23F-Proteins Notes PDF

FNH 250: Nutrition Concepts & Controversies PROTEINS Chapter 6 1. INTRODUCTION ................................................................................................................................... 2 2. AMINO ACIDS .......................................................................

FNH 250: Nutrition Concepts & Controversies PROTEINS Chapter 6 1. INTRODUCTION ................................................................................................................................... 2 2. AMINO ACIDS ...................................................................................................................................... 2 A. BASIC STRUCTURE .................................................................................................................................. 2 B. GROUPS OF AMINO ACIDS ................................................................................................................... 2 C. RECYCLING/DEAMINATION OF AMINO ACIDS ................................................................................. 3 D. DIETARY ASPECTS OF AMINO ACIDS .................................................................................................. 4 1. Complete Proteins ........................................................................................................................... 4 2. Incomplete Proteins ......................................................................................................................... 4 3. Combine Plant Proteins ................................................................................................................... 4 3. PROTEINS ............................................................................................................................................. 5 A. AMINO ACIDS LINKED TOGETHER ...................................................................................................... 5 1. Sequence .......................................................................................................................................... 5 2. Shape and Configuration................................................................................................................. 5 B. DENATURATION OF PROTEINS ............................................................................................................ 6 4. DIGESTION & ABSORPTION OF PROTEINS....................................................................................... 6 A. DIGESTION ............................................................................................................................................... 6 B. ABSORPTION ........................................................................................................................................... 6 C. TRANSPORTATION ................................................................................................................................. 6 5. PROTEIN QUALITY ............................................................................................................................... 7 6. FUNCTIONS OF PROTEINS ................................................................................................................. 7 A. SUPPORT GROWTH, MAINTENACE & REPAIR – VITAL BODY PROTEINS ....................................... 7 B. ENZYMES .................................................................................................................................................. 8 C. HORMONES ............................................................................................................................................. 8 D. CELL MEMBRANES .................................................................................................................................. 8 E. BODY FLUID BALANCE ........................................................................................................................... 8 F. pH BALANCE IN BLOOD ........................................................................................................................ 8 G. CONTRIBUTION TO IMMUNE FUNCTION ........................................................................................... 8 H. FORMATION OF GLUCOSE/PROVISION OF ENERGY ....................................................................... 9 7. FOOD SOURCES OF PROTEIN ............................................................................................................ 9 A. ANIMAL SOURCES................................................................................................................................... 9 B. PLANT SOURCES ..................................................................................................................................... 