Carbohydrates

1. Carbohydrates Will Brown Lecture 4 1/12/2012

2. Outline and Content • Objective – To identify basic structure, sources, and digestion of carbohydrates. Also to identify how carbohydrates affect blood glucose and some of the issues associated with to little or to much • Content • Eat This, Not That • Carbohydrate • Simple • Complex

3. Which should you eat? In addition, the Dorito's come with 2 g of fiber.

4. Introduction • What are carbohydrates? • Sugar molecules arranged in various ways • Why do we love carbohydrates do much? • One of the primary flavors was developed for carbohydrates – sweet! • Provide the main energy source for the body • 4 kcal/gram • Stored in either liver or muscles as glycogen • Also available in the blood as glucose

5. Where are carbohydrates produced? • Primarily made by green plants • Plants are able to transform solar energy into chemical energy • What is the name of this process?

6. 6 CO2 + 6 H2O → C2H12O6 + 6 O2 So 6 carbon dioxides along with 6 water molecules and some energy from the sun results in 1 glucose molecule and oxygen

7. Simple carbohydrates

8. Simple Carbohydrates • Two main forms of simple carbohydrates • Monosaccharides – One sugar • Disaccharides – Two sugars • Can anybody give an example of a simple carbohydrate? • Food labels list both mono and di under “Sugars”

9. Monosaccharides glucose, fructose, galactose Disaccharides Sucrose glucose+fructose Lactose glucose+galactose Maltose glucose+glucose

10. Monosaccharides • Single unit of sugar • Three most basic forms • Glucose • Fructose • Galactose

11. Glucose • Most common form of sugar found in the body • AKA: Dextrose • Not common in food as single sugar • Most comes from breakdown of sucrose • Most forms of sugar are converted to glucose once in the body

12. Fructose • AKA: Fruit sugar • After absorption transported to liver • Either converted to glucose or converted to other compounds, i.e.: fat • Most fructose comes from the refined product high-fructose corn syrup • Forms the other half of the sucrose molecule

13. Galactose • Very similar in structure to Glucose • Not found in large amounts in nature • Forms half of the disaccharide Lactose • Glucose forms the other half • Converted to Glucose or Glycogen in the liver

14. Disaccharides • Two molecules of sugar • Sucrose • Glucose and Fructose bonded together • Sources: honey, sugarcane, sugar beets, and maple sugar • Not produced by animals • Lactose • Glucose bonded to Galactose • Produced in milk synthesis • Maltose • Glucose bonded to Glucose • Comes from breakdown of starch • Important sugar in fermentation process

15. Complex Carbohydrate

16. Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

17. Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

18. Digestible Complex Carbohydrates • AKA: Polysaccharidesand starch • Long chains of sugar molecules bonded together – can be >1000 molecules of sugar • Plants store CC in 2 main forms • Amylose • Amylopectin

19. Digestible Complex Carbohydrate • Enzymes breakdown starch at the end of the chain • Amylose is slower to digest than amylopectin • As a result amylopectin raises blood sugar faster • All carbs are listed on nutrition labels as “Other Carbohydrates” • Glycogen is primary sugar found in the body • Stored in muscles and liver • Glucose molecules bonded together • Highly branched; even more so than amylopectin • Can quickly raise blood glucose levels

20. Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

21. Complex Carbohydrates: Fiber • Made up primarily of polysaccharides • Can not be digested by humans • 6 types of Fiber • Cellulose • Hemicellulose • Pectins • Gums • Mucilages • Lignin -- Carbohydrate fibers -- Non-carbohydrate fiber

22. Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

23. Soluble fibers • Pectins, gums and mucilages • AKA: viscous fiber • Dissolve or swell when placed in water • Source: found around and inside plants • Readily digested by bacteria – fermentable • Found in foods under various names • Guar gum • Gum arabic • Locust bean gum • Pectin for jam and jellies

24. Soluble fiber • Pectin • Galacturonic acid • Also others • Mucilages • Galactose • Manose • And others

25. Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

26. Insoluble Fiber • Comprised of cellulose, hemicellulose, and lignin • AKA: nonfermentable fiber • Do not readily dissolve in water • Sorce: form the structural parts of plants • Cell wall, bark, etc. • Not readily metabolized by commensal bacteria • Bran is rich in hemicellulose and lignin • Outer covering of all whole grains

27. Insoluble Fiber • Cellulose • Glucose • Hemicellulose • Xylose • Galactose • Glucose • Small amounts of other monosaccharides • Lignin • Multi-ringed alcohols • That is why it is called a “noncarbohydrate”

28. Carbohydrates on Food Labels • Sugars = all mono and disaccharides • Dietary fiber = fiber present in the food • Does not include added or “functional” fiber • Now you can find “total fiber” • Number of complex carbs is total carbs – DF – sugars

