Nut 101 - 6 Proteins PDF

PROTEINS Essen%al nitrogenous compound for living organisms Named by Jöns Jakob Berzelius (1838) Derived from the Greek word “proteios” – meaning "primary" or "of first importance" Its importance was understood aJer 1926 1926: James B. Sumner demonstrated that urease is a protein...

PROTEINS Essen%al nitrogenous compound for living organisms Named by Jöns Jakob Berzelius (1838) Derived from the Greek word “proteios” – meaning "primary" or "of first importance" Its importance was understood aJer 1926 1926: James B. Sumner demonstrated that urease is a protein enzyme 1958: Frederick Sanger determined the sequence of the first idenTfied protein → insulin 1958: Structure of the first proteins idenTfied: → Hemoglobin → Myoglobin Proteins, unlike carbohydrates and fats, contain nitrogen in their structure.  PROTEINS Essential nitrogenous component for living organisms" (16% of the protein's weight is nitrogen) Cells & Enzymes Are composed of PROTEINS Cells are constantly changing and renewing themselves, and this requires proteins. Without sufficient protein intake, cells cannot renew themselves. ESSENTIAL!!  PROTEINS Proteins, with nearly infinite functions and diversity, act as mediators in almost all processes within a cell!!! Proteins are the most abundant macromolecules in the body. 50% of our body's dry weight consists of proteins! Proteins have large molecular weights.  PROTEINS The source of body proteins is the protein obtained through food. It is essential to consume protein from external sources, as the body cannot produce protein from carbohydrates or fats. The body does not have a protein reserve, only a short-term protein backup for emergency situations.  The chemical structure of proteins Proteins are large and complex molecules. When broken down, they are separated into simpler structures known as ‘amino acids’. Proteins are formed by the combination of numerous and diverse amino acids.  All proteins are composed of 20 amino acids. The unique sequence of amino acids gives a protein its specific characteristics and determines its function. There are approximately 130 amino acids that do not form part of proteins but have significant functions!  AMINO ACIDS They are composed of carbon, oxygen, hydrogen, and nitrogen. Additionally, two amino acids also contain sulfur, which are referred to as sulfur-containing amino acids (metionin, sistein) These amino acids are present in limited quanTTes in some foods. To improve protein quality, it is recommended to consume a variety of foods together. These amino acids differ from each other in terms of structure and properties. AMINO ACIDS Building block of protein: Amino acids Building block of protein: Amino acids Example of an amino acid Amino acids consist of 4 parts: 1- α Carbon – C (1 H bonded) 2- Amino group - NH2 (carries nitrogen, (+) charged) 3- Carboxyl group - COOH (acid group, (-) charged) 4- Side group - Different for each amino acid Note:16% of the protein's weight is nitrogen  AMINO ACIDS The structure of an amino acid Amino Carboxyl Group Group (NH₂) (COOH Variable (R) Group Alpha Carbon (C): The central carbon atom to which all other groups are attached. Amino Group (NH₂): Contains nitrogen and is positively charged. Carboxyl Group (COOH): The acidic group, negatively charged. Hydrogen Atom (H): A single hydrogen atom bonded to the alpha carbon. Variable (R) Group: The side chain unique to each amino acid, determining its properties and characteristics.  AMINO ACIDS Building blocks of proteins. All amino acids contain an amino group (NH₂) and a carboxyl group (COOH). All amino acids contain carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). -Lysine and methionine also contain sulfur (S). Dipeptide: 2 amino acids Tripeptide: 3 amino acids Polypeptide: More than 10 amino acids Protein: Large polypeptides  AMINO ACIDS Animal cells are unable to synthesize the amino group (NH₂) Plants, however, can synthesize the amino group from atmospheric nitrogen and produce amino acids  AMINO ACIDS Proteins contain In Plants; 15-18% Nitrogen (NH₂) from the soil, nitrogen. CO₂, and H₂O combine to form amino acids (AA) and proteins. In Animals: Proteins obtained from plants are broken down into amino acids (AA). These amino acids are converted, rearranged, and combined to synthesize the animal's own Tssue proteins. Classification of Amino Acids 1. Based on their side chains and pH. 2. Based on their essential (indispensable) nature.  