Intro to Nutrition Notes - PDF

Chapter 1: Intro to nutrition Nutrition – a science that studies all the ingredients that occur between living organisms and food Nutritional science – ties together aspects of many scientific fields: Chemistry, Biology, philology biochemistry, food science Diet –...

Chapter 1: Intro to nutrition Nutrition – a science that studies all the ingredients that occur between living organisms and food Nutritional science – ties together aspects of many scientific fields: Chemistry, Biology, philology biochemistry, food science Diet – foods and beverage you consume as a whole Nutrients – chemical substances in food that provides energy, structure, and regulation of body processes Essential nutrients: o Obtained only from a diet o They are not producing by the body or in large amounts to meet needs o They are not essential for growth and the maintenance of life o Example – Vitamin C Nonessential dietary nutrients: o Substances in food that are not essential for life, but beneficial for health o Ex. Lecithin is a substance found in egg yolks ▪ Contains choline – needed for nerve function, but it is produced in the human body, so it is not essential to obtain from the diet Phytochemicals- substances found in plant foods that are not essential nutrients o Ex. Sulforaphane in broccoli Zoochemical – substances found in animal foods that are not essential nutrients o Ex. Conjugated Linoleic Acid in meats Fortified or enriched foods – addition of nutrients to a food or beverage product o Ex. Milk with added vitamin A Dietary supplements – products intended for ingestion in the diet. Contains one or more of the following: o Vitamins, minerals, amino acids, plant-derived substances, concentrates, and extracts Six Classes of Nutrients: Nutrient classification: o Energy-yielding – Carbs and protein 4 kcal/g Lipids 9 kcal/g o Macronutrients – Carbs, Lipids, Protein, Water o Micronutrients – B Vitamins, Vitamin C, A, D, E, K, Calcium, and Iron o Inorganic – Minerals, Water o Organic – Carbs, Lipids, Protein, and Vitamins Carbs – rice, bread, sugar Protein – animal-based, plant-based  Lipids – fatty fish, nuts, seeds, oils Energy provided by foods is measured in kilocalories Simplest form of carbs are sugars Complex carbs (like starch or flour) are made up of sugars linked together by chemical bonds. Fatty acids o Saturated fatty acids o Unsaturated fatty acids o Trans fatty acids May promote certain diseases o Saturated fatty acids May help to prevent certain diseases o Unsaturated fatty acids Cholesterol o Found in smaller amounts in diet than triglycerides ▪ 300-600 mg cholesterol vs. 60-100 g total fat Proteins: o Required for growth, Maintenace and repair of body o Can also supply energy o Madu up of amino acids o Linked together in different combinations Water: o Water is a macronutrient- required in large amounts but does not provide kilocalories ▪ Lubricant, tranport fluid, regulates body temp, etc. o Require more than any other nutrient o Can’t store water – water lost by the body must be replaced Micronutrients provide no energy o Antioxidants, coenzymes, cofactors Includes vitamins and minerals Very important for good health but are required in small amounts Found in most fresh foods Vitamins are organic molecules Regulate body processes o Help utilize energy form carbohydrates, lipids, and proteins o Bone growth, vision, blood clotting, etc. 13 substances identified as vitamins  Minerals are inorganic molecules o Regulate body processes o Provides structure >16 essential minerals needed Major minerals o In body or needed by body in an amount greater than 100mg/day or 0.01% of body weight Trace minerals o In body or needed by body in an amount of 100 mg/day or body weight or less All reactions that occur in the body are called metabolism Proper regulation of metabolism is called homeostasis - maintenance of stable internal environment Each nutrient plays a role in helping to maintain homeostasis and health Undernutrition: Deficiency of energy or nutrients Starvation is the most severe form Overnutrition: o Excessive intake of energy and nutrients -> overweight and obesity o Adverse or toxic reactions in the body may occur o Examples: ▪ Iron – liver failure ▪ Vitamin b6 – nerve damage Nutrigenetics – the study of how our genes affect the impact of nutrients or other food components on health Nutrigenomics – the study of how nutrients and the food we consume affects the activity of our genes How to choose a healthy diet: o Contains right amount of energy o Contains proper types and balance of nutrients o Working principles of a healthy diet ▪ Consume nutrient-dense foods and meals ▪ Eat a variety of foods ▪ Balance your food choices ▪ Everything in moderation Nutrient density is a measure of the nutrient a food provides compared to its energy content o Ex. Low fat milk is more nutrient dense than sweetened iced tea  There are no good foods/bad foods Balancing foods allow all foods to fit in a healthy diet The scientific method o Advances in nutrition are made using the scientific method o The scientific method uses an unbiased approach to examine the interaction of food, nutrients, and health Observation o Asking questions Hypothesis o Educated guess or prediction Experimental Steps o Methods or steps done to test the hypothesis Theory o Explanation based on scientific study and reasoning Study populations in Nutrition Research: Cells: o Extracted from humans or animals or grown in the laboratory o Used for studying nutrient involvement in metabolic reactions or genetics in specific cell types Animal Models: o Used to study nutrient utilization and disease development o Allows researchers to study disease pahways in organs/tissue beyond what is feasible in humans Human Subjects: o Used to study nutrient utilization and disease development in relation to clinical outcomes and to inform dietary recommendations o Can study broad populations or specific groups Observational Studies o Epidemiology ▪ Observation of relationships