Chapter 4: Carbohydrates

Carbohydrate Body’s favorite source of energy Consists of Monosaccharides, Disaccharides, & Poly- saccharides Protein sparing. Prevents ketosis Carbon, Oxygen and Hydrogen

CHO in Food

Dietary Carbohydrate Requirement ►55% to 70% of total kcal intake should come from Carbohydrate. ►This is approximately 275 grams to 350g daily if you consume 2000 kcal per day. Less than 50 grams should be from added sugar (sucrose, HFCS).

Monosaccharides “Simple Sugars” Glucose: Is present in every disaccharide. Makes up polysaccharides exclusively. Blood sugar. All MS are converted to glucose in liver Fructose: Sweetest of MS. Honey, Fruit Galactose: Most always bound with glucose. Found in milk. Not very sweet.

Disaccharides “Sugars” Maltose (Gluc + Gluc) Fermentation Alcohol production Sucrose (Gluc + Fruc) Sugar Lactose (Galactose + Gluc) Milk products

Formation of Disaccharide Condensation creates water

How Disaccharides are split Hydrolysis uses water to separate monosaccharides from disaccharides.

High Sugar Diets Empty calories Soda replacing milk Calories adding to excess Dental caries exposure to teeth High glycemic index Blood glucose response of a given food Influence by various factors

Recommendation for Simple Sugar Intake No more than 10% of total kcal/day around 50 grams Reduce intake of fruit juices, fruit “drinks”, and soda. Avoid sweet, processed food including: Cakes, pastries, muffins, doughnuts. Check labels! Sugar is added to a wide range of food and beverages during processing

Complex Carbohydrates Complex Carbohydrates are called “Polysaccharides” There are 3 kinds: Starch Glycogen Dietary fiber

Starch Many monosaccharides bound together Storage form of carbohydrate in plants

Glycogen Storage form of CHO for animals and human Highly Branched. More sites for enzyme action Found in the liver and muscles

Dietary Fiber (Non-starch polysaccharides) Body cannot break the bonds Types: Insoluble (fermentable) Cellulose hemicellulose lignin Soluble (viscous) gums, mucilages pectin Resistant starches: beans, unripe bananas, raw potatoes.

Foods that Provide Fiber Insoluble Fiber Wheat bran Whole grain breads, cereals Vegetables Soluble Fiber Fruits Oats Legumes However, most foods contain a little of both

Soluble and Insoluble Fiber

Actions And Benefits of Dietary Fiber Softens stool and bulks stool Promotes peristalsis exercise for the intestines. Prevents Diverticulosis. Fermentation provides SCFA Delays glucose absorption Affects transit time of food in GI tract Insoluble accelerate transit Soluble slows transit Soluble fiber can lower blood cholesterol

Diverticula

Recommended Dietary Fiber Intake 20-35 gm of fiber/day (10-13 gm/1000 kcals) Children: age +5gm/day Ave. U.S. intake: ~16 gm/day Too much fiber (>80 gm/d) will: require extra intake of fluid bind to some minerals develop phytobezoars Will cause cramps, gas, diarrhea.

Phytate Anti-nutrient Found in foods high in fiber, soy, wheat, seeds, legumes Binds to ZN, CA, FE, MG, CU A problem when consuming too much fiber, especially when not use to it.

Blood Glucose Regulation Blood Glucose Regulated by: Insulin: Stimulates uptake of glucose into the cells. Facilitates storage of glycogen and the conversion of excess carbohydrates to fat Glucagon: Stimulates liver cells to break down glycogen for glucose or to produce glucose from protein and glycerol. This is called “gluconeogenesis”. Hypoglycemia Reactive hypoglycemia Occurs 2-4 hours after eating a meal Possibly due to release of epinephrine. Fasting hypoglycemia Can occur in healthy people. Insufficient glucagon. Hyperglycemia. Too much glucose in the blood stream. Indicative to diabetes.

You are a pediatric nurse at a private practice You are a pediatric nurse at a private practice. A long time patient of yours comes in for a physical. Although Leticia is a healthy and energetic adolescent, today she looks a little pale and fatigued. When you ask her how she is feeling Leticia states that she’s feeling a little shaky and light headed. She also states that she tends to feel this way almost every morning about 2 hours after breakfast, then the symptoms subside within an hour. Concerned with resolving her problem, your ask her what she usually has for breakfast. Leticia replies that she usually has a large plain bagel with jelly, and a glass of juice. Assume Leticia is telling the truth about what she ate, and that she does not have a biological disorder, what is the likely cause of her light-headedness? What advice would you give her?

Glycemic Index A measurement of glucose response to a particular type of food. The greater the glucose response, the higher the value. (White bread = 100) High glycemic foods create high insulin levels increases fat synthesis and storage Increases blood triglycerides Increases hunger Increases insulin resistance

Digestion of Carbohydrates

Digestion of Carbohydrate in the Mouth Saliva contains amylase Starch is broken down to shorter saccharides Taste the sweetness with prolong chewing Proceeds down the esophagus

Digestion of Carbohydrate in the Stomach The acidic environment stops the action of salivary amylase No further starch digestion occurs

In the Small Intestine Pancreatic amylase is released Intestinal cells release enzymes Maltose + maltase glucose + glucose Sucrose + sucrase glucose + fructose Lactose + lactase glucose + galactose Monosaccharides are absorbed

CHO Digestion

Portal Vein Transport absorbed monosaccarhides Delivers them to the liver Liver can: transform them into glucose release them back into the blood stream store as gylcogen (or fat)