Classification of Amino Acids Aliphatic Side Chains: Glycine, Alanine, Valine, Leucine, Isoleucine Aromatic Side Chains: Phenylalanine, Tyrosine, Tryptophan Hydroxyl Group Side Chains: Serine, Threonine Sulfur-Containing Side Chains: Methionine, Cysteine Acidic Side Chains: Glutamic acid, Glutamine, Aspartic acid, Asparagine Basic Side Chains: Lysine, Arginine, Histidine, Ornithine  AMINO ACIDS Amino acids are divided into two categories in the human body: those that can be synthesized and those that cannot. Essential Amino Acids: These cannot be produced by the human body and must be obtained through diet. Non-Essential Amino Acids: These can be synthesized from other amino acids in the body. Amino acids that cannot be synthesized by the body and must be obtained from external sources are called essential (indispensable) amino acids.  AMINO ACIDS There are eight essential amino acids that the human body cannot produce and must obtain through dietary sources. – Triptofan – Treonin – İzolöysin – Löysin Sources – Lizin Dietary Protein – Metionin – Fenilalanin – Valin For infants, the amino acids histidine and arginine are also considered essential.  AMINO ACIDS Essential a.a Semi-Essential Amino Non-Essential Acids* Amino Acids 1. Leucine 1. Alanine 2. Isoleucine 2. Glycine 3. Valine 1. Arginine 3. Asparagine 2. Histidine 4. Aspartic Acid 4. Methionine 5. Lysine 5. Glutamic Acid 6. Phenylalanine 6. Proline 7. Threonine Essential in Children, 7. Hydroxyprolin Not in Adults 8. Tryptophan 8. Cysteine 9. Tyrosine 10. Serine  Amino acids released through protein digestion are utilized in metabolism for various purposes, including: Protein biosynthesis, Carbohydrate biosynthesis, Energy production, Endogenous amino acid synthesis, Biosynthesis of nitrogen-containing organic biomolecules, such as purine and pyrimidine bases in nucleic acids, Ammonia and urea biosynthesis Amino acids exist freely in red blood cells, intracellular and extracellular fluids, and are transported throughout the body via circulation. Key Reactions of Amino Acid Metabolism Transamination Deamination  Transamination Transamination reactions involve both the catabolism and anabolism of amino acids. They play a crucial role in: Energy production Glucose synthesis (gluconeogenesis) Synthesis of fats or ketone bodies Synthesis of non-essential amino acids These reactions primarily occur in hepatocytes (liver cells) and, to a lesser extent, in heart and skeletal muscle cells, taking place in the cytoplasm.  Example: Transamination Reactions Alanine + α-Ketoglutarate → Glutamate + Pyruvate Pyridoxal Phosphate Aspartate + α-Ketoglutarate Glutamate + Oxaloacetate Pyridoxal Phosphate Valine + α-Ketoglutarate Valine Aminotransferase Glutamate + Keto-isovalerate Pyridoxal Phosphate Pyruvate, oxaloacetate: Substrates for glucose in the TCA cycle The amino acids that contribute the most to the TCA cycle are; alanine, aspartate, and glutamate. Alanine's hepatic gluconeogenesis rate is much higher than that of all other amino acids. Krebs Cycle / Tricarboxylic Acid Cycle (TCA Cycle) / Citric Acid Cycle  Deamination Deamination is the process of removing amino groups from amino acids as NH₃ (ammonia). Deamination results in the release of ammonia, which is then used for urea synthesis in the urea cycle. Simultaneously, the carbon skeleton These processes, transamination and of the amino acid is converted into deamination, primarily occur in the cells of keto acids, which can be used for the liver and kidneys. energy production or other metabolic pathways. Transamination and deamination occur simultaneously and are often interconnected through a central molecule, glutamate.  AMINO ACIDS Non-Essential Amino Acids: Approximately 70 g/day of protein synthesis tissue proteins, enzymes, and hormones ow n m) Dige akd olis Abs stion e Br atab sis orpt ion (C the olism amino acid pool n Sy nab (A Transamination and deamination processes in the liver. Excretion via Kidneys: (0.9-1.0 g/day) Alpha-Keto Acids The amino acid pool refers Oxidation not to stored amino acids, Ammonia (NH₃) but rather to the total Acetyl-CoA amount of free amino Urea Krebs Cycle (TCA Cycle): acids available in the body. Urine ATP  AMINO ACIDS Every cell has the ability to synthesize large amounts of specific proteins. For synthesis, essential amino acids (EAA) must be obtained from dietary sources. For the synthesis of non-essential amino acids, amino groups and α-keto acids are provided. The synthesis of amino acids occurs through transamination reactions  AMINO ACIDS METABOLISM The amino group is removed via oxidaTve deaminaTon (in the liver). The amino group is converted into urea and excreted in the urine. A small amount of the amino group is used for the synthesis of non-essenTal amino acids. If a meal contains a large amount of protein, more than half of the absorbed amino acids undergo deaminaTon, while the remainder circulates as free amino acids. Branched-chain amino acids mostly remain in their free form in circulaTon.  