ę Her Majesty the Queen in Right of Canada, represented by the Minister of Health Canada
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Cat. No.: H164-109/4-2009E-PDF (PDF Version)
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Canada's Food Guide recommends that Canadians consume at least 150 grams (5 ounces) of cooked fish each week as part of a healthy pattern of eating. Experts around the world agree with this recommendation (WHO/FAO, 2003; US 2005 Dietary Advisory Committee, 2005; UK Scientific Advisory Committee on Nutrition, 2005; European Food Safety Authority, 2005). Yet, many women may avoid eating fish altogether because of concerns about the safety of fish intake during the pregnancy.
Some types of fish contain environmental contaminants like methyl mercury (Forsyth et al, 2004). However, in general, the majority of fish sold in Canada have levels of mercury far below the maximum limitFootnote 1 set by Health Canada (Dabeka et al, 2004). Health professionals play an important role in encouraging women of childbearing age to eat fish regularly and in informing them about the types of fish to choose most often to limit exposure to environmental contaminants.
Key messages on fish for women of Childbearing Age
Vary the types of fish you eat and follow advice from Health Canada to limit your exposure to environmental contaminants such as mercury. The recommended intake for some predatory fish is less than 150 grams (5 ounces) per month. Refer to Health Canada's website. Consult local, provincial or territorial governments for information about eating locally caught fish. Environment Canada's website provides useful links.
Experts agree that fish can contribute to a healthy diet during pregnancy (UK Scientific Advisory Committee on Nutrition, 2005; European Food Safety Authority, 2005; IOM, 2007; Kris-Etherton et al, 2007). The benefits of eating fish are greater than not eating fish, when pregnant womenFootnote 2 choose the recommended types and amounts (IOM, 2007).
Women who eat fish while pregnant give their growing fetus important nutrients. Fish is a unique choice among the Meat and Alternatives food group because of its fat profile; compared to other choices, fish is generally lower in saturated fats and higher in the long chain polyunsaturated omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Fish also contains high quality protein and other essential nutrients: vitamins (such as vitamin D and choline) and minerals (such as selenium, iodine, iron, zinc and copper). (See table 1.)
Several observational studies have shown a positive association between higher intakes of fish than is typically consumed by North American women and small increases in gestational length (Olsen et al, 2006; Guldner et al, 2007; IOM, 2007; Haugen et al, 2008) as well as an association between higher intakes of fish and higher indices of child neurodevelopment (Hibbeln et al, 2007; IOM, 2007; Oken et al, 2008). Higher intakes of fish, however, can increase a woman's exposure to contaminants. The types and amounts of contaminants differ among the types of fish and other seafood consumed; exposure to some contaminants may have negative effects on infant outcome (Oken et al, 2005; Guldner et al 2007; Halldorsson et al, 2007). Women should therefore be advised to eat fish during pregnancy and to choose those fish known to have lower levels of contaminants (see next sections).
|Food||Content per 75 g (cooked)|
|Total fat (g)||ALA (mg)||DHA (mg)||EPA
|IronTable 1 footnote a (mg)||Magnesium (mg)||Potassium (mg)||Zinc (mg)||Selenium (mcg)||Vitamin D
Table 1 footnotes
|Salmon, Atlantic, farmed||9.26||85||1093||518||1.88||0.26||22||288||0.32||31||5.10|
|Sockeye salmon, canned||7.58||65||835||554||1.75||0.67||21||262||0.58||26.6||14.62|
|Rainbow trout, farmed||5.40||62||615||250||1.58||0.25||24||331||0.37||11.2||4.79|
|Jack mackerel, canned||4.72||32||597||326||1.39||1.53||28||146||0.76||28.3||4.72|
|Coho salmon, wild||3.22||41||494||301||0.79||0.28||23||326||0.42||28.5||12.67|
|Rainbow trout, wild||4.36||140||390||351||1.21||0.28||23||336||0.38||9.9||5.25|
|Halibut, Greenland (Turbot)||13.3||41||378||506||2.33||0.64||25||258||0.38||35.1||14.25|
|Omega-3 enriched eggs||9||n/a||150||n/a||2.25||n/a||n/a||n/a||n/a||n/a||n/a|
|Light tuna, canned||0.62||2||167||35||0.18||1.15||20||178||0.58||60.3||0.91|
|Chicken, dark meat||7.30||68||38||8||1.99||1.00||17||180||2.10||13.5||0.07|
Source: Amounts are approximate, based on Canadian Nutrient File, 2007b, with the exception of omega-3 enriched eggs (Sindelar et al, 2004).