between diet, health and disease patterns in different populations ▪ Focuses on patterns, rather than cause-and-effect scenarios ▪ Hypothesis-generating for follow-up study ▪ Ex. Comparing % saturated fat from calories and coronary heart disease incidence o Case-control ▪ Track backward from outcome to exposure  ▪ Are inherently retrospective o Cohort Human intervention studies o Involves experimental manipulation of some members of the population o Observations and measurements are made to determine the effects of this manipulation o Ex. Diet and heart Disease, Calcium supplement vs. Placebo pill Depletion-Repletion studies o The nutrient is eliminated in the diet until deficiency when symptoms appear, nutrient is added back to the diet to a level which symptoms are eliminated o Ex. Calcium and Osteoporosis and Vitamin C and Scurvy Balance study o Compares the total amount of nutrient that enters the body compared to the total amount that leaves the body. MyPlate: o Released in 2001 o Included visual recommendations for portion size o Emphasis of proportionality, variety, moderation, and nutrient density My Plate Messages o Find your healthy eating style and maintain if for a lifetime o Make half your plate fruits and vegetables o Make half of your plate fruits and vegetables o Make half your grains whole grains o Move to low-fat or fat-free milk or yogurt o Vary your protein routine Food Labels: o Regulated by the FDA o More than 98% of all processed, packaged foods contains standard food labels o Meat and poultry labels are regulated by the US Department of Agriculture. Required information on Nutrition facts label o Name of the product o Net contents or weight o Sell by date o Manufacturer Ingredients are listed in order from highest weight to lowest weight  Label claims: o Nutrient content descriptors are established by the FDA o ex. low, high, free, reduced, lean, high potency, antioxidant Health claims o Describes the relationship between a food, food component, and/or dietary supplement ingredient with a disease or health condition risk o FDA-Regulated Structure/Function claim o Not regulated, it is based on the manufacture’s review and interpretation of the scientific literature o It must contain a disclaimer o Describe the role of the nutrient or ingredient in maintaining normal structure and function in humans Food served in restaurants, delicatessens, and bakeries are not required to carry labels unless the food is from establishment that has 20 or more locations Diatary supplements o 50% of American adults take some kind of supplement The digestive system o Ingestion and digestion of food ▪ Ingestion – taking in food into the body via the mouth o Facilitates the movement of nutrients into the body o Responsible for eliminating unabsorbed waste Digestion o Breaking down food into components small enough so it can be absorbed into the body o Energy-yielding nutrients: carbs, proteins, fats. Can only be broken down by enzymes The nervous system o Sends nerve signals to help control the passage of food throughout the digestive track. The endocrine system o Produces hormones to regulate food intake and the function of digestive organs Cardiovascular system o After absorption, the cardiovascular system transports nutrients to individual cells The urinary system  o Responsible for the elimination of fluids The respiratory system o Responsible for removing carbon dioxide from the body Integumentary system o Removes water and minerals through the skin o Ex. Sweat Absorbtion – process of taking substances directly into the body Structure of the gut wall: o Mucosa ▪ Absorption of digestion end products o Internal connective tissue ▪ Contains nerves and blood vessels ▪ Provides support, delivers nutrients to mucosa o Smooth muscle ▪ Involuntary contraction mixes and propels food o External connective tissue ▪ Provides support and protection Mucus o Viscous fluid secreted by the glands of the GI track o Responsible for lubricating and protecting the digestive track from harsh environments Enzymes o Protein molecules that speed up the rate of chemical reactions without undergoing any change Amylase acts with starch Pepsin, Trypsin, Chymotrypsin act with protein strand to individual amino acids Lipase acts on triglyceride to fatty acids and glycerol Transit time o The amount of time it takes for food to pass through the length of the digestive track o Healthy adults: 24-72 hours Nerve signals o Stimulated by the thought, sight, smell, and presence of food o Causes muscle contractions that churn, mix, and propel food through the gut o Stimulate or inhibit gastric secretions o Coordinate digestive activity with other functions  Hormones o Chemical messengers produced in an organ that is released into the bloods and generates a response at other locations within the body o Helps to prepare different areas of the gut for the arrival of food o Regulates nutrient digestion and the rate of food moving through the system o Ex. Gastrin is activated when food enters digestive tract Head o The cephalic response – involves signals form the nervous system o The sights, sounds, and smells of food prepare the nervous system Esophagus o Connects the pharynx to the stomach o Peristalsis – muscular contractions that moves the food down the esophagus o Sphincter – regulates the passage of food to the stomach Stomach o Temporary storage site for food o Production of hydrochloric acid o Chyme – comprised of bolus and gastric juice o Very little absorption occurs in the stomach ------------------------------------------------------------------------------------------------------------------ Tooth decay o Cavities and loss of teeth Tube feedings o Enteral nutrition ▪ Tube feeding ▪ Placement of a tube down the throat or through the wall of the GI tract ▪ Liquid diets are placed inside of the tube Total Parenteral Nutrition o Nutrients are provided directly through the circulatory system Hepatic Portal Circulation (Carbohydrate, Protein, Water-Soluble Vitamins)  o