Chapter 5 - Carbohydrates
The chemical bonds between individual sugar units in fiver ________ digested by enzymes in the human GI tract
cannot be
Added Sugars
Any sugars added during food manufacturing, such as honey, syrups, and concentrated fruit and vegetable juices. Added sugars do not include sugars found naturally in foods
Most carbohydrates are composed of ______
Carbon, oxygen, and hydrogen
Condensation Reaction
Chemical reaction in which a bond is formed between 2 molecules by the elimination of a small molecule, such as water. The linking of 2 monosaccharides occurs in a condensation reaction
Which of the following actions help in the digestion of carbohydrates?
Chewing, Cooking
Disaccharide
Class of sugars, including lactose and sucrose, that are formed by the chemical bonding of 2 monosaccharides
Total Fiber
Combination of dietary fiber and functional fiber in a good; also called fiber
Sucrose
Common table sugar. Disaccharide composed of fructose bonded with glucose by an alpha bond
Oligosaccharides
Complex carbohydrates that contain 3 to 10 monosaccharides. The beta bonds in oligosaccharides cannot be broken down by our digestive enzymes, meaning they pass undigested into the large intestine where bacteria metabolize them, producing gas and other by-products
Metabolic Syndrome
Condition characterized by poor blood glucose regulation, hypertension, increased blood lipids, and abdominal obesity; usually accompanied by lack of physical activity; previously called Syndrome X.
Diverticulosis
Condition of having many diverticula in the large intestine; asymptomatic.
What may occur as a result of excessive straining during defecation?
Hemorrhoids, Diverticula
Hyperglycemia
High blood glucose, above 125 mg/100 ml (dl) of blood.
Insulin
Hormone produced by beta cells of the pancreas. Among other processes, insulin increases the synthesis of glycogen in the liver and the movement of glucose from the bloodstream into muscle and adipose cells
Diverticula
Pouches that protrude through the exterior wall of the large intestine. Can be caused by the high pressure of exertion, which may be caused by a diet lacking adequate fiber, causing one to exert excessive force during defecation
Carbohydrates Function
Primary fuel source for cells, especially the cells of the central nervous system and red blood cells. Muscles also rely on carbohydrates to fuel intense physical activity
Foods that are good sources of carbohydrate include peas, dried beans, and dairy. In these foods, the carbohydrate content is diluted with _____.
Protein and fat
Digestible Carbohydrates
Provide a primary source of energy as glucose, spare protein from use as an energy source, and prevent ketosis. Most of the digestible carbohydrates in our diet are broken down to glucose
Non-Nutritive Sweeteners
Provide no food energy. Includes tagatose, advantame, sucralose, stevia, monk fruit, aspartame, and more.
Glycemic Index (GI)
Ratio of the blood glucose response to a given food, compared with a standard (typically, glucose or white bread).
Chemical digestion of carbohydrate begins in the mouth through the action of
Salivary amylase
Lactose maldigestion that occurs from a specific cause, such as long-standing diarrhea, and results in a decline in lactase production is considered _____ lactose maldigestion
Secondary
Lactose maldigestion that occurs from a specific cause, such as long-standing diarrhea, and results in a decline in lactase production is considered ______ lactose maldigestion.
Secondary
Monosaccharides
Simple sugars, such as glucose, fructose, and galactose, that is not broken down further during digestion
Soluble fibers help to regulate blood glucose by ____
Slowing the absorption of glucose from the small intestine
Gums
Soluble fiber consisting of chains of galactose and other monosaccharides; characteristically found in exudates from plant stems
Mucilage
Soluble fiber consisting of chains of galactose and other monosaccharides; characteristically found in seaweed
Pectin
Soluble fiber containing chains of various monosaccharides; characteristically found between plant cell walls
Amylase
Starch-digesting enzyme from the salivary glands or pancreas. Amylase breaks down the starch into smaller polysaccharides (called dextrins) and disaccharides
Cellulose
Straight-chain polysaccharide of glucose molecules that is indigestible because of the presence of beta bonds; part of insoluble fiber
Sugar Alcohols
Sweeteners that are structurally related to sugars but provide less energy than monosaccharides and disaccharides because they are not well absorbed. Sugar alcohols are not easily metabolized by bacteria in the mouth and in large quantities, sugar alcohols can cause diarrhea.
Nutritive Sweeteners
Sweeteners that can be metabolized to yield energy. Includes, lactose, maltose, glucose, sucrose, and fructose
Glucose
The most abundant monosaccharide, contains 6 carbons. Also called dextrose. A primary source of energy in the body. Found in table sugar (sucrose) bound to fructose
In which part of the GI tract does a minor amount of carbohydrate digestion begin?
The mouth
Glycogen
The storage form of carbohydrate in humans and other animals; also contains many glucose units linked together with alpha bonds. The branched structure of glycogen allows it to be broken down quickly by enzymes in the body cells where it is stored. Liver and muscle cells are the major storage sites for glycogen
General Formula for Carbohydrates
(CH2O)n or Cn(H2O)n, where n represents the number of times the formula is repeated. For example, the chemical formula of glucose is C6H12O6, or (CH2O)6
The Dietary Guidelines for Americans recommend limiting added sugar to no more than _____ of total daily energy intake for those aged 2 and older.
