By Gretchen Vannice, MS, RDN
I’m surprised this question doesn’t come up more often: why so many forms of Omega-3s? There is one form of calcium (calcium), one form of vitamin C (ascorbic acid), but several forms of omega-3s. What’s more, the various forms of omega-3s have more differences than commonalities. Let me explain.
The four forms of omega-3s we hear about the most are ALA, SDA, EPA, and DHA. They are fatty acids, that is, fat-based nutrients with unique chemistry. Hint: it’s the unique chemistry that make them unique to human health.
Omega-3s share chemistry in common and beyond that, they differ. Where they are found, the functions they perform, and the amount recommended to consume all differ.
For example, ALA and SDA are found in plant-based foods, they work differently from EPA and DHA; the United States has a recommendation for an Adequate Intake for ALA, but not an optimal amount and not a Recommended Daily Allowance (RDA).
On the other hand, EPA and DHA naturally occur only in foods from the sea, that is fish, seafood, and fish oils. In fact, the colder and deeper the water, the more EPA and DHA in the fish and seafood. EPA and DHA have identified roles in human health and are required for normal growth and development. We, the people, can produce some EPA when we eat ALA and SDA, but negligible DHA. EPA is the primary molecule that works in tandem to balance other essential fats and is particularly valuable in reducing inflammation. DHA is conditionally essential in infant development because babies require DHA for normal development. And DHA is part of our cell structures; it’s found throughout our body but concentrated in human brains, eyes, and sperm. Now, whether we have enough EPA and DHA to do their assigned jobs completely depends on our diet and supplements.
We cannot make omega-3s fats in our bodies, but we need them, and that is why we need to eat them. We get far too little omega-3s; most Americans fall short of meeting minimum intake needs and don’t come close to reaping the documented benefits. While on the topic, we can’t make omega-6 fats either, but we get plenty in our diet.
The chemistry shared by omega-3 fats is this: the first double bond is located on the 3rd carbon from the omega end of the fatty acid chain. Not simple! No chemistry happens on the omega end, so this naming system was plausible; an omega-3 will always be an omega-3. While the sources and functions of the various forms differ, they have this chemistry in common. It was originally thought that humans could produce enough EPA and DHA from ALA, but human research has documented that we can’t. We don’t. And our health status and diet further complicate this simple fact.
Before I go, I want to give tribute to the scientist who first named omega-3s. Dr. Ralph Holman, a native Minnesotan, was a lipid chemist and pioneer in essential fatty acid research and metabolism at the University of Minnesota. When he identified the chemistry of omega-3s, he applied his Christian faith to name them, based on the bible passage “I am the Alpha and the Omega”. The first double bond on the 3rd carbon from the omega end. These seemingly oddly-named nutrients are, indeed, essential for human health.
Disclaimer: This information is offered for educational purposes only. It is the opinion and scientific interpretation of the author. It is not intended as medical advice of any kind. The educational information provided is not intended to diagnose, treat, mitigate, or cure any disease nor has this been reviewed or approved by the FDA.
Scientific References are available upon request.
Gretchen Vannice is the Director of Nutrition Education and Research for Wiley Companies. She is a globally recognized expert, author, and speaker in omega-3 research and education.