The proportion of n-3 acids among the 20- and 22- carbon highly unsaturated fatty acids (HUFA) of tissues can vary from 20 to 80 percent depending on voluntary food choices of individuals. Such food choices are the origin of essential n-3 and n-6 HUFA in the tissues of humans.

This review describes how my research on membrane lipids led me to believe that American should eat more n-3 (omega-3) and less n-6 (omega-6) fats. The belief has roots from my early studies in graduate school, which included the organic chemistry of many different fatty acids and made me wonder whether each fatty acid might have a special action in health.

Combining concepts of enzyme kinetics with those of acyl chain structures helped me appreciate that our health results from a paradoxical combination of:
1-selective chain interactions with protein enzymes and receptors
2-which often are promiscuous in responding to available substrates and ligands.

This perspective grew gradually during my 50-year study of membrane lipids as I tried to learn whether the chemical property of acyl chains used by the enzyme synthesizing membrane lipids is the same as the mediating the biological success or failure of resulting membrane lipids.