Nutrition for Exam 2 PDF

Carbohydrates Two types of Carbohydrates Simple Monosaccharides (C6H12O6) - Fructose - Glucose - Galactose Disaccharides (C12H22O11) - Maltose → maltase (glucose + glucose) - Sucrose → sucrase (fructose + glucose) - Lactose → lactase (g...

Carbohydrates Two types of Carbohydrates Simple Monosaccharides (C6H12O6) - Fructose - Glucose - Galactose Disaccharides (C12H22O11) - Maltose → maltase (glucose + glucose) - Sucrose → sucrase (fructose + glucose) - Lactose → lactase (galactose + glucose) - disaccharide enzymes are secreted by the intestinal wall and are digested in the small intestine Complex Polysaccharides - Glycogen (storage form of carbohydrates in liver and muscle of humans and animals) - Starches (storage form of carbohydrates in plants) - Fibers (in the cell walls of plant cells) Monosaccharides Hexoses - 6 carbons e.g. fructose, glucose, galactose Pentoses - 5 carbons Polysaccharides Starch - Amylose (linear chain) - Amylopectin (branched) Glycogen - Highly branched structure  - Stored in the liver and muscle - Only liver glycogen can be hydrolyzed to restore blood glucose levels Differences in linkages between glucose molecules in starch and cellulose Starch - alpha 1-4 linkage Cellulose - beta 1-4 linkage Human GI tract won’t make enzyme to Cleave beta 1-4 linkage Dietary Fibers Water soluble - Partial digestion by microorganism - Byproducts are absorbed - Acts to lower blood cholesterol Types:  - Beta-glucans (oatmeal) - Pectin (any kind of fruits, vegetables) - Some hemicelluloses (gums: agar, carrageenan, guar) Insoluble fibers - Function - provides bulk to stool, which is important for the health of the colon (prevents diverticulosis, colon cancer) Types: - Cellulose - Most hemicelluloses - Lignin - carrots Recommendations for Fiber 14 g/every 1000 kcal/day soluble/insoluble ¼ : ¾ Eat at least 2 cups fruits and 2.5 cups veggies for a 2000 kcal diet Choose whole grains from grains group (make half of your grains whole) Glycogen and starch are examples of complex carbohydrates Glycogen is the storage form of energy in humans/animals Starch is the storage form of energy in plants If starch is highly branched, it is called amylopectin Is starch is unbranched it is called amylose Digestion and Absorption Hydrolysis to monosaccharides - Amylase (salivary) in mouth - Amylase (pancreatic) in small intestine released from pancreas - Disaccharidases (intestinal brush border) Absorption - Different mechanisms depending on sugar - Rapid - Portal vein to liver - Fructose & galactose converted to glucose in liver Lactose Intolerance Deficiency of lactase - Intestinal disease - Genetic inefficiency of enzyme lactase Symptoms  - Diarrhea - Gas - Bloating Treatment - Manage daily intake rather than restrict intake Absorption Active transport - Glucose - Galactose Facilitated diffusion - Glucose and galactose - Carbohydrate-rich meal - Fructose-specific transporter Liver - Conversion of fructose and galactose Glucose Balance Maintain glucose at 70-99 mg/dL by hormones produced in pancreas Insulin (when blood glucose is high) when hyperglycemic - Released by the pancreas after a meal causes tissues to take in blood glucose - Glucose can be used for energy or storage - Glucagon - when blood glucose is low Glucagon (when blood glucose is low) when were hypoglycemic - Released by the pancreas during fasting states - Glucose released from liver glycogen stores - Glucogenesis - the building of novel glucose molecules in the body as compared to glucose, which is split from the prolonged storage molecule glycogen Diabetes Type 1 - Insulin dependent (need insulin shot) - Onset - childhood Type 2 - Insulin independent - Cells don’t respond as well to insulin (needs more) - Onset - overweight adults - Progresses more slowly than type 1 - (sometimes take meds to increase insulin release from pancreas, later requires insulin) Symptoms of both - Glucosuria (presence of glucose in urine), frequent urination, thirst, hyperglycemia (high blood glucose) Sweeteners types: - Sugar - Sugar alcohol - less calories, protects teeth from decay - Alternative sweeteners - doesn’t provide calories Sugars Includes natural and ‘made’ sweeteners - Nutritive sweetener Sucrose - benchmark for sweeteners - Lactose (RS=0.2), maltose, glucose - Fructose (RS=1.8) - Fructose is hygroscopic (attracts water) - High fructose corn syrup used in soft drinks, etc. - Same caloric content (4 kcals/g) - No health benefit over another Health Effects of sugar Dental caries Bacteria ferment sugars producing acid Food factors associated with tooth decay - Time of food in mouth - Sticky foods - Frequency of sugar consumption Food choices can reduce the activity of dental caries Sugar Alcohol Still contribute calories as do sugars - 0.2-2.6 