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Carbohydrates ch4


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Carbohydrates ch4

  1. 1. The Body’s Choice for Energy
  2. 2. <ul><li>Energy : 4 kcal/gram </li></ul><ul><li>Recommendations: 50-60% of total energy intake from CHO </li></ul><ul><ul><li>Emphasis on whole grains, fruits and vegetables (<10% of total energy intake from simple sugars) </li></ul></ul><ul><ul><li>At LEAST 50-60 grams CHO/day to prevent KETOSIS </li></ul></ul><ul><ul><ul><li>Low CHO intake  incomplete breakdown of fat  ketone bodies  ketosis (disturbs acid-base balance) </li></ul></ul></ul><ul><li>CHO has a “ protein-sparing ” effect </li></ul><ul><ul><li>Long-term starvation  protein “wasting” in muscles, heart, liver, kidneys, other organs </li></ul></ul>
  3. 3. <ul><li>Simple Sugars </li></ul><ul><ul><li>Monosaccharides </li></ul></ul><ul><ul><li>Disaccharides </li></ul></ul>Fig. 4.2 Fig. 4.3
  4. 4. <ul><li>Complex CHO </li></ul><ul><ul><li>Polysaccharides </li></ul></ul><ul><ul><ul><li>Starches = amylose (straight chain) and amylopectin (branched chain) </li></ul></ul></ul><ul><ul><ul><li>Glycogen = “animal starch” </li></ul></ul></ul><ul><ul><li>Oligosaccharides </li></ul></ul>Fig. 4.4
  5. 5. <ul><li>Human and animal storage form of glucose </li></ul><ul><li>Highly branched </li></ul><ul><li>Only synthesized and stored in muscle and liver </li></ul><ul><li>Liver glycogen supplies blood glucose </li></ul><ul><ul><li>Exhausted in ~ 18 hours </li></ul></ul><ul><li>Muscle glycogen used only for muscles </li></ul>
  6. 6. <ul><li>Non-digestible CHO (from plants) </li></ul><ul><li>Recommendation: 25 grams/day for women or 38 grams/day for men (from food best) </li></ul><ul><li>Two basic types: </li></ul><ul><ul><li>Insoluble fiber (nonfermentable) </li></ul></ul><ul><ul><li>Soluble fiber (viscous) </li></ul></ul>
  7. 7. <ul><li>Insoluble fiber </li></ul><ul><ul><li>Sources: wheat products, brown rice, fruit and vegetable peels, fibrous plant foods (ex: celery) </li></ul></ul><ul><ul><li>Function: increases fecal bulk allowing easier waste elimination and regularity </li></ul></ul>
  8. 8. <ul><li>Soluble fiber </li></ul><ul><ul><li>Sources: insides of fruits and vegetables (apples, bananas, etc.), legumes, barley, oats, white rice </li></ul></ul><ul><ul><li>Function: slows gastric emptying, slows glucose absorption, decreases “bad” cholesterol </li></ul></ul>
  9. 9. <ul><li>Non-caloric or lower caloric sweeteners </li></ul><ul><ul><li>Sugar alcohols – sorbitol, xylitol </li></ul></ul><ul><ul><ul><li>1.3-3 kcal/gram </li></ul></ul></ul><ul><ul><ul><li>May cause diarrhea </li></ul></ul></ul><ul><ul><ul><li>Noncariogenic </li></ul></ul></ul><ul><ul><li>Aspartame – Nutrasweet, Equal </li></ul></ul><ul><ul><ul><li>Made from 2 amino acids (including phenylalanine) </li></ul></ul></ul><ul><ul><ul><li>4 kcal/gram but is about 200 times sweeter than sucrose </li></ul></ul></ul><ul><ul><ul><li>Can be altered by cooking (protein-based) – not dangerous but does not taste sweet </li></ul></ul></ul><ul><ul><ul><li>No more than 50 mg/kg body wt (14 cans diet soft drink!) </li></ul></ul></ul><ul><ul><ul><li>PKU = phenylketonuria – cannot metabolize phenylalanine, so can’t have aspartame </li></ul></ul></ul>
  10. 10. <ul><li>Sucralose – Splenda </li></ul><ul><ul><ul><li>Sucrose derivative </li></ul></ul></ul><ul><ul><ul><li>600 times sweeter than sucrose </li></ul></ul></ul><ul><ul><ul><li>Heat stable, good for baking </li></ul></ul></ul><ul><ul><ul><li>Not well-absorbed, rest excreted by kidneys </li></ul></ul></ul><ul><li>Stevia </li></ul><ul><ul><li>Extract from South American shrub </li></ul></ul><ul><ul><li>100 to 300 times sweeter than sucrose </li></ul></ul><ul><ul><li>GRAS classification by the FDA </li></ul></ul>
  11. 11. <ul><li>Amylase = starch-digesting enzyme </li></ul><ul><ul><li>Produced in mouth (salivary or alpha-amylase) and pancreas (pancreatic amylase) </li></ul></ul><ul><li>Other enzymes produced by small intestine cells (sucrase, lactase, etc.) </li></ul><ul><li>Monosaccharides absorbed across small intestine absorptive cells into capillaries  portal vein </li></ul><ul><li>Soluble fiber fermented by bacteria in large intestine  gas, acids </li></ul>
  12. 12. <ul><li>Hyperglycemia = over 125 mg/dl </li></ul><ul><li>Normoglycemia = 70-100 mg/dl </li></ul><ul><li>Hypoglycemia = below 40 to 50 mg/dl </li></ul><ul><li>Diabetes - inability to handle glucose properly </li></ul><ul><ul><li>Diabetes is characterized by chronic hyperglycemia with sometime dangerous episodes of hypoglycemia </li></ul></ul>