29. Carbs in the Diet • Recommended Daily allowance of Carbohydrate = 130g • Should comprise 45-65% of daily calories • Example: for 2000 calorie diet that is between 900 to 1300 calories • Look for nutrient dense carbohydrates • Fruit, vegetables, beans, etc. • Avoid processed carbohydrates • Refined sugars and refined grains

30. Carbs in the Diet • Why is it necessary to eat whole grains? • What is a whole grain? • During the refinement process the bran is removed • Leaves very little if any fiber – mostly starch • Why is this a problem? Easily digestible carbohydrates quickly raise blood sugar

31. Which should you eat? Process of making grits has high concentration of starch and reduced fiber

32. Carbs in the Diet: Sweeteners • Two categories • Nutritive • Alternative • Nutritive sweeteners provide calories • Sugars – Used in many types of food • Sugar alcohols – limited uses • Alternative sweeteners provide no calories • Saccharin • Aspartame • Alternative sweeteners are “sweeter” on a per gram basis compared to nutritive sweetners

33. Carbs in the Diet: Nutritive Sweeteners • All monosaccharides and disaccharides • Sucrose is the benchmark to measure relative sweetness • Sucrose = 1.0 • If >1 then sweeter than sucrose • If < 1 then not as sweet as sucrose • High Fructose Corn Syrup (HFCS) is used extensively as a sweetener is food • ~55% Fructose • Made by refining corn • As sweet as sucrose but cheaper to make

34. Carbs in the Diet: Nutritive Sweeteners • Other types of sugars found in food • Brown Sugar – sucrose with molasses • Turbinado sugar – partially refined sugar; AKA: raw sugar • Honey – plant nectar enzymatically broken down by bees • Can cause botulism in infants – recommended to not give to children under the age of 2 • Inverted sugar – sucrose that is heated until “inverted”

35. Which should you eat? Natural maple syrup not only has fewer calories but also is high in manganese.

36. Carbs in the Diet: Nutritive Sweeteners • Sugar Alcohols • Sorbitol and Xylitol are examples • Much lower calorie content than sugars • Sugar = 9 kcal/g • Sugar alcohol = ~2.6 kcal/g • Converted to glucose much slower; resides longer in SI • If consumed in large amounts can cause diarrhea • Found in sugarless gum, breath mints, and candy • Must be listed on food labels • If one is used, must be listed by name • If 2 or more than “sugar alcohol” is listed

37. Carbs in the Diet: Alternative Sweeteners • AKA: artificial sweeteners • Found in many forms and many brand names • Yield little to no calories when eaten • No RDA, instead have ADI – Acceptable Daily Intake • The amount 100 times less than the no harmful effect level in animal studies • 6 are approved in the US • Saccharin • Aspartame • Sucralose • Neotame • Cyclamate • Acesulfame-K

38. Saccharine • The oldest alternative sweetener • First produced in 1879 • Approved for use in over 90 countires • Sold in pink packets – Brand name Sweet ‘N Low® • 50% of market share in USA • Originally thought to increase cancer risk • No longer listed as carcinogen • Studies had the rats consuming a crazy amount of it and saw marginal increases in bladder cancer

39. Aspartame • Sold in blue packets – brand name Equal® • Approved in over 90 countries • Endorsed by numerous diet and medical groups • 200 times sweeter than sucrose • Yields 4 kcal/g • Made of phenylalanine, aspartic acid and methanol • Because more protein than sugar, looses sweetness with prolonged heating, not good for cooking • ADI – 50mg/kg of body weight • ~80 packets of Equal® • Some adverse effects have been reported • Considered safe for pregnant women – consult your physician

40. Sucralose • Sold as the brand name Splenda® • 600 times sweeter than sucrose • Made by adding 3 Cl to sucrose • Does not breakdown when heated • Not readily absorbed so most excreted in feces • Small amounts taken up secreted by kidneys

41. Neotame • Recently approved by FDA • Approved for use in many applications • Not meat or poultry • 7000-13,000 times sweeter than sucrose • Does not breakdown when heated • Similar in structure to aspartame • Safe in general population and does not carry the PKU warning of aspartame

42. Acesulfame-K • Sold under the brand name Sunette® • 200 times sweeter than sucrose • Heat stable • Approved by FDA in 1988 – in Europe since ’83 • Not digested by the body • K stands for potassium

43. Tagatose • Brand name = Naturlose® • Altered form of fructose • Poorly absorbed • Yields 1.5 kcal/g • Eventually fermented in LI so thought to act as prebiotic

44. Stevia • Brand name = Sweet Leaf® • Derived from South American shrub • 100-300 times sweeter than sucrose • Provides no energy • Available in Japan since ‘70s but not approved in US till 2008