AMINO ACIDS METABOLISM As a result of deamination, amino acids are converted into: In the muscle, the NH₂ group is transferred to form Pyruvic acid alanine. Alanine is transported to the liver, where it undergoes Oxaloacetic acid deamination, resulting in the formation of a keto acid. The keto acid is converted into glucose in the liver, which is crucial for energy production, especially Acetic acid during glucose deficiency. α-Ketoglutaric acid These intermediates enter the Krebs cycle.  AMINO ACIDS METABOLISM The conversion of some amino acids into others occurs in the liver *mediated by amino transferase and vitamin B6.  Glycogenic Both Glycogenic Ketogenic and Ketogenic Alanine Tyrosine Asparagine Aspartate Non-Essential Cysteine Glutamate Glutamine Glycine Proline Serine Arginine Isoleucine Leucine Histidine Phenylalanine Lysine ELZEM Methionine Tryptophan Threonine Valine If an amino acid (AA) converts to glucose → Glycogenic If an amino acid (AA) converts to ketones → Ketogenic k  Interconvertible Amino Acids Amino Acid Precursor Cysteine Methionine Tyrosine Phenylalanine Arginine Glutamine/Glutamate, Aspartate Proline Glutamate Histidine Adenine, Glutamine Glycine Serine, Choline Phenylalanine: It is significant in genetic and metabolic conditions. In newborns, it is associated with the genetic condition PKU (Phenylketonuria). Phenylalanine → Tyrosine. Phenylalanine Hydroxylase Branched-Chain Amino Acids (Valine, Leucine, Isoleucine): Used in liver disease and kidney failure. Utilized in stress and severe burns.  UTILIZATION OF AMINO ACIDS IN THE BODY Amino acids are utilized for the synthesis of new proteins: 1. Tryptophan: Used in the synthesis of niacin (vitamin B3) and the neurotransmitter serotonin. 2. Methionine: Acts as a methyl donor and is involved in the synthesis of sulfur-containing compounds like cysteine. 3. Tyrosine: Plays a role in the synthesis of thyroid hormones and adrenal medulla hormones (e.g., epinephrine). 4. Glycine: Involved in the synthesis of porphyrin, which forms the core structure of hemoglobin. 5. Histidine: Precursor for histamine, which has a vasodilatory effect in the circulatory system.  UTILIZATION OF AMINO ACIDS IN THE BODY 6. Arginine: Involved in urea synthesis and the formation of high-energy creatine phosphate. 7. Glutamine + Asparagine: Provide amino groups for various biochemical reactions. 8. Glutamic Acid: Serves as a precursor for the neurotransmitter GABA (gamma-aminobutyric acid). 9. Arginine and Glutamine: Act as immune enhancers in enteral nutrition products.  STRUCTURE OF PROTEIN Proteins are the molecular instruments through which genetic information is expressed.  STRUCTURE OF PROTEIN From the earliest bacteria in ancient times to the complex life forms of today... Everyone is made up of the same 20 amino acids (AA).  STRUCTURE OF PROTEIN Proteins are formed when one amino acid (AA) binds to another through a specific covalent bond. First discovered AA: Asparagine (1806) Last discovered AA: Threonine (1938) Naming of Amino Acids The names of amino acids were given in accordance with the sources from which they were first isolated: Arginine: From asparagus (asparagus). Glutamate: From gluten (gluten). Tyrosine: From tyros in Greek (cheese). Glycine: From glykos in Greek (sweet)  STRUCTURE OF PROTEIN For the synthesis of body proteins (such as tissues, hemoglobin, enzymes, and hormones), all 20 amino acids must be present simultaneously and in sufficient amounts. Body proteins contain these amino acids in specific proportions. One type of amino acid cannot be substituted for another. The sequence of amino acids in a protein determines its unique characteristics.  STRUCTURE OF PROTEIN Primary Structure (A linear chain of amino acids) Secondary Structure (Hydrogen bonds play a role; involves peptide + hydrogen bonds; forms a helix shape) Tertiary Structure (Molecule folds into chains, specific layers, and fibrils; involves peptide + hydrogen bonds + disulfide bonds) Quaternary Structure (Contains multiple subunits; polypeptide subunits are held together by weak bonds; involves peptide + hydrogen bonds + disulfide bonds)  Primary Structure: Peptide Bond The bond between two amino acids is called a ‘peptide bond’ Polypeptide: 50–100 amino acids Protein: More than 100 amino acids The primary structure is linear; for the protein to function, it must have a three-dimensional structure.  Secondary Structure: α-Helix structure (spiral structure): Hydrogen bonds (H bonds) β-pleated sheet structure (layered structure) Random coil Tertiary Structure: Formed by folding and bending Has a spherical shape Disulfide bonds are important The tertiary structure includes both primary and secondary structures Quaternary Structure: Formed when two or more polypeptides with tertiary structure come together to create an advanced structure. Many proteins become functional only after achieving this structure.  