Blood vessels Capillaries: Small, thin-walled blood vessels in the small intestine, circulatory system, and lungs o Collect nutrient-rich blood from the digestive organs and deliver them to the liver. Destination of nutrients to cells o The blood carries the nutrients to cells o Nutrients cross cell membranes o Inside the cell nutrients are used for energy or are used to build substances for the body Catabolic pathways o Complex -> simple substance o Glucose broken down to energy Anabolic pathway o Simple -> complex substance ATP o Energy from the catabolic reactions is converted to ATP o ATP is used by the body to preform energy-requiring activities o Breaking the high energy bonds can result in Muscular contraction or Body tissue repair Organ systems responsible for the elimination of waste: Urinary system o Elimination of fluids through the kidneys Digestive system o Elimination of feces through the anus Respiratory system o Removes carbon dioxide from the body through the lungs Integumentary system o Removal of water and minerals through the skin Carbohydrates serve as the basis of our diet Located in a variety of food sources Energy: 4kcal/g The nutritional impact of carbohydrates depends on whether it is refined or in its natural state Refined carbohydrates are foods that underwent processing Unrefined carbohydrates are foods that remain in its natural state The 2020-2025 dietary guidelines for Americans recommend < 10% of calories should come from added sugar  Structure of a grain kurnel o Endosperm ▪ Largest portion of a grain kernel ▪ Contains starch and protein ▪ Some vitamins and minerals o Bran ▪ Outermost layer ▪ Concentrated source of dietary fiber, vitamins, and minerals o Germ ▪ Kernal base ▪ Embryo where sprouting takes place ▪ Source of vegetable oils and vitamin E Glucose o Main provider of energy for the body o Produced by plants during photosynthesis o Foods ▪ Component of disaccharide or starch Galactose o Component of lactose Fructose o Sweeter taste compared to glucose o Fruits, vegetables, honey o High fructose corn syrup Maltose o Glucose + Glucose o Formed when starch is broken down in the intestines Sucrose (table sugar) o Glucose + Fructose o Sugar cane, sugar beets, honey, maple syrup Lactose (milk sugar) o Glucose + Galactose o Occurs naturally in animal foods Complex Carbohydrates o Oligosaccharides ▪ Some are formed during polysaccharide breakdown in the gut ▪ Food sources: beans, onions, bananas, garlic ▪ Not digested by enzymes in the digestive tract  Glycogen is the storage form of carbohydrate in animals comprised of highly branched chains of glucose molecules Stored in the muscle and liver Dietary Fiber: Found intact in plants Functional Fiber: Beneficial physiological effects Soluble Fiber: Pectins, gums, some hemicelluloses o Dissolve in water or absorb water to form viscous solutions. o Broken down by the intestinal microflora o May lower blood cholesterol Insoluble Fiber: Cellulose, some hemicellulose, lignin o Opposite of soluble fiber. o Cell wall in plants o Wheat and Rye bran Pectin – soluble fiber in fruit o Gel – addition of sugar and acid o Thickening Agent Xanthan and Locust Bean Gum o Soluble fiber that combines with water ▪ Prevents solutions from separating o Gravies, pudding, reduced-fat salad dressing o Frozen desserts Wheat Bran – breads and muffins o Reduced caloric content of foods Steps of Carbohydrate digestion o Step 1: Action of Salivary Amylase ▪ Starch is broken down into shorter polysaccharides o Step 2: Inactivation of Salivary Amylase by Stomach Acid ▪ No starch digestion occurs o Step 3: Pancreatic Amylase ▪ Breaks down starch to disaccharides and oligosaccharides o Step 4: Digestion of disaccharides and oligosaccharides ▪ Disaccharides and oligosaccharides are broken down into monosaccharides by enzymes o Step 5: Utilization of fiber and indigestible carbohydrates Lactose Intolerance o Lactase available in minimal amounts o Undigested lactose -> Large intestine  ▪ Draws in water ▪ Metabolized by bacteria producing acids and gas Symptoms: Cramps, abdominal distention, flatulence, diarrhea o Decline in enzyme activity with age; infections/diseases. o Affects between 30 – 50 million adults Asian, African, Native Americans, and Mediterranean populations Indigestible Carbohydrates o Fiber o Oligosaccharides o Resistant starch Health benefits o Increase the amount of water or bulk in intestine o Stimulate GI Motility o Promotes growth of healthy microflora o Slows nutrient absorption Fiber helps slow the digestion and absorption of nutrients Glucose, fructose, and galactose travel to the liver via the hepatic portal vein Galactose and fructose are metabolized for energy Glucose is stored as glycogen in the liver or released into the blood Glycemic response o Rate, magnitude, and duration of the rise in blood glucose that occurs after a particular food or meal is consumed Affected by: o Amount of type of carbohydrate consumed o Amount of fat and protein present in the food o Rate the food leaves the stomach o Rate of digestion and absorption in the small intestine Greatest Response – refine sugars and starches o Leaves the stomach quickly Glycemic index o Ranking of how a food affects blood glucose compared to an equal amount of carbohydrate from a reference food (ex. White bread or pure glucose) o >70 – high glycemic index o < 55 – low glycemic index Glycemic load o Index of glycemic response that occurs after consuming certain foods o Glycemic index x grams carbohydrate per serving  Classifying Glycemic Load Score o 20 or more = high o < 11 = low Insulin o Released in response to high carbohydrate meal o Insulin facilitates the uptake and storage of glucose into the muscle, liver, and fat-storing cells Glucagon o Released in response to low blood glucose levels o Increased glycogen breakdown to glucose o Increased gluconeogenesis Blood Glucose Peak o Insulin response o Glucose is stored in the cells Blood Glucose Dip o Glucagon Response o Release of glucose from the liver into