kcal/g - Nutritive sweetener - More slowly absorbed and metabolized - Can cause diarrhea if eaten in large amounts - Do not cause tooth decay - Sorbitol (RS=0.6) - most common in US - Candies, gum - Xylitol (RS=0.9) - used in gum Alternative Sweeteners Artificial sweeteners - Non-nutritive sweeteners - Large doses and adverse effects Stevia - an herbal product - Generally recognized as safe The FDA has set the ADI for aspartame at 50 mg per kg (1kg = 2.2 lb of bodyweight per day (50 mg/kg/day) Fate of Carbohydrates Energy production - Anaerobic - glycolysis pathway - Yields a little energy - 2 ATP/glucose - Aerobic - Krebs cycle (TCA) - Yields a lot of energy - 36-38 (32) ATP/glucose Formation of glycogen for later use - Stored in liver (small stores) - Muscle Excess is Converted to FAT - Unlimited storage potential for fat - Through body fat comes mostly from dietary fat Recommended Intake of carbohydrates 45-65% of total calories Dietary essential source of energy for some cells (red blood cells and brain) - Very low carb diets are unhealthy (>50g/day) - Forces body to produce glucose another way: muscle protein is broken down to make glucose (gluconeogenesis) - Much more breakdown of body fat occurs to provide energy via ketone bodies - These are toxic to the body, though they give energy to the brain, they need to be excreted in the urine or it can upset the body pH - Ketosis - fatigue and dehydration - Most diets contain at least 200 g carbs so this is not an issue Conditions where ketone bodies are formed Low carbohydrate diets Starvation (no food at all) Untreated diabetes - Your body thinks there is no glucose (since you can’t move it into the cells or tissues) - Glucose builds up in the blood instead, meaning you have to get energy elsewhere Lipids Types of Lipids Triglycerides - major dietary form of fat (95%) Phospholipids Sterol (e.g. cholesterol) - only present in animal product Composed of elements C, H, O Triglycerides Glycerol + 3 fatty acids Fatty acids - Vary in length (4-22 C) - Vary in number of C - C double bonds - Have acid end (COOH) and methyl (CH3) end of molecule - Acid end attached to glycerol via ester bond - Saturated fatty acids - no double bonds between carbons - Monounsaturated fatty acids - one double bond between carbons - Polyunsaturated fatty acids - more than one double bond between carbons - Name them omega based on how far the double bond is from the methyl end Other glycerides - Simple triglyceride - all 3 fatty acids attached to the glycol is the same (18 carbon) - Mixed triglyceride - more than 1 type of fatty acid attached to it - mono/diglyceride - Mono - only one fatty acid attached - Di - two fatty acids attached Classifying fatty Acids Length (affects absorption) - Short ( GD —---> MG + 2FA - Emulsification - Bile salts (acids) Absorption and Transport of Dietary Fat Absorption - Formation of micelles - Diffuse from lumen into mucosal cell Transport - Long chain fatty acids - Repackaged into triglycerides and carried into chylomicron (dietary lipid transporter) - Chylomicrons enter lymph then blood (at subclavian vein) - Short + medium chain fatty acids - Enter blood directly, without being packages into triglycerides or chylomicrons Enterohepatic Circulation of Bile Bile is made of cholesterol Eating fats can help lower blood cholesterol Types of Lipoproteins (transport lipids) Chylomicrons - Largest and least dense - Transport diet-derived lipids (dietary lipids) - Liver removes remnants from blood - Transport dietary triglycerides in the body - Rich in triglycerides - Originate from intestine Very-low-density lipoproteins (VLDL) - Made in the liver - Proportion of lipid shift (losing TG) - Rich in triglycerides - Distributes triglycerides to other tissues Low Density lipoproteins (LDL) - Cell needs  - Liver regulation - Transports cholesterol to other tissues - Rich in cholesterol High Density lipoproteins (HDL) - Remove cholesterol from cells and takes it back to the liver - Carry cholesterol to liver for recycling - Anti-inflammatory properties - High in protein Chylomicrons - highest amount of triglycerides, least dense, VLDL - made in liver, then shrink in bloodstream as cells take up triglycerides LDL - high levels have negative health implications, higher in cholesterol and lower in triglycerides, taken up by cells after binding to receptor HDL - carry cholesterol back to the liver for recycling or excretion Function of Lipid Source of energy Satiety value Carrier of fat soluble vitamins Palatability Insulator  Structural integrity of cells - phospholipids Synthesis of cholesterol Regulator of body functions - eicosanoids made from fatty acids - Can decrease blood clotting and blood pressure (omega 3 acids) - Can increase blood clotting and blood pressure (omega 6 acids) Many Diseases/Conditions impacted by Dietary fat Heart disease - Elevated LDL cholesterol a risk factor - Saturated fats increase LDL cholesterol - Promotes blood clotting - Ways to lower dietary saturated fat - Trans fats increase LDL and lower HDL cholesterol - Dietary cholesterol - around 300 mg from diet - Eat more plant-based foods, avoid fried and processed food Obesity - energy output < energy intake - Treatment: - Cutting fat from diet often reduces kcal (decrease in total calories) - Focus on complex CHO w/ fiber for satiety - Lose weight Cancer - Promotion rather than initiation of cancer - Dietary fat and cancer risk - Differs for various types of cancer Dietary Advice DRI and dietary guidelines - 20-35% of daily energy from fat - Less than 10% from saturated fat - As little trans fat as possible - Consume about 10% of calories as monounsaturated fat (monos are not harmful to the heart - Consume about 10% of calories as polyunsaturated fat - Provides essential fatty acids - omega-3 and omega-6 fatty acids DRI - Linoleic acid (omega-6) - 5-10% of daily energy - Linolenic acid (omega-3) - 0.6%-1.2% of daily energy - Avoid getting too little fat  - Recommendation: one teaspoon of fat at meals No longer limit to 1 subunits (weak) more than one polypeptide chain associated with it Structure can be denatured “unraveled” with acids Which types? When does this happen? Protein Functions: Regulation of water balance Catalyze reactions - Enzymes Growth and maintenance of tissue - Muscles, bone Formation of essential body compounds - T3-T4; hormones: insulin, glucagon, etc. Transfer of nutrients - Albumin carries small fatty acids, minerals, etc. retinol binding protein - Vitamin A Maintenance of appropriate ph - Can donate or accept hydrogen ions - buffer Defense - Antibodies and other immune system components Detoxification - Protein in liver to break down drugs Energy production - 4 kcals/g Water Balance Body water distributed into compartments Balance of water maintained by dissolved proteins and electrolytes (e.g. Na+, K+) compartments - Intracellular (within cells) - Extracellular - Intercellular (between cells) - interstitial - Intravascular (within vessels) Regulation of Fluid Balance Osmotic pressure - Protein in vessel, too large to move out, draws water into vessel Digestion & Absorption Acid - denatures protein Proteases - Secreted as zymogens (inactive enzyme) - Stomach: pepsinogen → pepsin (initiates protein digestion in stomach) - Pancreas: releases other proteases which act in small intestine - Endo - Exo - Mucosal cells: peptidases Protein → smaller polypeptides (pepsin, HCl) Polypeptides → tripeptides, dipeptides, amino acids (proteases; pancreatic) Peptides → amino acids (tripeptidases/dipeptidases) Absorption of dipeptides or single amino acids occurs via Active Transport Several carriers depending on amino acid Amino acids are absorbed directly into blood liver - Some amino acids and combined and synthesized into plasma proteins - Some amino acids are transported to cells and synthesized into proteins Protein quality Complete proteins - contain all the essential aa required amount needed by human body - well utilized by body - Foods from animal sources - Contains all of the essential amino acids in adequate amounts - Soy protein Incomplete proteins - require additional protein to be utilized by body - Protein from most plant sources - Limited in amount of one or more essential amino acid - Limiting amino acids: 1st, 2nd, 3rd - Legumes most limiting in methionine - Cereals/rice most limiting in lysine - If not enough of one or more types of amino acids, protein synthesis will not continue, so protein can’t be made  Complementation (complimentary protein) - process of combining foods with different limiting amino acids to make complete protein - Peanuts, beans - limiting amino acids methionine, tryptophan - Corn, wheat, rice - limiting amino acids Lysine, Isoleucine Peanut butter on wheat bread Red beans and rice Succotash (lima beans and corn) Evaluation of Protein Quality Amino acid score - Measurement of actual amount of each amino acid in a food or in the diet as a whole - Expressed as a ratio - Mg AA/g protein (test protein) - Mg AA/g protein (reference protein - complete) - Score is that from AA that is lowest - Problems - doesn’t account for how our digestive system actually absorbs them PDCAAS = protein digestibility x amino acid score Why become a vegetarian? Involuntary reason - Shortage of animal foods Voluntary reasons - Religion - Ecological or political beliefs - Economics - Curiosity  - Health Types of Vegetarian Fruitarian - fruits, nuts, honey Vegan - no flesh foods (including eggs or dairy) Lacto vegetarian - no meat but allow dairy Ovo vegetarian - no meat but