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Food “combining”

Food “combining” . Some holistic medicine advocates have suggested that combining fats, proteins and carbohydrates in a meal prevents proper digestion of these macronutrients What do you think?. Digestion pathways. Carbohydrates; enzymes in saliva begin the process

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Food “combining”

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  1. Food “combining” • Some holistic medicine advocates have suggested that combining fats, proteins and carbohydrates in a meal prevents proper digestion of these macronutrients • What do you think?

  2. Digestion pathways • Carbohydrates; enzymes in saliva begin the process • Proteins: pepsins in stomach initiate breakdown • Fats: Lipases excreted in walls of small intestine and pancreas • So……………………triage results?

  3. Conclusion • It is not an issue to combine all 3 macronutrients in a single meal !!

  4. 8. Lipids – Fats & Oils Chapter 15

  5. A lipid is an organic substance found in living systems that is insoluble in water but is soluble in organic solvents. Lipids vary widely in their structures. They have mostly C,H and some have a few polar atoms/ functional groups. Lipids

  6. Lipids include: fats and oils steroids waxes Fats & oils make up 95% of the nutritional lipids, the other 5% are steroids. Waxes are functional only. Fats are solid triglycerides Oils are liquid triglycerides

  7. Fats and Oils The Triglycerides We Eat CH2-O2C-R HOCH2-CHOH-CH2OH Fatty acid side chains CH-O2C-R’ (glycerol) CH2-O2C-R” Triglycerides/fatty acids are characterized/named by: 1) The length/number of carbons in the side chains 2) The number of carbon-carbon double bonds in the side chains(the degree of unsaturation).

  8. Representative Fatty Acids C12-C18(also C20) Dietary Fats and Oils CH3-(CH2)12-COOH CH3-(CH2)14-COOH CH3-(CH2)16-CO2H CH3-(CH2)7-CH=CH-(CH2)7-CO2H CH3-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-CO2H CH3-CH2-CH=CH-CH2-CH=CH-CH2-CH=CH-(CH2)7-CO2H (1) (2) (3) (4) (5) (6) Name Class Mp(oC) (1) Myristic acid 58 Saturated C-14 (2) Palmitic acid 63 Saturated C-16 (3) Stearic acid 71 Saturated C-18 (4) Oleic acid 4 Monounsaturated C-18 (5) Linoleic acid - 5 Polyunsaturated C-18 (6) Linolenic acid - 11 Polyunsaturated C-18

  9. Fatty Acid Content of some Fats/Oils

  10. Canola (Canadian-oil-low acid) • Oil from Canadian rapeseed • Has “ideal ratio” of omega-6 to omega-3 fatty acids of 2:1 • Also very low in saturated fat

  11. Olive oil • Deemed to be the most “heart healthy” • Highest % of monounsaturated fatty acids • Extra virgin (1st press)

  12. Oxidation of Organic Compounds, eg. fatty acids O2 -C-C-C-COOH -C-COH-C-COOH saturated difficult O2 -C=C-C-COOH -COH-COH-C-COOH unsaturated easy oxidation = decomposition = rancidity more saturated = more stable, ie. longer ‘shelf life’, eg. commercial baked goods more unsaturated = faster deterioration, ie. need antioxidants to protect compounds(in the body?)

  13. FATTY ACIDS (TRIGLYCERIDES) Solid: longer chains saturated(only C-C) eg. animal fat, butter Liquid: unsaturations (C=C) eg. many vegetable oils (olive, sunflower)

  14. Unsaturates can’t fit well into a solid lattice

  15. Body fat is stored energy The body converts the unused carbohydrates, proteins and triglycerides that make up our macronutrients into small globules of fat that end up in the specialized cells of adipose tissue, the fatty tissue of the body. One pound of adipose tissue stores, and provides when needed, ~3500 Cal of energy.

  16. The high energy density of fat - its ability to store energy (9 Cal/gram) compactly in relatively little space and with relatively little weight, compared with carbohydrates and proteins (4 Cal/gram), allows us to carry stores of energy with us. It give humans and other animals the mobility and freedom necessary for survival

  17. Water in the Camel’s Hump C54H108O6 + 78O2 54CO2 + 54H2O + zillion Cal (triglyceride from C18H36O2 x 3 ie glycerol tristearate) Metabolism requires oxygen, produces energy, carbon dioxide and water

  18. Fat = Essential Energy Most of our long term energy supplies operates via the formation, storage and metabolism of body fat (triglycerides). Short term energy storage, from one meal to another, occurs through a starch-like substance called glycogen(a carbohydrate).

  19. Adipose Tissue / Fat Adipose tissue forms cushioning shields around our major organs, protecting them against damage from physical shock and provides insulation to our bodies, guarding against a rapid loss of body heat to the external environment . Fats carry the flavours and vitamins of many of our foods although fats have no flavours of their own, eg. carrying vitamins A, D, E and K from our foods to our tissues. Fatty acids form not only the triglycerides but other compounds as well, including such vital classes as prostaglandins and phospholipids.