9 8. RECOMMENDATIONS FOR PROTEIN INTAKE .................................................................................. 9 A. DIETARY REFERENCE INTAKE ............................................................................................................... 9 9. HIGH PROTEIN DIETS .........................................................................................................................10 10. PROTEIN DEFICIENT DIETS ............................................................................................................... 11 11. VEGETARIAN DIETS ............................................................................................................................12 Proteins 1. INTRODUCTION Proteins -minor source of energy; 4 kcal/gram -repeating units of different amino acids -we do not store PRO in our bodies (unlike CHO & FAT) -vital functional (working) and structural components in all cells e.g., -enzymes -cell repair -hormones -blood transport proteins -immune bodies -muscles, tendons, ligaments -visual pigments -hair, skin, nails -supply N in a form humans can use -both plant and animal sources -major part of lean body mass in the body (muscle, bone, organs, connective tissue, skin) -must consider both the quantity and quality of dietary PRO sources 2. AMINO ACIDS -amino acids (aa) contain C, H, O and N; some contain S atoms -aa have an amino end, acid end, and H and a side chain attached to a central carbon atom A. BASIC STRUCTURE -different side chains result in different properties for each amino acid Aliphatic – alanine, glycine, isoleucine, leucine, valine; Aromatic – phenylalanine, tryptophan, tyrosine; Acidic – aspartic acid, glutamic acid; Basic – arginine, histidine, lysine; Hydroxylic – serine, threonine; Imino – proline; Sulphur-containing – cysteine, methionine; Amidic – asparagine, glutamine B. GROUPS OF AMINO ACIDS 1. Essential amino acids (eaa) -can’t synthesize at all or in enough quantity to meet body needs -9 of the 20 aa are essential for adults (10* for children) histidine (His) lysine (Lys) threonine (Thr) *arginine (Arg) isoleucine (Ile) methionine (Met) tryptophan (Trp) leucine (Leu) phenylalanine (Phe) valine (Val) -if deprived of any one of these eaa, protein synthesis stops and the body breaks down it's own proteins to supply the limiting eaa 2. Non-essential amino acids (non-eaa) alanine (Ala) aspartic acid (Asp) serine (Ser) asparagine (Asn) glutamic acid (Glu) -available in diet, or synthesized in body cells via TRANSAMINATION – see Figure 6-13, p. 184 =transfer of an amine group from one aa to a keto-acid (C-skeleton) to form a new aa: requires vitamin B6 FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 3 of 15 3. Semi-essential amino acids (typically non-eaa become eaa under certain conditions, e.g., critical illness) arginine (Arg) glutamine (Gln) glycine (Gly) proline (Pro) cysteine (Cys) tyrosine (Tyr) Example: normally Cys is synthesized from methionine (Met) and Tyr from phenylalanine (Phe) -when adequate quantities of Met and Phe are consumed, the body uses them to make PRO and to make Cys and Tyr (hence, Cys and Tyr are non-essential) -with inadequate dietary intake of Met and Phe, Cys and Tyr become conditionally-essential, that is there isn’t enough Met and Phe to make sufficient Cys and Tyr to meet our needs -Met and Phe are used up quickly which ultimately prevents PRO synthesis, the body then breaks down it's own proteins to supply Met and Phe -Cys and Tyr then need to be consumed in the diet -PRO synthesis is an ‘all or none’ situation – all aa needed to synthesize a protein must be present for the synthesis to occur C. RECYCLING/DEAMINATION OF AMINO ACIDS -each day more amino acids are recycled in the body than are consumed in the diet ~300 g/day synthesized in body, ~100 g/day consumed -recycling of aa in body is called PROTEIN TURNOVER – the synthesis and degradation of endogenous proteins; turnover reduces our dietary need to take in larger quantities of protein than what we consume in the diet -catabolism of aa to form energy (e.g., gluconeogenesis) occurs via DEAMINATION (mostly occurs in the liver) =the loss of an amino group from an aa, leaving a C-skeleton (keto-acid that is used to make GLU) -byproduct of deamination of the amino group is ammonia (NH3), which is toxic to the body -the liver converts ammonia to a less toxic form called UREA and releases it into bloodstream -kidneys filter urea from the blood and excrete it in the urine -remaining C-skeletons can be burned for fuel or converted into GLU for energy use -we don’t store proteins in the body – when they are in the body, they are in use (e.g., structural, functional) -when proteins are