HNF 461 1st Edition Lecture 24 Outline of Last Lecture I Lipoprotein A Lp a II Apolipoprotein E a Apo E2 b Apo E3 c Apo E4 III LDL Receptor IV Particle Size Outline of Current Lecture I Essential Fatty Acids II Overview of FA Synthesis III Synthesis of EPA and DHA IV Omega 6 n 6 and Omega 3 n 3 Competition V Composition of the Heart s Phospholipid Fatty Acids VI Essentiality of Long Chain n 6 and n 3 Fatty Acids VII Dietary Reference Intakes VIII Tissue Distribution IX General Benefits of EPA and DHA Current Lecture Long Chain n 6 and n 3 Synthesis Pt 1 1 Essential Fatty Acids a Dietary essential fatty acids are C18 2 n 6 and C18 3 n 3 b Arachidonic Acid AA C20 4 c Eicosapentaenoic Acid EPA C20 5 d Docosahexaenoate DHA C22 6 2 Overview of FA Synthesis These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Palmatate 16 carbon saturated FA chain is formed from excess acetyl CoA b Palmatate Stearate 18 carbon FA chain via elongation c Stearate oleate C18 1 via desaturation by delta9 enzyme from the ER d Oleate linoleate C18 2 via desaturation from delta12 enzyme i Humans don t have enzyme only plants ii Linoleate is a dietary essential FA e Linoleate alpha linolenate C18 3 via desaturation by delta15 enzyme i Humans don t have enzyme only plants ii Alpha linolenate is a dietary essential FA iii Alpah linolenate EPA and DHA f Linoleate gamma linolenate C18 3 arachidonate C20 4 i This process can occur in the human body ii Arachidonate is a metabolically essential FA 3 Synthesis of EPA and DHA a C18 3 Alpha linolenate C18 4 by delta6 desaturase that introduces a new double bond at the 6th carbon position b C18 4 C20 4 by elongation which adds two carbons to the chain elongation shifts the double bonds down by two carbons c C20 4 C20 5 EPA by delta5 desaturase that adds a new double bond at the 5th carbon d To go from EPA to DHA must elongate chain from 20 carbons to 24 carbons after elongation C24 5 C24 6 by delta6 desaturase 2 carbons are then removed from the chain to form C22 6 DHA e NOTE Humans have delta5 delta6 and delta9 desaturase enzymes 4 Omega 6 n 6 and Omega 3 n 3 Competition a n 6 and n 3 fatty acids compete against each other if you have more n 6 FAs then n3 metabolism will be compromised b Ratio between n 6 and n 3 15 25 1 overwhelming amount of n 6 compared to n 3 fatty acids in the body i Preferred ratio 4 1 5 Composition of the Heart s Phospholipid Fatty Acids TRT Linoleic Acid Arachidonic Acid Alpha Linolenic Acid EPA and DHA C18 2 C20 4 C18 3 n 3 Control 15 21 0 1 5 Fish Oil 14 16 0 1 12 Flax Oil 15 20 0 3 6 a Fatty acids are major components of the phospholipid bilayer of the cell membrane b Fish Oil good source of EPA and DHA c Flax Oil good source of alpha linolenic acid d C18 1 is oleic acid major component 50 of triglyceride droplets in fat tissue 6 Essentiality of Long Chain n 6 and n 3 Fatty Acids a C18 2 n 6 is needed for proper skin function needed for the skin water layer b If the body is deficient in C18 2 n 6 FA then the body cannot synthesize C20 4 c AA is believed to be directly responsible for normal lifespan blood clotting and the ability to reproduce d In mice DHA is responsible for reproduction main long chain essential FA in sperm 7 Dietary Reference Intakes a AI in adult females 12 g linoleic acid and 1 1 g alpha linolenic acid per day b AI in adult males 17 g linoleic acid and 1 7 g alpha linolenic acid per day c No dietary reference set for EPA and DHA i Typical intakes are 90 mg day of EPA and 150 mg day of DHA ii New proposal of a DRI of 250 500 mg of EPA DHA day 8 Tissue Distribution a Alpha linolenic acid C18 3 n 3 minor component of tissues b EPA C20 5 n 3 generally speaking a minor component of tissues but in some tissues can contribute to a large portion of the makeup c DHA C22 6 n 3 major component of membrane phospholipids in retinal photoreceptors cerebral gray matter testes and sperm 9 General Benefits of EPA and DHA a Reduce arrhythmias b Reduce atherosclerosis c Decrease platelet aggregation d Decrease plasma triacylglycerol e Slightly increase HDL f Decrease proinflammatory eicosanoids
View Full Document
Unlocking...