Chapter 1 Macronutrients (CHO, Lipids, Proteins) Nutrients • Macronutrients o CHO o Protein o Fat• Micronutrients o Vitamins (water and fat-soluble) Must be obtained from the diet (13 vitamins) o Minerals Macrominerals (major minerals) 100 mg or more/day intake • Calcium, magnesium, potassium, etc. Microminerals (trace elements) less than 100 mg/day • Dietary mineral that is needed in minute quantities for proper growth, development, and physiology of organism • Iron, zinc, selenium, etc. Functions of Nutrients • Promotion of growth and development o Anabolic (building) environment is desirable for optimum growth • Provision of energy o Energy is from the MACRONUTRIENTS (not b-vitamins or caffeine as most energy drinks claim) • Regulates metabolism • Maintains structure and integrity o This includes cell walls for example Carbohydrates • Composed of Carbon, Oxygen, and Hydrogen • (CH2O)no Can also be expressed as a ratio of 1:2:1o C6H12O6• CHO is an important fuel during exercise • CHO rich foods include: o Grains o Pasta o Potatoes o Rice o Beans o Sugar or sucrose Different Carbohydrate Categories o Monosaccharides (ONE sugar molecule) Includes: • Glucoseo Also called dextrose or blood sugar • Fructose o Also called levulose or fruit sugar• Galactose Disaccharides (TWO monosaccharides linked) • Sucrose (glucose + fructose) o **Provides 20-25% of daily energy intake in Western diet o Examples are beet and cane sugar, brown sugar, table sugar, maple syrup, and honey • Lactose (glucose + galactose) o Examples are milk sugar • Maltose (glucose + glucose) o Examples are beer, cereals, germinating seeds (only small amounts in our diet) o Oligosaccharides (THREE to NINE monosaccharides linked) Includes: • Seed legumes (peas, beans, and lentils) Not digested well, but metabolized by bacteria located in the lower intestineo Polysaccharides (TEN or MORE monosaccharides linked) 10 to 20 monosaccharides = maltodextrin Up to thousands of monosaccharides: • Includes: o Pastao Potatoo etc. Starch (complex carbohydrate) • 50% of our total daily CHO intake; storage form of CHO in plants• Contains two components amylose and amylopectin • Amlyose and amylopectin are broken down and digested at different rates o Amylopectin can be digested FASTER because it has multiple branches Has increased surface area allowing it to be more exposed to digestive enzymes o Amylose is digested SLOWER because it is a long chain; 200-4000 twisted in helical coil) Fiber (nonstarch, structural polysaccharide) • Exists EXCLUSIVELY in PLANTS• Gives “bulk,” binds chemicals and fats, and shortens transit time for food • Includes: o Insoluble Cellulose Hemicellulose Lignino Soluble Pectin Gums • Recommended intake: o Men: 38 g/day o Women: 25 g/day Glycogen • Storage polysaccharide found in mammalian muscle (300-900 g) and liver (80-100 g) o Upper limit = 15 g/kg of bw• Consists of irregularly shaped, branched polysaccharide polymero Structure is SIMILAR to amylopectin in plant• MAJOR source of CHO energy for active muscle during exercise o Liver glycogenolysis (break down of glycogen) extramuscular glucose Functions of Carbohydrates o Energy source o Muscle glycogen and blood glucose can provide 32 kcal/minute during very high-intensity exercise o 1500-2000 kcal (375-500g) of TOTAL storage Exceeding the cells’ capacity to store glycogen triggers conversion and storage of excess dietary CHO calories as FAT.o Affects of Metabolic Mixtures and Spares Protein o Glycogen stores rapidly deplete during these three conditions: Starvation Reduced energy intake and low-CHO diets Prolonged strenuous exercise o These conditions will trigger an increase need for glucose synthesis or gluconeogenesis from both PROTEIN and the GLYCEROL portion of the fat o In extreme cases, gluconeogenesis may reduce lean tissue masso Metabolic Primer/Prevents Ketosis o When glycogen stores are depleted like the scenarios stated above can cause more FAT MOBILIZATION than oxidation o Can cause incomplete fat breakdown which then causes an accumulation of acetone like by-products called KETONE BODIES As a result acidosis or ketosis can occur o Fuel for CNSo CNS requires CHO to function properly o Brain uses blood glucose as its fuel Glycemic Load o Glycemic index provides a measure of how quickly blood sugar levels rise after eating a particular type of food o GI = ratio of BG response COMPARED to white bread o Therefore, white bread = 100/100 on the glycemic index o When blood glucose spikes, there is a hormone response to foods o Hyperinsulinemia o Stimulation of fat synthesis o Increased oxidative damage and inflammation o Rebound hypoglycemia can lead to over eating Glycemic Index vs. Glycemic Load o Glycemic index – o Comparison of blood sugar response (% increase) between consuming 50 g of CHO from the food item and 50 g of pure glucose o Glycemic load – o [GI * (g of CHO/serving)/100] High: ≥20 Medium: 11-19 Low: ≤10 Fats • SECOND major macronutrient• They dissolve poorly in water o Categories: Simple • Neutral fats – consists primarily of triglycerides • Triacylglycerols – major storage form in fat in adipose cells o 98% of dietary lipids o Contains a glycerol (3-carbon –OH molecule) o Three fatty acids, attach to glycerol molecule to form TG Compound • Triglycerides combined with other chemicals (phospholipids, lipoproteins) • Make up cell integrity and cell surface Derived • Formed from simple and compound lipids • Contain hydrocarbon rings (i.e., cholesterol) Types of Fatty Acids• Saturated fatty acids (SFA) o No double bonds, and carbons are completely saturated with hydrogens • Unsaturated fatty acids (UFA) o Contains a number of double bonds along the carbon chain Monounsaturated fatty acids (MUFA) • Contains only one double bond • Includes canola oil, olive oil, safflower and sunflower oil • Liquid at ROOM temperature Polyunsaturated fatty acids (PUFA) • These are you essential fatty acids like omega-6 and omega-3 • Can either promote inflammation or inhibit inflammation o Alpha-linolenic = omega-3 Omega-3 Alpha-linolenic acid DHA (docosahexanoic acid) or EPA (eicosapentaenoic acid)o Linoleic = omega-6 Omega-6 Linoleic acid Arachidonic acid• Note:
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