catabolized inside cells, some free aa may be released into bloodstream, usually attached to blood transport proteins (e.g., albumin), and usually travel to the liver for dismantling; the other aa will remain in the cell and be re-used to make new proteins -each cell contains a small pool of aa arising from dietary intake, aa recycling, and internal PRO breakdown -amino acids pool inside cells can be used to: -synthesize other proteins (e.g., hormones, neurotransmitters, membrane pumps) -synthesize non-essential amino acids (via transamination) -recycled into vitamins (e.g., Trp à niacin, a B vitamin) -deaminated to produce keto-acids and N -keto-acids (C-skeletons) can be: -burned for immediate energy -synthesized into FA for storage as potential energy -ketogenic aa broken down and C-skeleton used to produce fat -used to synthesize GLU -glucogenic aa broken down and C-skeleton used to produce GLU -N converted to ammonia (toxic); liver then detoxifies ammonia to form UREA (non-toxic); kidneys excrete urea in urine FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 4 of 15 D. DIETARY ASPECTS OF AMINO ACIDS -the quality of dietary proteins is measured by how much nitrogen is retained in the body, or by how well the protein supports body growth (e.g., children) -chemical and biological methods are used to determine protein quality (refer to Appendices at end of this set of notes) -quality depends on digestibility of the protein and “completeness” of the eaa in the food relative to human needs -reference proteins are often egg whites or milk protein (casein) 1. Complete Proteins = "High Quality Proteins" -provide all eaa in adequate quantities that meet human needs -generally animal foods -used most efficiently by body to support human growth, maintenance and/or repair 2. Incomplete Proteins = "Low Quality Proteins" -one (or more) eaa is lacking in adequate quantity to support human growth, maintenance and/or repair -the ‘limiting aa’ = the eaa in lowest concentration in a food -generally from plant protein foods and we can't consume enough to overcome the deficit -to ensure vital body protein synthesis continues, it is advisable to… 3. Combine Plant Proteins (Mutual Supplementation) to provide a full complement of eaa Plant Source Limiting aa Good Plant Source of Limiting aa Dishes of Complementary Protein legumes Met, Trp grains, nuts, seeds tofu + rice grains Ile, Lys legumes, vegetables lentil curry + rice nuts/seeds Ile, Lys legumes, vegetables soybeans + ground sesame seeds vegetables Met, Trp grains, nuts, seeds green beans + almonds GRAINS NUTS, SEEDS VEGETABLES LEGUMES LEGUMES are plants that have a single row of edible seeds within a pod (e.g., peanuts, dried peas, beans & lentils). GRAINS are seeds of various grasses such as wheat, rye, oats, barley, and rice. Examples of SEEDS are sesame, sunflower and pumpkin. There are many types. Examples of NUTS are hazelnuts (filberts), almonds, pine nuts, cashews & brazil nuts. There are many types. FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 5 of 15 -by combining plant protein foods over the period of a day (recommended at each meal for children; on a daily basis for adults), you ensure an adequate quality of total dietary protein -complementary PRO should be consumed at each meal or 2 consecutive meals for children -adults require ~15% of their PRO intake as eaa; typical diets contain ~50% of PRO as eaa -infants and preschoolers require 32-43% of their PRO intake as eaa to support growth -dietary advantages of consuming plant-based protein foods include: fibre, lower SFA, no cholesterol, increased phytochemicals Learning Objectives Describe the basic structure of proteins and how proteins differ from carbohydrates and fat. Distinguish between essential and non-essential amino acids from a nutritional perspective. Define the term “protein turnover”, and explain its importance in human health. Define the term “complete protein”. Name 3 food examples. Identify at least 3 combinations of plant foods that provide a complete complement of the essential amino acids. Name the process of catabolizing body proteins for metabolic use in the body. 3. PROTEINS A. AMINO ACIDS LINKED TOGETHER 1. Sequence (primary structure) -enzyme-mediated condensation reactions under direction of DNA -linked aa via strong PEPTIDE BONDS where the amino end of one aa is linked to the acid end of a different aa -aa linked in 1000s of different sequences -refer to pages 176-177 in text 2. Shape and Configuration (secondary structure represents localized segments (e.g., coiled regions); tertiary structure represents overall 3-D arrangement) -due to side chains of aa, attractive and repulsive forces create a chain with a stable 3-D structure -proteins often bristle with