  20. Saponification/Hydrolysis of a Triglyceride triglyceride glycerol soaps

  21. Omega - 3 Fatty Acids - Especially in Fish Oils ! Mainly 20 & 22 C’s, polyunsaturated and 1st ‘ene’ is 3 from -end. Eicosapentaenoic acid (EPA): 20(5,8,11,14,17) mp –50OC ! Docosahexaenoic acid (DHA): 22(5,8,11,14,17, 20) also -linolenic: 18(9,12,15)

  22. Why ‘Omega – 3’ FA ? Low incidence of heart disease amongst populations that eat lots of fat BUT mostly as fish ! eg. Inuit & Greenlanders SatMonoPoly(16 &18)-3(20 &22) Cod 15 29 20 35 Herring 20 5 21 53 Don’t like fish? Try omega 3 eggs!

  23. Omega-3 eggs • Chickens are fed flaxseed, which contains high levels of omega-3 fatty acids. After 10 days, this modifies the fat content in the egg yolk to contain more omega-3 fatty acids and less saturated and omega-6’s • In 1997, this was the Canadian New Product of the year

  24. Omega-3 Chickens

  25. Omega-3 meats • Present work (Guelph) on chickens, turkeys, pigs to obtain meat with high omega-3 fat content via diet alterations • Coming soon to a supermarket near you!

  26. Other omega -3 enriched products • Orange juice • Other fruit juices

  27. Cis vs. Trans Fatty acids • Almost all natural unsaturated fatty acids have cis stereochemistry in C=C’s. • Small amounts of trans are produced in stomachs of ruminating animals by partial enzymatic hydrogenation of polyunsaturated fats, and thus are present in small amounts in milk and butter

  28. Commercial Hydrogenation of Fatty Acids ‘cis’ ‘trans’ unsaturated saturated unsaturated natural natural unnatural good bad bad

  29. An unwanted byproduct • Trans fats increase the level of Low density lipoprotein (LDL). • Thus they are deemed to be “heart unhealthy” since LDL tends to deposit cholesterol in the arteries rather than transport it (as does HDL) to cells for use in cell membrane construction.

  30. How are trans fats metabolized? • Catabolism (breakdown) of all fats • Catalyzed by lipases to free FA’s and glycerol • FA’s split by beta oxidation into 2C units (Acetyl Co), or propionyl CoA if odd #C’s • Need bile salts to emulsify fats and allow absorption by the intestine (occurs 1st)

  31. Also have anabolism • Macromolecules (ie Proteins) synthesized using 2C units derived from fat metabolism, amino acids etc • Essential link between energy producing (catabolic) and energy utilizing (anabolic) pathways is ATP (adenosine triphosphate) • Details much beyond the scope of this course!!

  32. ‘Trans’ = Saturated; in shape and ‘badness’ !

  33. Incomplete Labels !

  34. ‘Trans Fats’ - Misleading Labels

  35. ‘Trans Fats’ – an Informative Label

  36. Cholesterol - a steroidal alcohol (atherosclerosis!) High – red meat, egg yolks, dairy products Low – egg whites, yoghurt None ! – fruits, veggies, vegetable oils

  37. Properties of Cholesterol very insoluble in water, C27H46O solid, mp. 149o compact, stiff/rigid

  38. Cholesterol is Absolutely Essential ! The average male (80kg/170lb) contains ~220gm About: 50% in cell membranes 40% converted to bile acids to ‘emulsify/ transport’ lipids (liver> gall bladder> intestines) some converted to hormones (testosterone, estrogens, cortisone) in 80kg male (~gms) blood 16 muscle 45 brain 50 adipose tissue 45 skin 18 liver 8 heart/kidney, etc. 8 adrenal glands 2 alimentary tract 7

  39. Cell Membrane Structure (lipid bilayer)

  40. Cholesterol Transport in vivo • Cholesterol is insoluble in water, hence to transport it through the bloodstream, our bodies wrap it in a sheath of proteins and varying amounts of triglycerides to form lipoproteins. • High Density Lipoproteins (HDL’s) transport excess cholesterol to the liver for disposal “good cholesterol” • LDL’s (Low Density Lipoproteins) and VLDL’s tend to deposit cholesterol on arterial walls “bad cholesterol”

  41. Structural features: HDL vs LDL • HDL contains unsaturated cis Fatty acids • LDL contains more saturated and trans fatty acids • Both contain apolipoproteins and phospholipids which are oriented with hydrophobic part on inside and outer hydrophilic edges exposed

  42. Cholesterol in gallstones • Bile : used in fat digestion • Contains water, cholesterol, bile salts , proteins and bilirubin (waste product) • If bile contains too much cholesterol, it can harden into gallstones • Extraction of cholesterol from gallstones (removed by surgery) is a common lab experiment! • Size can range from grains of sand up to golf ball!

  43. Source of bile acid • Produced in liver • Stored and concentrated in the gallbladder • Secreted into small intestine • If gallstone blocks exit duct, then gallbladder may need to be removed • Fat digestion becomes more difficult, but not impossible

  44. Gallstones

  45. Some real ones!! • Courtesy of the Ottawa Hospital!

  46. Some Risk factors for gallstones • Gender: Women 2x as likely; excess estrogen from pregnancy, BC pills, HRT all may increase cholesterol levels • Weight: even moderate obesity • Diet: high fat, low fibre diet increases level of cholesterol in bile • Rapid weight loss: crash diets as body tries to metabolize fat • Age.>60: body secretes more cholesterol into bile

  47. Lipid Content (mg) per servingof common foods • Includes cholesterol • Saturated fatty acids • Unsaturated fatty acids

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