Omega-3 Nutrition Summary for Dietitians

omega-3 nutrition

This article will summarize the must-know information about omega-3 nutrition and fish oils for registered dietitians. Dietitian Success Center’s membership includes access to vitamin & mineral supplement guides, a comprehensive yet simplified reference for finding the best supplements for your clients.

Written by Miranda Galati, RD 
Reviewed by Olivia Farrow, RD, MHSc


Omega-3 Nutrition Summary for Dietitians

The two main classes of polyunsaturated fats (PUFAs) are omega-3 fatty acids (omega-3s) and omega-6 (omega-6s) fatty acids (1). While both play important roles in the body, omega-3s are particularly important for health (1).

There are three different types of omega-3 fatty acids (1):

  • Alpha-linolenic acid (ALA): present in plant oils such as flaxseed, soybean and canola oils.
  • Eicosapentaenoic acid (EPA): present in fish oils, krill oils and phytoplankton.
  • Docosahexaenoic acid (DHA): present in fish oils, krill oils and phytoplankton.

“Fish oil” refers to omega-3 supplements containing mostly EPA and DHA (2). This specific combination of omega-3s has been studied extensively for its health benefits. Fish oil may include supplements derived from fish or those that have been artificially manufactured (2).

Omega-3s are considered essential, which means we need to consume them from food or supplements to obtain adequate amounts in the body (3). ALA can be converted to DHA and EPA in the liver, but only in negligible quantities (2).


Omega-3 Nutrition: Amounts Needed

In both Canada and the United States, dietary reference intakes (DRIs) have been established for ALA, but not EPA or DHA (14). No upper limits have been established for omega-3s (14). 

DSC’s omega-3 supplement guide includes an overview of some omega-3 dose recommendations. 


Omega 3 Deficiency

Essential fatty acid deficiency (omega-3 and/or omega-6) is rare (1). No cut-offs have been established for plasma concentrations of EPA or DHA, so inadequacy or deficiency is difficult to determine (1).

Symptoms of omega-3 nutrition deficiency may include rough, scaly skin and dermatitis (1). Although low omega-3 status may play a role in mental health, dry eyes, joint health and more, there is insufficient evidence to suggest that the presence of these ailments signals an omega-3 deficiency (1).


Omega-3 Nutrition Tips To Increase Intake

The Dietary Guidelines for Americans suggest the following to increase intake of omega-3s in the diet (1):

  • Consume 8 ounces (about 2 palm-sized portions) or more of fish or seafood per week.
  • Choose fish or seafood highest in EPA and DHA and low in mercury, such as salmon, anchovies, sardines, Pacific oysters, and trout
  • Women who are pregnant, may become pregnant, or breastfeeding should consume 8 to 12 ounces (about 2-3 palm-sized portions) of low mercury fish or seafood per week.

The most recent Canada’s Food Guide does not detail recommended fish intake for Canadians in regards to omega-3 nutrition (5). Previous recommendations suggested 150 grams (about 2 palm-sized portions) or more of fish or seafood per week with additional precautions around mercury (6).


Food Sources 

A diet rich in omega-3 nutrition can be sufficient for most healthy individuals (1). The following tables share food sources of omega-3s, listed in order of highest to lowest concentration (1).

Food Sources of ALA 

Food Serving ALA (grams)*
Flaxseed oil 1 Tbsp 7.26 
Chia seeds 1 ounce (~2 Tbsp) 5.05 
English walnuts 1 ounce (~14 halves) 2.57 
Flaxseed, whole 1 Tbsp 1.6
Canola oil  1 Tbsp  1.28 
Soybean oil 1 Tbsp  0.92 
Black walnuts 1 ounce (~14 halves) 0.76 
Mayonnaise 1 Tbsp  0.74 
Edamame frozen  ½ cup prepared 0.28 
Refried beans, vegetarian ½ cup  0.21 

(178) *Values are approximate.

Food Sources of EPA and DHA

Food Serving DHA (grams)* EPA (grams)*
Salmon, atlantic, farmed 3 ounces, cooked(~ 1 palm) 1.24  0.59 
Samon, atlantic, wild 3 ounces, cooked(~ 1 palm) 1.22 0.35 
Herring, atlantic 3 ounces, cooked(~ 1 palm) 0.94  0.77 
Sardines, canned in oil ½ cup, drained 0.76 0.71
Mackerel, atlantic 3 ounces, cooked(~ 1 palm) 0.59  0.43 
Salmon, pink, canned and drained 3 ounces, drained(~ 1 palm) 0.63  0.28 
Trout, rainbow, wild 3 ounces, cooked(~ 1 palm) 0.44  0.40 
Oysters, eastern, wild, cooked 3 ounces, cooked(~ 1 palm) 0.18 0.23
Sea bass, cooked 3 ounces, cooked(~ 1 palm) 0.18 0.47

(178) *Values are approximate.