positive and negative charges on their surfaces -shape is also stabilized by hydrogen bonds and disulfide bonds between aa -proteins can assume one of 2 major configurations: 1. Globular – spherical (e.g., immunoglobulins) 2. Coiled – fibrous, more linear (e.g., fibrinogen) -the final 3-D structure determines the function of the protein -sometimes 2 or more separate chains of protein must link together to form a larger AGGREGATE in order for the protein to be functional (e.g., Hb) -sometimes a PRO needs a mineral to become active (e.g., Iron in Hb) FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 6 of 15 B. DENATURATION OF PROTEINS -can be due to many different conditions: heat, agitation, change in pH, heavy metals, alcohol, etc. -altered 3-D shape that leads to a loss of shape of the protein -denaturation can occur to different degrees -once a certain point of denaturation (loss of shape, uncoiling) occurs, it is irreversible and protein loses function -used as an advantage by the body: -e.g., in stomach -acid denatures (uncoils) many forms of protein to increase exposure of the PRO to digestive enzymes (digestive enzymes actually ‘digest’ the protein) -other examples: wine added to marinades – alcohol denatures the protein in meat and tenderizes it; lemon juice added to milk causes curdling (denaturing) of milk proteins -denaturing of proteins in some foods may reduce their tendency to cause allergic reactions 4. DIGESTION & ABSORPTION OF PROTEINS A. DIGESTION -primary role is to provide amino acids to the body -mouth -no proteolytic (PRO-digesting) enzymes; chewing and mixing with saliva -stomach -hormone GASTRIN causes release of gastric juice (HCl, water, digestive enzymes) 1. acid uncoils (denatures) protein so digestive enzymes can act on peptide bonds 2. acid activates: HCl pepsinogen PEPSIN (proenzyme) (active proteolytic enzyme) PEPSIN digests ~10% of protein in the stomach -small intestine -when polypeptides enter small intestine, SECRETIN & CCK cause release of pancreatic juice which includes TRYPSIN, an important PRO-digesting enzyme -crypt glands in intestinal wall produce di- and tri-peptidases that hydrolyze small peptides into aa B. ABSORPTION 1. 2. 3. Free Amino Acids -under normal conditions only free aa are actively absorbed into the bloodstream -competition exists among different aa for the same protein carrier Di- & Tri-peptides -absorbed into intestinal cell by different carriers than those used to absorb single aa -di- and tri-peptides that enter intestinal cells are hydrolyzed to single aa within the cells -ONLY single aa enter bloodstream Intact Proteins -absorption normally doesn't occur in adult life -an infant's intestinal tract is not fully developed, therefore, intact proteins can leak between intestinal cells into the bloodstream (~first few years of life) -foreign substances in the bloodstream elicit an immune response causing release of ANTIBODIES resulting in an allergic reaction C. TRANSPORTATION -only free amino acids enter the bloodstream and travel directly through the portal vein to the liver for metabolism FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 7 of 15 Food Allergy -an immune response (antibodies, histamines, etc.) to a PRO in a food -need to eliminate offending food(s) -young children with food allergies often outgrow the allergy Food Intolerance -does not involve the immune system = adverse reaction to food (e.g., skin rash) -moderate your intake of these foods: e.g., MSG in Oriental foods; sulfites in wines; tartrazine =yellow food dye; tyramine in aged foods, such as cheeses; lactose in milk Learning Objectives Explain how proteins are digested, absorbed, transported, and synthesized in our bodies. Describe the difference between food allergy and food intolerance. 5. PROTEIN QUALITY -the quality of protein is measured by how much Nitrogen is retained by the body, or by how well the protein supports growth -this depends on the digestibility of the PRO (dependent upon the configuration of the PRO and other foods it is consumed with) and its ‘completeness’ (eaa profile) relative to human needs -common measures used to determine protein quality include: Amino Acid Score (AAS), Biological Value (BV), Protein Digestibility Coefficient Amino Acid Score (PDCAAS), Protein Efficiency Ratio (PER), and Net Protein Utilization (NPU). Refer to pp. 185-186 in the text and the 2 appendices at the end of these PROTEIN class notes. You will not be examined on the material in the 2 appendices. 