Part I: Understand the Various Forms and Functions of Omega-3 Fatty Acids

Wednesday, May 04, 2011 by: Andrew Kim
Tags: omega-3s, functions, health news

(NewsTarget) For many years, much attention has been given to only certain members of the omega-3 family. Alpha linolenic acid (ALA), the most basic substrate of the omega-3 family, has often been neglected. However, ALA's role in the body is becoming better known and appreciated.

ALA has three fates. It can be metabolized for energy (beta-oxidation), used as a carbon source for the production of other molecules (carbon cycling), or converted to long chain derivatives.

ALA and its derivatives - eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA) - incorporate into the cell membranes, influencing eicosanoid synthesis, cell signaling cascades, and gene expression.

It has been argued that humans cannot adequately convert ALA to DHA. However, studies indicate that omega-3 fatty acids accumulate in a tissue-dependent manner and convert to derivatives in a tissue-selective manner. This new understanding implies that different tissues accrete and metabolize omega-3 fatty acids differently based on need. For example, the brain rapidly utilizes and converts plasma ALA to DHA, whereas the heart does not.

Human and animal dietary studies show that ALA alone may be able to provide adequate amounts of EPA and DHA. Past studies report low conversion rates from ALA to EPA and extremely low rates from ALA to DHA. Insights provided by the new paradigm described above suggest that these numbers reflect the rates of the body as a whole instead of at the level of individual tissues.

When adequate doses of ALA are consumed, DHA-requiring tissues and the liver are able to amply supply DHA. The liver is the primary organ responsible for the conversion from ALA to its various derivatives. When ALA in the diet is low, the liver compensates by up-regulating the rate of conversion to meet the body's need for EPA and DHA. Therefore, the plasticity of the liver and the slow turnover rate of DHA (i.e. in the brain) may allow ALA to adequately meet the body's omega-3 demands, even when dietary intake is low on some days (see note).

Contrary to popular belief, all ALA is not converted to derivatives. The body uses up to twenty times more ALA than its derivatives (95% stay as ALA, leaving only 5% to be broken down into derivatives). Therefore, ALA is anything but a passive molecule.

New research continues to uncover the virtues of ALA. Some of the many benefits of ALA include:

-Cardiovascular protection
-Proper neural development
-Anti-inflammatory (independent of EPA)
-Neuro-protection
-Improved cholesterol profile
-Lower blood pressure
-Improved lung function in asthma patients
-Greater improvement of inflammatory bowel disease (IBD), ADHD, and autoimmune diseases (as compared to fish oil).
-Maintenance of long chain omega-3 fatty acids in the tissues.
-Treats dry eye syndrome (when applied topically)
-Anti-depressant effect

Vegans may benefit from ALA supplementation to provide and maintain adequate levels of longer chain derivatives of omega-3, which are predominantly found in animal foods. For the rest, consume enough ALA and LA* - about a teaspoon total a day in the correct ratio** - along with some derivatives found in whole foods, and let your body sort out the rest.

* linoleic acid
**see "Clear up the Misconceptions about Omega-6 Fatty Acids"

Note: Deficiencies of biotin, Vitamin E, protein, zinc, magnesium, B12, and B6 interfere with the activity of desaturases and elongases. Refined sugars, starches, trans-fatty acids, and insulin disrupt EFA metabolism as well. Saturated fats, which are resistant to oxidation, protect and enhance utilization of EFAs.

Part II will review the other members of the omega-3 family

Sources

1.Pharmacology (Rang and Dale)
2.Nutrition: A Health Promotion Approach (Webb)
3."Update on alpha-linolenic acid" (Nutrition Reviews; 2008)
4."Alpha-linolenic acid and its conversion to longer chain n-3 fatty acids: Benefits for human health and a role in maintaining tissue n-3 fatty acid levels"(Progress in Lipid Research; 2009)
5."Drops of fatty acid curb symptoms of dry eye syndrome in animal model: Topical alpha-linolenic acid shows promise as alternative application, bypasses many side effects" (Dana; 2008)
6."Subchronic Alpha-Linolenic Acid Treatment Enhances Brain Plasticity and Exerts an Antidepressant Effect: A Versatile Potential Therapy for Stroke"(Neuropsychopharmachology; 2009)
7.Primal Body-Primal Mind (Gedgaudas)
8. "The Fats of Life" (Pond)

About the author

Andrew Kim
[email protected]