10%
What percentage of Americans shows the signs of lactose maldigestion?
25%
How much energy does glucose provide per gram?
4 kcal
How many grams of carbohydrates is needed daily to prevent ketosis?
50-100 g/day
Galactose
6-carbon monosaccharide that forms a 6-membered ring with oxygen in the ring; an isomer of glucose. Consists of glucose joined to galactose by a beta bond
Approximately ______ of the world's population is lactose intolerant
75%
Recommended Intake of Carbohydrates
According to the RDA, adults need about 130 g/day of digestible carbohydrate to supply adequate glucose for the brain and central nervous system to prevent the partial replacement of glucose by ketone bodies as an energy source. The Food and Nutrition Board recommends 45-65% of total energy intake should be carbohydrates
Glycemic Load (GL)
Amount of carbohydrate in a food multiplied by the glycemic index of that carbohydrate. The result is then divided by 100.
Diabetic Ketosis
Develops when insulin production is inadequate or cells resist insulin action, thereby preventing glucose from entering body cells. Cells then rely on ketone bodies from the breakdown of fats for energy. The accumulation of these ketones in the blood results in a more acid pH, a condition called diabetic ketoacidosis, which is a very serious complication of untreated or poorly controlled diabetes
Maltose
Disaccharide made of 2 glucose molecules joined by an alpha bond
Hyperactivity ___ result from consuming a diet high in refined carbohydrates.
Does not
The primary function of carbohydrate in the diet is to provide
Energy
Lactase
Enzyme made by absorptive cells of the small intestine; digests lactose to glucose and galactose.
Maltase
Enzyme made by absorptive cells of the small intestine; digests maltose to 2 glucoses
Sucrase
Enzyme made by the absorptive cells of the small intestine; digests sucrose to glucose and galactose.
A diet excessive in ______ may decrease the absorption of essential minerals such as iron and zinc.
Fiber
Functional Fiber
Fiber added to foods that has been shown to provide health benefits
Dietary Fiber
Fiber in food
Soluble Fibers
Fibers that either dissolve or swell in water and are metabolized (fermented) by bacteria in the large intestine; include pectins, gums, mucilages; more formally called viscous fibers
Insoluble Fibers
Fibers that mostly do not dissolve in water and are not metabolized by bacteria in the large intestine. These include cellulose, some hemicellulose, and lignins; more formally called nonfermentable fibers
Gluconeogenesis
Generation (genesis) or new (neo) glucose from certain glucogenic amino acids
When blood glucose levels drop, the pancreas releases _____ to raise blood glucose levels:
Glucagon
Most digestible forms of carbohydrates are broken down to ________
Glucose
Lactose
Glucose bonded to galactose; found in milk and other dairy products
Carbohydrate Family
Includes sugar, starch, and fiber. Most forms are composed of carbon, hydrogen, and oxygen. Plants are the main source of carbohydrates - during photosynthesis, plants produce glucose by using carbon and oxygen from carbon dioxide in the air, hydrogen from water, and energy from the sun. Plants either store the glucose or transform it into starch, fiber, fat, or protein
Diverticulitis
Inflammation of the diverticula caused by acids by bacterial metabolism inside the diverticula
Lignin
Insoluble fiber made of a multi-ringed alcohol (noncarbohydrate) structure
Polysaccharides
Large carbohydrates containing from 10 to 1000 or more monosaccharide units; also known as complex carbohydrates. The polysaccharides include some that are digestible, such as starch, and some that are largely indigestible, such as fiber. Their digestibility is determined mainly by whether the glucose units are linked together by alpha or beta bonds
When a person does not consume enough dietary carbohydrates, the metabolism of fats is ____.
Less efficient
When a person does not consume enough dietary carbohydrates, the metabolism of fats is _______
Less efficient
Fasting Hypoglycemia
Low blood glucose that follows about a day of fasting.
Reactive Hypoglycemia
Low blood glucose that may follow a meal high in simple sugars, with corresponding symptoms of irritability, headache, nervousness, sweating, and confusion; also called postprandial hypoglycemia.
Hypoglycemia
Low blood glucose, below 50 mg/100 ml (dl) of blood.
Primary Lactose Intolerance
May occur in up to 75% of the world's population. Those who have Asian, African, or Latino/Hispanic backgrounds are more likely to experience lactose intolerance than Caucasians. Many are able to consume moderate amounts of lactose with little or no intestinal discomfort because bacteria in the large intestine break down the lactose
Fructose
Monosaccharide with 6 carbons that forms a 5-membered or 6-membered ring with oxygen in the ring; found in fruits and honey
Hemicellulose
Mostly insoluble fiber containing galactose, glucose, and other monosaccharides bonded together