6. FUNCTIONS OF PROTEINS -must consume enough kcal to meet energy needs or body (endogeneous) proteins will be broken down to amino acids which in turn will be broken down and used for production of GLU -there is constant PROTEIN TURNOVER = degradation and synthesis of endogeneous PRO – this process of recycling of aa lowers our need for dietary intake of PRO A. SUPPORT GROWTH, MAINTENACE & REPAIR – VITAL BODY PROTEINS -dying or injured cells replaced with new cells and new proteins -visual pigments allowing us to see in colour and black and white w collagen (PRO) matrix of bone into which minerals like calcium and magnesium are deposited w connective tissue, tendons, ligaments and scar tissue w muscle w blood clotting w blood transport proteins (e.g., Hb, transferrin, albumin; lipoproteins necessary to transport fat around in the blood) -most of these proteins are constantly being broken down, resynthesized, or repaired (e.g., intestine -constant "sloughing off" of GI tract cells due to short life span of 2-3 days) -with adequate supply of protein in diet, amino acids can be efficiently recycled FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 8 of 15 -with inadequate supply of protein in diet, the rebuilding/repairing process slows and organs (e.g., muscle, kidney, heart, liver) become smaller and less efficient, all except for the brain (resistant to breakdown) -visual pigments, such as opsin and rhodopsin, allow us to see -collagen forms the matrix into which minerals (e.g., calcium, magnesium, phosphorus, fluoride) are deposited in bone and teeth; collagen is a triple-helix PRO -blood clotting factors -a cut in the skin or an injury to tissue elicits a response which results in the production of FIBRIN, a mass of protein fibres that ‘plugs’ the leak and stops the bleeding -blood transport proteins -some blood transport proteins move freely in body fluids and carry nutrients from one organ to another -e.g., Hemoglobin in bloodstream and Myoglobin in muscle - carry oxygen to cells -e.g., Transferrrin protein – carries Iron and Zinc in the blood B. ENZYMES -all are proteins -catalyze reactions; lock and key fit with substrate; recycled -enzyme supplements are treated like all other PRO in the diet, they get denatured in the stomach, digested in the small intestine and absorbed as single aa, not as the functioning enzyme advertised on the label C. HORMONES -can be steroid (fat), protein, or protein-derivative based e.g., Insulin -polypeptide (51 aa in length); must be injected; if taken orally, it is treated as any other PRO entering the digestive tract and would be denatured by the stomach acid and digested in small intestine; must be injected e.g., Thyroid Hormones -help regulate the body's metabolic rate & body temperature D. CELL MEMBRANES -“protein islands in a sea of lipids" -other PRO's act as RECEPTORS for hormones or lipoproteins (e.g., LDL) -other PRO's act as PUMPS to maintain electrolyte balance in the cell (e.g., Na/K pump) -some PRO's act as CARRIERS for absorption of nutrients into cells (e.g., GLU, FRU, GAl) E. BODY FLUID BALANCE -mainly 2 types of blood proteins, albumin and globulins, that maintain body fluid balance -if there is inadequate PRO intake: -there are fewer and smaller proteins in the blood -fluid accumulates between the cells = EDEMA (swollen tissue) = pools of extracellular fluid -often see edema in children with PRO malnutrition (e.g., in developing countries) F. pH BALANCE IN BLOOD -a very narrow range for normal blood pH = 7.35-7.45 -proteins in the blood act as BUFFERS (accept or donate H+ ions), to maintain a consistent blood pH level G. CONTRIBUTION TO IMMUNE FUNCTION -ANTIBODIES = large protein molecules that respond to foreign invaders (antigens) in the body -each antibody is designed to destroy just one invader -inadequate PRO (and other nutrient) intake compromises the function of the immune system FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 9 of 15 H. FORMATION OF GLUCOSE/PROVISION OF ENERGY -at rest, the brain uses ~35% of the body's energy needs (mostly in the form of GLU) -proteins supply ~5% of body energy; cells mostly use FAT and CHO as a source of energy -if you don’t consume enough CHO to supply the GLU your body needs, your body turns to finding internal sources of GLU -this process is called GLUCONEOGENESIS -the carbon-skeletons of glucogenic amino acids are used to supply GLU at times of low CHO intake and low blood glucose levels (i.e., the brain, in particular, uses GLU) -amino acids must have the amino group (Nitrogen) deaminated before being used for energy 7. FOOD SOURCES OF PROTEIN A. ANIMAL SOURCES -average meat serving size = 100g (3 oz.), or ~20g PRO -1 large egg ~4g PRO -1 cup (250mL) milk ~10g PRO; 175 mL yogourt ~9g PRO -the most PRO-dense food is water-packed tuna with >85% of total kcal coming from PRO B. PLANT SOURCES -also supply minerals and dietary fibre -supplies less SFA and no cholesterol (only found in animal foods) -provides phytochemicals (e.g., vitamin