Many people equate eating fish with doing something good for their health. This may be due to the illusion that fish swim in clean waters, or to the fact that they have a very different shape and form than the land animals we use for food. There even seems to be a deeply ingrained notion that aquatic animals are not part of the animal kingdom classification and that consuming fish is similar to—and just as beneficial as—consuming plant foods.
So, should we be eating fish to promote health?
Four Major Problems With Fish
1. Animal protein and IGF-1
Just like the proteins in dairy, eggs, and meat, the protein in fish also contains a higher proportion of essential amino acids, which results in our bodies producing increased levels of the hormone IGF-1 (insulin-like growth factor 1).[i] [ii] [iii]
IGF-1 stimulates cell division and growth, and it is associated with cancer proliferation and malignancy. The role of IGF-1 in cancer promotion is well understood, and animal protein, including fish, is associated with increased circulating levels of this hormone (and thereby with increased risk of cancer development).[iv] [v] [vi] [vii] [viii]
2. Cholesterol and saturated fat
While fish is frequently touted for its preformed long-chain omega-3 fatty acids (EPA and DHA), it is important to note the following:
- Although some fish contain a small (but nutritionally adequate) amount of these essential nutrients, most of the remaining fats in fish meat are saturated fats and cholesterol which (despite popular opinion to the contrary) are highly associated with cardiovascular disease.
- For example, three ounces of bass has some 74 milligrams of cholesterol, about the same as the 75 milligrams of cholesterol found in a 3-ounce serving of beef.[ix]
- Fish only contain omega-3 fatty acids because they get them from the plants they eat. Omega-3 is found in whole plants like nuts, seeds, beans, vegetables and fruits in adequate amounts.
- As humans, we do not need to eat any cholesterol in our diets, as our bodies synthesize all the cholesterol we need for our physiologic functions. Eating cholesterol despite this fact can be problematic for our health, as it increases our risk of developing heart disease.
3. Contaminants and pollutants
Fish are very commonly the subject of health risk advisories, the majority of which are caused by contamination of their ocean habitat with heavy metals like mercury, industrial byproducts like dioxin and PCBs (polychlorinated biphenyls), and pesticides/insecticides like chlordane and DDT.[x]
A recent study sampled fish from around the world and found unsafe levels of mercury in up to 84 percent of them (and the situation promises to only get worse, as mercury emissions are continuing to increase on a global scale.[xi])
Mercury is a neurotoxic heavy metal that is difficult to eliminate from the body once ingested. It can cause a wide variety of neurologic disturbances and can inhibit normal cardiac physiology when it accumulates in the heart muscle.[xii] It also has the capacity to cross the placenta barrier in pregnant women and can cause central nervous system damage to a developing fetus.[xiii]
4. What fish doesn’t have
Another important factor to consider beyond the dangerous qualities of fish (animal protein, cholesterol, fat, and toxins), is what it lacks. Fish, like beef and other meats, is also missing fiber, beneficial carbohydrates, healthy phytochemicals, and macronutrients in the right proportions, which makes it a poor choice as a health-promoting food.
But Fish Is “Less Bad” Than Red Meat, Right?
In some respects, fish does appear to be less disadvantageous to health than some other animal foods. However a food doesn’t become a health food just because it may have less severe problems as compared with something else that’s even more harmful to our body. In terms of weight, diabetes risk, and other important health indicators, researchers find that fish eaters might do better than meat eaters as a group, but they don’t do nearly as well as plant-based eaters.
In Conclusion …
Consumption of fish should not be encouraged from a health perspective, given not only its unacceptable levels of mercury, dioxin, and PCBs (the toxicity of which is well established), but also the cholesterol and saturated fat content, and the inherent increased cancer risk associated with animal protein in general.
The ideal (or “gold standard”) diet from a health standpoint remains a whole-food, plant-based diet, which means eating vegetables, grains, legumes, nuts, fruits, and seeds, while excluding animal food (like fish).
This is a fortuitous fact too, because plant-based foods are also generally far easier to produce, use less water, and generate a significantly lower environmental footprint than do animal foods. In contrast, the practice of obtaining animal foods (including fish) for human consumption devastates the environment on many different fronts, and is simply not sustainable at current and ever-growing demand levels.)
[i] MF McCarty. Vegan proteins may reduce risk of cancer, obesity, and cardiovascular disease by promoting increased glucagon activity. Med Hypotheses. 1999 Dec.; 53(6): 459-85.
[ii] NE Allen, PN Appleby, GK Davey, R Kaaks, S Rinaldi, TJ Key. The associations of diet with serum insulin-like growth factor I and its main binding proteins in 292 women meat-eaters, vegetarians, and vegans. Cancer Epidemiol Biomarkers Prev. 2002 Nov.; 11(11):1441-8.
[iii] NE Allen, PN Appleby, GK Davey, TJ Key. Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men. Br J Cancer. 2000 Jul.; 83(1):95-7.
[iv] LD Youngman, TC Campbell. Inhibition of aflatoxin B1-induced gamma-glutamyltranspeptidase positive (GGT+) hepatic preneoplastic foci and tumors by low protein diets: evidence that altered GGT+ foci indicate neoplastic potential, Carcinogenesis. 1992 Sept.; 13(9):1607-13.
[v] GE Dunaif, TC Campbell. Relative contribution of dietary protein level and aflatoxin B1 dose in generation of presumptive preneoplastic foci in rat liver. J Natl Cancer Inst. 1987 Feb.; 78(2):365-9.
[vi] TC Campbell. Dietary protein, growth factors, and cancer. Am J Clin Nutr 2007; 85:1667.
[vii] D Ornish, G Weidner, WR Fair, R Marlin, EB Pettengill, CJ Raisin, S Dunn-Emke, L Crutchfield, FN Jacobs, RJ Barnard, WJ Aronson, P McCormac, DJ McKnight, JD Fein, AM Dnistrian, J Weinstein, TH Ngo, NR Mendell, PR Carroll. Intensive lifestyle changes may affect the progression of prostate cancer. J Urol. 2005 Sept.; 174(3):1065-9; discussion 1069-70.`
[viii] DL Kleinberg, TL Wood, PA Furth, AV Lee. Growth hormone and insulin-like growth factor-I in the transition from normal mammary development to preneoplastic mammary lesions. Endocr Rev. 2009 Feb.; 30(1):51-74. doi: 10.1210/er.2008-0022. Epub 2008 Dec 15.
[ix] United States Department of Agriculture, Agricultural Research Service. National Nutrient Database for Standard Reference. Release 27. Available here (accessed Sept. 26, 2015).
[x] United States Environmental Protection Agency NLFA Advisories Where You Live User’s Guide.Available here (accessed Sept. 9, 2015).
[xii] Aschner M, Aschner JL. Mercury Neurotoxicity: Mechanisms of Blood-Brain Barrier Transport. Neurosci Biobehav Rev. 1990 Summer; 14(2):169-76. Available here (accessed Sept. 26, 2015); see also Azevedo BF, et al. Toxic Effects of Mercury on the Cardiovascular and Central Nervous Systems. J Biomed Biotechnol. 2012; 2012: 949048. Available here (accessed Sept. 26, 2015).
[xiii] Gundacker C, Hengstschlager M. The Role of the Placenta in Fetal Exposure to Heavy Metals. Wien Med Wochenschr. 2012;162:201-206.