NURS 1013 Lecture 2_ Macronutrients PDF

Macronutrients NURS 1013- NUTRITION OBJECTIVES At the end of this session, students will be able to: Describe the classification and sources of essential nutrients Identify sources- local/international of food and their nutrients Indentify the major functions of essential nutrients Relate the functi...

Macronutrients NURS 1013- NUTRITION OBJECTIVES At the end of this session, students will be able to: Describe the classification and sources of essential nutrients Identify sources- local/international of food and their nutrients Indentify the major functions of essential nutrients Relate the functions of the nutrients to the body’s requirements CARBOHYDRATES Carbohydrates:- A macronutrient containing carbon, hydrogen and oxygen which provides an Atwater factor of 4 kcal/g  (Tucker & Dauffenbach, 2011) They are stored energy, synthesized by plants and have the general formula (CH2O)N. The simplest form is glucose (C6H12O6) and are readily soluble and can be oxidized to water and carbon dioxide providing energy for the hosts tissue.  (Cummings & Mann, 2007) FUNCTIONS OF CARBOHYDRATES Supply energy to the body.  Atwater factor of 4kcal/g. many cells use both fats and protein but RBC, brain and CNS prefer carbs as the source of energy Carbohydrates are needed to spare proteins- if energy needs are not met the body will use protein and fats to provide energy.  This compromises the essential bodily functions which rely on protein substrates.  (Tucker & Dauffenbach, 2011; Cummings & Mann, 2007) FUNCTIONS OF CARBOHYDRATES Prevent ketosis which can compromise brain function. 50-100g/d of carbs needed to prevent ketosis; Provide substrates to make essential components for the body.  Ribose- DNA, keratin- fingernails, glycoproteins- blood clotting and immunology Adds flavour to the diet  (Tucker & Dauffenbach, 2011; Cummings & Mann, 2007) FUNCTIONS Soluble fiber      Promotes laxation (bowel movement) Prevents/treats constipation Reduces cholesterol levels (soluble fiber) Delays gastric emptying and lowers postprandial blood glucose Unconfirmed in its role to reduce gastrointestinal cancers  (Tucker & Dauffenbach, 2011; Cummings & Mann, 2007) SOURCES Food groups    staples, vegetables, fruits, legumes FDBGs CLASSIFICATIONS OF CARBOHYDRATES Class/ Degree of Polymerization Sub-group Principal component Simple sugars (1-2) I. Monosaccharides II. Disaccharides III. Polyols (sugar alcohols) Glucose, fructose, galactose Sucrose, lactose, maltose Sorbitol, mannitol, lacitol Oligosaccharides (3-9) Short chain carb i. Malto-oligosaccharides (α-glucan ) ii. Non α-glucan oligosaccharides Maltodextrins Polysaccharides (≥10) I. Starch (α-glucans) II. Non starch polysaccharides Amylose, amylopectin, modified starches Cellulose, hemicellulose, pectin, plant gum (Cummings & Mann, 2007) Raffinose, stachyose, fructo and galact0-oligosaccharides CLASSIFICATIONS OF CARBOHYDRATES Simple Sugars Complex carbohydrates Byproduct of the hydrolysis of complex carbohydrates Product of the polymerization of simple sugars Includes both naturally occurring and added sugars and syrups Food containing starch and fiber Examples include- Fructose, galactose, Has source in plant and animal originglucose starch in plant & glycogen in animal (Tucker & Dauffenbach, 2011) Carbohydrate classification Rapid digestible Amylose and amylopectin are Abbreviation examples RDS Slowly digestible SDS Resistant starch RS (Cummings & Mann, 2007) TERMS RELATED TO CARBOHYDRATES Sucrose- (table sugar) glucose + fructose Lactose- (milk sugar) glucose + galactose Maltose- (byproduct starch digestion) glucose + glucose Whole grain- refers to complex carbs (starch) that has not been overly modified by processes such as milling.  usually retain the outer portions of the grain - the bran & germ. Fiber- found in foods that have plant based origin.  Insoluble- makes up the cell walls of the plant food/ structural fiber  Soluble- found inside the cell of the plant and forms a gel-like material in the digestive tract.  (Tucker & Dauffenbach, 2011) TERMS RELATED TO CARBOHYDRATE Total sugars:- all sugars, from whatever source present in the food Intrinsic and extrinsic sugars:- naturally occurring in cell walls/added to foods; does not describe lactose (milk sugar) Glycaemic carbohydrates- carbohydrates that contribute to raising the blood sugar Glycaemic index- the measure of how much blood glucose is raised following two hours after the ingestion of 50 g of carbohydrate compared to the effect of 50 g of sucrose/white bread. Closer the number to 0 the lower the GI.  