NSC 310 Chapter 4 Objectives

Fiber

in the plant foods, the non-starch polysaccharides that are not digested by human digestive enzymes, although some are digested by GI tract bacteria

simple carbohydrates

monosaccharides and disaccharides (the sugars)

complex carbohydrates

polysaccharides (starches and fibers)

Summarize carbohydrate digestion and absorption

-In the digestion and absorption of carbohydrates, the body breaks down starches into the disaccharide maltose. Maltose and the other disaccharides (lactose and sucrose) from foods are broken down into monosaccharides, which are absorbed. The fibers help to regulate the passage of food through the GU system and slow the absorption of glucose, but they contribute little, if any, energy. -Lactose intolerance is a common condition that occurs when there is insufficient lactase to digest the disaccharide lactose found in milk and milk and milk products. Symptoms are limited to GI distress. Because treatment requires limiting milk and milk products from the diet, other sources of riboflavin, vitamin D, and calcium must be included.

Describe how added sugars can contribute to health problems

-Sugars increase the risk of dental caries; excessive intakes displace needed nutrients and fiber and contribute to obesity when energy intake exceeds needs. -A person deciding to limit daily sugar intake should recognize that not all sugars need to be restricted, just concentrated sweets, which are relatively empty of other nutrients and high in kcalories. Sugars that occur naturally in fruits, vegetables, and milk are acceptable. Alternative sweeteners may help limit kcalories and sugar intake.

Identify the monosaccharides, disaccharides, and polysaccharides common in nutrition by their chemical structures and major food sources.

-The carbohydrates are made of carbon (C), oxygen (O), and hydrogen (H). Each of these atoms can form a specified number of chemical bonds: carbon forms four, oxygen forms two, and hydrogen forms one. -The three monosaccharides (glucose,fructose,and galactose) all have the same chemical formula (C6H12O6), but their structures differ. The three disaccharides (maltose, sucrose, and lactose) are pairs of monosaccharides, each containing a glucose paired with one of the three monosaccharides. -The sugars derive primarily from plants, expect for lactose and its component galactose, which come from milk and milk products. -Two monosaccharides can be linked together by a condensation reaction to form a disaccharide and water. A disaccharide, in turn, can be broken into its two monosaccharides by a hydrolysis reaction using water. -The polysaccharides are chains of monosaccharides and include glycogen, starches, and dietary fibers. Both glycogen and starch are storage forms of glucose-glycogen in the body, and starch plants-and both yield energy for human use. The dietary fibers also contain glucose (and other monosaccharides), but their bonds cannot be broken by human digestive enzymes, so they yield little, if any, energy. (pg 101)

Explain how the body maintains its blood glucose concentration and what happens when blood glucose rises too high or falls too low

Dietary carbohydrates provide glucose that can be used by the cells for energy, stored by the liver and muscles as glycogen, or converted into fat if intakes exceed needs. -All of the body's cells depend on glucose; those of the central nervous system are especially dependent on it. -Without glucose, the body is forced to break down its protein tissues to make glucose and to alter energy metabolism to male ketone bodies from fats. -Blood glucose regulation depends primarily on two pancreatic hormones: insulin to move glucose from the blood into the cells when levels are high and glucagon to free glucose from glycogen stores and release it into the blood when levels are low.

Identify the health benefits of, and recommendations for, starches and fibers

clearly, a diet rich in starches and fibers supports efforts to control body weight and prevent heart disease, some cancers, diabetes, and GI disorders. For these reasons, recommendations urge people to eat plenty of whole grains, vegetables, legumes, and fruits- enough to provide 45-65 percent of the daily energy intake from carbohydrates.

Carbohydrate

compounds composed of carbon, oxygen, and hydrogen arranged as monosaccharides or multiples of monosaccharides. Most, but not all, carbohydrates have a ratio of one carbon molecule to one water molecule (CH2O)n

Describe the protein-sparing action of CHO

the carbohydrate provides glucose to meet the body's energy needs so protein can be put to other uses

Satiety

the feeling of fullness and satisfaction that occurs after a meal and inhibits eating until the next meal. Satiety determines how much time passes between meals.