Chapter 4 - Carbohydrates: Plant-Derived Energy Nutrients
Adequate Intake (AI) for Fiber
25 g/day for women 38 g/day for men 14 g fiber for every 1,000 kcal/day
How Much Carbohydrate? AMDR:
45% to 65% of daily calories
Fasting Hypoglycemia
Pancreas produces too much insulin, even when someone has not eaten
Reactive Hypoglycemia
Pancreas secretes too much insulin after a high-carbohydrate meal
How Much Carbohydrate? RDA:
130 grams/day To supply adequate glucose to the brain
Diabetes
Inability to regulate blood glucose levels
Lactose Intolerant
Insufficient enzyme lactase to digest the lactose-containing foods Symptoms: gas, cramping, diarrhea
Glycemic Index
A foods' potential to raise blood glucose
The Liver & Carbohydrate Digestion
All monosaccharides re converted to glucose by the liver. Glucose circulating in the blood is our primary energy source. Excess glucose is stored as glycogen in the liver and the muscles
Type 1 Diabetes
Body does not produce enough insulin. Causes hyperglycemia (high blood glucose). Requires insulin injections. May be autoimmune disease
Soluble Fibers
Complex carbohydrate. Dissolve in water, viscous, and gel-forming. Fermentable, digested by intestinal bacteria. Associated with risk reduction of cardiovascular disease and type 2 diabetes. Examples: pectin, gum, mucilage Found in: citrus fruits, berries, oats, and beans
Fiber
Complex carbohydrate. Long polysaccharide chains. Dietary Fibers - non digestible parts of plants Functional Fibers - non digestible forms of carbohydrates extracted from plants and have known health benefits Total Health Benefits = Dietary Fiber + Functional Fiber
Insoluble Fibers
Complex carbohydrate. Not water-soluble, non viscous. Cannot be fermented by bacteria in the colon. Promote regular bowel movements, alleviate constipation, and reduce diverticulosis Examples: lignins, cellulose, hemicellulose Good sources: whole grains, seeds, legumes, fruits, and vegetables
Starch
Complex carbohydrate. Plants store carbohydrates as this. Amylose - straight chain of glucose Amylopectin - branched chain of glucose Resistant Starch (fiber) - glucose molecules linked by beta bonds are largely indigestible Sources: graines, legumes, fruits, and vegetables
Glycogen
Complex carbohydrate. Storage of glucose for animals (humans). Not found in food and therefore not a source of a dietary carbohydrate. Stored in liver and muscles
Polysaccharides
Consists of HUNDREDS TO THOUSANDS of glucose molecules. Starch, glycogen, and fibers
Oligosaccharides
Contain 3 TO 10 monosaccharides
Monosaccharides
Contain ONE molecule. Glucose, fructose, and galactose
Disaccharides
Contain TWO molecules. Lactose, Maltose, and Sucrose
Simple Carbohydrates
Contain one or two molecules. Commonly referred to as sugars
Glycemic Load
Determines effect of a food on a person's glucose response. Grams of carbohydrates are multiplied by the glycemic index
Carbohydrate Digestion
Digestion that occurs in the small intestine, NOT the stomach
Digesting Fiber
Do not have enzymes to digest fiber. Bacteria in Large Intestine can break down some fiber. Most fiber remains undigested and is excreted
Monosaccharides in Digestion
Enzymes digest disaccharides to monosaccharides: Maltase, Sucrase, Lactase. These monosaccharides are absorbed into the cells lining the small intestine and enter bloodstream
Ketosis in the Role of Carbohydrates
Fats breakdown during fasting forms ketones. Excess ketones increase blood acidity and cause ketoacidosis. Sufficient energy from carbohydrates prevents ketone production as alternate energy source
What are Carbohydrates?
Important source of energy for all cells. Composed of Carbon, Hydrogen, and Oxygen. Good sources found in fruits, vegetables, and grains
Type 2 Diabetes
Insulin Sensitivity: cells become less responsive to insulin Metabolic Syndrome: a cluster of risk factors that increase risk for this type Once known as adult-onset diabetes Increasing in children and adolescents Causes: genetics, obesity, and physical inactivity Treatment: weight loss, healthy eating, regular exercise, medications
Simple Carbohydrates in Diets: Simple Sugars
Lead to tooth decay, may increase "bad cholesterol", decrease "good cholesterol", contribute to obesity
Hypoglycemia
Low blood glucose. Symptoms: shakiness, sweating, anxiety, weakness
Low Glycemic Index
Low to moderate fluctuations in blood glucose. Benefits: risk reduction for heart disease and colon cancer. Foods: beans, fresh vegetables, whole wheat
Blood Glucose
Must be closely regulated. Controlled by these hormones: Insulin Glucagon Epinephrine Norepinephrine Cortisol Growth Hormone
Fortified foods
Nutrients added that did not originally exist in the food (or existed in insignificant amounts)
Enrichment foods
Nutrients ar lost during processing and have been added back so the food meets a specified standard
Gluconeogenesis
Occurs when a diet is deficient in carbohydrate. The body will make its own glucose from protein. Amino acids from these proteins cannot be then used to perform any of their other functions
Non-Nutritve (alternative) Sweeteners
Provide little or no energy. Safe for adults, children, people with diabetes
Energy in the Role of Carbohydrates
Red blood cells use only glucose for energy. Both carbohydrates and fats supply energy for daily activities. Glucose is especially important for energy DURING exercise
Epinephrine and Norepinephrine
Secreted by adrenal glands and nerve endings when blood glucose is low. Increases glycogen breakdown in the liver releasing glucose into the blood. Responsible for "fight or fight" response
Glucagon
Secreted by alpha cells of the pancreas. Stimulates the liver to convert glycogen to glucose. Stimulates gluconeogenesis, the production of glucose from amino acids
Insulin
Secreted 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 and convert it to glycogen
Cortisol and Growth Hormone
Secreted by the adrenal glands to act on the liver, muscle, and adipose tissue. Cortisol: Increase gluconeogenesis, Decrease muscle Glucose use Growth Hormone: Decrease muscle glucose uptake, Increase fatty acid mobilization, Increase glucose output
Nutritive Sweeteners
Sucrose, fructose, honey, and brown sugar contain 4 kcal energy per gram Slow-absorbing sugar alcohols: 2-3 kcal/gram
High Glycemic Index
Sudden surge in blood glucose
Glucose
The most abundant carbohydrate. Produced by plants through Photosynthesis