetes, or pancreatic β-cell function function. In general, there appears to be an inverse association of dietary and plasma n-3 fatty acids with metabolic syndrome in humans, which most authors attribute to inhibition of inflammation (a pathway for muscular insulin resistance and β-cell death).

        This cohort study tried to disentangle the ω3’s from the contaminants in inflammation markers, and supports Dr. Greger’s theory. Similarly this study found crude salmon oil caused metabolic syndrome in rats, but refined salmon oil (with the contaminants removed) did not. One older study that found marine oil impaired pancreatic insulin production, but its not at all clear whether the fish oil was refined to remove POPs.

  • HemoDynamic, M.D.

    I would change the last sentence in the last article you quoted from, “SHOULD require our greatest attention.” to, “DEMANDS our greatest attention!”
    Well put together!

  • Andreas

    i am so glad to have found this site. thank you so much!

  • PlantBasedMama

    This article mentions that people living in southern states (the “Stroke Belt”) are significantly more likely to eat two or more servings of fried fish a week. I wonder if the analyses have taken into consideration the cooking methods most common among the “two or more servings a week” groups.

    • My question exactly.

      • It is interesting that “reductionistic” thinking and research is coming up with alot of ideas for the cause of type 2 diabetes… in this case omega 3 & dioxin. The science clearly supports that high fat consumption is associated with diabetes and obesity. You can view other video’s on this site relating to diabetes. I think especially relevant is which highlights the work of Dr. Neal Barnard’s research (he is the founder and leader of PCRM) which demonstrates a low fat diet is the best treatment for type two diabetes… vegans need to avoid oils and minimize nuts at least until they are off medications and their fasting sugars have returned to normal range. Since fish is so high in fat it should be avoided regardless of cooking methods and it is not a surprise that fish consumption is related to type two diabetes.

        • Simon

          Why are the Japanese healthier than us when their diet is mostly fish?

          • Toxins

            The okinawan population of Japan did not eat alot of fish, their diet was mostly sweet potato. As Jeff Novick has shared:

            Caloric Restriction, the Traditional

            Okinawan Diet, and Healthy Aging

            The Diet of the World’s Longest-Lived People and Its Potential Impact on Morbidity and Life Span

            Ann. N.Y. Acad. Sci. 1114: 434–455 (2007).

            TABLE 1. Traditional dietary intake of Okinawans and other Japanese circa 1950

            Total calories 1785

            Total weight (grams) 1262

            Caloric density (calories/gram) 1.4

            Total protein in grams (% total calories) 39 (9)

            Total carbohydrate in grams (% total calories) 382 (85)

            Total fat in grams (% total calories) 12 (6)

            Saturated fatty acid 3.7

            Monounsaturated fatty acid 3.6

            Polyunsaturated fatty acid 4.8

            Total fiber (grams) 23

            Food group Weight in grams (% total calories)


            Rice 154 (12)

            Wheat, barley, and other grains 38 (7)

            Nuts, seeds Less than 1 (less than 1)

            Sugars 3 (less than 1)

            Oils 3 (2)

            Legumes (e.g., soy and other beans) 71 (6)

            Fish 15 (1)

            Meat (including poultry) 3 (less than 1)

            Eggs 1 (less than 1)

            Dairy less than 1 (less than 1)


            Sweet potatoes 849 (69)

            Other potatoes 2 (less than1)

            Other vegetables 114 (3)

            Fruit less than 1 (less than 1)

            Seaweed 1 (less than 1)

            Pickled vegetables 0 (0)

            Foods: flavors & alcohol 7 (less than 1)

            Data derived from analysis of U.S. National Archives, archived food records, 1949 and based on survey of 2279 persons.

            Some points

            Their diet was 85% carb, and 6% fat. Sweet potatoes (a Japanese sweet potato) made up almost 70% of their calories. Nuts were less than 1% of calories (the equivalent of 1/10 of an ounce a day) Oil was less than 2% of calories (which is about 1 tsp a day) and sugars were less than 1% of calories (less than a tsp a day)

            The total animal products including fish was less than 4% of calories which is less then 70 calories a day. That is the equivalent of around 2 oz of animal products or less a day

  • Jkr

    Isn’t everything on earth, including fruit and vegetables, subject to pollutants???

    • Thea

      Jkr: Yes, you are right, but that is not the whole story. It is important to keep in mind a phenomenon called bio-accumulation. What this means is that pollutants accumulate/get more concentrated the higher up the food chain you go.

      This is a general principal, so I would guess that there are plenty of exceptions. But in general, what this means is that you can minimize your exposure as much as possible by eating lower on the food chain – ie, eating plants rather than animals like fish.

      Hope that helps.

    • Most of the persistent organic pollutants are fat soluble. They accumulate more in organisms with high fat… vegetables, fruit, complex carbohydrates and beans are low in fat. The point Thea makes below is a good one. Bioaccumulation occurs naturally but is worse in commercial animal feeding practices where the by catch of fish and products from slaughtering operations are fed back to animals. You want to make sure that you wash your produce to remove any residual pesticides or chemicals.

      • guest

        What about nuts and seeds that are high in fat. Wouldn’t they accumulate POP’s for so than low-fat plant sources?

  • If this is true, why does the American Diabetes Association recommend people eat MORE seafood:

    • nat

      Most likely so you can get sick, go to the hospital and give them money to keep you staying sick by taking a bunch of their “medicine”.. Its all about $$$

      Also, its not necessarily consuming seafood that is bad, (free of contaminations, it’s good for you!) but humans have polluted this world soo badly, in this particular case, the seafood..which comes from water… and we all know how much the water has been contaminated.. even worse now, hundreds of tons of contaminated water from the fukushima nuclear reactor are being dumped into the pacific ocean. Nuclear experts are telling US gov’t to test west coast waters and pacific seafood sold in the US, yet they refused to do so. Why would they refuse? There’s so much the mainstream media is keeping from you, but if you keep searching for answers in the right places, you will find.. keep in mind, you definitely will never find any truths from government sources, since they tried to convince people at one point that consuming any contaminated fish is safe.

