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Fish, Mercury, Omega-3 and Pregnancy
Fish and mercury
Certain fish contain significant amounts of contaminants such as mercury, which can interfere with the baby’s optimal development. For this reason, some fish are to be favored over others. Here are a few guidelines:
- Light canned tuna can be eaten liberally, whereas canned albacore tuna should be limited to a maximum of 150 g or 5 oz per week and fresh or frozen tuna should be limited to a maximum of 150 g or 5 oz per month.
- King mackerel has a high mercury content and should be limited, but other types of mackerel are minimally contaminated and are an excellent source of DHA.
- Other fish to limit given their high mercury content are shark, swordfish, marlin, mahi mahi, pike, bass, bar (yellow bass), walleye, lake trout (touladi) and muskellunge.
- The fish that are the richest in omega-3 and can be eaten liberally are blue mackerel, salmon, trout (except for lake trout), sardines and herring.
Omega-3 and vegan diet
In the case of a vegan diet, the nutritional intake is often rich in omega-6 but poor in omega-3. This disproportion decreases the transformation of ALA into DHA. To meet the needs of omega-3, it is necessary to increase the amount of omega-3 consumed and to decrease that of omega-6. The main sources of plant-based omega-3 (ALA) are flaxseed, canola, and camelina oil, flaxseed and chia seeds, soybeans and walnuts. The body can convert ALA to DHA, but the conversion rate is low, at only 2 to 4%. So, for example, 1000 mg of ALA provides only about 20 to 40 mg of DHA. Thus, vegan women should prioritize plant-based foods rich in omega-3, but should also consume a vegan omega-3 supplement made from algae during pregnancy and breastfeeding.
SOSCuisine’s Pregnancy and Breastfeeding meal plans have been designed to optimize the intake of omega-3 during these important phases of life.
References
- Middleton et coll. (2018) Omega‐3 fatty acid addition during pregnancy. Cochrane Database Syst Rev; Issue 11.
- Carlson. Nutrition Gaps in pregnancy : The Role of DHA and Choline for Mother and Child. FNCE 2019.
- U.S. Food and Drug Administration (FDA) Advice about Eating Fish for Women Who Are or Might Become Pregnant, Breastfeeding Mothers, and Young Children. (Updated July 2019) https://www.fda.gov/food/consumers/advice-about-eating-fish
- Dietitian team from the Montreal Diet Dispensary: How to ensure an adequate omega-3 intake during pregnancy? (Updated April 19,2016) 2020).https://www.dispensaire.ca/en/posts/ensure-adequate-omega-3-intake/
- Health Canada (2009). Prenatal Nutrition Guidelines for Health Professionals: Fish and Omega-3 Fatty Acids. https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/fn-an/alt_formats/hpfb-dgpsa/pdf/pubs/omega3-eng.pdf
- American Pregnancy Association (2021) Omega 3 Fish Oil and Pregnancy. https://americanpregnancy.org/healthy-pregnancy/pregnancy-health-wellness/omega-3-fish-oil-and-pregnancy/
- Adam et coll. (2022) Evidence based recommendations for an optimal prenatal supplement for women in the US: vitamins and related nutrients. Maternal Health, Neonatology and Perinatology;8(4).
- Quebec Gouvernement (2022) Fish consumption recommendations
https://www.quebec.ca/en/health/nutrition/healthy-eating-habits/fish-consumption-and-health/recommendations - Dietitian team from the Montreal Diet Dispensary: Should fish be avoided during pregnancy because of its contaminants? (Updated June 1, 2021). https://www.dispensaire.ca/en/posts/should-fish-be-avoided-contaminants/
- Dietitian team from the Montreal Diet Dispensary: I don’t eat fish. How can I be certain I eat enough omega-3 during my pregnancy? (Updated Novemebre 30, 2020) https://www.dispensaire.ca/en/posts/dont-eat-fish-enough-omega-3/
Author
Kathryn holds a Bachelor Degree in Nutrition as well as a Bachelor and a Master Degree in Kinesiology, all from Laval University. She is a Registered Dietitian and active member of the Ordre professionnel des Diététistes Nutritionnistes du Québec (ODNQ) and of the American Academy of Nutrition and Dietetics. She holds the Monash University's certification for the FODMAP diet and IBS, and has considerable clinical experience in that area. She is also an accomplished athlete, having ran track and cross-country at a national level. Kathryn specializes in sports nutrition, weight loss, diabetes, as well as heart and gastrointestinal health.
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