Omega-3 Content in Seafood Products

By: Daniel Imperiale

Last Updated: Aug 8, 2022

Seafood products are often lauded for their omega-3 content, which can support all kinds of health goals. But what exactly are omega-3s, and how do you balance the nutritional components of certain kinds of seafood with known toxins like mercury?

Here, we’ll take a close look at specific seafood options to see which ones offer you the most benefits and the least risk.

What are omega-3s?
What are the health benefits of omega-3s?
Can you have too many omega-3s?
Balancing mercury and omega-3s in seafood
Sustainable seafood consumption
References

Fatty acids are building blocks for fat, which is important for our bodies’ continued survival. There are multiple fatty acids, several of which are included under the omega-3 umbrella. Two major omega-3s are found in seafood: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). A third common omega-3, alpha-linolenic acid (ALA), resides in plant oils you find in nuts and seeds.¹ And other omega-3s, such as docosapentaenoic acid (DPA), are becoming more interesting as we learn about them.

ALA is the only one that’s an essential fatty acid, which means your body can’t make it on its own. Your body can break ALA down into EPA and DHA, but not in sufficient amounts compared to what you can get from seafood.²

Omega-6 and omega-9 fatty acids also play important roles in our health. Omega-6s even play a crucial part in your body’s utilization of omega-3s. But unlike omega-3s, omega-6s actually promote inflammation, so you want to get the minimum amount necessary for your health without triggering excess inflammation. According to some research, the ideal ratio of omega-3s to omega-6s is 1:1, but the average Western diet is more than 15:1 omega-6s to omega-3s.¹¹

Omega-9 fatty acids are particularly important for healthy skin. The body can make enough of these to keep your skin healthy if you have enough omega-3s and omega-6s in your system, but a deficiency of omega-9s can have unpleasant consequences like dandruff, dry skin and eyes, and even hair loss. That leads many to supplement or seek our foods rich in omega-9s, just to be on the safe side. Some of those foods include:

• Avocados
• Olives
• Sesame oil
• Almonds
• Peanuts
• Macadamia nuts
• Pecans
• Pistachio nuts
• Cashews
• Hazelnuts

Omega-3 fatty acids boast various health benefits that are widely studied and agreed upon among much of the scientific community. They include benefits for:

• Heart health³
• Depression⁴
• Vision⁵
• Alzheimer’s⁶
• Cancer prevention⁷
• Arthritis⁸
• Stroke prevention⁹
• Neonatal and infant development¹⁰

The heart health benefits that omega-3s offer are particularly impressive. One meta-analysis of 14 clinical studies — each of which boasted over 1,000 participants — showed decreases in major adverse cardiac events, myocardial infarction, and stroke.³

As good as omega-3s are for you, it is possible to have too much of them. That said, any side effects associated with omega-3s are mild and far from life-threatening. They may include:

• Bad breath
• Unpleasant taste in the mouth
• Nausea
• Diarrhea
• Heartburn
• Stomach discomfort
• Headaches
• Smelly sweat

These side effects usually occur only in instances where individuals chronically consume more than 5g/day of omega-3s. That’s the equivalent of about nine ounces of king salmon every day. If you get the majority of your omega-3s from seafood, you may need to be more concerned about mercury than anything else.

Generally speaking, mercury concentrations in seafood increase as you move up the food chain. That typically means that larger fish contain more mercury than smaller fish. However, the same is not true of omega-3s. A better indicator of omega-3 concentration than size is the darkness of a fish’s flesh (not the scales, but what’s underneath). That means fish like salmon, herring, mackerel, and bluefish will have significantly more fat content than fish like cod, pollock, or flounder. And most of that fat content is omega-3 fatty acids.

Here’s a look at the kinds of seafood with the highest omega-3 content and their corresponding mercury levels. Even with bountiful omega-3s, you should eat seafood that’s high in mercury no more than a few times per month and moderate your consumption of seafood with medium levels. You can eat seafood with low levels of mercury freely.¹²

These kinds of seafood have far fewer omega-3s in them. However, the ones with low levels of mercury are still safe to eat as great sources of healthy fat and lean protein.

The EPA has additional resources you can use to navigate healthy seafood options. Most fish and krill oil supplements are processed in a way that removes traces of heavy metals, so if you’re worried about your mercury consumption, a supplement might better support your peace of mind.

