The relationship between fish consumption and diabetes risk may be due to toxic pollutants that build up in the aquatic food chain.
Fish and Diabetes
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
In the past two years, six separate meta-analyses have been published on the relationship between fish consumption and type 2 diabetes. The whole point of a meta-analysis, though, is to compile together the best studies done to date, and see what the overall balance of evidence shows. The fact that there are six different ones published recently highlights how open the question remains. One thread of consistency, though, was that fish consumers in the United States tended to be at greater risk for diabetes.
If you include Europe too, then fish-eaters appeared to have a 38% increased risk of diabetes. On a per-serving basis, that comes out to be about a 5% increase in risk for every serving of fish one has per week. To put that into perspective, a serving of red meat is associated with a 19% increase in risk—but, that’s per day. Just one serving a week of fish is 5%, so a serving a day would be like a 35% increase in risk—worse than red meat, but why?
Well, fish intake and omega-3 fats may increase type 2 diabetes risk by increasing blood sugar levels, as found in a review of the evidence commissioned by the U.S. government. An increase in blood sugars in diabetics given fish oil. Or, it may be because the omega-3s cause “oxidative stress.” 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. Or, it may be because of the “environmental contaminants” that build up in fish.
It all started with Agent Orange. We sprayed twenty million gallons of the stuff on Vietnam, and some of it was contaminated with trace amounts of dioxins. Though the Red Cross there estimates a million Vietnamese were adversely affected, what about all the servicemen, the U.S. servicemen, who were exposed, spraying it across the countryside? Reports started showing up that veterans exposed to Agent Orange appeared to have higher diabetes rates than unexposed veterans—a link that’s now officially recognized.
These so-called “persistent organic pollutants…are mainly man-made [industrial] chemicals…, and…among the most hazardous compounds ever synthesized. [They] include…dioxins,…PCBs, and certain…chlorine-containing pesticides, [all of] which are highly resistant to [breaking down in the environment].”
“Initially described for their deleterious effect[s] on reproductive function” and their ability to cause cancer, “there is now [a] growing body of evidence showing that exposure to [these pollutants] leads to metabolic diseases,” such as diabetes. This is “a breakthrough that should require our greatest attention.”
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- M Zhang, E Picard-Deland, A Marette. Fish and Marine Omega-3 Polyunsatured Fatty Acid Consumption and Incidence of Type 2 Diabetes: A Systematic Review and Meta-Analysis. Int J Endocrinol. 2013 2013:501015 Epub 2013 Sep 8.
- C Lee, A Liese, L Wagenknecht, C Lorenzo, S Haffner, A Hanley. Fish consumption, insulin sensitivity and beta-cell function in the Insulin Resistance Atherosclerosis Study (IRAS). Nutr Metab Cardiovasc Dis. 2013 23(9):829 – 835.
- JS Zheng, T Huang, J Yang, YQ Fu, D Li. Marine N-3 polyunsaturated fatty acids are inversely associated with risk of type 2 diabetes in Asians: A systematic review and meta-analysis. PLoS ONE. 2012 7(9):e44525.
- DO Carpenter. Environmental contaminants as risk factors for developing diabetes. Rev Environ Health. 2008 23(1):59 – 74.
- JHY Wu, R Micha, F Imamura, A Pan, ML Biggs, O Ajaz, L Djousse, FB Hu, D Mozaffarian. Omega-3 fatty acids and incident type 2 diabetes: A systematic review and meta-analysis. Br J Nutr. 2012 107 - Suppl - 2:S214 – 27.
- A Wallin, D Di Giuseppe, N Orsini, PS Patel, NG Forouhi, A Wolk. Fish consumption, dietary long-chain n-3 fatty acids, and risk of type 2 diabetes: Systematic review and meta-analysis of prospective studies. Diabetes Care. 2012 35(4):918 – 929.
- J Ruzzin. Public health concern behind the exposure to persistent organic pollutants and the risk of metabolic diseases. BMC Public Health. 2012 12(20):298.
