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Introduction
Omega-3 fatty acids have long been associated with various health outcomes. A type of omega-3 called alpha-linolenic acid (ALA) is found in various plant foods such as flax seeds or chia seeds. Other omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are found typically in marine food sources such as oily fish (e.g. salmon, mackerel) and algae. And while higher intakes of such foods have shown benefit, there has been some confusion over the benefit of such nutrients due to some large omega-3 supplementation trials reporting null findings.
So what should we make of the current evidence base? Does supplementation lead to heart disease risk reduction or not? Do we need direct sources of EPA and DHA in the diet? Does ALA have unique benefits? What is an omega-3 index and why is it important?
In this episode, fatty acid expert Dr. Bill Harris dives into each of these questions and clarifies what the current evidence tells us about the effect of these fatty acids on our health.
Related resources
- [04:02]Fatty acid definitions/subtypes
- [09:14]Omega-3 status & the Omega-3 Index (O3I)
- [20:03]Omega-3 supplementation trials for CVD
- [41:15]DHA, brain health, cognition in later life, development, etc
- [49:45]Should we be concerned about omega-6 fatty acids?
- [56:40]Danny’s Key Ideas (Premium content)
Guest Information
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Dr. Harris is an internationally recognized expert on omega-3 fatty acids and how they can benefit patients with heart disease. He obtained his Ph.D. in Human Nutrition from the University of Minnesota and did post-doctoral fellowships in Clinical Nutrition and Lipid Metabolism.
His interest in omega-3 fatty acids began with his postdoctoral work when he published his first study on the effects of salmon oil on serum lipids in humans (1980). Since that time he has been the recipient of five NIH grants for studies on the effects of omega-3 fatty acids (EPA and DHA) on human health. He has more than 300 publications relating to fatty acids, including omega-3s, in medical literature and was an author on two American Heart Association scientific statements on fatty acids: “Fish Consumption, Fish Oil, Omega-3 Fatty Acids and Cardiovascular Disease” (2002), and “Omega-6 Fatty Acids and Risk for Cardiovascular Disease” (2009) both published in the journal Circulation
Danny Lennon has a master’s degree (MSc.) in Nutritional Sciences from University College Cork, and he is the founder of Sigma Nutrition.
Danny is currently a member of the Advisory Board of the Sports Nutrition Association, the global regulatory body responsible for the standardisation of best practice in the sports nutrition profession.
Key Ideas
What can we actually conclude based on current evidence?
There are two main themes I want to highlight when considering this question:
- Converging lines of evidence
- Recommendations based on context
1: Converging lines of evidence
When evaluating the evidence base in order to answer a practical question, we don’t want to rely on one study type or one set of studies. Rather, we can look across the whole evidence base, and see if there is general agreement across different lines of evidence. Of course, some types of evidence carry much more weight, and that should be noted.
But if we take the topic of omega-3 intake and cardiovascular health for example. It would be a mistake to take a large omega-3 supplementation trial such as VITAL or the STRENGTH trial, see that the findings were regarded as null, and then extrapolate that to mean either omega-3 intake or status is unimportant for CVD risk reduction.