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NUTR1010 Final: After Midterm 2
NUTR1010 Final: After Midterm 2

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University of Guelph
NUTR 1010
Jess Haines

Nutrition Midterm #2 Fat • Lipids • Insoluble in H20 (i.e. oils) • Forms: o Triglycerides (95% dietary and body fat) o Phospholipids (5%) o Sterols (in part) Fatty acid chain LENGTH • Short: <6 carbon atoms • Medium: 6-12 C • Long: >14 C o Most of food we eat is long chain (most abundant in diet) Fatty acid chain SATURATION • Saturated fatty acid o No dbl bonds; all C atoms saturated w/ hydrogen o Solid (butter, beef fat) OR liquid (coconut oil, cream) @ room temp • Monounsaturated fatty acid o 1 dbl bond o Liquid @ room temp (olive, canola oil, oil in cashew nuts) • Polyunsaturated fatty acid o 2+ dbl bond o Liquid @ room temp (canola, corn = safflower oils) Fatty acid chain SHAPE • Saturated = straight + rigid molecule • Unsaturated = becomes bendy or kinky (bend called a cis) • “Trans” formation look straight like saturated o Trans fats are man-made thru hydrogenation Phospholipids • 2 fatty acids, glycerol backbone, and phosphate • Soluble in water • Help maintain cell membranes Sterols • Ring-like structure • Cholesterol most common o Make bile in liver o Makes hormones o Makes some type of vit D Absorption of fat • Occurs in small intestine o With help ofmicelles ▪ Spherical, made of bile and phospholipids (water soluble). Transport free fatty acids and monoglycerides to mucosal cells (intestinal wall) o Once inside mucosal cell: ▪ Long-chain fatty acids and monoglycerides are repackaged into triglycerides ▪ Triglycerides packaged with protein and phospholipids into chylomicrons (still in intestinal cell) Chylomicron • Lipoprotein (lipid [insoluble] + protein [soluble]) • “suitcase” that carries triglycerides (outside is protein; inside, fat) • st Transports triglycerides out of mucosal cell 1 into lymph, then into blood near heart, then body tissues. o Why lymph 1 ? Because “suitcase” too big to cross from intestinal cell to blood. Lymph vessels are bigger. 3 fates of fat inside chylomicrons 1. Source of energy 2. Make lipid-containing compounds in body 3. Become part of body fat (stored) Desirable lipoprotein concentrations • LDL-cholesterol (<3.5mmol/L)  want low • HDL-cholesterol (m >1.0mmol/L; f >1.2mmol/L)  want high • Total cholesterol (<5 .s)m of LDL + HDL + VLDL • Triglycerides, from VLDL (<1.7) Dietary fat Why do we need it? • Source of energy. As exercise intensity increases, we use/burn more CHO for energy + use less fat o @ lower intensity: we use/burn more fat than CHO 9kcal/g o o Major source of fuel at rest • Make lipid containing compounds in body o i.e. cholesterol = precursor to vitamin D3, testosterone, estrogen, bile acids o e.g. essential fatty acids make compounds that reg many body functions ▪ linoleic acid = essential fatty acid • omega -6 fatty acid • polyunsaturated fat in veg oils • metabolized in body to arachidonic acid (precursor to things regulating blood pressure and clotting) • ***ESSENTIAL = MUST BE OBTAINED THRU DIET. DOESN’T REFER TO IMPORTANCE ▪ Alpha-linoleic acid = essential • Omega-3 • Polyunsaturated in soybased foods, leafy greens, canola oil, fish oil, etc. • Metabolized in body to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)  decrease inflammation, clotting, triglycerides. Therefore decrease risk heart disease. • Become part of body fat Provide protection (insulation and padding) o o Maintain integrity of cell membranes o Energy store • Dietary fat also o Helps transport fat-soluble vit: A, D, E, K o Contribute to flav and texture of food o Gives feeling of satiety – feel fuller , longer. AMDR for fat • 20-35% total energy • Goal = 44-78g fat/day Fat in NorthAmerica • AMDR = 20-35% o NA – 30-35% • Saturated fat = <7% o NA – 9-10% • Trans fat = absolute min (don’t need at all) o NA – 3% energy intake in trans fat Too much saturated fat • Risk heart disease o Increase synthesis of LDL cholesterol o Decrease uptake of LDL cholesterol into cell o THEREFORE LDL cholesterol increase circulating in blood Trans fat undesirable • Increase LDL cholesterol o Decrease HDL cholesterol • Strong association with heart disease Essential fat • AMDR omega-6 = 5-10% o We meet this: marg, mayo, veg oil, dressing • AMDR omega-3 = 0.6-1.2% o We DON’T meet this: fish, shrimp, flax, canola oil, etc. Monounsaturated fat • 10% of energy • “heart healthy” • Decrease LDL cholesterol • HDL cholesterol neutral • Sources: canola and olive oil, cashews Dietary cholesterol • Animal sources • Doesn’t affect blood cholesterol • Saturated and trans fat increase blood cholesterol Increase plant source of fat, decrease animal source and processed food Fish • High mercury: o Shark, swordfish, tuna, marlin, orange roughy, escolar • Safer choice: o Anchovy, capelin, char, hake, herring, mackerel, rainbow trout, salmon, shrimp, clam, mussel, oyster, canned light tuna Structure of amino acid • Central carbon molecule o Amine group – contain nitrogen Acid group o o Hydrogen o Side chain – varies from amino acid to amino acid 9/20 amino acids = essential • Obtained from diet ▯ 11/20 amino acids = nonessential • Produce sufficient amounts to meet needs o By transferring N-containing group from essential amino acid to diff amino acid o “TRANSAMINATION” Protein • Cell growth, repair, maintenance • Act as enzymes (ie. Amylase) and hormones (insulin) • Play role in o Transport (electrolyte balance) o Immunity (antibodies) o Muscle contraction (actin and myosin – “motor proteins”) • Energy store when fat and CHO inadequate • Body cant store protein How is protein made • 2 amino acids bond, amine group of one binds to acid group of another o Creates peptide bond What if mistake in amino acid sequence? • Structure of protein changes  because structure determines function…  …change in structure = change in function o When hemoglobin changes structure, becomes “sickled” Sickle cell disease • Hemoglobin changes shape and cant carry oxygen inside RBC o As a result, those with sickle cell have lower oxygen in cells • Sickle cells can stick together and clog small blood vessels. Called “vasoocclusion” o Can lead to tissue and organ damage A dietary protein with all essential amino acids = complete (high quality)
 A dietary protein without all essential amino acids = incomplete (low quality) High vs Low quality protein • High: Animal source o o 2 veg protein are complete: soybean and quinoa o Highly digestible (~90%) • Low: o Veg source (grain, veg, legume) o Protein in legumes = ~80% digestible o Protein in grain and veg = ~60-90% digestible Mutual supplementation • >2 incomplete proteins = complete protein (i.e. rice and beans = complementary proteins) • Not necessary to consume complementary protein in same meal, however should be during same day as protein cant be stored Pepsin in stomach breaks protein into single amino acids Too much protein? • Amino acids stripped of N (deamination) • Deamination: o N forms ammonia o Carbon skeleton • Liver pulls
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