- J Ruzzin, DH Lee, DO Carpenter, DR Jacobs Jr. Reconsidering metabolic diseases: The impacts of persistent organic pollutants. Atherosclerosis. 2012 224(1):1 – 3.
- GL Henriksen, NS Ketchum, JE Micalek, JA Swaby. Serum dioxin and diabetes mellitus in veterans of operation ranch hand. Epidemiology. 1997 (3):252-258.
- Y Zhou, C Tian, C Jia. Association of fish and n-3 fatty acid intake with the risk of type 2 diabetes: A meta-analysis of prospective studies. Br J Nutr. 2012 108(3):408 – 417.
- P Xun, K He. Fish Consumption and Incidence of Diabetes. Diabetes Care. 2012 35(4):930–938.
- CH MacLean, WA Mojica, SC Morton, J Pencharz, RH Garland, W Tu, SJ Newberry, LK Jungvig, J Grossman, P Khanna, S Rhodes, P Shekelle. Effects of omega-3 fatty acids on lipids and glycemic control in type II diabetes and the metabolic syndrome and on inflammatory bowel disease, rheumatoid arthritis, renal disease, systemic lupus erythematosus, and osteoporosis. Evid Rep Technol Assess. (Summ) 2004 (89):1 – 4.
- VM Montori, A Farmer, PC Wollan, SF Dinneen. Fish oil supplementation in type 2 diabetes: a quantitative systematic review. Diabetes Care. 2000 Sep;23(9):1407-15. Review.
Images thanks to falco via Pixabay, Brian K. Grigsby via Wikimedia, and James Nachtwey via flickr
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
In the past two years, six separate meta-analyses have been published on the relationship between fish consumption and type 2 diabetes. The whole point of a meta-analysis, though, is to compile together the best studies done to date, and see what the overall balance of evidence shows. The fact that there are six different ones published recently highlights how open the question remains. One thread of consistency, though, was that fish consumers in the United States tended to be at greater risk for diabetes.
If you include Europe too, then fish-eaters appeared to have a 38% increased risk of diabetes. On a per-serving basis, that comes out to be about a 5% increase in risk for every serving of fish one has per week. To put that into perspective, a serving of red meat is associated with a 19% increase in risk—but, that’s per day. Just one serving a week of fish is 5%, so a serving a day would be like a 35% increase in risk—worse than red meat, but why?
Well, fish intake and omega-3 fats may increase type 2 diabetes risk by increasing blood sugar levels, as found in a review of the evidence commissioned by the U.S. government. An increase in blood sugars in diabetics given fish oil. Or, it may be because the omega-3s cause “oxidative stress.” 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. Or, it may be because of the “environmental contaminants” that build up in fish.
It all started with Agent Orange. We sprayed twenty million gallons of the stuff on Vietnam, and some of it was contaminated with trace amounts of dioxins. Though the Red Cross there estimates a million Vietnamese were adversely affected, what about all the servicemen, the U.S. servicemen, who were exposed, spraying it across the countryside? Reports started showing up that veterans exposed to Agent Orange appeared to have higher diabetes rates than unexposed veterans—a link that’s now officially recognized.
These so-called “persistent organic pollutants…are mainly man-made [industrial] chemicals…, and…among the most hazardous compounds ever synthesized. [They] include…dioxins,…PCBs, and certain…chlorine-containing pesticides, [all of] which are highly resistant to [breaking down in the environment].”
“Initially described for their deleterious effect[s] on reproductive function” and their ability to cause cancer, “there is now [a] growing body of evidence showing that exposure to [these pollutants] leads to metabolic diseases,” such as diabetes. This is “a breakthrough that should require our greatest attention.”
Please consider volunteering to help out on the site.
- M Zhang, E Picard-Deland, A Marette. Fish and Marine Omega-3 Polyunsatured Fatty Acid Consumption and Incidence of Type 2 Diabetes: A Systematic Review and Meta-Analysis. Int J Endocrinol. 2013 2013:501015 Epub 2013 Sep 8.
