NUTR 225 Ch. 4

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  1. Carbohydrates
    • - One of three macronutrients
    • - Sources include fruits and vegetables
  2. Glucose
    • - Most abundant carbohydrate
    • - produced by plants through photosynthesis
  3. Simple carbohydrates contain...
    • - One or two molecules
    • 1) Monosaccharides: contain only one molecule (glucose, fructose, galactose)
    • 2) Disaccharides: contain two molecules (lactose, maltose, sucrose)
  4. Disaccharides
    - Glucose + Galactose
    - Glucose + Glucose
    - Glucose + Fructose
    • Glucose + Galactose = Lactose (milk sugar)
    • Glucose + Glucose = Maltose (starch molecules)
    • Glucose + Fructose = Sucrose (sugar cane, beets, honey)
  5. Complex carbohydrates
    • Long chains of glucose molecules (polysaccharides)
    • e.g.: starch, glycogen, most fibers
  6. Starch
    • Storage form of glucose in plants;
    • - grains, legumes, and tubers
  7. Glycogen
    • Storage form of glucose in animals
    • - stored in liver and muscles
  8. Fiber
    • Forms the support structures of leaves, stems, and plants.
    • 1) Dietary fiber: non-digestible part of plants (grains, rice, seeds, legumes, fruits)
    • 2) Functional fiber: carbohydrate w/known health effects, which is extracted from plants and added to foods (cellulose, guar gum, pectin, psyllium)
  9. Soluble fiber
    • - Dissolves in water
    • - Easily digested by bacteria in colon
    • - Citrus fruits, berries, oats, and beans
  10. Insoluble fibers
    • - Found in whole grains (wheat, rye, brown rice)
    • - Promote regular bowel movements, alleviate constipation, reduce risk for diverticulosis
  11. Why do we need carbohydrates?
    • 1) Energy
    • - 4 kcal/g
    • - Red blood cells only rely on glucose for energy
    • - Prevents excessive ketones (can result in high blood acidity and ketoacidosis)

    • 2) Fiber
    • - May reduce risk of colon cancer and heart disease
    • - Can enhance weight loss
    • - Helps prevent hemorrhoids, constipation, diverticulosis

    High-fiber diet = less cholesterol in blood
  12. Digestion of Carbohydrates
    • -Mouth-> Chewing stimulates salivary amylase, which breaks down starch into maltose
    • -Stomach-> Salivary amylase is destroyed; no carb digestion yet.
    • -Pancreas-> Pancreatic amylase is secreted into small intestine
    • -Small intestine-> Pancreatic amylase breaks down starch into maltose; Enzymes in small intestine break down disaccharides into monosaccharides; monos absorbed into blood stream
    • -Liver-> Monos travel from blood stream to liver via portal vein, convert into glucose, transport to cell for energy; excess glucose is stored as glycogen in liver
    • -Large intestine-> Some carbs pass into large intestine undigested; bacteria ferment carbs; remaining fiber is pooped out
  13. Storage of glycogen
    • -Small intestine-> dietary carbs from stomach delivered into small intestine
    • -Liver-> Glucose and other monos transported to liver; blood levels of glucose maintained for brain and other body cells
    • -Muscle-> Glucose transported to muscle for energy expenditure
  14. Insulin
    • - Hormone secreted by the pancreas that helps transport glucose from the blood into cells.
    • - Stimulates the liver and muscles to take up glucose and convert it to glycogen
  15. Glucagon
    • -Hormone secreted by pancreas to stimulate breakdown of glycogen to glucose
    • -Stimulates gluconeogenesis, the production of "new" glucose from amino acids.
  16. Glycemic Index
    • - Measure of a food's ability to raise blood glucose levels
    • - Foods w/low glycemic index have more fiber, may reduce risk of heart disease, colon cancer, prostate cancer
  17. Carbohydrate intake
    • - RDA recommends 130g/day
    • - 45-65% of daily calorie intake should be carbs
    • - Focus on foods high in fiber and low in added sugars
  18. Problems w/eating too much sugar
    • - Dental problems
    • - increased levels of "bad cholesterol"
    • - may contribute to obesity
  19. Fiber intake
    Adequate Intake of fiber is 14g/1000kcal (25g women; 38g men)
  20. Alternative sweeteners (3)
    • 1) Nutritive sweeteners: 4kcal/g (sucrose, fructose, honey, brown sugar)
    • 2) Sugar alcohols: 2-3kcal/g
    • 3) Non-nutritive sweeteners: little to no kcal/g
  21. Diabetes
    • Inability to regulate blood glucose levels
    • -Three types: Type I, Type II, and gestational diabetes
  22. Symptoms of diabetes
    1) Type I: frequent urination, unusual thirst, extreme hunger, unusual weight loss, extreme fatigue, irritability

    2) Type II: Frequent infections, blurred vision, cuts/bruises slow to heal, tingling/numbness in hands or feet, recurring skin/gum/bladder infection, Type I symptoms
  23. Type I Diabetes
    • - >10% of all cases
    • - not enough insulin
    • - high blood sugar levels
    • - diagnosed in adults
    • - may lead to kedoacidosis, coma, death
  24. Type II Diabetes
    • - Develops progressively over time
    • - unresponsive to insuline, impaired fasting glucose, pre-diabetes
    • - Pancreas may become unable to produce insulin
  25. Who is at risk of diabetes?
    • - Obesity, genetics, physical inactivity, poor diet
    • - Metabolic syndrome (high waist circumference, high BP, high blood lipids/glucose)
    • - Increased age, yet younger people and children are now commonly diagnosed
Card Set
NUTR 225 Ch. 4
Nutrition 225 Final
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