Factors affecting it include fiber content, preparation style and the presence of other macronutrient such as fat or protein.  (Tucker & Dauffenbach, 2011) HUMAN NEEDS Minimum required to prevent ketosis is 50g/d.  Total required by the RBCs, kidney & brain is 180g body can make about 130g from non-Carb sources  hence 50g needed from daily intake. During pregnancy & lactation 100g/d is minimum FAO (1998) suggests that at 55%- 75% as acceptable normal ranges for adult intake  10% from free sugars  35% from intrinsic and milk sugars  No consensus on fibre contribution UK suggests 18g/d  (Cummings & Mann, 2007) Current evidence suggest 45- 65% with 14 g of fibre per 1000 kcal (DeBruyne, Pinna, & Whitney, 2015) HUMAN NEEDS OF CARBOHYDRATES Carbohydrates should compromise 45-65% of total calories per day- (USDA 2010) Carbohydrate calculation=  Total daily est. needs (kcal) * 45-65% (0.45- 0.65)= total kcal/d from carb  Total kcal/d from carb / 4 kcal/g= rec. g of carb/d  Example for 200Kcal/d diet  2000kcal * 0.45- 0.65= 900- 1300kcal/d for Carb  900-1300kcal/d carb / 4kcal/g= 225-325g of carb per day CALORIC VALUE Atwater factor traditionally 4kcal/g (17kJ/g). as Monosaccharides they provide 3.4 kcal/g (15.7kJ/g). RS- 2kcal/g (8Kj/g) there metabolism is less efficient, and they are digested in the colon.  (Cummings & Mann, 2007) PROTEINS  Proteins are macronutrients that are composed of multiple amino acids. (Tucker & Dauffenbach, 2011) (Bender & Millward, 2005)  Proteins are fundamental structural and functional elements within every cell.  Proteins are polymers of amino acids joined by peptide bonds  (Jackson, 2007) FUNCTIONS OF PROTEINS Product/Function Examples Nucleotides Formation of DNA, RNA, ATP, NAD Energy transduction ATP, NAD Neurotransmitters Serotonin, adrenaline, noradrenaline, acetylcholine Membrane structures Head groups of phospholipids: choline, ethanolamine Porphyrin Heam compounds, cytochromes Cellular replication Polyamines Fat digestion Taurine, glycine-conjugated bile acids Fat metabolism Carnitine Hormones Thyroid, pituitary hormones (Jackson, 2007) FUNCTIONS OF PROTEINS Class of activity Functionality Structural support Body- skeleton, skin, epithelia Tissue- connective tissue and ground substance Cell- cellular architecture Protective- body’s defenses Barrier- non-specific defenses- skin, keratin, tears, mucin Inflammation- acute phase proteins Immune response- cellular and humoral response Transport and communication- between cells and organs Plasma proteins:- albumin, transferrin, apolipoproteins Hormones:- insulin, glucagon, growth hormones Cell membrane receptors:- intracellular communications/second messenger Enzymatic Extracellular:- digestive, clotting, haemoglobin, )2, CO2 transport, acid base balance Metabolic pathways:- glycolysis, protein synthesis, citric acid cycle, urea cycle (Jackson, 2007) FUNCTIONS OF PROTEIN Tissue growth and repair- proteins provide raw material  Anabolism and catabolism- production of new cellular material; destruction of body tissues for reuse or excretion  Nitrogen balance:- the difference between the amount of nitrogen taken and the amount excreted; 1g N per 6.25 g protein Protein synthesis Cellular building of protein specific for the body’s needs Immune function  Large proteins are used to synthesise antibodies in response to invading antigens (harmful substances) (Tucker & Dauffenbach, 2011) FUNCTIONS OF PROTEIN Energy  Normally the body prefers carbohydrates as fuel but when utilized protein provides 4kcal/g energy Regulation of the body; enzymes, hormones, fluid and pH balance  Enzymes are organic substances that are necessary to catalyse body functions such as digestion and metabolism; catalysts – remain unchanged after reactions and are substrate specific.  