STRUCTURE OF PROTEIN Each organ and individual in the body has a unique protein structure. As a result of damage/mutation in DNA, a different amino acid sequence in the protein chain can lead to the formation of a non-functional protein. What is Denaturation? ‘Denaturation’ refers to the disruption of a protein's three-dimensional structure without breaking its peptide bonds. Heat, acids, bases, alcohol, heavy metals, and certain other agents can cause denaturation Denatured protein??? Denatured proteins: Are easier to digest, Have reduced solubility in water, Lose their natural characteristics, Undergo disruption of their helical structure, leading to shape changes and conversion into a polypeptide state, Lose their functionality (e.g., they no longer exhibit enzymatic activity). When the structure of a protein is disrupted, digestive enzymes can act on it more easily, resulting in faster digestion.  Examples of denaturation: The solidification of an egg when cooked, Foam formation when egg whites are whipped, The curdling of milk when acid is added, The marination of meat or fish with various sauces. Meringue  HE He at Denatured proteins are digested more quickly and easily. Their nutritional value does not change. In addition Marination to heat treatment, Whipping processes also cause the structure of proteins to break down, such as: making them easier to digest.  ‘Renaturation’ Renaturation refers to the process by which proteins regain their three- dimensional structure and restore their biological activity after being denatured.. Protein Metabolism  DIGESTION Pepsinogen + water Protein + water Polypeptide + Amino Acid Protein digestion in the stomach: Approximately 10-15% of protein digestion occurs in the stomach. Stomach: Stomach acid facilitates the denaturation of proteins. ‘Pepsinogen’ secreted in an inactive form by the stomach, is activated by stomach acid to become pepsin. Pepsin is effective in breaking peptide bonds, initiating protein breakdown into smaller peptides and amino acids. The enzyme rennin (found in infants) works with calcium ions to precipitate milk protein (casein). Pancreas: When food passes from the stomach to the small intestine, the pancreas secretes inactive digestive enzymes known as pancreatic proteases. - Proteases are enzymes that play an active role in protein digestion. These enzymes are activated by combining with secretions from the small intestine: – Trypsinogen (inactive) → Trypsin (active) – Chymotrypsinogen (inactive) → Chymotrypsin (active) – Procarboxypeptidase (inactive) → Carboxypeptidase (active) – Proelastase (inactive) → Elastase (active) Small Intestine: The small intestine is the primary organ where digestion takes place. Digestion occurs with the help of pancreatic proteases secreted by the pancreas. Trypsinogen is converted into trypsin with the assistance of enterokinase secreted by the small intestine. Enzymes such as aminopeptidase and dipeptidase further break down peptides into amino acids.  Enterocytes secrete cholecystokinin, which stimulates the pancreas to release pancreatic proteolytic enzymes into the intestinal lumen via the pancreatic duct Trypsinogen → (Enterokinase) → Trypsin Chymotrypsinogen → (Trypsin) → Chymotrypsin Procarboxypeptidase → (Trypsin) → Carboxypeptidase Proelastase → (Trypsin) → Elastase  Trypsin: Breaks down amino acids, especially lysine and arginine. Creates small peptides. Chymotrypsin: Breaks down regions containing amino acids like tryptophan, phenylalanine, and tyrosine. Carboxypeptidase: Cleaves the carboxyl end of the peptide chain Result: Ready for absorption as; amino acids, dipeptides, and tripeptides  Digestive Challenges Oligosaccharides, non- starch polysaccharides, Antitryptic factors dietary fiber in legumes Increase viscosity in the intestine Inhibit protein digestion Reduce the effectiveness of enzymes Proper cooking reduces the Decrease protein negative effects of digestibility these factors EMİLİM Absorption Enterokinase trypsinogen trypsin Chymotrypsinogen Chymotrypsin Trypsin- Chymotrypsin small polypeptides +H2O smaller polypeptides +amino acids Aminopeptidase and Carboxypeptidase smaller polypeptides +H2O Tripeptides-dipeptides Amino acids Tripeptidase and Dipeptidase tripeptides and dipeptides + H2O Amino acids Free amino acids after absorption Absorption occurs in the jejunum and ileum  DIGESTION Amino acids pass from the small intestine into the bloodstream through: – Simple diffusion – Active transport  Proteins are absorbed as free amino acids. They are transported to the liver via the portal vein. The majority of absorption occurs through active transport, which requires ATP and the vitamin B6 coenzyme pyridoxal phosphate. A small portion is absorbed through simple diffusion.  