Lipid conversion factors

A conversion factor (F) have to be used to convert g FAME/100g FAME to g Fatty acids/g lipids. This conversion factor is defined as the weight of fatty acids in 1 gram total fat (or in other words, the proportion of fatty acids in the total fat fraction).

If the fat fraction in a food consists only of triglycerides the conversion factor is:

If a food contains also other fats (like cholesterol or phospholipids) F can be derived using data on the amount of fatty acids in the different fat fractions. For example the derivation of the conversion factor (F) for egg lipids is as follows:

Posati, L.P. et al (1975), Comprehensive evaluation of fatty acids in foods. III. Eggs and egg products. J. Amer. Diet. Ass. 67(2): 111-15

Egg fat contains triglycerides, lecithin, cephalin and cholesterol (first column). Triglycerides contain 95.6% fatty acids, lecithin 70.8%, cholesterol 0% (second column). The last row shows the amount of fatty acid for each of the lipid fractions. Summarizing these values gives F.

Thus F is food specific.

An overview of food specific conversion factors can be found in the next table.