Young Ju, Ph.D.

Most types of fats are synthesized in the body, but omega-3 fatty acids are essential fatty acids which cannot be synthesized in the body and must be obtained from foods or supplements.  You may see the three main omega-3 fatty acids identified by their acronyms:  alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

Omega-3 Fatty Acid Food Sources (1,2)

Eating a variety of foods can provide adequate amounts of omega-3 fatty acids. After ingesting ALA-containing foods, a small amount of ALA is converted to EPA and DHA by multiple enzymatic reactions. The most common food sources of ALA are green leafy vegetables, flax seeds, chia seeds, and vegetable oils.  Flaxseed oil in particular contains high amounts of ALA.  EPA and DHA are found in high amounts in oily fishes, fish oils, and algae oils. (Food sources of ALA are shown in Table 1 and  ALA, EPA, and DHA in Table 2.)

Omega-3 Fatty Acid Supplements (3, 4)

Omega-3 fatty acid dietary supplements are one of the nonvitamin/nonmineral dietary supplements most commonly used by U.S. adults and children. Omega-3 fatty acids are available in several formulations, including fish oil, krill oil, cod liver oil, and algae oil.  Although doses vary, a typical fish oil supplement contains about 1 gram (=1,000 mg) fish oil, containing up to 30% of combined EPA and DHA (0.3 grams).  Some omega-3 supplements contain ALA (0.6 – 1.8 grams) with 0.5 – 10% of combined EPA and DHA. Some supplements contain just EPA and DHA (0.6 – 0.9 grams). 

Potential Health Benefits of Omega-3 Fatty Acids

Omega-3 fatty acids in food and dietary supplements have been extensively studied for their health benefits. Research studies have shown positive anti-inflammatory and antioxidant effects from fish oil and omega-3 supplementation.  Strong evidence of health benefits has been observed in human studies (3, 4) including: 

• In cardiovascular diseases, fish oil and omega-3 fatty acid supplements (0.8 – 1 gram/day) may reduce the risk of some cardiovascular disease, especially for people with existing coronary heart disease.

• In neurodegenerative diseases, fish oil and omega-3 fatty acid supplements (0.2 – 4 grams/day) may improve certain aspects of cognitive function, including attention, processing speed, and immediate recall for people with mild cognitive impairment.

• In rheumatoid arthritis, fish oil and omega-3 fatty acid supplements (at least 2.7 grams/day) may be helpful as a combinational treatment with prescription drugs for relieving the symptoms of rheumatoid arthritis. 

Omega-3 fatty acids have been shown similarly to impact the health and performance of athletes in numerous ways, including:

• management of inflammation

• enhancement of muscle recovery

• protection of brain health and function. 

In sports nutrition studies, omega-3 fatty acid supplementation (4 grams/day) may provide anti-inflammatory properties and be beneficial to the injured athlete (5, 6, and 7).  In athletic performance, EPA and DHA supplementation may improve endurance capacity and delay onset of muscle soreness (8).

How Much to Take

Recommended Daily Adequate Intake levels of omega-3 fatty acids are 1.1 grams for adult women (19 years and older) and 1.6 grams for men (9). Although recommendations vary widely, most health organizations recommend an intake of at least 0.25–0.5 grams of combined EPA and DHA.  A blood test called the Omega-3 Index can assess the amount of EPA and DHA in the body as a percent of total blood fatty acids (3,4). The ideal range is 8% or higher. The Omega-3 Index can be used as a biomarker for cardiovascular disease risk; suggested cutoffs are <4% (high risk); 4-8% (intermediate risk); >8% (low risk) (10). The average Omega-3 Index in American adults is around 5%. 

Essential fatty acid deficiency in healthy Americans is very rare. However, patients with nutrient mal-absorption conditions (e.g., certain types of cancer, gastrointestinal diseases, or HIV/AIDS, etc.) are at risk of omega-3 inadequacy.  Reported outcomes of omega-3 fatty acid deficiency are vision problems, sensory dysfunction, skin atrophy, and cognitive decline. 

Potential side effects of omega-3 supplements are mild including fishy taste, bad breath, bad-smelling sweat, headache, heartburn, nausea, and diarrhea.  EPA and/or DHA supplements at high doses may cause bleeding problems. Therefore, people who take blood-thinning medications should discuss possible interactions with their physicians. The FDA has concluded that EPA and DHA supplements at combined doses of up to about 5 g/day are safe.

REFERENCES

1. US Department of Agriculture ARS. USDA National Nutrient Database for Standard Reference, Release 26. Available at: http://www.ars.usda.gov/ba/bhnrc/ndl

2.Oregon State University. Omega-3 fatty acid content in fish. https://seafood.oregonstate.edu/sites/agscid7/files/snic/omega-3-content-in-fish.pdf

3. Office of Dietary Supplements, National Institute of Health. Omega-3 fatty acids. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/

4. Linus Pauling Institute. Micronutrient Information Center: Essential Fatty Acids https://lpi.oregonstate.edu/mic/other-nutrients/essential-fatty-acids#reference205

5. Joyce D. Sports Injury Prevention and Rehabilitation. Routledge; New York, NY, USA: 2015.

6. Smith et al. Omega-3 polyunsaturated fatty acids augment the muscle protein anabolic response to 

hyperinsulinaemia–hyperaminoacidaemia in healthy young and middle-aged men and women. Clin. Sci. 2011a, 21:267.

7.  Smith et al. Dietary omega-3 fatty acid supplementation increases the rate of muscle protein synthesis in older adults: A randomized controlled trial. Am. J. Clin. Nutr. 2011b, 3:402.

8. Thielecke F and Blannin A. Omega-3 Fatty Acids for Sport Performance-Are They Equally Beneficial for Athletes and Amateurs? A Narrative Review. Nutrients 2020, 12(12):3712

9.  Food and Nutrition Board, Institute of Medicine. Dietary Fats: Total Fat and Fatty Acids. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, D.C.: National Academies Press; 2002:422-541.

10.  Harris WS. The omega-3 index as a risk factor for coronary heart disease. Am J Clin Nutr.2008;87(6):1997S-2002S.

People with any other health problems should talk to their healthcare providers about fat intake. As always this information is provided for your reference and you use at your own risk; you should rely on your medical professional for medical advice.