NUTR 251 Exam 1

• • Nutrition: SCIENCE of food, the NUTRIENTS and the substances therein; their action, interaction, and balance to health and disease; and the PROCESS by which the organism ingests, digests, absorbs, transports, utilizes, and excretes food substances.
  • Nutrients
  • MACRONUTRIENTS: carbs, lipids, proteins, water
  • MICRONUTRIENTS: vitamins & minerals 
• • Carbs: Made up of C, H, and O.
  • Primarily obtained from fruits, vegetables, grains, beans, provide 4 kcal/g
  • Simple: sucrose, blood glucose
  • Complex: Starch, glycogen, fiber
• • Proteins: Made up of C, H, O, and N 
  • Main structural components in body, provides 4 kcal/g
  • Peptide-bonded amino acids
• • Lipids: Made up of C, H, and O
  • Insoluble in water
  • Provides 9 kcal/g
  • Fats: Lipids that are solid in RT (saturated)
  • Oils: Liquid in RT (unsaturated) 
  • Triglycerides, phospholipids, sterols 
  • Essential fatty acids: must be obtained from diet (e.g. Linoleic acid - omega-6, Alpha-linolenic acid - omega-3)
  • Cell membrane, regulate blood pressure, regulate nerve transmission
• • Vitamins: Main function to enable chemical reactions 
  • 13 vitamins, 2 groups: 
  • FAT SOLUBLE: vitamins A, D, E, and K. More likely to accumulate and be toxic 
  • WATER SOLUBLE: vitamin C and B-vitamins, more likely to be destroyed by cooking, excreted from body more readily 
• • Minerals: Inorganic substances, do not contain C-Hs. Not destroyed by cooking
  • MAJOR minerals needed in gram amounts daily
  • TRACE mineral needed in <100 mg daily 
• • Water: NEED this the most! 
  • Functions: solvent, lubricant, transports nutrients, regulates body temp. It’s a drink and food and a byproduct of metabolism. 
• Alcohol provides energy, but is it a nutrient? NO 

  • KCAL: amount of heat energy needed to raise the temp of 1000 grams of water by 1˚C. More appropriate than calorie. 
• KCal problem example:

   1 slice of bread + 1 teaspoon of peanut butter contains: 16 g Carbs, 7 g protein, 9 g fat. Total kcals?

  16 g CHO x 4 kcal + 7 g PRO x 4 kcal + 9 g FAT x 9 kcal = 173 kcal
• Describe the factors that influence our food choices. 

  • Hunger: physical need for food
  • Appetite: psychological desire to eat 
  • Food flavor, texture, appearance
  • Availability
  • Health and nutrition concerns, knowledge, beliefs
  • Cost
  • Health awareness
• Discuss the components and limitations. 

  • ANTHROPOMETRIC
  • Height, weight, waist circumference, skin fold thickness
  • BIOCHEMICAL
  • Nutrients and their metabolites in blood, urine, feces
  • CLINICAL
  • Physical appearance, psychological surveys, movement, skin condition, blood pressure
  • DIETARY
  • 3-day diet record, 24-hour recall, food frequency questionaire
  • ENVIRONMENTAL
  • Education, income, housing 
• • DRIs: Developed by FNH set for almost 40 nutrients, recommendations for people based on age group, gender (after age 9), pregnancy, and lactation. 
• • EARs: Estimated to meet the needs of ½ of the people in a certain life stage (50% of population needs met by EARs) 
• • RDAs: Nutrient amount sufficient to meet the needs of nearly ALL healthy individuals (97-98%). Set to prevent chronic disease rather than just prevent deficiency. RDA is higher than average human needs. 
• • AIs: Intake recommendation set when there are INSUFFICIENT DATA to establish an EAR. Should still cover 97-98% of population. 
• • ULs: Max daily intake amount not likely to cause adverse health effects in almost all individuals. Applies to chronic daily use, consider this a “ceiling”. (Too much of something= risk)
• • EERs: Estimate of energy needs according to height, weight, biological sex, age, physical activity pattern. Listed values inform the average daily energy (kcal) for each life-stage group. EERs are estimates b/c energy needs depend on many variables.  
• • AMDRs: established for macronutrient guidance. Not a DRI, meant to reduce risk of nutrition-related chronic diseases while providing recommended nutrient intakes. 
• NUTRIENT DENSITY: tool for assessing nutrient quality of an individual food. 

  1. ND = RDA/AI
  2. Kcal/EER
  3. Nutrient dense foods provide a greater contribution to your nutrient need than your kcal need 
• Daily values (DVs): Generic standards developed by FDA. Used to determine the % DV found on the NUTRITION FACTS PANEL on food labels. Set for 4 groups: people over age 4, infants, toddlers, pregnant/lactating women. 

  *DRIs are age and gender specific, DVs can apply to everyone.*
• Nutrition Facts panels and the claims permitted on food packages must include the product name, name/address, amount of product, ingredient list in descending order by weight, ingredients that are common allergens, and nutrition facts panel.
• Nutrient content claims describe the nutrient content of a food.
• Health claims describe the relationship between a disease and a nutrient, food, or food constituent, such as a diet with sufficient calcium may reduce the risk of osteoporosis.
• STRUCTURE-FUNCTION claims, which are the least regulated, describe how a nutrient affects the body structure or function.
• The FDA has oversight and claims must comply with regulations.
• Explain the uses and limitations of nutrient composition databases. 

