In 1982 the Nobel Prize for Physiology was awarded to three researchers, Sune Bergstrom, Bengt Samuelsson, and John Vane, for their elucidation of the pathway by which arachidonic acid becomes prostglandins and leukotrienes. These compounds cause pain and inflammation. John Vane was able to determine where aspirin fit in all this (blocking the creation of prostaglandins), and how it affected pain and inflammation. I remember this because someone at Rice University managed to get Bengt Samuelsson as a speaker, and his lecture was really excellent. From this research we now have a whole stable of NSAIDs: knowing where aspirin worked, people tested other compounds to create a whole array of drugs.
This work is important because omega 3 fatty acids work on the tail end of this same process. It turns out that dietary omega 6 fatty acids are the precursers to arachidonic acid. Omega 3 and omega 6 fatty acids use the same enzymes in these pathways, and they are competitive inhibitors of each other. Hence, by reducing the ability of the body to turn omega 6 fatty acids into arachidonic acid and then into prostaglandins, omega 3 fatty acids can reduce inflammation.
Of the omega 3 fatty acids, the most effective are the long chain omega 3s, DHA and EPA. This can cause issues for vegans, as they need to get their omega 3s in the form of ALA. ALAs then need to be converted to DHA and EPA by the body, but that conversion is regarded as “limited” by the research we have at the time. Or is it?
One novel interpretation of the data is provided by Doctor Bill Lands. Lands argues that the conversion itself is being limited by the overwhelming presence of omega 6 fatty acids. In other words, the conversion of omega 3s from 18 chain (ALA) to 20 (EPA) and 22 chain omega 3s (DPA) works much better the less omega 6 is around in the first place. It was the writer and diabetic David Mendosa who noticed this before I did, so if you want the details, please check out Mr. Mendosa’s article on his blog. It includes charts (table 2 is the important one) and a link to a video of Bill Lands’s presentation to military physicians.
The take home is pretty simple. If ALAs are your main source of omega 3s, you need to work at reducing your omega 6 intake. If you’re taking fish oils or eating a lot of fish, it’s not as crucial to lower omega 6s to get a medical effect (If table 1 of David Mendosa’s article is correct, though, it might extend your lifespan).