Different Types of Supplements

DSC’s omega-3 & fish oil supplement summary includes information on the different types of supplements available including:

  • Fish oil
  • Krill oil vs cod liver oil
  • Algae based omega 3
  • Flaxseed oil

Algae omega 3 benefits those following a vegetarian or vegan diet (9). However, algae based dha epa levels may differ from fish oils.


Contraindications for Omega-3 Supplementation

Individuals taking any medications affecting blood clotting or who have an allergy to fish or shellfish should consult their healthcare provider prior to beginning fish oil supplements (910).


Safety and Further Guidance

Regulation of dietary supplements differs in Canada and the United States. Anyone choosing to consume an omega-3 or other dietary supplement should consider the following precautions:

  • In the United States, consult with a third-party organization that tests supplement quality and claims, such as, NSF International, or U.S. Pharmocopeia (USP) (11). 
  • In Canada, look for an 8-digit Natural Product Number (NPN) or Homeopathic Medicine Number (DIN-HM) on the label to ensure it has been reviewed by Health Canada for safety, effectiveness and quality (12). 

DSC’s omega-3 supplement guide includes a thorough omega-3 supplement reference chart with the different types of omega-3 supplements available, such as algae based omega 3, and an overview of the benefits and disadvantages of each, including krill oil antioxidants. Brand examples and cost comparisons are also included in the omega-3 supplement reference chart for dietitians.


Omega-3 Nutrition: Take-home Messages for Dietitians

  • The 3 different types of omega-3s are ALA from plants, EPA from fish and seafood, and DHA from fish and seafood.
  • Fish oil supplements contain a blend of EPA and DHA. Fish oil is the form of omega-3 supplement best studied for its potential health benefits.
  • Adequate omega-3 consumption can be achieved through diet by eating 2 palm-sized portions of fatty fish per week.
  • Fish oil supplements are considered low risk for most people, except individuals taking any medications affecting blood clotting.

At DSC, we make it easier for dietitians and dietetic students to build expertise in topics including omega-3 and fish oil supplements. Our vitamin and mineral supplement guides, nutrition courses, ready-to-use client handouts, and community can help you feel more confident. 

Dietitian Success Center is THE professional development resource for dietitians and dietetic students. Our mission is to make it easier for dietitians and dietetic students to build expertise. We do this through evidence-based online nutrition courses, community, and ready-to-use client handouts. Plus – we give you the tools to start and grow your dietitian private practice! 



  1. National Institutes of Health (NIH). 2021. “Office Of Dietary Supplements – Omega-3 Fatty Acids.”  National Institutes of Health . March 26, 2021.
  2. 2021. “Fish Oil: Summary Of Scientific Research.” Examine.Com. January 6, 2021.
  3. Alberta Health Services. 2016. “Omega-3 Fats for Heart Health.” Alberta Health Services. January 2016.
  4. Health Canada. 2006. “Dietary Reference Intakes.” Government of Canada. June 29, 2006.
  5. Government of Canada. 2019. “Appendix B: Summary Of Guidelines And Considerations.” Canada Food Guide. January 22, 2019.
  6. Health Canada. 2010. “Eating Well With Canada’s Food Guide.” Food and Nutrition. March 4, 2010.
  7. “Canadian Nutrient File (CNF) – Search By Food.” n.d. Government of Canada. Accessed May 20, 2021.
  8. “FoodData Central.” n.d. U.S. Department of Agriculture. Accessed May 20, 2021.
  9. Hopp, Craig, and David Shurtleff. 2018. “Omega-3 Supplements: In Depth.” National Center for Complementary and Integrative Health (NCCIH). May 2018.
  10. Bays, Harold E. 2007. “Safety Considerations with Omega-3 Fatty Acid Therapy.” The American Journal of Cardiology 99 (6): S35–43. 10.1016/j.amjcard.2006.11.020.
  11. National Institutes of Health (NIH). 2020. “Office Of Dietary Supplements – Dietary Supplements: What You Need To Know.” Office of Dietary Supplements. September 3, 2020.
  12. Government of Canada. “Licensed Natural Health Products Database (LNHPD) .” January 4, 2019.

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