antioxidants) -generally plants supply <20% of their total kcal as PRO -vegetables & fruit provide very little PRO -limiting amino acids are characteristic of plant PRO sources, therefore, need to consume combinations of plant sources to provide full complement of eaa -examples: kidney beans (1 cup ~13g PRO), amaranth (1 cup, cooked ~10g PRO), almonds (30g ~6g PRO), sunflower seeds (1/2 cup ~8g PRO) 8. RECOMMENDATIONS FOR PROTEIN INTAKE A. DIETARY REFERENCE INTAKE 1. RDA a. infants b. adults -0-6 months: 2.0 g PRO/kg body weight per day -6-12 months: 1.3 g PRO/kg body weight per day -1-3 years: 1 g PRO/kg body weight per day -0.8 g/kg.d -endurance/elite athletes or those with a large muscle mass may increase to 1-1.5 g PRO/kg body weight -reference 19-30 year old male: weight: 70 kg, 56 grams PRO/day -reference 19-30 year old female: weight: 57 kg, 46 grams PRO/day 2. AMDR: 10-35% of total Energy intake FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 10 of 15 Learning Objectives Describe at least 6 roles for proteins in our bodies. List the Acceptable Macronutrient Distribution Range (AMDR) for proteins and the DRI-RDA for a healthy adult. Based on your own body weight, determine your RDA for protein intake (g/day). 9. HIGH PROTEIN DIETS -high protein diets have been the center of a much attention with claims leading to rapid and sustained weight loss -obesity rates are not decreasing and sustainability of initial weight loss most often doesn’t occur -many nutritional/health concerns are associated with high protein diets § crowd out more nutrient-dense foods § decreased legume & whole grain intake – legumes often used in place of meat in diet; reduced micronutrient and fibre intake § decreased fruit and vegetable intakes – leads to decreased fibre, micronutrient and phytochemical intakes à increased risk of cancer § dehydration – due to increased water requirements of PRO metabolism (~7X that required for CHO or FAT), and removal of unnecessary N groups in the form of urea in the urine; if enter into ketosis, increased ketone flow through kidneys pulls water out of body § possibly increased calcium losses in urine when over the RDA for protein; calcium released from bone to neutralize effects of sulphur-containing amino acids in blood; recommended ratio between 16:1 to 20:1 Ca(mg):PRO(g) § usually due to high animal-based protein intakes see increased SFA & dietary cholesterol à increased risk for cardiovascular disease and obesity (energy-dense foods) § increased potential for kidney damage – in people susceptible to renal disease § risk of cancer?? – high red meat intake may be associated with increased risk of colon, pancreatic, prostate &/or breast cancer; difficult to distinguish whether effects from PRO or SFA in red meats § increased cost – through animal foods and/or supplements § single amino acid supplements – costly; can crowd out absorption of other amino acids -common side effects: dehydration, constipation, fatigue, nausea, hyperlipidemia, salt and water depletion -better to moderate your overall energy intake – protein, carbohydrates, fat and alcohol – and be physically active doing activities that you enjoy every day Learning Objective Identify the nutrient and health impacts of high protein diets. FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 11 of 15 10. PROTEIN DEFICIENT DIETS – PROTEIN ENERGY MALNUTRITION (PEM) (Refer to pages 187-189 in the text.) § protein and energy malnutrition often seen together § usually occurs in early childhood § also seen in adults with disease conditions: HIV/AIDS, cancer, liver/kidney diseases, anorexia § many factors contribute to PEM § younger child’s relatively high need for energy and protein § diets low in nutrients § infrequent food intake due to inadequate food supply, food inequity, poverty, food distribution issues, insufficient land to farm, natural disasters, etc. § infection – viral, bacterial, parasitic, fungal § inappropriate formula preparation § full or partial recovery of PEM possible; CHO, PRO, sanitary water & salt first; later add fat § 2 common PEM classifications – MARASMUS (chronic) and KWASHIORKOR (acute) Marasmus Kwashiorkor Chronic PEM Infancy (usually less than 2 years) Severe deprivation, or impaired absorption of protein, energy, vitamins & minerals Develops slowly Severe weight loss Acute PEM Older infants and young children (1-3 years) Inadequate protein intake relative to kcal intake, or more commonly infections Rapid onset Some weight loss Severe muscle wasting, with no body fat Some muscle wasting, with retention of some body fat Growth: 60-80% weight-for-age Edema (fluid & electrolyte imbalance) Enlarged fatty liver Apathy, irritability, sadness Loss of appetite Growth: <60% weight-for-age No detectable edema