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Omega-3 Fatty Acids: Side Effects and Food Sources

Summary

Omega-3 fatty acids, essential fats the body cannot produce on its own, are crucial for heart health, brain function, and reducing inflammation. They are commonly found in fatty fish like salmon, mackerel, and sardines, as well as in flaxseeds, chia seeds, and walnuts. Despite their benefits, consuming high doses of omega-3 supplements can lead to side effects such as gastrointestinal issues, increased bleeding risk, and potential interactions with medications.

A piece of salmon with black text Description automatically generated

Continuing with our series of talks on omega-3. Today we will discuss the side effects and sources for individuals that have food restrictions. You may remember that the adequate daily intake for various age groups and genders ranges from 0.5 g – 1.6 g daily ALA intake. Most of the studies that target cardiovascular system improvements, cancers, brain health, etc. use 1g or greater than 1g of DHA and EPA for a daily dose. ALA in our body converts to DHA and EPA by only 1-5%. Hence, in my opinion the daily adequate intake of ALA 1.6 g for adults is not sufficient. It means about 16 mg of DHA and EPA which is a far cry from what we need to realize omega 3’s full potential.

Previously Covered Topics in This Series:

  1. Omega-3 to Omega-6 ratio. Does it matter? [8]
  2. Omega-3 sources and the quantities needed. [9]

Side Effects of Omega-3 Fatty Acids

While omega-3 fatty acids are generally considered safe and beneficial, excessive intake can lead to some side effects:

Bleeding

High doses of omega-3s can increase the risk of bleeding, particularly in people who take blood-thinning medications or have bleeding disorders. The reason is that the DHA and EPA have mild tendency to reduce platelet aggregation. On the flip side, this effect is potentially beneficial for cardiovascular health. This effect also is dose dependent and is observed more at 3g/day intake. Having said that a systemic review published in 2017 found no impact on bleeding tendency before or after surgery. [7]

Gastrointestinal Issues

Some people may experience nausea, diarrhea, indigestion, or bloating.

Allergic Reactions

Rarely, omega-3 supplements (especially fish oil) can cause allergic reactions.

Vitamin A Toxicity

High doses of fish liver oils (rich in omega-3s) can lead to vitamin A toxicity due to high vitamin A content. For example, one tablespoon of cod liver oil (14 gm) has more than 400% of the daily vitamin A required dose. [4, 5]

Vitamin E Deficiency

Studies have shown that prolonged regular use (more than 2 months) of fish oil can result in lower vitamin E levels in young individuals. The mechanism behind this is that the DHA and EPA are susceptible to free radical attacks. Vitamin E acts as a scavenger to neutralize the free radicals. Vitamin E also inserts itself in the cell membrane to protect the omega 3. Result is a deficiency of vitamin E. This is why many fish oil supplements add vitamin E to the servings. [6]

Metal Contamination

Some fish oil supplements may contain trace amounts of heavy metals like mercury, though reputable brands test for and minimize these contaminants.

Omega-3 Food Sources for Different Diets

1. Vegans:

  • Flaxseeds and Flaxseed Oil: Rich in alpha-linolenic acid (ALA), a type of omega-3.
  • Chia Seeds: Also high in ALA.
  • Hemp Seeds: Good source of ALA.
  • Walnuts: Contains ALA.
  • Algal Oil: Derived from algae, it’s a direct source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

2. Vegetarians:

  • Flaxseeds, Chia Seeds, Hemp Seeds, Walnuts: As listed for vegans.
  • Algal Oil: Similar to vegans, for direct DHA and EPA.
  • Perilla Oil: Another plant-based oil rich in ALA.

3. Regular Food Eaters (Omnivores):

  • Fish and Seafood: Salmon, mackerel, sardines, anchovies, and herring are rich in EPA and DHA.
  • Flaxseeds, Chia Seeds, Walnuts: Plant-based sources of ALA.
  • Eggs: Some eggs are fortified with omega-3s.
  • Grass-Fed Meat and Dairy: These can have higher levels of omega-3s compared to conventional meat and dairy.

4. Carnivores:

  • Fatty Fish: Salmon, mackerel, sardines, anchovies, and herring.
  • Grass-Fed Meat: Contains higher levels of omega-3 compared to grain-fed meat.
  • Organ Meats: Some organ meats, like liver, can contain small amounts of omega-3s.

References

  1. Omega-3 Fatty Acids – Health Professional Fact Sheet https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/ 
  2. Fish oil – Mayo Clinic https://www.mayoclinic.org/drugs-supplements-fish-oil/art-20364810 
  3. Omega-3 Fatty Acids: An Essential Contribution – The Nutrition Source https://nutritionsource.hsph.harvard.edu/what-should-you-eat/fats-and-cholesterol/types-of-fat/omega-3-fats/ 
  4. Food Data Central  https://fdc.nal.usda.gov/fdc-app.html#/food-details/173577/nutrients 
  5. 8 Little-Known Side Effects of Too Much Fish Oil https://www.healthline.com/nutrition/fish-oil-side-effects#TOC_TITLE_HDR_2 
  6. Effect of long-term fish oil supplementation on vitamin E status and lipid peroxidation in women – PubMedhttps://pubmed.ncbi.nlm.nih.gov/1826131/
  7. No impact of fish oil supplements on bleeding risk: a systematic review – PubMed
    https://pubmed.ncbi.nlm.nih.gov/28552094/
  8. Omega-6 to Omega-3 Ratio – DrBeen https://www.drbeen.com/articles/omega-6-to-omega-3-ratio/
  9. Omega-3 Sources and Daily Quantity – DrBeen on YouTube https://www.youtube.com/watch?v=DcN0tRb7KQ4
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