Benders'dictionary of nutrition and food technology

184bonds (e.g. C18:2), followed by the position of the first doublebond from the methyl end of the molecule as n- or ω (e.g. C18:2n-6, or C18:2 ω6). See Table 8 of the Appendix.fatty acids, essential (EFA) fatty acids that cannot be made inthe body and are therefore dietary essentials – two polyunsaturatedfatty acids: linoleic (C18:2 ω6) and α-linolenic (C18:3 ω3).Several other fatty acids have some EFA activity in that theycure some, but not all, of the signs of (experimental) EFA deficiency.Arachidonic (C20:4 ω6), eicosapentaenoic (EPA C20:5ω3) and docosahexaenoic (DHA C22:6 ω3) acids are physiologicallyimportant, although they are not dietary essentials sincethey can be formed from linoleic and α-linolenic acids.Estimated average requirement for ω6 PUFA is 1% of totalenergy intake (260 mg/MJ) and for ω3 PUFA is 0.2% (50 mg/MJ),with a recommendation that total PUFA intakes should notbe more than 10–15% of total energy; a desirable intake, and thebasis of reference intakes, is 8–10% of energy intake, about2–2.6 g/MJ.fatty acids, free (FFA) or non-esterified (NEFA) Fatty acids maybe liberated from triacylglycerols (triglycerides) either byenzymic hydrolysis (when they are generally known as nonesterifiedfatty acids, NEFA, or unesterified fatty acids, UFA) oras a result of hydrolytic rancidity of the fat. Determination ofNEFA is therefore an index of the quality of fats.Free fatty acids circulate in the bloodstream, bound toalbumin. They are released from adipose tissue in the fastingstate, as a fuel for muscle and other tissues. The normal concentrationin plasma is between 0.5 and 2 µmol/L, increasing withfasting and exercise.fatty acids, polyunsaturated Long-chain fatty acids containingtwo or more double bonds, separated by methylene bridges:—CH 2 —CH=CH — CH 2 —CH=CH — CH 2 —.fatty acids, unesterified, non-esterified (NEFA) See fatty acids,free.fatty acids, volatile Short-chain fatty acids, acetic, propionic andbutyric, which, apart from their presence in some foods, areproduced by bacteria in the human intestine and rumen ofcattle from undigested starch and dietary fibre. To someextent they can be absorbed and used as a source of energy.Butyric acid formed in the colon may have some anticarcinogenicaction, and is a significant metabolic fuel for colonicenterocytes.fat, unsaturated fats containing a high proportion of unsaturatedfatty acids.fat, yellow See spread, fat.