No fatty liver Anxiety, apathy Good appetite possible Hair is sparse, thin and easily pulled out Skin is dry, thin and easily wrinkles Hair is dry and brittle, easily pulled out, changes colour, becomes straight Skin develops lesions Learning Objective Distinguish between the different types of protein energy malnutrition. Identify who is at greatest risk for each type and key differences in body appearance for each type. FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 12 of 15 11. VEGETARIAN DIETS (HIGHLIGHT 2, P. 57-61 IN TEXT) A. Types (Shaded types represent common types of vegetarian diets.) -there are numerous definitions to describe various “vegetarian diets” -these diets are ordered from more common to less commonly consumed diets Type Foods Consumed Semi-vegetarian All plant foods, sometimes seafood, Generally no nutrient concerns when consuming poultry, eggs and/or dairy a well-balanced and mixed diet products Same as semi-vegetarian, but Generally no nutrient concerns when consuming excludes poultry a well-balanced and mixed diet Lacto-ovo-pesco vegetarian Nutrient Concerns Lacto-ovo-pollo vegetarian Same as semi-vegetarian, but excludes seafood Lacto-ovo vegetarian All plant foods, plus dairy products Generally no nutrient concerns when consuming and eggs a well-balanced and mixed diet Lacto-vegetarian All plant foods and dairy products Generally no nutrient concerns when consuming a well-balanced and mixed diet, except iron Ovo-vegetarian All plant foods and eggs Calcium, vitamin D, riboflavin, iron Vegan (strict vegetarian) All plant foods only Calcium, vitamin D, B-12, riboflavin, iron, zinc Macrobiotic diet Increasingly restrictive vegan diet – All nutrients at extreme at extreme only brown rice, water and herbal tea consumed Only raw and dried fruits, honey, Most nutrients, except essential fat and CHO nuts, seeds and vegetable oil Fruitarian B. Why People Eat Vegetarian Diets -religious, traditional, and ethical reasons -environmental reasons -health benefits FNH 250: Nutrition Concepts & Controversies Generally no nutrient concerns when consuming a well-balanced and mixed diet FNH 250 Nutrition Concepts & Controversies Page 13 of 15 C. Nutritional Challenges -plant food sources for nutrients of concern to vegans and restricted eaters Nutrient Plant Food Sources Vitamin B-12 Fortified products (e.g., cereal/bars, meat analogues, yeast grown on vitamin B-12 medium) Vitamin D Fortified products (e.g., margarines, soy products); exposure to sun in summer months Calcium Fortified products (e.g., soy milks, tofu, OJ); almonds; some green leafy vegetables (e.g., kale) Riboflavin Enriched and whole grain products; mushrooms; beans; nuts; seeds; some green leafy vegetables Iron Enriched and whole grain products; beans; nuts; seeds; some green leafy vegetables Zinc Whole grain products; beans; nuts; seeds; wheat germ D. Tips for Meal Planning Plant-based Diets -basic dietary planning principles need to be incorporated (e.g., variety, balance, adequacy) Learning Objectives Describe the term “vegetarian/plant-based diet”. How would you clarify this term for a family member or friend? Discuss reasons why people choose to eat vegetarian/plant-based diets. Identify potential nutrients of concern for 5 common vegetarian/plant-based eating patterns, and sources of these nutrients in the diet. Describe potential health benefits of vegetarian/plant-based diets. Plan a one-day menu for your father that consists of 3 meals and a snack and will provide complete proteins using only plant food sources for each meal and snack. After much consideration, you have decided to adopt a vegan dietary pattern. When you share the news with your friends, they raise concern about adequate nutrition when only eating plant foods. You give them 4 reasons why you have chosen to adopt a vegan diet; however, you still need to convince them that you’ve studied this way of eating sufficiently enough that you can describe 4 health benefits and how you are going to manage 4 potential nutrients of concern being a vegan. FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 14 of 15 NOTE: You are not responsible for the material in these Appendices. APPENDIX 1. METHODS USED FOR MEASURING PROTEIN QUALITY I. CHEMICAL METHOD Amino Acid Score Chemical Score = mg of specific eaa in 1 g PRO test food (X 100) mg of same eaa in 1 g of PRO reference food -get a chemical score for EACH eaa in test food -the amino acid score (AAS) is the lowest chemical score for any of the essential amino acids (not averaged) -Advantages/Disadvantages -advantages -done in a lab, simple, inexpensive, can score mixtures of proteins -disadvantages -doesn't account for human digestibility of the PRO, chemicals used may destroy some eaa making AAS