Hemp Oil in Cosmetics

Household & Personal Products Industry, Oct, 2001 by George R. Whalley

Fatty Acid Nomenclature

Most fatty acids are better known by their trivial names rather than by their systematic names, but in some cases this can be quite confusing. The systematic name of a fatty acid is derived from its parent hydrocarbon having the same number of carbon atoms. The position of unsaturated carbon atoms may be indicated in two ways: by a numerical system which designates the carbon of the carboxyl group as 1 subsequent carbon atoms as 2, 3, 4, etc. A second method uses letters of the Greek alphabet to denote the position of carbon atoms in the chain, but in this case the carbon atom of the carboxyl group is not designated. Omega (w) is used to denote the terminal carbon atom.

A simple naming system is also used where the carbon number is shown followed by the number of the double bonds; e.g., C16:0 for palmitic acid (16 carbon atoms with no double bonds) and C16:1 for palmitoleic acid (16 carbon atoms with one double bond, etc.). The position of unsaturated bonds is also indicated by reference to the terminal or omega positions. This system is frequently used to describe essential fatty acids.

Hemp oil, like all other natural fixed oils, is largely composed of mixed fatty glycerides or mixed esters of fatty acids and glycerol, and it is the nature of these component acids which determine the general properties of the oil. The fatty acid composition of hemp oil varies slightly according to variety, growing conditions, geographical location and climate, but resembles that of borage and evening primrose. The oil is characteristically rich in polyunsaturated acids, especially in linoleic and alpha-linolenic acids, with up to 2% content of the important gamma-linolenic acid. Here's the principal fatty acid profile of refined hemp oil:

Fatty Acid                             %
C16:0 Palmitic                      5-12
C16:1 Palmitoleic             0.5 (max.)
C18:0 Stearic                      1-4.5
C18:1 Oleic                        10-16
C18:2 Linoleic                     45-65
C18:3 Alpha linolenic              14-30
C18:3 Gamma linolenic           1 (min.)
C18:4 Octadecatetratraenoic          0-2
C20:0 Arachidic                      0-2
C20:1 Eicosenoic                1 (max.)
C22:0 Docosanoic                1 (max.)
C24:0 Tetracosanoic             1 (max.)

Essential Fatty Acids

The human body requires some 50 essential ingredients to maintain its normal healthy fuction, two of which are obtained from oils and fats. These are the so-called essential fatty acids (EFAs) and are usually referred to as omega 6 (linoleic acid, C18:2 w6) and omega 3 (alpha-linolenic acid, C18:3 w3). Both acids occur in hemp oil in a unique ratio of omega 6/omega 3 of 3:1, together with gamma linolenic acid, C18:3 w6. Essential fatty acids are important because they cannot be synthesized by the body and must be sourced from natural oils. The term essential implies ingestion of the individual acids where most other fatty acids can be produced by the body from other fatty sources. This combination of unsaturated fatty acids ensures that any long-term use of an oil such as hemp is able to supply the necessary EFAs without causing problems of either excess or deficiency.