the blood Glucose o Broken down to provide energy o Delivered to tissues via blood stream Cellular Respiration Step 1 Glycolysis – the breakdown of glucose in half into two pyruvate molecules o Cytoplasm o Anaerobic Metabolism ▪ Oxygen is not required for this reaction Step 2 Acetyl CoA Formation o Acetyl CoA formation is the second step of cellular respiration o Aerobic Metabolism – oxygen is required o Acetyl CoA formation occurs in the mitochondria of the cell o Yield's – 2 Acetyl CoA Step 3 The Citric Acid Cycle o Acetyl-CoA + Oxaloacetate -> Citric Acid o The end products of the Citric Acid Cycle are: ▪ 4 C02 molecules ▪ Electrons ▪ 2 ATP Step 4 The Electron Transport Chain  o Occurs in the mitochondria o Requires oxygen o Aerobic Metabolism o The end products are the ETC are: ▪ ATP (-30/glucose) ▪ Water ATP: o Contains 3 phosphate groups o generated from cellular respiration ADP: o Forms when a phosphate group and its high energy bond is released during muscle contraction AMP: o Forms when a phosphate group and its high energy bond is released during muscle contraction Low levels of glucose can cause confusion, seizures, and ultimately coma To maintain blood glucose in the normal range when carbohydrate intake is low, glucose can be obtained from the following: o Glycogen broken down to glucose o Production of new glucose from amino acids Gluconeogenesis o Occurs in either the liver or kidney cells o Requires energy o Pyruvate or oxaloacetate are formed, which then forms glucose Ketone body formation o The body lacks carbohydrate to make oxaloacetate in the Citric Acid Cycle Type 1: o Autoimmune: Immune system destroys the cells that make insulin. o Diagnosed before age 30; 5-10% of diagnosed cases of diabetes. o Genetics, viral infections, toxin exposure, abnormalities in immune system. Type 2 o Accounts for 95% of diagnosed cases of diabetes. o Insulin resistance (cells do not respond to insulin) à limited glucose enters cells. o Family history, overweight, sedentary lifestyle. o Minority Groups: Native Americans/Alaska Natives, African Americans, Hispanic  Gestational o Pregnancy o Possible causes hormonal changes o High levels of glucose in the mother’s blood can increase risk of complications for the unborn child (macrosomal baby, development of type 2 diabetes). o Disappears after birth, but may have increases risk for developing type 2 diabetes Diabetes o Fasting blood glucose > 126mg/100ml Prediabetes o Fasting blood glucose 100 – 125 mg/100ml Normal o Fasting blood glucose < 100 mg/100ml Hypoglycemia o Significant drop in blood sugar Symptoms o Irratability, nervousness, sweating, shakiness, anxiety, rapis heartbreak, headache Occurs when: o Diabetics: o Over medication o Imbalance between insulin level and carbohydrate intake o Treatment – hard candy, juice o Non-diabetics o Consumption of high carbohydrate foods o Abdominal insulin secretion due to Reactive Hypoglycemia o Occurs in response to high carbohydrate foods o Rise in blood glucose stimulates overproduction and release of insulin o Glucose drops rapidly to abnormal levels Fasting Hypoglycemia o Abnormal insulin secretion not related to food intake o Related to hormonal deviations, tumors Epidemiological studies have shown that the incidence of colon cancer in lower in populations that consume diets high in fiber Carbohydrate recommendations  o RDA: 130/ grams/day for adults and children o AMDR: 45-65% of energy o AI (atiquite intake) for fiber ▪ Men – 38g ▪ Women 25g MyPlate recommends 6 ounces of grain foods per day Whole grain recommendation – 3 ounces per day Alternate sweeteners – not considered carbs, and provide little to no energy Lipids: Lipid – a chemical term which includes fat and related substances (e.g., cholesterol, phospholipid) o No widely accepted definition of “lipid” o Fat = fatty acids in foods = primarily triglyceride o Contribute texture, flavor, aroma to foods o Generally, lipid-soluble (od not dissolve in water) o Fats – solid fats; oils – liquid fats Fats and oils – 9 kcal per gram American diet contains –33% kcal from fat o Natural in foods and visible – e.g. stripes of solid fat in bacon o Added to foods during processing and hidden – e.g. fired foods Unsaturated fats from olive oils, fish, and nuts: decreased health risk Saturated fats from meats, cheese, dairy: increased health risk Phospholipids – chemical group attached to lipids Phosphoglycerates o Glycerol molecule, two fatty acids, and a phosphate group o Lecithin – choline added to the phosphoglycerate Diets high in cholesterol may increase blood cholesterol in some people Evidence on heart disease risk is weak Plant sterols can help May decrease risk of heart disease à limit absorption of dietary cholesterol through competition Found in plant oils and added to many products (e.g., Beneco The lipid digestion process: Lipid transport depends on solubility in water Short and medium chain triglycerides o Relatively more water-soluble o Pass directly to portal vein and to liver  Long-chain fatty acids, cholesterol, and fat-soluble vitamins o Connot enters bloodstream directly to liver o Must first enter the lymph packaged into lipoproteins Lipoproteins- transport particles for water-insoluble lipids/vitamins o Water insoluble lipids are enveloped in phospholipids, cholesterol, and proteins Transport function of lipoproteins o Lipids from the small intestine to other cells o Lipids from the liver to other cells o Lipids from body cells back to the liver Chylomicrons, VLDL, IDL, LDL, HDL are all lipoproteins Chylomicrons – the largest lipoproteins and contain the greatest proportion of triglycerides o Secreted from the small intestine o Diet-derived triglycerides, cholesterol, phospholipids, & small amount of protein o Transport lipids from the mucosal cells of the small intestine through the lymphatic vessels o Chylomicrons are too large to enter capillaries that lead to liver o Enter ____________________, then delivered to the blood, bypassing liver o Holds mostly triglycerides o Deliver