inaccurate II. BIOLOGICAL METHODS A. Protein Digestibility-Corrected Amino Acid Score (PDCAAS) PDCAAS = Amino Acid Score x digestibility coefficient for PRO -compares the eaa content of a protein food with eaa requirements of preschool children and corrects for digestibility -get eaa profile of test food (i.e., mg eaa/g protein in food) -compare to eaa requirements for preschool children (mg eaa/g protein) -the eaa with the lowest ratio; get Amino Acid Score (AAS) -multiply AAS by protein digestibility for test food (as determined by rat studies) -Advantages/Disadvantages -advantages -will meet or exceed requirements for all humans, except infants (age for fastest growth rate) -disadvantages -measures only one food source of protein (vs. meal) -often overestimates amount of amino acids absorbed -values truncated to 100% B. Digestible Indispensable Amino Acid Score (DIAAS) DIAAS = Amino Acid Score x digestibility coefficient in the ileum for protein = mg of digestible dietary indispensable amino acid (eaa) in 1 g of the dietary protein X100 mg of the same dietary indispensable amino acid (eaa) in 1g of the reference protein -digestibility based on true ileal (distal part of small intestine) digestibility of individual amino acids (amount of aa leaving the small intestine) FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 15 of 15 -ratio determined for each dietary eaa; lowest % score designated as DIAAS & used as indicator of protein quality -recent related scientific article: Potential impact of the digestible indispensable amino acid score as a measure of protein quality on dietary regulations and health. Nutr Rev 2017 Aug; 75(8): 658–667. -Advantages/Disadvantages -advantages -provides truer value for absorption of individual amino acids than PDCAAS, which measures crude protein digestibility -disadvantage -true ileal digestibility for individual amino acids not well characterized in humans; more research needed C. Protein Efficiency Ratio (PER) PER = weight gain (g) PRO intake (g) -Advantages/Disadvantages -advantages -standardized (to casein) values -useful for determining values for infants -disadvantages -only considers protein used for growth -doesn't account for PRO used for maintenance (adults) D. Net Protein Utilization (NPU) -accounts for digestibility, otherwise the same as BV NPU = N retained X100 N consumed -2 sequential N-balance tests are used (like BV) TEST 1 -no PRO fed to subjects -measure N-losses in urine and feces TEST 2 -measured amount of PRO fed to subject -measure nitrogen urinary and fecal losses N retained = N absorbed – urinary N N intake = total N consumed -Advantages/Disadvantages -advantages –done in human subjects, accounts for digestibility because testing total food N intake rather than food N absorbed -disadvantages -expensive, a low NPU score does not distinguish between poor digestibility of the food protein or poor amino acid content of the protein FNH 250: Nutrition Concepts & Controversies FNH 250 Nutrition Concepts & Controversies Page 16 of 15 APPENDIX 2. DETERMINING PROTEIN REQUIREMENT ESTIMATE -we need adequate amounts of protein from which non-essential amino acids can be synthesized, and we need adequate quantities and proportions of essential amino acids -through a series of steps (factorial method) we get a final recommendation of 0.8 g PRO/kg of body weight each day for Nitrogen balance -a person can be in various states of Nitrogen balance Balance: Intake (I) = Output (O) -positive balance: I > O -growth, weight gain -balance: I = O -expected in healthy adults on weight maintenance diet -negative balance: I < O -weight loss -mostly from inadequate intake or illness, surgery Determining Nitrogen balance: 1. Measure the nitrogen (grams) lost in urine using a 24-hour urinary urea nitrogen (UUN) test 2. Add 4 to the UUN value (this accounts for non-urinary losses of nitrogen: feces, skin, sweat…) 3. Determine nitrogen intake by dividing the daily protein by 6.25 (assumes protein is ~16% nitrogen) 4. Nitrogen balance = value from calculation 3 – value from calculation 2 • If the value from point 4 is ‘0’, the person is in nitrogen balance • If the value from point 4 is negative, the person is in negative nitrogen balance (indicating catabolism) • If the value from point 4 is positive, the person is in positive nitrogen balance (indicating anabolism) 5. Multiple grams of N obtained from calculation 4 by 6.25 to convert to grams of protein Practice example 1: 24hr UUN = 15g N, protein intake = 95 grams/day Answer: –24g protein/day. The person is losing 24 grams of protein per day. Practice example 2: 24hr UUN = 12g N, protein intake = 100 grams/day Answer: 0g protein/day. The person is in nitrogen balance. FNH 250: Nutrition Concepts & Controversies