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Lipid

Lipid. Lipid. Molecules made up of long hydrocarbon chains Fatty Acids - single chain hydrocarbons with 4 – 22 carbons Triglycerides - 3-carbon glycerol backbone with three fatty acids attached to the 3 carbons Diglycerides - above with 2 fatty acids

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Lipid

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  1. Lipid

  2. Lipid Molecules made up of long hydrocarbon chains Fatty Acids - single chain hydrocarbons with 4 – 22 carbons Triglycerides - 3-carbon glycerol backbone with three fatty acids attached to the 3 carbons Diglycerides - above with 2 fatty acids Monoglycerides - above with 1 fatty acid Phospholipids - glycerol with fatty acids attached to carbons 1 & 2 with a phosphorous attached to the 3rd. Cholesterol - 3 6-carbon & 1 5-hydrocarbon rings (modified to produce the various steroids)

  3. Structure of some lipids EFA’s Glycerol Fatty Acids

  4. Dietary Fat is a source of the Essential Fatty Acids: Linoleic and α-linolenic acid. • Arachidonic acid (AA) is synthesized from linoleic acid; • Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are synthesized from α-linolenic acid • Arachidonic acid is made into various proinflammatoryprostaglandins, leukotrienes, and thromboxanes; • - predominantly PGE2, PGI2, TXA2, LTB4, and LTC4; the START signals for inflammation • - as inflammatory responses progress toward resolution, increased synthesis of COX-2 and 12- & • 15-lipoxygenase enzymes shifts production of proinflammatory eicosanoids to the production of • anti-inflammatory lipoxins from AA; essentially STOP signals for inflammation • DHA and EPAare made into anti-inflammatory signaling compounds called resolvins, • protectins, and maresins; essentially the STOP signals for inflammation • EPA can be made into the less proinflammatory PGE3, PGA3, PGD3, and TXA3/TXB3, and • LTB5; and reduces production of PGE2 and LTB4

  5. Physiologic/Metabolic uses: Synthesize steroid hormones from cholesterol Synthesize bile from cholesterol & FFA Membrane phospholipids Essential component of PDH & α-kGDH Primary storage form of NRG & major substrate for energy (especially at rest) Absorption of Fat soluble vitamins (A, D, E, &K) Common Food Sources (oils) linoleic: corn, safflower, soybeans, peanuts, sunflower seeds… α-linolenic: soybeans, linseed, flax, most other seed oils…

  6. AI 12 & 17 g/day linoleic acid (C18:2; n6, 9 - all cis): F / M; based on on median intake 1.1 & 1.6 g/day α-linolenic acid (C18:3; n9, 12, 15 - all cis) F / M; based on median intake Or: 10 - 35% of total calories (9kcal/g)… so… lets see what you have to eat to… Some older texts suggested a minimum total intake of 20g/day to insure a sufficient uptake of fat soluble vitamins which greatly underestimates the actual dietary lipid requirement (RDAs are based on fatty acid intake, not TG intake and eating exactly 12g linoleic acid or 1.1 g α-linolenic acid would obviously necessitate eating more than 13g total fat since the EFA are a small minority of total FFAs) EFA Content of various foods in % of total FA Linoleic α-Linolenic % Fat by Wt Canola Oil ~ 26 - 100 Corn Oil ~ 35 - 65 - 100 Olive Oil ~ 3 - 20% ~ 1% 100 Palm Oil ~ 6 - 12 ~ 0.5 100 Peanut Oil ~ 14 - 43 ~ 0.4 100 Flax Oil ~ 14 ~ 50 - 60 100 Beef (grain-fed-trimmed) ~ 3.4 ~ 0.4 ~ 5 Beef (grass-fed-trimmed) ~ 4.4 ~ 1.2 ~ 2.5 Chicken (skinless-breast) ~ 21 ~ 0.9 ~ 4.5 Salmon (Norway-wild) ~ 1 ~ 1 (2%EPA/20% DHA) ~ 3 - 4 Human Milk ~7 - 18 ~ 1 ~ 2 - 4 Cow Milk Fat ~ 2.6 ~ 1.6 ~ 0, 1, 2, or ~3.5 Based on the EFA content of common foods (as a percent of total fatty acids) you clearly have to eat a lot more grams of fat than the RDA (as expressed in grams for the EFA’s) ) – 60 g/day would not be an outlandish estimate if you consume the usual (North American) array of fats (see next slide…)