Absorption Imbalances among amino acids (AAs) affect their absorption because AAs compete for transport mechanisms. For efficient AA absorption, methionine in food should be present in lower amounts compared to other AAs. In a food source containing equal amounts of methionine, phenylalanine, and alanine, methionine can inhibit the absorption of the other AAs.  DIGESTION The effect of food processing on amino acid absorption: The absorption rate of lysine, which forms a complex with fructose (fructolysine), is significantly reduced. This compound is produced during the Maillard Reaction, which occurs when proteins and carbohydrates are processed at high temperatures.  METABOLISM The body does not store free amino acids. Any excess beyond what is required for tissue proteins and the synthesis of certain nitrogen-containing compounds is broken down and used for energy as fat or carbohydrates. However, cellular proteins contribute to an amino acid pool, which can meet demands when needed. Amino acids are primarily used for the synthesis of new proteins. They also have specific functions, such as tyrosine being used in the synthesis of thyroid hormones. Purpose: To prevent abnormal protein accumulation, To allow rapid changes in protein concentration when needed, To provide an easily accessible source of amino acids. Every day, 300 g of protein is synthesized (requires ATP) and broken down (requires ATP). ) Synthesis Breakdown (Anabolism): (Catabolism) PROTEIN TURNOVER 20% of Basal Metabolic Rate (BMR) is used for protein turnover.  How Are Amino Acids Used in Tissues? Intracellular Reactions of Amino Acids: Conversion to keto acids Conversion to biological amines Utilization of Amino Acids in the synthesis of non-protein nitrogen (NPN) compounds In protein synthesis Excretion via the kidneys  Functions of Proteins Proteins make up approximately 15% of body weight. Structural Proteins Form components of cell membranes, muscles, bones, and skin. – Examples: Collagen (found in bones and skin) Keratin (in hair and nails) Regulatory Proteins Enzymes: Catalyze biochemical reactions. Hormones: Regulate physiological processes (e.g., insulin). Immunity: Support immune function (e.g., antibodies). Transport: Facilitate transport in cells and blood (e.g., hemoglobin). Fluid and Mineral Balance: Maintain homeostasis by regulating fluid and electrolyte levels.  Functions of Proteins Growth and Development Repair of damaged tissues Blood clotting (fibrin formation) Cell regeneration Protein synthesis and breakdown (protein turnover) Provision of amino acids for the body Maintenance of acid-base balance If consumed in excess, proteins are stored as fat.  Functions of Proteins Enzymes All enzymes are composed of proteins. The tertiary structure of proteins gives them their enzymatic properties. Proteins catalyze chemical reactions. They have both anabolic (building) and catabolic (breaking down) functions.  Functions of Proteins Hormone Synthesis The structure of some hormones is made of proteins. Examples: Insulin Cholecystokinin Growth hormone Antidiuretic hormone Some reproductive hormones  Functions of Proteins Immune Function An ‘antibody’ is a protein produced by the immune system in response to the presence of an antigen. It multiplies in the presence of foreign elements and deactivates them.  Functions of Proteins Transport Proteins Hemoglobin Myoglobin Serum Albumin Transferrin etc  Functions of Proteins Fluid Balance Proteins in the blood help maintain appropriate fluid levels within the vascular system. This is achieved through osmotic pressure. Body Protein Reserves: In a 70 kg man, there are 11 kg of protein distributed as follows: 43% in skeletal muscle 12% in other structural tissues (skin, blood, etc.) 10% in visceral tissues (liver, kidneys, etc.) 32% in other tissues (brain, liver, heart, bone). Protein Balance and Requirements To determine the body's protein requirements, nitrogen (N) balance studies are conducted Nitrogen Intake from Food Nitrogen Loss Nitrogen Balance: The state where the amount of nitrogen consumed through food equals the amount of nitrogen excreted by the body. Protein Balance and Requirements If the amount of protein consumed through food is low, the nitrogen intake will be less than the nitrogen excreted →→→ Negative (-) nitrogen balance →→→ Increased breakdown of proteins in tissues. If the protein intake exceeds the amount excreted, some nitrogen is retained in the body →→→ Positive (+) nitrogen balance →→→ Increased protein synthesis in tissues. Protein Balance and Requirements Negative Nitrogen Balance: Low protein intake Intake of low-quality proteins Failure to meet requirements for all essential amino acids Inadequate energy intake Increased tissue protein breakdown due to surgery, injury, severe burns, fever, etc. In space missions, the lack of gravity also increases protein breakdown.  