triglycerides to the body cells VLDL – are smaller than chylomicrons but still contain a high proportion of triglycerides o Originates/is secreted from the liver o Liver is themajor lipid-producing organ in body o Excess CHO, protein, alcohol made into lipid o Triglycerides and cholesterol in liver o Incorporated into very-low-density lipoproteins (VLDL) o VLDL transports lipids out of the liver and delivers them to body cells o Holds mostly triglycerides LDL – contain a higher proportion of cholesterol than do other lipoproteins o Carrier of “bad” cholesterol o LDL contains less triglyceride & more cholesterol than VLDL (by percentage) HDL – are the densest lipoproteins due to their high protein content; they contain moderate amount of cholesterol o Carrier of the “good” cholesterol  Function of lipids in the body: o Absorption of fat-soluble nutrients, drugs, etc. o 2. Protection/insulation (adipose tissue) ▪ Deposits of adipose tissue Made up of adipocytes Located under skin and around internal organs Mainly stores triglyceride, provide stored energy Contributes to body shape definition Insulate body from temperature changes Protect internal organs against physical shock o 3. Lubrication (Oil glands in skin, tears) o 4. Structure ▪ o 5. Regulation of body processes ▪ o 6. Energy storage and ATP production ▪ CHO: 4kcal/g High potential energy ▪ FAT: 9kcal/g Highest potential energy ▪ Immediate source of energy 9from the diet_ or stored in adipose tissue for future use ▪ Fatty acids and glycerol can be used to produce energy in the form of ATP ▪ The majority of energy come from the breakdown of fatty acids via a process called beta=oxidation In mitochondria Begins metabolic pathway to produce ATP Fatty acid length (# of carbons in the carbon chain) Short (2-7 C) vs. medium (8- 12 C) vs. long fatty acids (14+ C), very-long (22+ C) Diets too lwo in fat: o Reduce absorption of fat-soluable vitamins, slows growth in early life, impairs functioning of the eyes, skin, liver, and other organs Diets too high in fat: o Increased energy -> body fat storage/ Atherosclerosis Development and the Role of LDL o Stage 1:  ▪ Healthy epithelial cells surrounded by smooth muscle o Stage 2: ▪ Entry of LDL particles into the artery wall, which are oxidized ▪ Accumulation of White blood cells, which become macrophages -> foam cells o Stage 3: ▪ macrophages and foam cells secrete growth factors o Stage 4: ▪ Plaque Enlargement Fibrous cap covers the plaque that continues to build up. o Stage 5: ▪ Fibrous Cap Rupture of fibrous plaque due to inflammation. ▪ Blood clots o Stage 6: ▪ Heart attack Impeded blood flow in the artery can result in a heart attack Risk factors for heart disease o Non modifiable ▪ Age ▪ Biological sex ▪ Genetic background ▪ Family history o Modifiable ▪ High blood pressure ▪ Physical activity ▪ Tobacco use ▪ Diet ▪ Smoking ▪ Overweight and obesity Dietary factors that increase risk: o Trans fat o Saturated fat o Sodium o Excess energy o Excess sugar o Alcohol  Proteins Sources of diatary protein: o Animal ▪ Meats – 3oz = kg 20g protien o Plant ▪ Legumes ▪ Nuts and seeds ▪ Grains Animal sources o B vitamins o Minerals – iron, zinc, calcium Plant sources o B vitamins o Minerals o Fiber o Photochemical o Unsaturated fats Protein in American diet – 88g/day o Fairly constant over last 30 years In the U.S. - 2/3 of dietary protein comes from animal sources o Meat, poultry, fish, eggs, and dairy products o Most concentrated sources of protein Most of the world relies on the plant sources for proteins o Grains, legumes o Less expensive, more flexible storage o As economy grows, proportion of animal foods eaten increases o Although most plant sources of protein are not used as efficiently by the body, they can easily meet most people’s needs Protein molecule – contructed of one or more folded, chain-like strands o Amino acids – are building blocks of protein o Contain at least carbon, hydrogen, oxygen, and nitrogen Types of Amino acids o Essential or indispensable amino acids – cannot be synthesized in sufficient amounts for needs o Nonessential or dispensable amino acids – can be synthesized in sufficient quantities for needs  o Conditionally essential amino acids – only essential and required by the diet in certain conditions Transamination – Synthesis of NEAA o Transfer of amino group to a carbon-containing molecule (alpha-keto acid) to generate a new amino acid o Alpha-keto acids are also important intermediates in glycolysis and citric acid cycle ▪ How we can use amino acids/protein for energy Amino acids that are essential in the diet under specific conditions or at specific times of life Essential only under o If made from an EAA that is limited in diet o Physical stress o Certain stages of life o Metabolic defects Protein Structure o Chemical bonds that link amino acids together = peptide bonds ▪ AA #1 acid group liked to AA #2 amino acid group o 2 AA linked = dipeptide o 3AA = tripeptide o 4-10 = oligopeptide o >10 AA linked = polypeptide o A protein = one or more polypeptide chains folded into a 3d shape Priortiy of absorption o 1. branched-chain amino acids o 2. essential amino acids o 3. non-essential amino acids Food Allergies o Can occur in some individuals when a dietary protein is absorbed without being completely digested o Common sources ▪ Milk, eggs, peanuts o Reaction to immune system ▪ 1st time – stimulation of the immune system ▪ 2nd time – immune system identifies protein as a foreign, harmful substance o Symptoms  ▪ Vomiting, diaria, rash, hives, drop in blood pressure, decreased breathing ▪ Anaphylaxis – most severe reaction Who is more prone to developing allergies o Leaky gut from damaged protein absorption is beneficial in infants – can absorb antibodies from breast milk to help fight infection Functions of protein Protein function: Amino Acid pool o 100g from dietary AAs + 200g recycled AAs from protein breakdown = 300g protein synthesized in the body/day Protein Turnover o Process by which proteins are continually