Chapter Objectives Understand simple vs complex carbs Explain

Chapter Objectives: - Understand simple vs. complex carbs - Explain the process of carb digestion and absorption - Describe how BG levels are affected by carb consumption - Understand how to increase carb intake and decrease sugar intake - Explain how carbs affect health

Carbohydrates • Sugars, Starches, Fibers • Major food sources: plants – Formed during photosynthesis Photo © Photo. Disc 2

Sugars Starches Fiber Copyright 2005 Wadsworth Group, a division of Thomson Learning

Photosynthesis 4

The Chemist’s View of Carbohydrates: Carbohydrates (CH 2 O)n Composed of carbon, oxygen and hydrogen Most, but not all, have a ratio of one carbon molecule to one water molecule CH 2 O Carbo = carbon Hydrate = with water

Carbohydrates classification: Simple carbohydrates: Monosaccharides Disaccharides Complex carbohydrates: Starch Fiber Glycogen

Simple Sugars Monosaccharides: single sugar unit – C 6 H 12 O 6 – Glucose • Found in fruits, vegetables, honey • “blood sugar” – used for energy – Fructose • “fruit sugar” • Found in fruits, honey, corn syrup – Galactose • Found as part of lactose in milk 7

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Condensation Copyright 2005 Wadsworth Group, a division of Thomson Learning

Hydrolysis Copyright 2005 Wadsworth Group, a division of Thomson Learning

• Disaccharides: two linked sugar units – Sucrose: glucose + fructose • “table sugar” • Made from sugar cane and sugar beets – Lactose: glucose + galactose • “milk sugar” • Found in milk and dairy products – Maltose: glucose + glucose • Found in germinating cereal grains • Product of starch breakdown 12

Complex Carbohydrates: Chains of more than two sugar molecules Oligosaccharides: – contain 3 -10 sugar molecules - Oligosaccharides – dried beans, peas, lentils • rafinose (gal-glu-fru) • stachyose (gal-gal-fru) • metabolized by intestinal bacteria • gaseous effects 13

• Polysaccharides: – contain 100’s or 1000’s of monosaccharide units – starch-digestible – fiber-indigestible

• Starch: – Long chains of glucose units • Amylose – straight chains • Amylopectin – branched chains; Plants store carbohydrates such as starch We digest (break down) starch to glucose - Grains, legumes, and tubers are good sources of starch in our diet - Resistant starch-not digested Found in grains, vegetables, legumes 15

• Glycogen: – Highly branched chains of glucose units - Animals store carbohydrate as glycogen - Stored in the liver and muscles - Not found in food and therefore not a source of dietary carbohydrate

• Dietary Fiber – Indigestible chains of monosaccharides Non-starch polysaccharides: long chains – Cellulose, hemicellulose, pectins, gums, mucilages • Other: Lignins, cutins, waxes – Found in fruits, vegetables, grains, legumes

Fiber - Dietary fiber occur naturally in plant, is the non- digestible part of plants - Grains, rice, seeds, legumes, fruits - Functional fiber is carbohydrate extracted from - plants and added to food or used as supplements - Cellulose, guar gum, pectin, psyllium - Total fiber = dietary + functional fiber

Fibers Differ from starch: the glucose units are connected by beta 1 -4 linkages; starch contains glucose units that are connected by alpha 1 -4 linkages Amylase only works on the alpha 1 -4 bonds, not beta 1 -4 bonds

Fibers classified: – Soluble fibers • Form gels (viscous) • Eisly digested by bacteria in the colon Fermentable - Insoluble fibers • Not form gels (nonviscous) • Less readily fermented • (Phytic acid)

Type of Fiber Soluble Fiber Gums, pectins, some hemicell, mucilages; Insoluble Fiber Cellulose, many hemicelluloses, lignins Major Food Sources Action in Body Fruits (apples, citrus), oats, barley, legumes * Delay GI transit. * Delay glucose absorption. *Lower blood cholesterol. wheat bran, corn braly whole grain breads & cereals, vegetables * Accelerate GI transit. *Increase fecal weight. *Slow starch hydrolysis. *Delay glucose absorption 23