Note: Meat from ruminants (cows, lamb, goats) is naturally low in DHA.
Health Canada recommends that women continue eating at least 150 grams (5 ounces) of cooked fish each week during pregnancy, as recommended in Canada's Food Guide. Health Canada also suggests that women pay special attention to the types of fish they eat. Since many pregnancies are unplanned, the advice presented in this document also applies to all women of childbearing age, including breastfeeding women.
Women should choose the types of fish that generally have low levels of contaminants, such as salmon, trout, herring, haddock, canned light tuna, pollock (Boston bluefish), sole, flounder, anchovy, char, hake, mullet, smelt, Atlantic mackerel and lake white fish.
Some types of fish contain contaminants such as methyl mercury. Women who eat too much of these types of fish can ingest too many contaminants. Health Canada issues retail fish consumption advisories. Advisories on local fish are available from provincial and territorial agencies. Environment Canada maintains a listing of authorities that are responsible for implementing fish consumption advice in each province and territory.
Women can limit the exposure to contaminants by choosing fish that generally do not contain levels that pose a health risk.
Methyl mercury is an organic form of mercury. It is the form of mercury found in fish. Toxicity can occur in humans exposed to methyl mercury. This form of mercury is particularly toxic to the central nervous system, with the developing infant brain being particularly sensitive. Methyl mercury can cross the placenta.
Fish accumulate methyl mercury from the surrounding water. Carnivorous fish also accumulate methyl mercury from the prey that they eat. This means that the amount of mercury in fish increases with the size and age of fish and with the type of food that the fish eats. Generally, predatory fish contain higher levels of methyl mercury. These fish include fresh and frozen tuna, shark, swordfish, marlin, orange roughy and escolar (Forsyth et al, 2004).
To minimize mercury exposure from fish, Health Canada has issued specific advice for women who are or may become pregnant as well as breastfeeding women to limit their intake of tuna (fresh and frozen), shark, swordfish, marlin, orange roughy and escolar to no more than 150 grams (5 ounces) per monthFootnote 3.
Health Canada also advises women who are or may become pregnant as well as breastfeeding women to limit their intake of canned (white) albacore tuna to no more than 300 grams (10 ounces) per weekFootnote 4. This advice does not apply to canned light tuna. Canned light tuna contains other species of tuna such as skipjack, yellowfin, and tongol, which are low in mercury. Pregnant women (and all others) do not have to limit the amount they eat of these types of canned tuna.
Health Canada monitors the concentrations of various chemicals in foods, including Polychlorinated Biphenyls (PCBs), in its ongoing Total Diet Study surveys. In addition, in 2002, Health Canada undertook a specific survey on farmed and wild caught fish and seafood products sold at the retail level. Based on these assessments, Health Canada has determined that Canadians are not exposed to PCBs and other contaminants in fish and seafood products sold in Canada at levels that pose a health risk, and that there is no need for specific consumption advice at this time (Tittlemier et al, 2004; Rawn et al, 2006).
Women need more omega-3 fatty acids in pregnancy (IOM, 2002). Omega-3 fatty acids are transferred across the placenta and play an important role in the growth and development of the infant.
There are different types of omega-3 fatty acids in the diet. The omega-3 fat, alpha-linolenic acid (ALA) is found in some vegetable oils, nuts and seeds. These include canola oil, flax oil, walnut oil, walnuts and flax seeds. Our bodies can convert ALA into other omega-3 fats including docosahexaenoic acid (DHA). DHA and another omega-3 fatty acid, eicosapentaonoic acid (EPA) are found only in animal tissue lipids. The Institute of Medicine has established Dietary Reference IntakesFootnote 5 values for ALA but not for EPA or DHA (IOM, 2002).
The best source of EPA and DHA is fatty fish; although DHA is found in other animal tissue lipids like eggs (see Table 1). DHA is an important omega-3 fatty acid in the brain. During pregnancy, DHA is transferred from the mother across the placenta and accumulates in the growing fetal brain and other tissues. After birth, DHA is transferred through breast milk. Dietary DHA contributes to the mother's DHA status, and pregnant and breastfeeding women with higher intakes of DHA transfer more DHA to their fetus, and supply more DHA in their breast milk (IOM, 2007).
