We have all heard of omega-3 fatty acids but how many of us really know what omega-3’s are, what omega-3 fatty acids do and why omega-3’s are important?
- Are fatty acid molecules composed of carbon, oxygen and hydrogen.
- The fatty acids we are interested in consist of linear carbon chains 18 to 22 carbons long
- They have a carboxyl group (COOH) at one end and a methyl group (CH3) at the other end
Saturation, Unsaturation and Polyunsaturation
- Fatty acids can be saturated and thus they do not contain double bonds
- This results in a straight molecule
- Fatty acids can be unsaturated and contain 1 or more double bonds
- These molecules bend at the double bond
- The more double bonds the more the molecule bends
- Of critical importance is the impact of unsaturation on the shape of the fatty acid molecule
Omega-3s: A Very Special Class of Fatty Acids
- Omega-3 fatty acids have their first double bond at the third carbon atom from the end of the carbon chain
- This omega-3 configuration must be contained in the human diet as we cannot synthesize it. Thus ALA is an essential fatty acid and a precursor for other omega-3’s
- Alpha linolenic acid (model above) has its first double bond at the 3rd carbon atom, the other 2 double bonds are at carbons 6 and 9
- If the first double bond is moved three carbons up the chain to carbon 6, (omega-6 fatty acid) with the other two at carbons 9 and 12 the shape of the molecule is altered with the bend moving to the middle of the molecule. Compare gamma linolenic acid (below) to alpha linolenic acid (above)
The omega-3 fatty acids of biological significance are:
- EPA (eicosapentaenoic acid) a 20 carbon, 5 double bond fatty acid C20:5n3
- DHA (docosahexaenoic acid) a 22 carbon, 6 double bond fatty acid C22:6n3
- EPA and DHA are poorly synthesized from ALA in the human body
- As the number of carbon atoms and double bonds increases, the shape of EPA and DHA becomes even more “bent” than ALA
- The size and shape of these molecules has a critical impact on their function in the body
What Is So Special About the Omega-3 Carbon Atom?
There are two impacts of the shape of EPA and DHA molecules that are driven by their omega-3 structure.
- The size and shape of these molecules plays a large role in allowing them to remain flexible while functioning in cell membranes
- DHA especially functions in cell membranes
- DHA’s flexibility allows metabolically important molecules to cross the cell membrane and enter or leave the cell
- Saturated fatty acids in the same function would be too rigid and may actually crystallize – not a good thing in a cell membrane!
Substrate specificity for enzymes and prostaglandin synthesis
- The shape of unsaturated fatty acid molecules, driven by their omega-3 or omega-6 status, has a very large impact on their substrate specificity for enzymes, especially those involved in prostaglandin (cell regulator) synthesis.
- Omega-6 fatty acids, especially linoleic acid (C18:2n6), are used to produce series 2 prostaglandins
- Omega-3 fatty acids, especially EPA, are used to produce series 3 prostaglandins.
- Series 2 prostaglandins (from omega-6 fatty acids) result in:
- Increased platelet aggregation, vasoconstriction, pro-inflammatory response, decreased oxygen flow, narrow respiratory passages, suppression of the immune system, increased pain, lower endurance
- Series three prostaglandins (from omega-3 fatty acids) have the opposite effect on each of these impacts
- Clearly, these classes of prostaglandins must be in balance for healthy functioning of the human body. Therefore, the ratio of omega-6 to omega-3 in the body and thus the diet must be in balance as well.
- For most of us in North America omega-6 and omega-3 are not in balance
- We over consume omega-6 and under consume omega-3
Omega-3’s have gained in consumer popularity and importance. Some projections indicate continued double digit growth well into the future.
Posts to Follow
In future posts we will cover: foods naturally high in omega-3’s, foods on the market fortified with omega-3’s, sources and types of omega-3’s for the product developer and issues around the use of omega-3’s in formulated food products.
Douglas Chapman & Associates can help incorporate omega-3’s into your products
If omega-3’s are of interest to your business, to improve the nutritional characteristics of your food products and thus allow your firm to participate in a rapidly growing segment, Douglas Chapman and Associates can help. We offer a comprehensive background in fats and oils. Contact us today: firstname.lastname@example.org