Hormones- chemicals released by glands in the body that are carried in the bloodstream that effects changes in other parts of the body  Fluid and pH balance- contain amino acids that buffers- that is facilitating constant pH even when exposed to acidic or basic substances; proteins also exert oncotic pressure or colloid osmotic pressure (Tucker & Dauffenbach, 2011) SOURCES Food from animals Legumes Fruits Vegetables Staples CLASSIFICATION OF AMINO ACIDS Essential (indispensable) Non-essential (dispensable) Conditionally essential Histidine Alanine Arginine Isoleucine Aspartic acid Cysteine Leucine Asparagine Glutamine Lysine Glutamic acid Glycine Methionine Serine Proline Phenylalanine Threonine Tryptophan Valine (Tucker & Dauffenbach, 2011) Tyrosine CLASSIFICATIONS OF PROTEINS Complete Proteins In complete protein High quality Low quality Contains all essential amino acidscorrect amounts important for humans Lacks at least one essential amino acid Animal protein sources- meat, poultry, Plant protein- peas, nuts, seeds and eggs, dairy, seafood along with plant grain (except soy). soy except gelatin which lacks tryptophan (Tucker & Dauffenbach, 2011) TERMS RELATED TO PROTEINS Nonessential amino acids- (dispensable) are those that can be synthesised by the body using available molecules from other amino acids Essential amino acids (indispensable):- those that cannot be synthesised by the body and must be consumed in the diet e.g. Branched chain amino acids important in muscle Limiting amino acid:- the essential amino acid found in the smallest quantity in the food source such as lysine and threonine in cereals and methionine and cysteine in legumes Conditionally essential amino acid (acquired indispensable)- under most circumstances the body can synthesise the amino acid but in some physiological situations when the body cannot; such as with prematurity and cysteine and proline.  (Tucker & Dauffenbach, 2011) TERMS RELATED TO PROTEINS Complementary proteins are proteins from different sources that combine to form complete proteins. Deanimation- a step in protein catabolism which involves the removal of nitrogen Protein turnover- the process by which proteins are continuously and simultaneously degraded and synthesised Protein quality is determined by the type and amount of amino acids and the digestibility of the food.  Animal sources digestibility is high; plant sources are low  Digestibility is affected by resistance of cell walls and presence of anti-nutritional factors  (Tucker & Dauffenbach, 2011) REQUIREMENTS FOR PROTEIN For adults 19-70 years= 0.8g/kg/d  The ranges are higher for pregnant women, infants and children  (Tucker & Dauffenbach, 2011) The maintenance requirement is 0.66g/kg/d  (Bender & Millward, 2005) The requirements for adults is 0.83g/kg/d  (Jackson, 2007) Accepted range is 0.6- 0.8g/kg/d CALCULATIONS OF REQUIREMENTS DRI- the level of intake recommended to meet the needs of 97.5% of a particular age and sex group DRI for adult e.g. 70kg man  70* 0.8/g/kg= 56g protein/d  (Tucker & Dauffenbach, 2011) LIPIDS Fats are also called lipids. They are organic compounds and are insoluble in water and are made of three elements carbon, hydrogen and oxygen.  (Tucker & Dauffenbach, 2011) Lipids are a group of compounds that are soluble in organic solvents such as petrol and chloroform but are insoluble in water. They increase flavour and palatability of food and play a major role in energy contribution.  (Mann & Skeaff, 2007) FUNCTIONS OF LIPIDS Functions of fat in the body Functions of fat in food Transports fat soluble vitamins- A, D, E, & K Provides essential fatty acids Cushions and protects organs Source of energy with 9kcal/g Insulates body to maintain core temperature Emulsifying agent Provides lubrication Taste and aroma Source of stored energy- adipose tissues Texture Component of cell membranes Transfers heat in cooking Component of myelin in the nervous system Causes satiety or fullness Building block for synthesis of other lipid based compounds such as hormones, Vitamin D, prostaglandins and bile (Tucker & Dauffenbach, 2011) FUNCTIONS OF LIPIDS Energy Storage  Density as triacylglycerol is the long term fuel storage reserve for organisms- most is in adapted adipose tissues adipocytes but some is liver and muscle. Structural functions: as components of cell membranes  Form part of cell membranes- barrier between internal and external cellular compartments mainly through phospholipids Specific functions in membranes  Pulmonary surfactant- fats prevent the lung from collapsing are protein- lipid mixture called surfactant (85% lipid)  Cell signaling- involved in converting extracellular into intracellular signals such as inositol phospholipids which mediate hormone and neurotransmitter actions  Eiconsanoids- precursor of many hormone like compounds (eicosanoids) functions include blood clotting and muscle contraction- main fatty acid precursor is arachidonic acid Yaqoob, Minihane, & Williams, 2007 SOURCES OF LIPIDS Fats & Oils Food from animals Vegetables Legumes Staples CLASSIFICATION OF FATTY