Even if you realize you need to eat more fish to up your omega-3 intake and balance out your omega-6 to omega-3 ratio, there’s still one potential hangup: sustainability. Some fisheries create significant environmental impact from trawling behaviors that can destroy reefs and catch and kill unintended species to the industry’s carbon footprint as a whole.

Fortunately, there are a few sources you can rely on for up-to-date information about which kinds of seafood and areas of production offer the most sustainability and support for the continued health of our oceans.

• The Ocean Conservancy offers various resources and a well-written blog that can guide you toward sustainable seafood consumption.
• The National Oceanic and Atmospheric Administration fishery division provides data and resources for individuals and businesses, including the full text of the U.S. law governing fishery sustainability in federal waters.
• Fish Watch allows you to search fish by name to see everything from current fishery management to taste profiles.

[1] National Center for Complementary and Integrative Health. (2018, April). Omega-3 Supplements: In Depth. National Institutes of Health, US Department of Health and Human Services. https://www.nccih.nih.gov/health/omega3-supplements-in-depth

[2] Office of Dietary Supplements. (2022, July 18). Omega-3 Fatty Acids Fact Sheet for Consumers. National Institutes of Health, US Department of Health and Human Services. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-Consumer/

[3] Shen, SC., Gond, C., Jin, KQ., Zhou, L., Xiao, Y., Ma, L. (2022, February 3). Omega-3 Fatty Acid Supplementation and Coronary Heart Disease Risks: A Meta-Analysis of Randomized Controlled Clinical Trials. Frontiers in Nutrition. https://doi.org/10.3389/fnut.2022.809311. Retrieved July 25, 2022 from https://www.frontiersin.org/articles/10.3389/fnut.2022.809311/full

[4] Wani, A.L., Bhat, S.A., Ara,A. (2015, September). Omega-3 fatty acids and the treatment of depression: a review of scientific evidence. Integrative Medical Research, 4(3): 132–141. doi: 10.1016/j.imr.2015.07.003. Retrieved July 25, 2022 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5481805/

[5] Zhang, A.C., Singh, S., Craig, J.P., Downie, L.E. (2020 April). Omega-3 Fatty Acids and Eye Health: Opinions and Self-Reported Practice Behaviors of Optometrists in Australia and New Zealand. Nutrients, 12(4): 1179. doi: 10.3390/nu12041179. Retrieved July 25, 2022 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230711/

[6] Ajith, T.A. (2018). A Recent Update on the Effects of Omega-3 Fatty Acids in Alzheimer’s Disease. Current Clinical Pharmacology, 13(4):252-260. doi: 10.2174/1574884713666180807145648. Retrieved July 25, 2022 from https://pubmed.ncbi.nlm.nih.gov/30084334/

[7] Freitas, R.D.S., Campos, M.M. (2019, May) Protective Effects of Omega-3 Fatty Acids in Cancer-Related Complications. Nutrients, 11(5): 945. doi: 10.3390/nu11050945. Retrieved July 25, 2022 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566772/

[8] Arthritis Foundation. (2015, July 29). The Benefits of Omega-3 Fatty Acids for Arthritis. Arthritis Today Magazine. http://blog.arthritis.org/living-with-arthritis/omega-3-fatty-acids-arthritis/

[9] Ueno, Y., Miyamoto, N., Yamashiro, K., Takaka, R., Hattori, N. (2019, November). Omega-3 Polyunsaturated Fatty Acids and Stroke Burden. Internation Journal of Molecular Science, 20(22): 5549. doi: 10.3390/ijms20225549. Retrieved July 25, 2022 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6888676/

[10] Bernardi, J.R., Escobar, R.d.S., Ferreira, C.F., Silveira, P.P. (2012) Fetal and Neonatal Levels of Omega-3: Effects on Neurodevelopment, Nutrition, and Growth. Scientific World Journal, 2012: 202473. doi: 10.1100/2012/202473. Retrieved July 25, 2022 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3483668/

[11] Simopoulos, A.P. (2002, October). The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomedicine & Pharmacotherapy, 56(8):365-79. doi: 10.1016/s0753-3322(02)00253-6. Retrieved July 25, 2022 from https://pubmed.ncbi.nlm.nih.gov/12442909/

[12] US Food & Drug Administration. (2014, October 6). Mercury Levels in Commercial Fish and Shellfish (1990-2012). https://www.fda.gov/food/metals-and-your-food/mercury-levels-commercial-fish-and-shellfish-1990-2012