- C Lee, A Liese, L Wagenknecht, C Lorenzo, S Haffner, A Hanley. Fish consumption, insulin sensitivity and beta-cell function in the Insulin Resistance Atherosclerosis Study (IRAS). Nutr Metab Cardiovasc Dis. 2013 23(9):829 – 835.
- JS Zheng, T Huang, J Yang, YQ Fu, D Li. Marine N-3 polyunsaturated fatty acids are inversely associated with risk of type 2 diabetes in Asians: A systematic review and meta-analysis. PLoS ONE. 2012 7(9):e44525.
- DO Carpenter. Environmental contaminants as risk factors for developing diabetes. Rev Environ Health. 2008 23(1):59 – 74.
- JHY Wu, R Micha, F Imamura, A Pan, ML Biggs, O Ajaz, L Djousse, FB Hu, D Mozaffarian. Omega-3 fatty acids and incident type 2 diabetes: A systematic review and meta-analysis. Br J Nutr. 2012 107 - Suppl - 2:S214 – 27.
- A Wallin, D Di Giuseppe, N Orsini, PS Patel, NG Forouhi, A Wolk. Fish consumption, dietary long-chain n-3 fatty acids, and risk of type 2 diabetes: Systematic review and meta-analysis of prospective studies. Diabetes Care. 2012 35(4):918 – 929.
- J Ruzzin. Public health concern behind the exposure to persistent organic pollutants and the risk of metabolic diseases. BMC Public Health. 2012 12(20):298.
- J Ruzzin, DH Lee, DO Carpenter, DR Jacobs Jr. Reconsidering metabolic diseases: The impacts of persistent organic pollutants. Atherosclerosis. 2012 224(1):1 – 3.
- GL Henriksen, NS Ketchum, JE Micalek, JA Swaby. Serum dioxin and diabetes mellitus in veterans of operation ranch hand. Epidemiology. 1997 (3):252-258.
- Y Zhou, C Tian, C Jia. Association of fish and n-3 fatty acid intake with the risk of type 2 diabetes: A meta-analysis of prospective studies. Br J Nutr. 2012 108(3):408 – 417.
- P Xun, K He. Fish Consumption and Incidence of Diabetes. Diabetes Care. 2012 35(4):930–938.
- CH MacLean, WA Mojica, SC Morton, J Pencharz, RH Garland, W Tu, SJ Newberry, LK Jungvig, J Grossman, P Khanna, S Rhodes, P Shekelle. Effects of omega-3 fatty acids on lipids and glycemic control in type II diabetes and the metabolic syndrome and on inflammatory bowel disease, rheumatoid arthritis, renal disease, systemic lupus erythematosus, and osteoporosis. Evid Rep Technol Assess. (Summ) 2004 (89):1 – 4.
- VM Montori, A Farmer, PC Wollan, SF Dinneen. Fish oil supplementation in type 2 diabetes: a quantitative systematic review. Diabetes Care. 2000 Sep;23(9):1407-15. Review.
Images thanks to falco via Pixabay, Brian K. Grigsby via Wikimedia, and James Nachtwey via flickr
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Fish and Diabetes
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Content URLDoctor's Note
This is the first of a three-part video series on the role industrial pollutants may play in our diabetes epidemic. Stay tuned for Diabetes & Dioxins and Pollutants in Salmon & Our Own Fat.
For more on the changing views surrounding fish oil supplements, see Is Fish Oil Just Snake Oil?
Other foods associated with diabetes risk include processed meat and eggs; see Bacon, Eggs, & Gestational Diabetes During Pregnancy and Eggs & Diabetes—while Indian gooseberries and flax seeds may help (see Amla vs. Diabetes and Flax Seeds vs. Diabetes).
Other videos that touch on how polluted our oceans now include:
- Fukushima & Radioactivity in Seafood
- Food Sources of Flame-Retardant Chemicals
- DDT in Umbilical Cord Blood
- Food Sources of Perfluorochemicals
- Fish Intake Associated with Brain Shrinkage
- How Long to Detox from Fish before Pregnancy?
- Microplastic Contamination & Seafood Safety
- Are Microplastics in Seafood a Cancer Risk?
- How Much Microplastic Is Found in Fish Fillets?
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