• Cellulose – makes walls of cells strong and rigid • Hemicelluloses – mixed with cellulose in cell walls – outer bran layer • Pectins – gel forming; in fruit

• Gums and Mucilages – thick, gel-forming – used by food industry to thicken, stabilize, • Lignins – not a carb; indigestible substances that make up woody parts of veg; and fruit seeds

Health Benefits of Fiber: Health effects –Heart disease –Diabetes –GI health –Cancer –Weight management

Functions of Fiber: May reduce the risk of colon cancer Help prevent hemorrhoids, constipation, and other intestinal problems May reduce the risk of diverticulosis May reduce the risk of heart disease May enhance weight loss May lower the risk of type 2 diabetes

Problems With Excess Fiber Consumption: - Too much bulk, fill up too soon - Abdominal discomfort - Binds minerals - May bind to some medications - Can cause constipation if plenty of fluids are not consumed

Carbohydrate Functions: C - Energy source, Glucose is the body’s main fuel 4 kcal/gm. - Energy for brain - Protein sparing - Builds glycogen - Antiketogenic - Fiber - bulking agent - Nucleic acid synthesis

Protein-Sparing Action of Carbohydrate is the main supplier of glucose in the body. Only glucose can provide energy for brain cells, other nerve cells, and developing red blood cells. If carbohydrate is not supplied in sufficient amounts in the diet, then glucose must be made from an alternative substrate protein. Body protein can be converted to glucose to some extent, but it does have its own job to do – build and repair tissues in the body. Body fat cannot be converted to glucose to any significant extent. Thus when a person does not replenish glucose and glycogen stores by eating dietary carbohydrate, the body relies on the dietary (and body) protein to make glucose. The conversion of protein to glucose is called as “gluconeogenesis”. Only adequate dietary carbohydrate can prevent this use of protein for energy, and this role of carbohydrate is known as it protein-sparing action.

Absorption:

What Happens to the Simple Sugars After Absorption? - Glucose, galactose, and fructose travel in blood from small intestine to liver. - Liver converts all fructose and galactose to glucose - Glucose is used for energy - Excess glucose is

Recommendations: RDA for carbohydrate – 130 g/day – 45% - 65% total daily energy intake Daily Value: 300 g/day. RDA for Fiber: Daily Value: 25 g/day Adequate Intake AI: 14 g/1000 kcal/day. It is best to get fiber from food (also a source of vitamins and minerals).

Lactose intolerance: Symptoms Causes Lactase deficiency

Glucose in the Body: - The primary role of glucose in the body is to supply the body’s cells with glucose to make energy (brain, nerves, red blood cells prefer glucose as primary fuel source) - Glucose that is not used by body cells – excess glucose is stored as glycogen in the liver; if glycogen stores are full, then excess glucose can be used to make fatty acids and stored in the adipose tissue

Regulation of Blood glucose level: Hormones control blood glucose levels: - Insulin - Glucagon - Epinephrine - Norepinephrine - Cortisol Growth hormone

Insulin - Produced by beta cells of the pancreas - Stimulates glucose transporters (carrier proteins) to help take glucose from the blood across the cell membrane Stimulates the liver to take up glucose andconvet it to glycogen

Glucagon - Produced by alpha cells of the pancreas Stimulates the liver to breakdown glycogen to glucose, glucose available to body cells - Stimulates the breakdown of body proteins to amino acids to form new glucose (Gluconeogenesis)

Epinephrine & Norepinephrine - Secreted by the adrenal glands and nerve endings when blood glucose is low - Stimulates the liver to breakdown glycogen toglucose - Responsible for our “fight or flight” reactions to danger