ACIDS Fatty Acid Classification Saturated fatty acids Examples: Lauric Myristic Palmitic Stearic Monounsaturated fatty acids Cis Configuration MUFAs e.g. : Oleic Trans Configuration MUFAs e.g.: Elaidic T-vaccenic (Tucker & Dauffenbach, 2011) Polyunsaturated fatty acids Omega 3 Fatty acids e.g.: linolenic EPA DHA Omega 6 Fatty acids e.g.: linoleic TERMS RELATED TO LIPIDS Triglyceride glycerol (3 carbon alcohol)molecule attached to three fatty acids- constitutes 95% of lipids Fatty acids even number chain of carbon atoms with hydrogens attached and a methyl group at one end and a carboxyl group at the other end. Saturated fatty acids fatty acids with carbons that are all fully bound with hydrogen (1 C- 4H); (solid at room temperature except coconut & palm oils). The SF has more of a straight line configuration. More chemically stable with longer shelf life. Monounsaturated fatty acids two hydrogen are absent and a C is not fully bound thus a SINGLE double bond occurs Polyunsaturated fatty acids two or more double bonds exist in the fatty acid (liquid at room temperature). (Mann & Skeaff, 2007 ; Tucker & Dauffenbach, 2011) TERMS RELATED TO LIPIDS Essential fatty acids: are fatty acids that are unable to be made by the body and must be supplied in the diet. Play role in healthy skin, normal growth, blood clotting & inflammation Trans fats: not fully saturated fats but they function like saturated fats in the body due to hydrogenation; have longer shelf life more resistant to oxidation Hydrogenation: chemical process of adding hydrogen to unsaturated fats. Phospholipids have a glycerol backbone with 2 fatty acids groups and a phosphate group. Which makes the compound soluble in fat (fatty acid end) and soluble in water (phospho lipid end) (Mann & Skeaff, 2007 ; Tucker & Dauffenbach, 2011) TERMS RELATED TO LIPIDS Sterols: Lipids with large interconnected rings of carbon; not required in the diet- e.g. cholesterol, vitamin D, testosterone and estrogen  Include of C, O, H, arranged in series of 4 rings with a range of side chains Cholesterol a sterol compound made in the liver from glucose and saturated fat.  Can be made into bile salts, made into steroid hormones and Vit D. Lipoproteins: compounds containing lipids and proteins that transport fats (Tucker & Dauffenbach, 2011) HUMAN REQUIREMENTS At least 15% of RDA for energy should be from fats and 20% for women in reproductive age  (Mann & Skeaff, 2007) DRI is 20-35% of total calories should be from fat  Less than 10% of calories from saturated fats  (Tucker & Dauffenbach, 2011) CALCULATIONS RELATED TO LIPIDS Total calorie needs/d * 25-35% (0.25-0.35)= calories from fat/d Calories from fat/d /9kcal/g= g fat/d Total calorie needs/d * less than 10% (0.1)= calories from saturated fat/d Calories from sat/d / 9kcal/g= g sat fat/d CALCULATIONS RELATED TO LIPIDS Example 2000kcal/d * 0.25-0.35= 500-700 kcal/d from fat 500-700 kcal/d / 9kcal/g= 55- 78g fat/d 2000 kcal/d * less than 0.1= less than 200 kcal/d 200 kcal/d / 9 kcal/d= less than 22 g saturated fat/d REFERENCES Bender, D. A. & Millward, D. J. (2005). Protein metabolism and requirements. In C. Geissler & H. Powers (Eds.), Human Nutrition (11th Ed.) (pp 143- 164). Edinburgh, UK: Elsevier Churchill Livingstone. Cummings, J. & Mann, J. (2007). Carbohydrates. In J. Mann & A. S. Truswell (Eds.), Essentials of human nutrition (pp 8-32). New York, USA: Oxford University Press. Jackson, A. (2007). Protein. In J. Mann & A. S. Truswell (Eds.), Essentials of human nutrition (pp 53-72). New York, USA: Oxford University Press. 40 REFERENCES Mann, J. & Skeaff, M. (2007). Lipids. In J. Mann & A. S. Truswell (Eds.), Essentials of human nutrition (pp 33-52). New York, USA: Oxford University Press. Tucker, S. & Dauffenbach, V. (2011). Nutrition and diet therapy for nurses. Boston, USA: Pearson. Yaqoob, P., Minihane, A. M., & Williams, C. (2007). Fat Metabolism. In C. Geissler & H. Powers (Eds.), Human Nutrition (11th Ed.) (pp 125- 141). Edinburgh, UK: Elsevier Churchill Livingstone. 41 ASSIGNMENTS Students are to complete the following questions Compare and contrast soluble and insoluble fibre Differentiate between rapidly digestible and slowly digestible sugars Describe the factors that may cause protein deficiency in vegans List two strategies that can be employed to prevent protein deficiency in vegans Identify two examples for each of the following classifications of lipids- MUFAs, PUFAs, Saturated fats List three roles of fats in the human body