  • Skeptical

    The Zhang reference says that seafood is protective against diabetes. For oily fish it says for every 80 grams consumed results in a 20 percent decrease in type 2 diabetes. I am going to look at the other references more clearly now.

  • Steve

    I guess Dr. Gregor has not heard of all of the “peer review” studies that have been done showing the benefits of “DPA” (a component of Omega 3 fatty acids) that were done “which did not rely on Greenland eskimo heart disease reports”.Eg. DPA lowers the risk of acute coronary events by 44%, DPA prevents formation of tumor-feeding blood vessels, DPA inhibits platelet aggregation better than DHA, DPA plays a role in slowing down dementia, DPA reduces genetic inflammation, DPA reduces genetic-based fat production, DPA & DHA reduce plaque formation.

    I learned this from one who, for “decades”, has worked with a Scientific Advisory Board (probably the very first scientific advisory board ever formed–by the company that coined the concept of a SAB). These scientists are of such high caliber that they always receive invitations to attend the most prestigious meetings “where new science breaks” The Greenland Eskimo data is “old hat” as far as they’re concerned. These scientists “cite studies done with people”, not just examine Greenland Eskimo data.

    As for the “pollutants”, this company (GNLD) is a “world leader” in product analysis and manufacture (has access to the most advanced laboratories worldwide), and is WELL CAPABLE of analyzing fish components for ANY toxin. They have a tolerance of 0% (anything detectible is DISCARDED).

    I honestly don’t know where this guy gets his data from, but sometimes I wish people would simply stop making generalizations, and talking out of their butts.

    • Tom Goff

      “I sometimes wish people would simply stop making generalizations, and talking out of their butts.”
      Amen!. And you believe everything about fish oil you are told by people who make their living selling fish oil? You don’t think that they may possibly have a conflict of interest?

  • Sebastian Tristan

    My girlfriend and I, we take vegan DHA supplements because we’re thinking about having a child. Will the vegan DHA – an Omega 3 fatty acid – put us at risk of developing diabetes?

  • Bobby5939

    Good lord,

    The asian culture thrives on fish, and look at them. Before anyone says “they have diabetes too”, that only started 25 years ago with the introduction of many Western Fast food traditions. Beyond that, they have us beat in health by a nautical mile.

  • kohl donovan

    this article is a joke. study doctor jack kruse. I’ve been eating raw meats and fish for a year now and my blood tests are far better than any vegan I’ve ever known, not to mention professional athletes.

    • Tom Goff

      I think the joke’s on you. Try Googling “Jack Kruse quack”.

      And yeah, the guy on the Twinkie Diet got really good test results too ….

      • Kohl Donovan

        Just looked at it, the people complaining about kruse are the simpletons who can’t grasp what he is saying at a quantum level, and no, the guy that ate twinkies did not have good test results. Lol.

        • Tom Goff

          You and reality haven’t been on speaking terms for some time then?

  • susan hu

    With vegan diet, how much fat should I consume? Dr. Barnard suggests very very fat intake, not even olive oil, avocado or walnuts. What do you think, Dr. Greger?

  • susan hu

    very low fat intake by Dr. Barnard.

  • What about eating boiled oysters? They should have much less heavy metals than predatory fish. And most of the heavy metals are in the hard part of oysters that humans do not eat.
    I just orderer some “Crown Prince Natural, Boiled Whole Oysters, Packed In Water, 8 oz (226 g)”. I plan to eat oysters to get more copper. My Blood Ceruloplasmin which measures copper is low and eating cashew nuts does not seem to help, although cashew nuts in average contain a lot of copper.

  • dtraist

    I am hoping Dr. Gregger or someone can reconcile why the Pescatarian group which also inlcuded egg/dairy eaters: “10% are pesco-vegetarian (Eat fish, milk and eggs but no red meat or poultry)” in the Adventist Health Studies lived the longest.

    Everything I read here (and in other areas) indicates fish is as bad as meat in many areas. Thus, the Adventist results contradict this as the “fish-eaters” outlived the Vegans

    “The adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs non-vegetarians was 0.88 (95% CI, 0.80–0.97). The adjusted HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73–1.01); in lacto-ovo–vegetarians, 0.91 (95% CI, 0.82–1.00); in pesco-vegetarians, 0.81 (95% CI, 0.69–0.94); and in semi-vegetarians, 0.92 (95% CI, 0.75–1.13) compared with nonvegetarians.”

    Am I missing something as this large trial of comparably matched subjects contradicts Dr. Greggor and other citations? Thank you!

    • payoung

      Hi dtraist, I agree, you are interpreting the data correctly. The thing I think is important to realize is that even in the non vegan groups the consumption of animal products is on average only about two servings per week which is significantly less than what the average meat eater would consume. So in effect these people still eat a mostly plant based diet. Now when you couple that with the other positive lifestyle factors that this group embodies like being physically active, low stress, community support etc. it essentially negates any of the potentially negative effects that animal products may possess. I often have patients who are resistant to giving up all animal products and I use this study as an example and tell them that if they are able to get everything else in their life right, and only eat animals once or twice a week they might be able to get away with it. (of course this is also provided they don’t already have some chronic illness they are trying to overcome…which by the way, is most often not the case or they wouldn’t be seeing me).