broken down and resynthesized ▪ Normal growth and maintenance of the body tissue ▪ Adaption to situation changes Gene o A section of DNA containing the information needed to synthesize mRNA, which can then get translated into polypeptide sequence --> folded to become functional proteins o Specific genes are expressed to synthesize specific proteins o Ex. Insulin, Lipase, LDI-receptor Gene expression is highly regulated and can be impacted by genetic variations Why is this important o Prevents the body from synthesizing proteins (and utilizing amino acids from the pool) unnecessarily o Ensures appropriate regulation of body processes Tissue/organ-specific expression o Some genes are only expressed in specific cells ▪ Ex. Genes for insulin and glucagon are expressed in the pancreatic cells only Gene expression may require, or be increased or decreased, by certain nutrients o Vitamin A – controls expression of genes involved in cell maturation and specialization of cells o Vitamin D – controls expression of genes involved in calcium transport, bone metabolism Limiting Amino acids – the essential amino acids that is available in the lowest concentration in the relation to the body’s needs o Some can be obtained by breaking down body proteins  Amino proteins = complete proteins Plant proteins = typically low in 1+ essential amino acids 4 kcal/gram o Carbohydrates – 4kcal/gram o However, body uses more energy to metabolize AA and utilize them for energy ▪ Carbs and fats are more efficient energy sources Amino hroup must be removed from amino acids (to for carbon skeletons) to be used for energy o Deamination – removes the nitrogen group from the amino acid, without generating a new amino acid o Transamination reactions can also generate carbon skeletons o Carbon skeleton broken do for energy o Amino group converted to urea and excreted in urine Low energy intake o Enzymes and muscle proteins are broken down to amino acids in order to make ATP or synthesize glucose o Provides energy, but functional proteins are lost ▪ 1. Dispensable proteins are broken down first. (converse critical proteins) ▪ 2. Critical proteins in heart and internal organs broken down ▪ 3. if more than 30% protein lost: Muscle strength is decreased Depressed immune function Loss of organ function Death High protein intake o Amino acids from protiens can be used for energy ▪ Deamination Excess energy and protein intake o Amino acids can be converted to fatty acids, which are stored as triglycerides in the adipose tissue Protein-energy malnutrition Kwashiorkor o Puro protein deficiency o Common symptoms – bloated to swollen belly from edema and fat accumulation in liver  o Associated with wearing off breast-milk to low-protein beverage that is high in fiber and difficult to digest Marasmus o Energy deficiency o Common symptoms – muscle wasting, depleted fat stores o Malnourished children, eating disorders High protein diets in healthy people o No short-term harm; long term effects are unknown High protein diet requires adequate hydration, liver, and kidney function o High protein diets increase ammonia and urea production High protein diets affecting disease in healthy people? o High animal protein linked to increased kidney disease risk in some epidemiological studies; inconclusive evidence o May be concern for those at greater risk for kidney disease o Increased risk of kidney stones Bone health o Meeting the recommended amount of protein is important for bone health o High protein diet associated with greater calcium loss in urine, but may also lead to greater calcium absorption Dietary protein promotes bone strength when calcium intake is adequate Adults require 0.8g protein/kg of body weight Acceptable macronutrient distribution range – 10-35% on energy in adults Proteins needs o Vary by life stage, health status, and physical activity o Increased during periods of growth, injuries/illnesses Current recommendations for protein intake are determines based on nitrogen balance studies Protein quality is a measure of how efficiently a protein in the diet is used to make body proteins by providing the essential amino acids. o Animal proteins generally > plant proteins o Less protein needed to be consumed to get required amino acids ▪ Easier to digest ▪ Supply essential amino acids in proper proportions for human needs. PDCAAS o A measure of protein quality that reflects the protein digestibility o It also reflects the proportion of amino acids present in the food. Energy – measured in kilocalories  Energy balance – energy consumption matches energy expenditure o “Calories in equal calories out” o Body weight remains constant Positive energy balance – energy consumption greater than energy expenditure Total energy expenditure o Energy used each day – preforming work or producing heat Major components of TEE o 1. Basal and resting metabolism – 60-75% of TEE ▪ Energy needed to stay alive, awake ▪ Basel energy expenditure = BMR x 24 ▪ BMR Rate of EE in morning upon waking, after 12 hours of fasting ▪ RMR More practical; 5-6 hours without food or exercise Typically, 10-20% higher than BMR Resting energy expenditure (REE) = RMR x 24 o Lean body mass ▪ Body mass excluding fat ▪ More metabolically active than fat mass ▪ BMR is well-predicted by LBM (-80% of variation) within and across species o 2. Physical activity ▪ All voluntary movement ▪ Metabolic cost of external work ▪ 15-30% of TEE – varies greatly ▪ Includes exercise and non-exercise activity thermogenesis o 3. Non exercise activity thermogenesis ▪ All energy expended via activity when not sleeping, eating, or preforming planned exercise Ie, energy expended form daily living Occupational and leisure-time NEAT o 4. Thermic effect of food ▪ Feeding acutely increases metabolic rate by –25-40% in humans Energy needed to digest, absorb, process, store nutrients from foods -10% of energy intake – varies with nutrients o To supply body 90kcal for use, need to eat – 100kcal  Metabolic cost o 2-3% of energy o 5. Adaptive thermogenesis ▪ Heat generation in response to environment and food intake Ex. Overeating, dieting Heat generated by exothermic metabolism reactions Metabolic rate increases 2-4-fold after cold exposure Boundry between Basel metabolism and adaptive thermogenesis not always clear Brain regulates adaptive thermogenesis Stoing energy and using sotred energy o Immediately after meals ▪ Excess energy form food is stored o In between meals ▪ Stored energy used to meet needs o Excess carbohydrates ▪ Stored as glycogen to a certain capacity -> surplus stored as fat o Excess protein, fat ▪ Amino acids used to translate/synthesize new proteins -> How fasting results in weight loss o Body needs steady supply of energy and glucose between meals ▪ Energy – breakdown of stored body fat ▪ Glucose – breakdown of glycogen stores or synthesized from amino acids o Rule of thumb – deficit of 3500 kcal=14,644 kJ 1lb of weight lost for energy needs In the United States, 68.5% of adults are classified as overwifght or obese Medical care costs related to boesity are esitmated to be around $200 billion annually Initial data about weight status is usually evaluated by calculating 1.9 billion adults ages 18 and older were identified as overweight o 650 million adults are obese Lean tissue o Bones, muscle, tissues, (except fat tissue) Bady fat tissue o Lacated under the skin and internal organs o Amount of fat depends on age, gender  Bioelectrical Impedance Analysis o Estimates body fat o Directing a low energy electrical current through the body and the resistance to flow is calculated. Skinfold thickness o Measurement of subcutaneous fat, used to estimate total body fat o Areas of measurement ▪ Triceps ▪ Subscapular area o Equation used to estimate total body fat Air displacement o Individual is assesed in an air-fillled chamber called BOD POD o Accurate, more convenient o Expensive Visceral fat – android obesity o Greater health risk o Easer to mobilize ▪ Floods liver and increases blood lipids Subcutaneous fat – gynoid obesity o Less of a health risk o Harder to mobilize Estimating energy requirements Direct calorimetry o Heat given off when placed in chamber o Expensive and impractical Indirect calorimetry o Oxygen use and carbon dioxide production o Not practical in free-living individuals Doubly-labeled water – dilution method o Ingest isotopes of oxygen and hydrogen o More practical, preferred method in clinics o Can measure TEE for up to 2 weeks Dietary Reference Intakes o DRI o Estimated Energy Requirements ▪ Amount of energy recommended by the DRIs to maintain body weight in a healthy individual  ▪ EER equations takes into account the following: age, gender, size, and activity level o If BMI is greater than 25 Mifflin St. Jeor World Health Organization Genetics o Up to 75% of variation in BMI between individuals attributed to genes o Risk of obesity ▪ No parents with obesity – 10% ▪ 1 parent with obesity – 40% ▪ 2 parents – 80% o Genes that regulate the level of body fat o Responsible for the proteins that affect energy intake, energy expenditure, and the efficiency of storing body fat Influence of Genes of Body weight o In a study with identical twins, twin pairs were overfed to tthe same extent o The twin pairs gained the same amount of weight and deposited fat in the same parts of the body o Variation in weight gain between sets of twins Environment o Up to – 25% of variation in BMI linked to environment Body weight tends to remain constant for long periods of time o Set point – level of body weight that resists change o Hypothalamus – region of the brain that regulates satiety and energy expenditure Insulin o Produced and released from the Pancras in response to elevated blood glucose levels Leptin o Hormone made in the adipose cells and interacts with the hypothalamus to influence energy intake and expenditure o Decreases food intake and increases energy expenditure o Concentrations in blood proportional to body fat o Increases/decreases in bloods as adipocytes o Lack of leptin better at preventing weight loss than leptin is at preventing weight gain ▪ Ex defense against starvation stronger than defense against obesity  Adaptive Thermogenesis o The change in energy expenditure that occurs due to changes in body temperature, trauma, and food intake Futile Cycling – metabolic dyregulation o Wats energy by allowing opposing biochemical reactions to occur at the same time ▪ Ex glycolysis and gluconeogenesis occurring at the same time Brown Adipose Tissue o A type of fat tissue that has more mitochondria than white adipose tissue -> increased in cold exposure, infancy, hibernation o The electron transport chain is separated from the mitochondria and generates heat o Prior studies have shown that high BMI and body fat are associated with low levels Weight-loss goals and guidelines o Loss of 5-15% of body weight reduces disease risk o Slow weight loss endures fat loss and not lean tissue o Rapid weight loss not likely maintained, significant portion as water weight o Realistic weight loss goals ▪ 10% loss of body weight in 6 months o Avoid yo-yo dieting ▪ Repeat cycles of weight loss and gain ▪ Lose lean body mass ▪ Regain in fat mass ▪ Increases or maintains body weight, but decrease baseline Metabolic Rate To ensure that most of the weight lost in fat from the adipose tissue, and not lean tissue, the recommended weight loss is between 0.5 to 2lb per week 1lb of body fat = 3500kcal o Losign a pound of adipose tissue requires decreasing intake and/or increasing expenditure by 2500 kcal Decreasing energy intake o Low energy diet, but high in nutrient density o If consuming a 1200 kcal diet/day, a multivitamin or mineral supplement is recommended o Medical supervision is recommended for those consuming 80 kcal/diet per day  Increasing physical activity o Exercise promotes weights loss, weight maintenance, and increases energy expenditure and muscle mass o 150 mintues of mederate activity is needed to promote weight loss and prevent gradual weight gain Modifying behavior o Process