  7. so let’s figure it out… average calories/day for adults 19 – 50 yrs: ~ 2400 F ~ 3000 M at 10% - 35% calories from fat… (240 – 840 kcal) (300 – 1050 kcal) EFA Content of various foods in % of total FA Linoleic α-Linolenic % Fat *Fat intake / kCal Fat intake / kCal Total “Food” Intake mean (range) by Wt (g) (g) to meet RDA Linoleic α-Linolenic (min g/kcal) Canola Oil ~ 26 - 100 48/432 - - Corn Oil ~ 50 (35 – 65) - 100 18-34 /162-306 - - Olive Oil ~ 10 (3 – 20) ~ 1 100 60-400/54-3600 110/990 110/990 Palm Oil ~ 9 (6 – 12) ~ 0.5 100 100-200/900-1800 220/1980 220/1980 Peanut Oil ~ 30 (14 – 43) ~ 0.4 100 30-85/270-765 275/2475 275/2475 Flax Oil ~ 14 ~ 50 (50 – 60) 100 86/774 2-3/18-24 86/774 Beef (grain-trimmed) ~ 3.4 ~ 0.4 ~ 5 353/3177 275/2475 7060/30,005 Beef (grass-trimmed) ~ 4.4 ~ 1.2 ~ 2.5 272/2448 916/819 10,880/44,880 Chicken (skinless-breast) ~ 21 ~ 0.9 ~ 4.5 57/513 122/1098 2711/11,454 Salmon - Norway - wild ~ 1 ~ 1 ~ 3-4 1200/10,800 110/990 30,000/125,000 Human Milk ~ 10 (7 – 18) ~ 1 ~ 2-4 67-171/603-1539 110/990 4275/ why bother Cow Milk (butter fat) ~ 2.6 ~ 1.6 ~ 2 461/4149 69/621 23,050/ “ Based on the EFA content of common foods (as a percent of total fatty acids) you clearly have to eat a lot more grams of fat than the AI (as expressed in grams for the EFA’s) *Fat Intake calculated for an (“average”) adult female (for males, the intake would be approximately 25% higher). Calculations of total food intake are based on that single food item being the sole source of EFAs. From these values it is clear that eating less than 30% of calories from common sources of fat is a near guarantee of EFA (borderline?) deficiency. It also is clear that the fat in meats & milk is not very relevant in terms of significant contributions to total EFA intake. Fats in “spreads”, cooking oils, and cheeses seem to make the most difference… and of the added fats, cold-press, virgin olive oil (tends to be at the lower end in linoleic content) and butter/cheese from cows, along with cooked fish 2x/week and maybe a small amount of added flax oil would be the most logical frequent choices to ensure adequate intake of the EFAs and of DHA & EPA . Using the average EFA content of oils... ~4g Flax oil ensures adequate α-Linolenic for both men and women. Add to that 46g and 65g Canola for linoleic requirements (♀ & ♂, respectively) to get minimum fat intakes of 50 and 69g! Or add 24 g and 34g of corn oil for a minimum total of 28g and 38g (♀ & ♂, respectively).... Or add 120 g and 170 g olive oil for a minimum of 124 and 174 g (♀ & ♂, respectively)... Or add 40 g and 57 g peanut oil for a minimum of 44 and 61 g (♀ & ♂, respectively)... And so on and so on and so on... With the exception of a flax/corn oil mix it looks like lots of fat calories are necessary...

  8. Α-Linolenic EPA ~ 0.2% ~ 63% ~ 37% DHA Pawloski et al. 2001

  9. One of those “evil” trans-fats Omega 3 Omega 6 Omega 3 Omega 3

  10. Steroid hormones are made from cholesterol

  11. Bile acids are also synthesized from cholesterol . . .

  12. Proinflammatory prostaglandins, leukotrienes, and thromboxanes are synthesized from arachidonic acid.

  13. Proresolution lipoxins are synthesized from arachidonic acid and proresolution resolvins, and maresins are synthesized from DHA and EPA to shut down an inflammatory response.

  14. Digestion/Absorption - Mastication in mouth Bolus w/ saliva/mucus • Lipids break up to tiny droplets in chyme from stomach/acid action - Bile from liver bile salts & acids made from cholesterol, fatty acids, sodium, potassium & chloride • Lipases from Pancreas

  15. Emulsification by bile salts and bile acids • FFA, MG, PL, gycerol, CHOL, absorbed • Glycerol metabolized, lipids resynthesized and packaged into chylomicrons (apoB-48, *apoC-II, apoC-III, apoE)

  16. Chylomicrons - Lipoprotein + lipids TG PL Chol ~85% ~9% ~4% released into lymph/blood ~ 50 : 50 ApoC-II activates lipoprotein lipase in capillaries Tissues remove FFA, PL Liver picks up chylomicron remnants

  17. Lipoprotein content of the chylomicron changes as it circulates throughout the body - acquiring the apo E & C2 from HDL Deliver dietary TG and PL to cells dietary CHOL to liver . . . apoE & apoB-48 are ligands for liver uptake of remnants . . . apoCII is ligand to activate lipoprotein lipase for removal of fatty acids in tissues . . .

  18. Delivers endogenous TG and PL to cells . . . apoE is ligand for liver uptake & apoB-100 is ligand for tissue uptake . . . apoCII is ligand to activate Lipoprotein lipase for removal of fatty acids Delivers CHOL to cells . . .

  19. HDL really serves as a circulating resevoir for apoE and apoC’s for efficient removal of LDL’s and lipids from the blood Function of these apoprotein ligands and the cellular receptors that recognize them have important implications for atherosclerosis Note that HDL also picks up CHOL from tissues and returns it to the liver for bile synthesis (CHOL excretion pathway)

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