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Carbohydrates

Carbohydrates. Carbohydrates. One of the three macronutrients A primary energy source, especially for neurons (nerve cells) CH 2 O Grains, fruits and vegetables. Question. Name ONE other macronutrient & tell me its energy content (kcal/gram). Where do Carbs originate?.

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Carbohydrates

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  1. Carbohydrates

  2. Carbohydrates • One of the three macronutrients • A primary energy source, especially for neurons (nerve cells) • CH2O • Grains, fruits and vegetables

  3. Question • Name ONE other macronutrient & tell me its energy content (kcal/gram)

  4. Where do Carbs originate? • As glucose in plants! • Glucose • Most abundant carbohydrate • Produced by plants (& other photosynthetic organisms) via photosynthesis • Simple or complex

  5. 0 Data • This is the general equation for photosynthesis—the process of capturing sunlight energy and converting it to chemical energy. Which of the following are the reactants of this reaction? • C6H12O6 and O2. • CO2 and H2O.

  6. Types of Carbohydrates • Simple contain 1 or 2 monomers • Monosaccharides contain 1 • Disaccharides contain 2 • Complex contain 100’s to 1000’s of monomers • Starches, glycogen, fibers

  7. Monosaccharides • Glucose: usually occurs with other sugars • Fructose: fruit & vegetable sugar • Galactose: Always occurs with glucose in foods

  8. Disaccharides • Lactose: Milk sugar (glucose + galactose) • Maltose: Malt sugar (glucose + glucose); by-product of digestion & fermentation in our bodies; substrate for fermentation in beer and liquor) • Sucrose: Naturally occurring fruit sugar

  9. Complex • Starch: Storage form of glucose in plants • Glycogen: Storage form of glucose in animals • Muscle and liver • Fiber: Form structural support elements of plants

  10. What happens to Complex Carbohydrates? • Starch • Digest starch to glucose • Convert it to usable energy, OR • store it as glycogen

  11. Complex Carbohydrates • Glycogen • Stored in the liver & muscles • Not a source of dietary carbohydrate

  12. Complex Carbohydrates • Fiber • Dietary fiberis the non-digestible part of plants • Grains, rice, seeds, legumes, fruits • Functional fiber is carbohydrate extracted from plants and added to food • Cellulose, guar gum, pectin, psyllium • Total fiber= dietary + functional fiber

  13. Digestion of Carbs • Begins in the mouth • Salivary amylasehydrolyzes starch to short polysaccharides & maltose • What kind of macromolecule is amylase? • Mechanical digestion with teeth • Stops in stomach • HCl denatures amylase • Resumes in SI • Pancreatic amylase also digests carbs to maltose

  14. Question • Name another digestive organ that directly adds secretions to the small intestine. • Stomach • Gall Bladder • Liver • a and b • b and c

  15. SI Monosaccharide enter capillaries within the intestinal villi. In the liver, galactose & fructose are converted to glucose. Monosaccharides travel to the liver via the bloodstream. Fig. 4-11, p. 110

  16. Transport & Use • ALL monosaccharides are converted to glucose by the liver • Q: Name one other monosaccharide. • Glucose circulating in the blood is our primary energy source • Excess glucose is converted to glycogen by the liver and skeletal muscles • Q: Is this an anabolic or catabolic process

  17. Storage of Glycogen

  18. Digestion of Carbohydrates • We do not have the enzymes necessary to digest fiber • Bacteria in large intestine can break down some fiber • Produce fatty acids and gas • Most fiber remains undigested and is eliminated with feces

  19. Question • Where does digestion of Carbohydrates NOT occur? • Mouth • Stomach • Small intestine • Large intestine

  20. Regulation of Blood Glucose • Amount of glucose (and therefore, access to quick energy) in the blood • Pancreatic cells produce, store and secrete two hormones, insulin and glucagon, which control level of glucose in the blood

  21. Regulation of Blood Glucose: Insulin • After eating, pancreas releases: • Insulin • Stimulates cells of the body to absorb glucose from the bloodstream • Stimulates the liver to absorb glucose and convert it to glycogen

  22. Regulation of Blood Glucose: Insulin

  23. Regulation of Blood Glucose: Glucagon • Glucagon • Stimulates the breakdown (hydrolysis) of glycogen to glucose to make quick energy available to cells of the body • Stimulates gluconeogenesis – production of glucose from amino acids (AA) • Where do these AA come from?