  13. 13. <ul><li>Insulin </li></ul><ul><ul><li>Produced by beta cells in pancreas in response to hyperglycemia </li></ul></ul><ul><ul><li>Binds to insulin receptors on cells, leading to an increase in glucose absorption by cells  return to normoglycemia </li></ul></ul><ul><li>Glucagon </li></ul><ul><ul><li>Produced by cells in pancreas in response to hypoglycemia blood glucose </li></ul></ul><ul><ul><li>Stimulates breakdown of glycogen in liver to glucose  return to normoglycemia </li></ul></ul>
  14. 14. Fig. 4.9
  15. 15. <ul><li>Three main types: </li></ul><ul><ul><li>Type 1 (insulin-dependent diabetes) </li></ul></ul><ul><ul><li>Type 2 (noninsulin-dependent diabetes) </li></ul></ul><ul><ul><li>Gestational diabetes </li></ul></ul><ul><li>Related to morbidity and mortality with other problems (kidney failure, heart disease, hypertension, poor wound healing, poor blood circulation) </li></ul>
  16. 16. <ul><li>Insulin-dependent or “childhood onset” diabetes </li></ul><ul><ul><li>Autoimmune disease – destruction of beta cells in pancreas  NO insulin made </li></ul></ul><ul><ul><ul><li>All patients with type 1 diabetes require daily insulin injections </li></ul></ul></ul>
  17. 17. <ul><li>Noninsulin-dependent or “adult onset” diabetes </li></ul><ul><ul><li>Genetic and lifestyle connection </li></ul></ul><ul><ul><li>Epidemic rise in incidence in US and other developed nations, including children </li></ul></ul><ul><ul><li>Characterized by insulin receptor insensitivity </li></ul></ul><ul><ul><ul><li>Usually, insulin not needed because the pancreas makes plenty </li></ul></ul></ul><ul><ul><ul><li>Pancreas ramps up insulin production, may eventually “wear out”  need for insulin injections </li></ul></ul></ul><ul><ul><ul><li>May be controlled with diet, exercise, and medications </li></ul></ul></ul>
  18. 18. <ul><li>Health risks caused by long-term elevated insulin: </li></ul><ul><ul><li>Increased blood TGs, smaller (more dangerous) LDL </li></ul></ul><ul><ul><li>Increased risk for heart disease </li></ul></ul><ul><ul><li>Increase fat deposits in adipose tissue and organs (including liver) </li></ul></ul><ul><ul><li>Increased blood clotting tendencies </li></ul></ul><ul><ul><li>Damage to kidneys </li></ul></ul>
  19. 19. <ul><li>Affects 3-5% of pregnancies </li></ul><ul><li>Normal for slight insulin insensitivity during pregnancy, but too much  hyperglycemia/gestational diabetes </li></ul><ul><ul><li>So very similar in symptoms to type 2 diabetes </li></ul></ul><ul><li>Usually resolves after birth </li></ul><ul><li>Both mother and child at higher risk for type 2 diabetes later in life </li></ul>
  20. 20. <ul><li>“ Forms” of sugar </li></ul><ul><li>Note: “Low fat” and “Fat-free” foods tend to be high in simple sugars </li></ul><ul><li>Bone health </li></ul><ul><ul><li>Soft drinks/sugary beverages may contribute to compromised bone health if replace milk </li></ul></ul>
  21. 21. <ul><li>Dental health </li></ul><ul><ul><li>Simple sugars are cariogenic </li></ul></ul><ul><ul><li>Sticky, gummy CHOs </li></ul></ul><ul><ul><li>Bacteria in mouth metabolize sugar  produce acids  dissolve tooth enamel </li></ul></ul><ul><ul><li>Fluoridated water and toothpaste help protect enamel, prevent dental caries </li></ul></ul>Fig. 4.12
  22. 22. <ul><li>Humans produce few enzymes that can break beta bonds in CHOs, including lactose </li></ul><ul><li>Lactose intolerance is reduced or absent lactase  maldigestion of lactose  fermentation by colon bacteria  bloating, gas, acid production, discomfort, diarrhea </li></ul><ul><li>Normal as we age (less dependence on milk for nutrients) </li></ul><ul><li>75% of world is lactose intolerant </li></ul><ul><ul><li>Esp. Asian, African, Hispanic American populations </li></ul></ul>
  23. 23. <ul><li>How to obtain calcium? </li></ul><ul><ul><li>Small portions of lactose-containing foods </li></ul></ul><ul><ul><li>Low lactose dairy (cheese, yogurt) </li></ul></ul><ul><ul><li>Lactase-treated products, lactase pills </li></ul></ul><ul><ul><li>Non-dairy calcium sources: </li></ul></ul><ul><ul><ul><li>Dark green, leafy vegetables (not spinach), including broccoli </li></ul></ul></ul><ul><ul><ul><li>Calcium-fortified OJ </li></ul></ul></ul><ul><ul><ul><li>Soy products, particularly calcium-fortified </li></ul></ul></ul><ul><ul><ul><li>Calcium-fortified cereals </li></ul></ul></ul>