Whether or not current diets provide sufficient ALA, or if ALA can be adequately converted to supply enough DHA during pregnancy and lactation, is uncertain (Plourde and Cunnane, 2007). While higher intakes of fish during pregnancy and breastfeeding have been linked to better infant and child development (see earlier section Fish contributes to a healthy pregnancy), there is no evidence that women who follow a healthy diet and eat no fish, such as lacto-ovo vegetarians, are at risk for pregnancy complications or poor child development.
Fish oil supplements and DHA enriched foods can provide important omega-3 fatty acids found in fish. However, there is insufficient evidence to draw any conclusion on the effects of fish oil supplements and DHA enriched foods on infant development (IOM, 2007). Additionally, the benefits of omega-3 fatty acids on complications of pregnancy (such as pre-eclampsia) remain uncertain, while research on omega-3 fatty acids and post-partum depression is incomplete (Makrides et al, 2006; Freeman, 2006; IOM, 2007; Freeman et al, 2008; Rees et al, 2008; Su et al, 2008).
Many women in Canada eat less fish than is recommended in Canada's Food Guide. Health professionals play an important role in providing information on healthy food choices and relaying appropriate messaging about contaminants in food. They can make women aware of the benefits of eating fish, as part of a healthy diet, and provide guidance on the types of fish to choose for limiting exposure to environmental contaminants like methyl mercury.
Points to review when talking with women about the benefits of fish:
Points to review when talking with women about limiting exposure to contaminants:
Points to review when talking to women who take fish oil supplements:
Dabeka R, McKenzie AD, Forsyth DS, Conacher HBS. 2004. Survey of total mercury in some edible fish and shellfish species collected in Canada in 2002. Food Additives and Contaminants 21(5):434-40.
European Food Safety Authority. 2005. Opinion of the Scientific Panel on Contaminants in the Food Chain on a Request From the European Parliament Related to the Safety Assessment of Wild and Farmed Fish. The EFSA Journal 236:1-118.
Forsyth DS, Casey C, Dabeka RW, McKenzie A. 2004. Methylmercury levels in predatory fish species marketed in Canada. Food Additives and Contaminants 21(9):849-56.
Freeman MP. 2006. Omega-3 fatty acids and perinatal depression: A review of the literature and recommendations for future research. Prostaglandins Leukot Essent Fatty Acids. 75(4-5):291-7.
Freeman MP, Davis M, Sinha P, Wisner KL, Hibbeln JR, Gelenberg AJ. 2008. Omega-3 fatty acids and supportive psychotherapy for perinatal depression: a randomized placebo-controlled study. J Affect Disord, 110(1-2):142-8. Epub 2008 Feb 21.
Guldner L, Monfort C, Rouget F, Garlantezec R, Cordier S. 2007. Maternal fish and shellfish intake and pregnancy outcomes: A prospective cohort study in Brittany, France. Environ Health 6:33.
Halldorsson ThI, Meltzer HM, Thorsdottir I Knudsen V, Olsen SF. 2007. Is high consumption of fatty fish during pregnancy a risk factor for fetal growth retardation? A study of 44,824 Danish pregnant women. Am J Epidemiol 166(6):687-96.
Haugen M, Meltzer HM, Brantsaeter AL, Mikkelsen T, Osterdal ML, Alexander J, Olsen SF, Batteteig L. 2008. Mediterranean-type diet and risk of preterm birth among women in the Norwegian Mother and Child Cohort Study (MoBa): a prospective cohort study. Acta Obstet Gynecol Scand 87(3):319-324.
Health Canada. 2007. Canadian Standards ("Maximum Limits") for Various Chemical Contaminants in Foods. Available online: http://www.hc-sc.gc.ca/fn-an/securit/chem-chim/contaminants-guidelines-directives-eng.php (Accessed March 11, 2009)
Hibbeln JR, Davis JM, Steer C, Emmett P, Rogers I, Williams C, Golding J. 2007. Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study. Lancet 369(9561):578-85.
Institute of Medicine. 2002. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients) (Washington DC: National Academy Press).
