GLOSSARY

Unsaturation means the presence of chain double bonds, not reduced satiety after eating or a low energy content.

Saturation concerns carbon–carbon double bonds in a fatty-acid chain, not fullness after eating or a food's energy content. One double bond defines monounsaturation; multiple bonds define polyunsaturation. Their positions and cis or trans geometry also matter, so counting bonds alone cannot explain every physical property or biological effect.

A double bond restricts the free rotation possible around a single bond. Cis geometry places chain segments on the same side and usually introduces a bend; trans places them on opposite sides. A trans fatty acid remains chemically unsaturated, but its nutritional implications should not be equated with those of ordinary cis-unsaturated fats.

The omega number locates the first double bond from the methyl end, which differs from the carboxyl end. Total carbon number and total double bonds are separate information. Omega therefore names a structural family rather than a quality score or speed of action; members can differ in length, food sources and function.