  Databases allow us to estimate the nutrient content of foods consumed. Estimates can include many factors that influence actual nutrient content of foods consumed. Some factors include prep/cooking method (eg. frying chicken in vegetable oil vs. butter). 

  ENERGY DENSITY compares total kcal per gram WEIGHT of food. 

  • ED = kcal/grams serving. 
  • Ex: a sandwich contains 150 kcal per 30 g serving. ED = 150/30 = 5. 
• 4 specific recommendations supporting the 4 themes:

  • Limiting added sugars
  • <10% of calories/day for ages 2+. Avoid added sugars for infants/toddlers
  • Limiting saturated fat
  • <10% of calories/day starting at age 2 
  • Limiting sodium intake
  • <2300mg/day (or even less if younger than 14)
  • Limiting alcoholic beverages (if consumed)
  • <2 drinks a day for men, <1 drink a day for women. 
• 5 vegetable subgroups:

  • DARK-GREEN
  • ORANGE
  • BEANS/PEAS (LEGUMES)
  • Can count as either VEGETABLES or PROTEIN
  • STARCHY
  • OTHER 

  Half of grain servings could be WHOLE GRAINS. 
• Describe the levels of organization of the body from cells to organ systems.

  Atoms/mols → Cells → Tissues → Organs → Organ system → organism 
• Gastrointestinal system

  • Functions to digest food and absorb nutrients
  • Controlled by nervous system/hormones
  • Aids in immune function
  • Acts as physical barrier
  • Produces immune components
  • Houses a lot of bacteria. 
  • Two major components:
  • GI Tract (hollow, muscular tube)
  • Accessory organs (assist with GI tract function)
  • Pancreas, gallbladder, liver
• GI Tract Anatomy

  • Anatomy:
  • (further in): Mucosa → Submucosa → Muscles → Serosa 
  • SPHINCTERS: ringlike muscles along GI tract. Act as valves to control flow of contents and allow digestive secretions to be thoroughly mixed. 
  • LOWER ESOPHAGEAL sphincter
  • PYLORIC sphincter. 
• GI Function - digestion

  • Digestion: large compounds in foods are broken down into smaller molecules
  • MECHANICAL: physical breakdown. Chewing, mixing, peristalsis.
  • CHEMICAL: chemical breakdown, enzymes, acids, gastric secretions. 

  PERISTALSIS: movement of food toward the anus. 

  SEGMENTATION: back-and-forth movement in the small intestine that breaks food into smaller pieces. 
• Mouth and Esophagus

  Mouth:

  • Mechanical and chemical digestion
  • AMYLASE: breaks down starches
  • LIPASE: breaks down fats 
  • Lysozymes: kills bacteria 
  • Salivda enhances taste/flavor. Smell is important for taste perception too. 

  Esophagus:

  • Passes food via peristalsis to stomach. 
• Stomach

  Mechanical:

  • Bolus 
  • Food remains in stomach for 2-3 hours
  • Minimal nutrient absorption (water, 20% of total alcohol → not a nutrient!) 
  • Mechanical digestion: bolus + gastric secretions = CHYME 
  • PYLORIC sphincter: controls release of chyme into small intestine 

  Chemical:

  • Hydrochloric acid: INACTIVATES ingested proteins and kills HARMFUL bacteria and viruses. 
  • MUCUS is secreted to protect the stomach lining. 
  • Breaks down fats: GASTRIC LIPASE
  • Breaks down protein: PEPSIN 
  • HCl inactivates amylase, intrinsic factor is needed for Vitamin B12 absorption.
• Small Intestine

  • 3 segments: DUODENUM, JEJUNUM, ILEUM (order: think DJ Ileum) 
  • VILLI and MICROVILLI: folds that make up the walls and increase absorptive capacity of small intestine. 
  • It is the MAJOR SITE of digestion and absorption. 
  • 70-90% of WATER is ingested.
• Small intestine

  Mechanical: segmentation, peristalsis of contents downthe small intestine.
• Small Intestine

  Chemical: 

  • Sodium bicarbonate NEUTRALIZES acidic chyme.
  • Bile EMULSIFIES fats.
  • PROTEASES partially digest proteins.

  Enzymes:

  • Peptidases: breaks down partially digested proteins
  • DISACCHARIDASES: break down disaccharides into monosaccharides.
  • Lipase: digests fat 

  Accessory organs:

  • Liver: creates BILE, stored in GALLBLADDER
  • Pancreas: produces SODIUM BICARB, pancreatic amylase, lipase, and proteases. 
• Large intestine

  • 3 main functions:
  • Absorb remaining water/electrolytes,
  • Form/remove feces
  • 75% water, 25% solids. Indigestible stuff. 
  • House MICROBIOTA → keeps GI tract healthy!
  • Some fatty acids, vitamin K, and biotin are produced by microbiota. 
• Nutrient absorbed from lumen in these two systems: CARDIOVASCULAR and LYMPHATIC. 

  Transport into these systems uses one of 4 methods: PASSIVE diffusion, facilitated diffusion, ACTIVE transport, endocytosis. 
• WATER SOLUBLE nutrients are absorbed into capillaries in villi and transported by cardiovascular system via HEPATIC PORTAL VEIN.