Protein Quality Negative Nitrogen Balance: Low protein intake Intake of low-quality proteins Failure to meet requirements for all essential amino acids Inadequate energy intake Increased tissue protein breakdown due to surgery, injury, severe burns, fever, etc. In space missions, the lack of gravity also increases protein breakdown.  Protein Quality EGG Complete Protein All of it is converted into body proteins!!! BREAST MİLK  Protein Quality Proteins from foods that contain limited essential amino acids experience losses during digestion, delaying their conversion into body proteins. Such proteins cannot fully meet the needs of a growing organism. Therefore, dietary proteins are categorized based on their degree of utilization in the body.  Protein Quality Low-Quality Protein: Proteins that contain some essential amino acids in amounts below the body's requirements and are difficult to digest (not fully utilized). High-Quality Protein: Proteins that contain all essential amino acids in sufficient amounts and are easy to digest (nearly fully utilized).) Complete Protein: Proteins that can be fully utilized by the body.  Protein Quality qHigh-Quality Protein qLow-Quality Protein:  Low-Quality Protein: All animal and plant-based foods contain protein, but the quantity and quality vary. In animal protein sources, the composition of essential amino acids aligns with human needs, whereas in plant protein sources, one or two essential amino acids are present in lower amounts than required. These less abundant essential amino acids in some protein sources are called the limiting essential amino acids of that protein. Proteins with essential amino acids in appropriate proportions are utilized by the body without significant loss in the digestive system. Since they contain all essential amino acids, these amino acids can combine to form body proteins easily and quickly.  Protein Quality In legumes, methionine and cysteine are the limiting essential amino acids. In grains, lysine and threonine are the limiting essential amino acids, in that order. In corn (maize): First limiting essential amino acid: Tryptophan Second limiting essential amino acid: Lysine Third limiting essential amino acid: Threonine  Protein Quality The limiting essential amino acid in wheat is lysine. Lysine, however, is abundant in milk and legumes. Even if an essential amino acid is limited in one food source, it can be found in large amounts in another.  Protein Quality Amino Asit Kompozisyonu; Missing ones: Lysine Threonien Methionine Cysteine Legumes Grains Mixed Animal proteins have higher protein quality compared to plant-based proteins. Mixing dairy products with grain products Combining grains with legumes Adding eggs to the diet all increase the protein quality of the diet!  Protein Quality Due to the unique characteristics of different protein sources in terms of essential amino acids: Combining grains and legumes – Example: Beans and rice, or traditional dishes like aşure (a Turkish dessert). Consuming grains with dairy group foods – Example: Milk-based desserts, or soups with milk/yogurt. These combinations can help balance deficiencies in essential amino acids.  Protein Quality Ensuring that a portion of daily foods comes from animal sources helps meet the essential amino acid requirements. Consuming dairy products together with grains can address the imbalance in essential amino acids. In families with low economic status and purchasing power, protein needs are mostly met from plant-based sources. Recently, due to efforts to limit saturated fat intake from animal sources, meat consumption has decreased, leading to an increase in plant- based protein intake.  Protein Quality The protein obtained from plants often contains lower amounts of certain essential amino acids, and its lower digestibility reduces the rate at which these proteins are utilized in the body. The amount and type of essential amino acids that are limited in one food source may be abundant in another. For this reason, consuming a varied diet is essential. In Terms of Protein Quality in the Diet... In terms of socio-economic conditions, for individuals who cannot consume relatively expensive foods such as meat and fish regularly and/or in sufficient amounts, it is recommended to: Combine foods that contain limited essential amino acids, And ensure the inclusion of EGGS in the diet.  