Fish oil: Good for my health… or not?

Fish oil - a source of omega-3

Stories from various news outlets (and even from different researchers at Oregon State University) have said:

This is confusing and frustrating for all of us. As is the case with most headlines, when you look more closely at the study details, explanations emerge.

We have been gathering information on omega-3 fatty acids for decades and slowly learning about the many, varied, and complex effects of omega-3 fatty acids on health.

When you read the next news headline, consider these important issues:

What intervention or supplement do they use?

Is the study about fish, fish oil capsules, omega-3 supplements, or EPA/DHA supplements? These terms are often used interchangeably but are, in fact, distinct interventions with their own unique composition of nutrients. These different sources of omega-3 fatty acids appear to have distinct biological effects with varying levels of significance.

The relationship of omega-3 fatty acids

Fish, fish oil capsules, omega-3 supplements, or EPA/DHA supplements are all sources of certain omega-3 fatty acids, so they have that in common. However, omega-3s are a broad category of fatty acids; some are higher in fish and fish oil supplements, while others are higher in plants and plant oils.
Inside the body, alpha-linolenic acid (ALA) can be converted to the other omega-3 fatty acids, including (but not limited to) the well-known omega-3s EPA and DHA. But our bodies aren’t very efficient at this conversion, so it is recommended to obtain EPA and DHA from additional sources. Marine sources like oily fish are the most common way of getting these omega-3s.

Fish is a food, however, and it is comprised of a complex mixture of nutrients. Fish contain omega-3 fats, but also provide protein, other fatty acids, vitamins, and minerals. People who eat fish may also have a different dietary pattern from those who do not.

Omega-3 supplements will also have a mixture of fatty acids, mostly from the omega-3 class of fatty acids, providing ALA, EPA, DPA, and DHA among others depending on the source. They also may provide some fatty acids that aren’t omega-3s, but hopefully not too much. Of you see more saturated fat than unsaturated fat on the nutrition label, you know the supplement can’t have many omega-3 fats.

Fish oil capsules also provide some omega-3 fatty acids (depending on the capsule, this could be between 20 to 80% of the total fatty acids), as well as other fatty acids and some fat-soluble vitamins. EPA/DHA supplements are concentrated sources of these two specific omega-3 fatty acids (possibly from fish) but may contain other omega-3s and other fatty acids.

What are they measuring?

Pay close attention to the study’s clinical endpoint of interest, such as disease diagnosis, symptom, or clinical event like a heart attack or stroke. Cardiovascular Disease (CVD) is a very general term, referring to diseases affecting the heart and blood vessels. It is more accurate to discuss the effects of dietary intake of oily fish, fish oil capsules, or a particular omega-3 supplement on cardiac arrhythmia (irregular heartbeat), stroke, hypertriglyceridemia (high blood lipids), or another specific disease endpoint.

For example, we know that EPA + DHA intake is associated with a reduced risk of sudden cardiac death, likely due to an anti-arrhythmic effect. This is a very specific outcome and a more accurate description of the scientific evidence.

Look at the study details.

fish-oil-benefits
For example, is there a significant change in blood or tissue levels of EPA/DHA in the study participants taking supplements? Are these changes in fatty acid associated with fasting blood triglycerides? If not, then no claim can be made for an association (good or bad) between omega-3 fatty acids and health status. Or, is the study designed to assess disease prevention or disease treatment? A nutrient or supplement that has value in preventing disease may or may not be effective in patients already diagnosed with disease.The methods section of a published scientific study will tell you the form and dose of omega-3 fatty acid that was tested, but this information is often not found in news articles.

Do they consult an expert?

Researchers know that omega-3 fatty acids do a lot in the body and have complicated biochemistry. And be forewarned: we are still gathering information and making discoveries — their role in preventing and treating CVD, Alzheimer’s disease, abnormal lipid levels in diabetes, depression, fatty liver disease, and inflammatory diseases like rheumatoid arthritis, is still being investigated.

The Micronutrient Information Center (MIC) article on Essential Fatty Acids presents a review of the science regarding the role of omega-3 fatty acids in health and disease; an update of this article will be posted soon.

Some recommendations:

  • salmon - a good source of fish oilIt is recommended to consume a minimum of 250-500 mg/day of EPA + DHA, which can be obtained by eating at least 2 servings of oily fish per week or by taking a dietary supplement.
  • The Linus Pauling Institute suggests that if you don’t regularly consume fish, consider taking a two-gram fish oil supplement several times a week. If you are prone to bleeding or take anticoagulant drugs, consult your physician before adding extra fish oil to your diet.

Lastly, feel free to ask us questions about fish oils, omega-3s and other micronutrients. You can contact us here (on our blog), contact us on Facebook, or through our website.

This article was contributed to this blog by Giana Angelo, PhD, a Research Associate and co-author of the Micronutrient Information Center.

 

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Giana Angelo

Giana Angelo is a nutrition scientist at the Linus Pauling Institute, where she has worked in the Micronutrient Information Center since October 2011. She conducted her postdoctoral research in the Division of Basic Sciences at Fred Hutchinson Cancer Research Center, and received her doctorate in Cell and Molecular Nutrition from Tufts University.