Institute of Medicine. 2007. Seafood Choices: Balancing Benefits and Risks. Committee on Nutrient Relationships in Seafood Selections to Balance Benefits and Risks (Washington DC: National Academies Press). Available online (Accessed March 10, 2009).
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Oken E, Østerdal ML, Gillman MW, Knudsen VK, Halldorsson TI, Strøm M, Bellinger DC, Hadders-Algra M, Michaelsen KF, Olsen SF. 2008. Associations of maternal fish intake during pregnancy and breastfeeding duration with attainment of developmental milestones in early childhood: a study from the Danish National Birth Cohort. Am J Clin Nutr 88(3):789-96.
Oken E, Wright RO, Kleinman KP, Bellinger D, Amarasiriwardena CJ, Hu H, Rich-Edwards JW, Gillman MW. 2005. Maternal fish consumption, hair mercury, and infant cognition in a U.S. cohort. Environ Health Perspect 113(10):1376-80.
Olsen SF, Østerdal ML, Salvig JD, Kesmodel U, Henriksen TB, Hedegaard M, Secher NJ. 2006. Duration of pregnancy in relation to seafood intake during early and mid pregnancy: prospective cohort. Eur J Epidemiol 21(10):749-58.
Plourde M, Cunnane S. 2007. Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements. Appl Physiol Nutr Metab 32(4):619-34.
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Su KP, Huang SY, Chiu TH, et al. 2008. Omega-3 fatty acids for major depressive disorder during pregnancy: results from a randomized, double-blind, placebo-controlled trial. J Clin Psychiatry 69(4):644-51.
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Health Canada sincerely thanks the members of the Expert Advisory Group on National Nutrition Pregnancy Guidelines who generously gave their time and expertise over the course of preparing these guidelines:
Aline Allain-Doiron, RD, Public Health Nutritionist-Dietitian, Regional Health Authority B, Zone 7
AndrÚe Gruslin, MD, FRCS, Director of the Post-graduate Residency Training Program in Obstetrics and Gynaecology, University of Ottawa
Sheila M. Innis, RD, PhD, Director of Nutrition Research Program, Child and Family Research Institute, University of British Columbia
Kristine G. Koski, RD, PhD, Director School of Dietetics and Human Nutrition, McGill University
Michel Lucas, PhD, MPH, RD, Epidemiologist/Nutritionist, Axe SantÚ des populations et environnement, Centre Hospitalier de l'UniversitÚ Laval (CHUL-CHUQ)
Ann Montgomery, RM, associate midwife and preceptor, Midwifery Collective of Ottawa
Deborah L. O'Connor, RD, PhD, Director of Clinical Dietetics, The Hospital for Sick Children, and Associate Professor, Department of Nutritional Sciences, University of Toronto
Kay Yee, RD, Public Health Nutritionist, Regina Qu'Appelle Health Region
Health Canada would also like to thank the many stakeholders who took part in the online consultation process and provided feedback on draft content of the guidelines.
The maximum limit set by Health Canada is 0.5 ppm in edible portion of all retail fish, with six exceptions: 1 ppm total mercury for the edible portion of escolar, orange roughy, marlin, fresh and frozen tuna, shark, and swordfish (Health Canada, 2007).
Pregnant women should thoroughly cook fish and seafood, including refrigerated smoked products. Eating raw or partially cooked fish and seafood increases the risk of contracting a food-borne illness such as listeriosis.
Recommendations for children and for adults in general are available on Health Canada's website: Mercury
Recommendations for children are available on Health Canada's website: Mercury in Fish
The Dietary Reference Intakes (DRIs) are a comprehensive set of nutrient reference values for healthy populations that can be used for assessing and planning diets. DRIs are established by Canadian and American scientists through a review process overseen by the U.S. National Academies, which is an independent, nongovernmental body.
Environment Canada maintains a listing of authorities that are responsible for implementing fish consumption advice in each province and territory.
Health Canada maintains a listing of provincial and territorial health ministries.
Although fish oil supplements are associated with cardiovascular health benefits, fish is still the preferred choice during pregnancy because it contributes nutrients other than omega-3 fatty acids to the healthy eating pattern.
According to Health Canada's Multi-vitamin/mineral supplement monograph, the vitamin A content per daily dose must not exceed the UL for vitamin A.