used to gradually promote change habitual behaviors Organic compounds essential in the diet to promote grwoth and health maintence Micronutrients – required in small amoutns If lacking in diet: o Deficiency symptoms occur If restored in diet o Deficiency symptoms resolve Fortification o The process of adding nutrients to food o The added nutrients are not originally found in the food (ex. Orange juice) o Indiscriminate fortification can increase risk potential nutrient toxicity Enrichment o Adding nutrients back to foods that have lost their nutrients ▪ Ex. Addition of B vitamins to white rice Niacin (vitamin B3) o Coenzymes in metabolic reactions to product ATP o Active coenzyme forms in Niacin: ▪ NAD ▪ NADP o Deficiency: Pellegra ▪ Early symptoms Fatigue Decreased Appetite Indigestion Bright red tongue ▪ Pellagra development and progression: 4 D’s Dermatitis Diarrhea Dementia Death Niacin Deficient  o Pellagra and corn diet – low tryptophan content of corn and low bioavailability of niacin in corn ▪ Big problem in southeastern U.S. in early 1900s ▪ Use of lime water frees niacin Common in Mexico and Latin America Pantothenic acid is a coenzyme in the acetyl CoA formation, deamination, and beta-oxidation Pantothenic o Function in the body – needed everywhere Abundant in o Meat, eggs, whole grains, and legumes Susceptible to damage by exposure to heat and low- or high-acid conditions Deficiency is rare – never been reported in humans Pyridoxine: o Active coenzyme form is pyridoxal phosphate ▪ Used for the activity of over 100 enzymes that are involved with the metabolism of carbohydrate, fat, and protein o Needed to produce and maintain the myelin coating on nerve cells o Needed for transamination reactions o Lowers homocysteine (CVD) Homocysteine o Elevated levels impact the structure and function of blood vessels Individuals born with homocysteine develop atherosclerosis at a young age Vitamin b6 promotes the formation of cysteine from homocysteine Active coenzyme form is pyridoxal phosphate Used for the activity of over 100 enzymes that are involved with the metabolism of carbohydrate, fat, and protein Needed to produce and maintain the myelin coating on nerve cells Needed for transamination reactions Lowers homocysteine (CVD) Vitamin B6 deficiency Neurological symptoms Anemia due to impaired hemoglobin synthesis At risk - low B6 & high protein diet Toxicity can cause nerve damage  Pain and numbness in extremities (>1 g/day) 2-6 g/day in some, inability to walk High-dose supplements available OTC and approach UL (100 mg/day) No adverse effects from food Biotin (vitamin B7) o Coenzyme for a group of enzymes that adds the acid group (-COOH) to molecules o Needed for the citric acid cycle and gluconeogenesis o Important for the production fo fatty acids and some amino acids o Dietary sources ▪ Liver ▪ Egg yolks ▪ Yogurt ▪ Nuts Biotin Deficiency- not common Observed in individuals with o Malabsorption o Protein-Energy malnutrition o Tube feedings or total parenteral nutrition without biotin Symptoms – hair loss, red skin rash, depression, lethargy Folate (vitamin B9) o Folate acid ▪ Readily absorbed ▪ Found primarily in fortified foods and supplements Particularly essential for pregnant women to receive adequate folate Vitamin B12 o Necessary for the proper absorption of iron in the body o Mady by bacteria, accumulates in animals ▪ Easily absorbed from animal products o Found almost exclusively in animal products ▪ Not in plants unless contaminated or fortified o Bacteria in human colon produce vitamin B12 but it can’t be absorbed o Vegans must supplement vitamin b12 or eat fortified foods Stomach in critical for absorption in intestine Functions of vitamin B12 o Needed to convert folate to active form for DNA synthesis – prevent anemia  o Body stores B12 more efficently than other B vitamins o Deficiency is due to poor absorption rather than low intake alone o Major deficiencies more common in elderly and veagans o Supplemental folic acid can mask B12 deficiency ▪ Anemia will not develop ▪ Irreversible nerve damage can develop Vitamin C o Functions: ▪ Antioxidant and coenzyme ▪ Maintains immue system ▪ Production of connective tissue ▪ Aids in iron absorption from plant sources o Can be destroyed by oxygen, light and heat, contact with copper or iron cookware ▪ Readily lost in processing ▪ Acid in juice protects from degradation Scurvy – vitamin C deficency diease o Weak collagen, blood vessels rapture o Historically a problem for armies and explorars o Lime and lemon juice required in rations for british sailors - “limeys “ Vitamin C UL is 2000 mg o Excess excreted in urine, nausea GI distress Stimulates immune function by various mechanisms o Highest amount of vitamin C in body is in immune cells Does Vitamin C cure the common cold Choline: o Essential nutrient – not classified as a vitamin o Very high amount in eggs, meat, dairy products as phospholipids o Needed for: ▪ Neurotransmitter acetylcholine ▪ Cell membranes, lipoproteins ▪ Homocysteine metabolism o Choline deficiency ▪ Fatty liver and muscle damage in adults ▪ Pregnancy – impairs fetals bra3in development  Fat-soluble vitamins Absorbtion and transport closely related to that of lipids Optimal absorption requires bile salts Initial transport requires chylomicrons to get them into circulation Stored in body lipid, especially adipose tissue and lipid droplets in liver Preformed vitamin A o Retinoid o Ex. Retinal, retinol, and retinoic acid o Derived from animal sources Pro vitamin A o Carotenoids and xanthophylls o Example: beta- carotene, lutein, lycopene o Derived from plant sources Vitamin A function o Different form have different functions: o Retinol – main circulating and storage form o Retinal – important for visual cycle ▪ Perception of light Minerals – inorganic elements needed by the body o Act as structural components and regulators of body processes Major minerals – needed in diet o >100 mg/day or present in body o >0.01% of body weight Trace minerals – needed in diet