Cortisol & Growth Hormone - Cortisolecreted by the adrenal glands to act on the liver, muscle, and adipose tissue Cortisol increase gluconeogenesis and decreases the use of glucose by muscles Growth hormone increases fatty acid mobilization and utilization, and increases liver’s output of glucose

bl Blood Glucose Regulation

Diabetes Mellitus: – Inability to regulate blood glucose levels – Persistent high blood glucose levels – Complications of high BG – Type 1: lack of insulin production • Treat with insulin – Type 2: cells are resistant to insulin • Treat with diet and exercise • May treat with oral medications • May treat with insulin 44

Three types: - Type 1 diabetes - Type 2 diabetes - Gestational diabetes Uncontrolled diabetes can cause nerve damage, kidney damage, blindness, and can be fatal

Diabetes – Type 1 Accounts for 10% of all cases Patients do not produce enough insulin Causes hyperglycemia (high blood glucose) Requires insulin injections May be an autoimmune disease Once known as juvenile-onset diabetes or insulin dependent diabetes mellitus (IDDM)

Diabetes – Type 2: Most diabetics have type 2 diabetes Progressive disease with biological changes occurring over time Body cells become resistant, or less responsive to insulin Hyperglycemia results when cells cannot take in the glucose from the blood Once known as non-insulin dependent diabetes mellitus (NIDDM)

- Cause is unclear but genetics, obesity, and physical inactivity play a large role - Treat with weight-loss diet, regular exercise, and, if necessary, medications - Healthy lifestyle choices may prevent or delay the onset of type 2 diabetes: - Balanced diet and regular exercise - Achieving and maintaining healthy body weight

Health effects of sugars Nutrient deficiencies

Health effects of sugars Dental caries Dental plaque

Accusations Against Sugars: - Sugar causes obesity: - Many high sugar foods are also high in fat, which can lead to overconsumption of kcals and thus obesity

- Sugar causes heart disease: – Sugar causes insulin production – Hyperinsulinemia has been linked to arterial damage and heart disease.

- Sugar causes misbehavior in children and criminal behavior in adults. - Sugar causes cravings and addictions: Sugars can raise serotonin levels and alter mood in some individuals.

Artificial Sweetener Facts: - Why artificial sweeteners? – unwanted calories in simple sugars – the connection of sucrose with tooth decay – sugar substitute for people with diabetes – sugar shortages

Alternatives to Sugar: Artificial sweeteners: - Non-nutritive (alternative) sweeteners - Provide little or no energy. Sugar replacers: - Nutritive sweeteners - Slow-absorbing sugar alcohols: 2 -3 kcal/gm.

Alternatives to Sugar: - Stevia

- Acceptable Daily Intake (ADI) - Artificial sweeteners and weight control

Saccharin: • Saccharin 300 times sweeter than sucrose • Saccharin taken off market when high doses caused cancer in lab animals • Saccharin was sole no-calorie sweetener available, its removal sparked public outcry • Saccharin returned by Congress mandate • Saccharin was found safe in 2000, no clear evidence that it causes cancer in humans

Aspartame: • Aspartame is 200 times sweeter than sucrose • Used in 4000 products worldwide, soft drinks, whipped toppings, jellies, cereals, puddings, medicines • Products carry a label warning people with phenylketonuria (PKU).

Is Aspartame Safe? • Safe level defined as 50 mg/kg body weight per day in U. S. and 40 mg/kg body weight per day in Canada • U. S. limit equals 20 aspartame-sweetened soft drinks or 55 desserts per day • Average intake in U. S. , Canada, Germany, and Finland from 2 to 10 mg per day, safely low • Claims of headaches, dizziness, or anxiety from small amounts not confirmed

Sucralose: • Non-caloric sweetener from sucrose, safe and 600 times sweeter than sucrose • Does not leave a bitter after taste • Is made from sugar has had three of it’s OH groups replaced by cholrine atoms • Used in hot and cold food products, soft drinks, baked goods, frosting, pudding, and chewing gum.