The Truth about Flaxseed Oil and Fat Loss
Chances are you've heard that fish
oil (which is high in omega-3 fatty acids) can reduce the risk
of heart disease, lower your blood pressure, as well as helping to speed up fat loss.
Because foods like chia seeds — the so-called "new super seed" — and flaxseed oil ALSO contain omega-3 fatty acids, it's easy
to confuse the two.
However, many don't realize that the omega-3 fatty acids
found in plant-derived products are not the same as those in fish. Nor have they been proven to deliver the same kind of benefits.
ALA, EPA and DHA
Fish oil contains two omega-3 fatty acids known as eicosapentaenoic
acid (EPA) and docosahexaenoic acid (DHA).
Plant-derived sources of omega-3 fatty acids, such as walnuts, chia seeds and flaxseed oil are rich in alpha-linolenic acid (ALA) which is the
"parent" fatty acid to DHA and EPA.
Although similar in structure, the benefits of ALA, EPA, and DHA are not the same.
You might also see ALA written as 18:3n-3. Although it might look like a foreign language, these letters and numbers give you plenty of information about the properties of the fat.
- A fatty acid contains a chain of carbon atoms bonded together. The number 18 means there are 18 carbons in the chain.
- The next number (in this case, 3) tells you that there are three double bonds in the chain.
- The final piece of information (n-3) tells you where the first double bond is located.
Compare ALA with EPA, one of the omega-3 fatty acids found in fish, and you'll see there are a few small but important differences.
EPA is written as 20:5n-3, which means that it has 20 carbon atoms in the chain — two more than ALA.
That's why you'll see ALA called a short-chain omega-3 fatty acid. EPA, on the other hand, is known as a long-chain omega-3 fatty acid.
Conversion
It's true that your body can convert alpha-linolenic acid into EPA and DHA. However, the conversion rate isn't particularly efficient and varies widely depending on your gender (women seem to be better at it than men) as well as the type of diet you eat.
A diet that's rich in trans-fatty fatty acids, for instance, will limit the conversion of alpha-linolenic acid into EPA and DHA. Consuming too many omega-6 fatty acids at the expense of omega-3 fatty acids also puts the brakes on the conversion of ALA into EPA and DHA.
The figure below shows the effect of alpha-linolenic acid (ALA) supplementation on ALA, EPA, and DHA concentrations in the body [2]. As you can see, while ALA raised EPA levels, it had no impact on DHA, which some researchers think is the more "active" fatty acid as far as fat loss is concerned.
So what does all of this mean for you?
All the research showing a small but significant benefit of omega-3 fatty acids on fat loss was done using fish rather than plant-derived sources of omega-3.
In fact, despite the hype, I haven't been able to find a single human study to show that alpha-linolenic acid, the omega-3 fatty acid found in foods like chia seeds or flaxseed oil, has any impact on body composition whatsoever.
If anyone knows of any that have been done, I'd love to hear about them.
About the Author
 Christian Finn holds a master's degree in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Muscle & Fitness, Fit Pro, Zest and other popular fitness magazines.
If you want better, faster results from the time you spend in the gym, click here now for instant access to his step-by-step muscle-building and fat-burning workout routines.
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References
1. Gerster, H. (1998). Can adults adequately convert alpha-linolenic
acid (18:3n-3) to eicosapentaenoic acid (20:5n-3) and docosahexaenoic
acid (22:6n-3)? International
Journal for Vitamin and Nutrition Research, 68, 159-173
2. Arterburn, L.M., Hall, E.B., & Oken, H. (2006). Distribution, interconversion, and dose response of n-3 fatty acids in humans. American Journal of Clinical Nutrition, 83, 1467S-1476S
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