Chapter 5 Lipids

Lipid Absorption

protein independent diffusion model- fatty acids, cholesterol, enterocyte through passive diffusion Protein dependent- fatty acids, cholesterol, enterocyte with transport proteins and receptors through facilitated CD36- important protein transporter of fatty acids in enterocytes NPC1L1- Niemann Pick C1 like 1 protein- Cholesterol transporter on brush border

Fat digestion

Fat Digestion: Fats-hydrophobic Digestive enzymes-hydrophilic; Functions at aqueous environment; Emulsified by bile salts

Essential fatty acids and n-3 fatty acids

Fatty acids cannot be synthesized in animal cells and therefore must consume in the diet Essential: linolenic(18:2 n-6) and a-linolenic (18:3 n-3) n-3: a-linolenic acid (18:3 n-3), EPA, DHA EPA and DHA: Hypolipidemic, anti-inflammatory and anti thrombotic effects of n-3 fatty acids Prevents atherosclerosis Fish oils ( cold water species like salmon) a-linolenic acid converted to EPA & DHA

Fatty nomenclature and Isomers

Isomers: Oleic acid (cis) Elaidic (trans-produced in hydrogenation)

Common Fatty Acids (omega notation and common name)

Saturated: Palmitic Acid - 16:0 Stearic Acid -18:0 Unsaturated: Oleic 18:1 (n-9) Linoleic 18:2 (n-6) a-linolenic acid 18:3 (n-3) Arachidonic acid 20:4 (n-6) Eicosapentanoiec 20:5 (n-3) Docosahexaenoic 22:6 (n-3)

Which of the following fatty acids is considered essential and must be supplied by the diet a. arachidonic acid b. omega-9 fatty acid c. linoleic acid d. γ-linolenic acid

c. linoleic acid