allow eggs Lacto-ovo vegetarian - no meat but allow eggs and dairy Pesco vegetarian - allow eggs, dairy and some fish (also called “almost vegetarian”) Health Issues in VEGAN diet Potential deficiencies reflect lack of dairy: Calcium, Vitamin D, Riboflavin Lack of animal products: Zinc, Iron, B12 (high fiber) Menus must be carefully planned to avoid these deficiencies Vegan diet is a risk to growing children and pregnant mothers Health Issues - Positives High intake of carbohydrate (complex), Vitamin A,E, and C, and carotenoids (antioxidants), magnesium, fiber Limited intake of saturated fat and cholesterol Death rates from chronic disease are lower among the vegetarian population This difference may be due IN PART to other lifestyle modifications Protein metabolism - protein has many functions Nitrogen status - reflects body protein levels (because N is only in protein) - Affected by life stage, energy status, hormones - Balance - body has the same amount from day to day - Positive nitrogen status - body adding protein (infants, children) - Growth hormone, insulin, testosterone - Negative nitrogen status - body losing protein (starving, burns, injuries, infections) - Glucocorticoids, glucagon, catecholamines Body can create new amino acids (ne) or use amino acids for energy Deamination  - Removing amino group from the amino acid and the amino group become ammonia - Ammonia becomes urea - Occurs in liver - Several of the amino acids lose - Can directly lose amino group from amino acid (by enzyme) - Products: carbone backbone + ammonia - If amino acid is to be used for energy, N is not needed, it must be eliminated Ammonia is toxic - Converted to a less toxic compound, urea (in the liver) - Urea is eliminated via the kidneys Remains: carbon backbone - Can be used to generate energy, make fat (ketogenic aa), carbohydrate (glucogenic) Transamination - Transfer an amino group from one amino acid to a keto acid - Makes a second new amino acid - Keto acid A + Amino acid B → Amino acid A + keto acid B - Liver can synthesize nonessential amino acids through the process of transamination Function of Deamination and Transamination Deamination - Insufficient fat and carbohydrate to meet energy needs - Insufficient essential amino acids to synthesize a complete protein - Dietary protein exceeds amount needed Transamination - To make nonessential amino acids - To begin the process of N removal from body - Not all amino acids can be directly deaminated, they have to be turned into those that can e.g. glutamic acid How much protein do we need? Healthy adult RDA: 0.8g/kg body weight Reference man: 56g protein Reference Woman: 44 g  Increased by 10-15 g/day for pregnancy About 8-10% of total calories Excess protein can’t be stored as protein Athlete Maybe increase to 1.0-1.5g/kg/day Endurance athletes use extra protein when carbs run out for energy Strength athletes use extra protein to build body protein\ Protein energy malnutrition Deficiency of protein, energy, or both Occurs in 2 forms or a combination - Marasmus - inadequate energy - Infancy (less than 2 yr) - Severe deprivation, or impaired absorption, or protein, energy, vitamins, and minerals - Develops slowly; chronic PEM - Severe weight loss - Severe muscle wasting, with no body fat - Growth: >60% weight for age - No detectable edema - No fatty liver - Anxiety, apathy - Good appetite possible - Hair is sparse, thin, and dry; easily pulled out - Skin is dry, thin, easily wrinkles - Kwashiorkor - protein deficiency - Older infants and young children - Inadequate protein intake or, more commonly, infections - Rapid onset; acute PEM - Some weight loss - Some muscle wasting, with retention of some body fat - Growth: 60-80% weight for age - Edema - Enlarged fatty liver - Apathy, misery, irritability - Sadness - Loss of appetite - Hair is dry and brittle, easily pulled out; changes color, becomes straight - Skin developed lesions Energy Metabolism Anabolic & catabolic Reactions: Glycogen Metabolism - the sum (total) or all the chemical reactions that go on in living cells Anabolism - reactions in which small molecules are put together to build larger ones - Requires energy - Using glycerol and fatty acids to produce triglycerides - Using amino acids to make protein Catabolism - reactions in which large molecules are broken down to smaller ones - Release energy - Breakdown of triglycerides into glycerol and fatty acids - Breaking down protein into amino acids Glucose to energy pathway Glycolysis - 2 pyruvate molecules - Hydrogen atoms carried to electron transport chain Pyruvate can be converted back to glucose - Liver cells and (to some extent) kidneys Quick energy needs - anaerobic - Pyruvate to lactate - Only carbohydrates Slower energy needs - aerobic - Pyruvate to acetyl CoA