  24. Regulation of Blood Glucose: Glucagon

  25. Food & Blood Glucose • Glycemic index: A food’s ability to raise blood glucose levels • Foods with a low glycemic index: • Don’t produce dramatic fluctuations in blood glucose • May increase HDL/LDL ratio (good cholesterol) • Are generally higher in fiber • May reduce the risk of heart disease and colon cancer

  26. Glycemic indices

  27. The Role of Carbohydrates • Energy • 4 kcal/kg • Red blood cells rely only on glucose for energy supply • Glucose is especially important for energy during exercise

  28. The Role of Carbohydrates

  29. The Role of Carbohydrates • Energy • When we do not have sufficient energy in the form of carbs, we produce ketones as an alternate energy source • Why not ketones? • Excessive ketones increase blood acidity • High blood acidity damages body tissues

  30. The Role of Carbohydrates • Energy • Insufficient carbohydrate intake forces the body to find an alternate source of glucose • Proteins are used for gluconeogenesis – the production of new glucose

  31. Role of Carbohydrates • Fiber • May reduce the risk of colon cancer • May reduce the risk of heart disease • May block or delay absorption of dietary cholesterol • **May enhance weight loss • Occupies space so you feel full; also absorbs water and expands • **Helps prevent GI diseases/disorders (hemorrhoids, constipation, diverticulosis)

  32. How Much Carbohydrate? • Recommended Dietary Allowance (RDA) is 130 grams/day just to supply the brain with glucose • 45-65% of daily calorie intake should be in the form of carbohydrates

  33. Type of carb matters • Most Americans eat too many simple sugars • Most of these come from added sugars • Added sugars = sugars and syrups added to food during processing • Common source is soda pop (~ 10 tsp. sugar per 12 oz. can) • Average American consumes 40 gallons each year!

  34. Simple vs. Complex Carbs • Diets high in simple sugars: • Contribute to dental problems such as cavities and gum disease • Cavity causing bacteria thrive on simple sugars • Are associated with increased levels of “bad cholesterol” and decreased levels of “good cholesterol” • These changes are known to cause heart disease

  35. Simple vs. Complex Carbs • Complex carbs come associated with fiber • Adequate Intake (AI) of fiber = 14 grams for every 1,000 kcal in the diet • Most Americans eat only 1/2 the recommended amount of fiber • Whole grain foods are a more healthful choice than foods with added sugar • Come stocked with lots of fiber & necessary vitamins and minerals

  36. Alternatives to sugar • Nutritive sweeteners • Contain 4 kcal energy per gram • Sucrose, fructose, honey, brown sugar, sugar alcohols • Non-nutritive (alternative) sweeteners • Provide little or no energy

  37. Alternative Sweeteners • Acceptable Daily Intakes (ADI) have been established for: • aspartame • sucralose • acesulfame-K • No ADI has been set for saccharin but it has been removed from the list of cancer-causing agents.

  38. Alternative Sweeteners

  39. Health Disorders • Three health disorders related to carbohydrate metabolism • Diabetes • Hypoglycemia • Lactose intolerance

  40. Diabetes • Diabetes • Inability to regulate blood glucose levels • Three types: • Type 1 diabetes • Type 2 diabetes • Gestational diabetes • Untreated diabetes can cause nerve damage, kidney damage, blindness, and death

  41. Diabetes • Type 1 diabetes • Accounts for 10% of all cases • Patients do not produce enough insulin • Causes hyperglycemia – high blood sugar (glucose) • Requires insulin injections • May be an autoimmune disease

  42. Diabetes • Type 2 diabetes • Most diabetics have Type 2 diabetes • Body cells are insensitive or unresponsive to insulin • Excess insulin is often produced • Causes hyperglycemia because cells cannot remove glucose from the blood

  43. Diabetes • Type 2 diabetes • Causes include genetic predisposition, obesity, and physical inactivity • Treated with diet, exercise, and possibly oral medications • Healthy lifestyle choices may prevent or delay onset of type 2 diabetes

  44. Hypoglycemia • Hypoglycemia • Low blood sugar (glucose) • Reactive hypoglycemia results when too much insulin is produced after a meal • Causes shakiness, sweating, anxiety • Fasting hypoglycemia results when too much insulin is produced even when the patient has not eaten

  45. Lactose Intolerance • Lactose intolerance • Insufficient lactase production = inability to digest lactose (milk sugar) • Symptoms = intestinal gas, bloating, nausea, cramping, diarrhea • Alternate sources of calcium • Tomato juice, seaweed, cabbage, squashes, beets

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