Protein Digestibility Proteins from animal sources such as eggs, milk, and meat: 91-100% Cereal proteins: 79-90% Legume proteins: 69-90%  Protein Digestibility Removing the bran from grains increases digestibility. The digestibility of chickpeas and lentils is higher compared to other legumes. When the digestibility of proteins from meat, eggs, and milk is taken as a reference (100): – Corn: 85 – Rice: 75 – White flour: 96 – Whole wheat flour: 86 – Beans (dry): 78  Protein Digestibility of Some Foods Foods True Protein Digestibility% Egg 97 Meat/chicken/fish 94 Milk/diary 95 Corn 85 Whole grian/Bulgur 86 Bread/flour/purified wheat 96 Millet 79 Oatmel 86 Oat 72 Peanut 94 Peanut butter 95 Brown rice 75 Rice 88 Bean 78 Lentil 85 Chickenpea 85 Pea 88 Starchy root vegetables, Potato, 89 Other vegetables 90  Amino Acid Utilization Not all amino acids in food can be utilized. The rates of digestion and absorption vary. – Animal proteins: ~90% utilization – Plant proteins: ~60-70% utilization The limited digestibility of proteins is influenced by several factors; Structural properties of the protein: Proteases act more slowly on insoluble fibrous proteins compared to soluble globular proteins. Protein denaturation: Digestibility can be easily improved by processes such as moderate heat application, which causes protein denaturation. Protein interactions: Proteins bound to metals, lipids, nucleic acids, cellulose, or other polysaccharides may have reduced digestibility. The limited digestibility of proteins is influenced by several factors; Antinutritional factors such as fiber, trypsin, or chymotrypsin inhibitors can reduce protein digestibility. Protein molecular size and surface characteristics are important. The digestibility of cereal proteins can be improved through proper grinding. High heat treatment, alkaline pH, or the presence of carbohydrates can decrease both digestibility and the bioavailability of amino acids (AA) due to the Maillard reaction. Absorption of amino acids and digestion of proteins exhibit biological variability among individuals.  Protein balance and requirement Requirement is defined as the amount necessary to maintain nitrogen balance – (determined as the amount of nitrogen (N) needed to compensate for lost N, measured in mg/kg/day). Nitrogen-to-protein conversion factors in foods: Milk protein: 6.38 The nitrogen-to- protein conversion Meat protein: 6.25 factor: Egg protein: 6.25 6.25 (average) Cereal proteins: 5.83 Proteins in oilseeds/nuts: 5.30 On average: Protein amount = Nitrogen amount × 6.25 Protein balance and requirement Protein requirement (g/kg body weight) Age(y) High-Quality and Example Plant-Based Diet Protein Sources 0.8-1.0 N requirement x 6.25 = Protein requirement (g/kg/day)  Factors for Converting Nitrogen to Protein Foods True Protein Digestibility% General (Meat/Egg) 6,25 Milk/diary 6,38 Whole grian/Bulgur 5,83 Wheat Bran 6,31 Low-Yield Flour, White Bread, Endosperm 5,7 Rice 5,95 Rye, Barley, Oats 5,83 Pasta 5,7 Soy/legumes 5,71 Nuts 5,46 Almond 5,18 Other Oilseeds (Sesame, Sunflower, Pine Nuts) 5,3 Vegetables 4,4 Chocolate/ cocoa 4,74  Protein balance and requirement In childhood, 33-39% of dietary nitrogen intake should come from essential amino acids (EAAs). In adults, this proportion is 15%. At least 1/4 of the total protein consumed by adults and at least half of the total protein consumed by children should be derived from animal sources.  Protein balance and requirement Protein requirements vary significantly with age. In infants and children, protein requirements per unit of body weight are higher. For adults, it is recommended that 10-20% of daily dietary energy comes from proteins.  Protein balance and requirement Body size: Individuals with larger body frames require more protein compared to those with smaller frames. Age: Children, being in a growth phase, have higher protein requirements per kilogram of body weight to support rapid growth. Gender: Men generally have more muscle tissue and less fat tissue than women. More protein is needed to support the renewal of muscle cells.  Protein balance and requirement Pregnancy: Protein requirements increase to support the growth of the baby and placenta, as well as the expansion of blood and tissue in the pregnant woman. Lactation: Additional protein is needed for milk production in the mammary glands.  CONDITIONS THAT INCREASE PROTEIN REQUIREMENTS Pregnancy and Lactation: – Add 15-20 g/day to the daily requirement with an animal- based diet. – Add 25 g/day to the daily requirement with a plant-based diet. Illnesses, Surgeries, Infections, and Burns: – Protein breakdown in the body increases under these conditions. Infants and Children with Growth and Development Delays: – 0.23 g of additional protein is required for every 1 gram of lost/deficient tissue. Athletes and Laborers: Causes of Protein Deficiency: Inadequate IntakeReasons include poverty, lack of awareness, and loss of appetite. 117 Causes of Protein Deficiency: Inadequate IntakeReasons include poverty, lack of awareness, and loss of appetite. -Incorrect Nutrition/Dietary Practices Due to Lack of Knowledge Media-driven diet trends: Following popular diets without proper understanding. Uninformed Vegan Diets: Vegan diets practiced without proper planning or knowledge of essential nutrient sources. Studies* suggest that women of childbearing age should be particularly cautious when following a vegan diet to ensure the health of both themselves and their baby. * The Effects of Vegetarian and Vegan Diet during Pregnancy on the Health of Mothers and Offspring. Nutrients. 2019;118 11(3):557.  Causes of Protein Deficiency: Digestive or Absorption Disorders: – Conditions such as celiac disease or inflammatory bowel diseases can impair the absorption of proteins. Protein Loss Due to Kidney Disease: – Nephrotic syndrome leads to significant protein loss through urine. Losses in Chronic Bleeding Conditions: – Conditions like ulcerative colitis result in chronic protein losses due to bleeding. 119 Causes of Protein Deficiency: Protein Loss in Burns: Protein is lost through wound exudates in burn injuries. Liver Failure: Reduced production of albumin due to impaired l iver function. Inadequate Total Energy and Carbohydrate Intake in the Diet: Proteins are utilized for energy production instead of their primary functions. 120  Effects of Protein Deficiency Reduced resistance to diseases Growth slows down and eventually stops Leading to an economic burden! Resulting in weakness and stunted height! More severe progression of illnesses Delays in mental development Adding to the economic burden! Leading to decline in academic performance! Decreased work capacity Resulting in further economic burden! 121  Effects of Protein Deficiency Blood cells and hemoglobin production depend on protein; Liver enzyme activity disruption leads to decreases Anemia! Wound healing is Deficiency in proteins that delayed transport nutrients in the Appetite decreases body Such as calcium-binding proteins, retinol-binding protein, transferrin, etc. 122  Effects of Protein Deficiency In children: Chronic protein deficiency → Leads to Kwashiorkor disease Protein + energy deficiency → Leads to Marasmus disease 123 More than 820 million people worldwide are struggling with hunger! 124 125 UNICEF, WHO, World Bank Joint Child Malnutrition dataset, September 2016 update  52 million children under the age of 5 are wasted, and 17 million are severely wasted. 155 million children are stunted. 45% of deaths among children under 5 are associated with wasting. 126  ADEQUATE PROTEIN INTAKE Proteins and Amino Acid Levels in the Blood are indicators of whether an individual is consuming adequate protein. These include: Albumin Prealbumin Globulin Transferrin These biomarkers help assess the body's protein status and overall nutritional health. A sign of malnutrition is a decrease in body weight. A sign of chronic malnutrition is short stature relative to age.  EXCESSIVE PROTEIN INTAKE (Over 200 g/day or >40% of energy from protein) Excessive protein intake exceeding twice the required amount increases calcium excretion through urine, leading to osteoporosis. (This occurs because the oxidation of sulfur-containing amino acids from animal sources increases acid load, which is buffered by pulling calcium from bones.) The workload for urea synthesis and excretion in the liver and kidneys increases, raising the risk of kidney stone formation. High animal protein intake also increases the consumption of saturated fat and cholesterol, elevating the risk of cardiovascular diseases and cancer. Excessive consumption of animal-based foods to meet high protein intake can result in constipation.  VEGETARIAN DIETS Lacto-vegetarian……………. Ovo-vegetarian……………… Lacto-ovo vegetarian……… Semi-vegetarian Vegan  VEGETARIAN DIETS Vegetarian Diets Lacto-vegetarian……………. Dairy products Ovo-vegetarian……………… Eggs Lacto-ovo vegetarian…….. Eggs and dairy products Semi-vegetarian (=white vegetarian): Exclude some animal-based foods from their diet (usually red meat) Vegan: Do not consume any animal-derived foods  VEGETARIAN DIETS Vegetarian diets are generally sufficient in vitamins and proteins, but deficiencies may occur in vegans. Plant-based proteins should be combined in a variety to balance essential amino acids (EAAs).  VEGETARIAN DIETS Vitamin and Mineral Deficiencies in Vegetarian Diets Iron Calcium Riboflavin Zinc Vitamin B12 (Not found in any plant-based foods, only present in animal-based foods)  PROTEIN SOURCES Foods Highest in Protein Legumes (20-25g/100g) Soybeans (30-35g/100g) Meat, chicken, fish (15-22g/100g) Protein quality Cheeses (15-25g/100g) should not be Grains (8-12g/100g) overlooked! Milk (3-4g/100g) Eggs (12-13g/100g) Taze sebze ve meyvelerdeki protein miktarları çok daha düşüktür!!!