Chapter 2: Carbohydrates

A carbohydrates is composed of

Carbon (C), hydrogen (H), and oxygen (O). I

Carbohydrates are classified according to the number of sugar (or saccharine) units that make up their structure:

Monosaccharides have one sugar unit, disaccharides have two sugar units, and polysaccharides have many sugar units.

The dietary reference intakes

Recommends that 46-60% of total kilocalories consumed come from carbohydrates, with a greater portion of that intake coming from complex carbohydrates.

Simple carbohydrates

Sugars with a simple structure of one or two single-sugar (saccharine) units; a monosaccharide is composed of one sugar unit, and a disaccharide is composed of two sugar units.

The unique use of nutrients provides the body with three essintial elements for life

1) energy to do its works; 2) building materials to maintain its form and functuons; 3) control agents to tegulate tese processes efficiently.

Glycogen

A complex carbohydrate found I animal tissue that is composed of many glucose units.

Glucose

The basic single sugar in human metabolism is glucose, which is the form of sugar circulating in the blood. It is primary fuel for cells. Glucose, a moderately sweet sugar, usually is not found as such in the diet, except in corn syrup or processed food items. The body supply of glucose mainly comes from the digestion of starch.

Body digests its basic fuel, carbohydrates, thereby releasing glucose.

The body then absorbs and, through blood circulation, carries this refined fuel to cells that need it. Glucose is burned in the specific and intricate equipment in these cell, and energy in the form of adenosine triphosphate is released through the process of cell metabolism.

Saccharide

The chemical name for sugar molecules; may occur as single molecules in monosaccharides ( glucose, fructose, galactose), two molecules in disaccharide ( sucrose, lactose, maltose), or multiple molecules in polysaccharide ( starch, dietary fiber, glycogen).

Photosynthesis

The process by which plants that contain chlorophyll are able to manufacture carbohydrates by combining carbon dioxide and water; sunlight is used as energy, and chlorophyll is a catalyst.

Lactose

The sugar in milk, which is formed in mammary glands. Its two single-sugar units are glucose and galactose. Lactose promotes the absorption of calcium and phosphorus, the presence of all three nutrients in milk is a fortunate circumstances. Lactose remains in the intestine longer than other sugars, and it encourages the growth of certain useful bacteria.

Monosaccharides

Which are the building blocks for all carbohydrates, require no digestion. Energy demands will determine if the monosaccharides are then used for immediate energy or stored as glycogen for later use.

The three single sugars in nutrition are

glucose, fructose, and galactose.

The human body can rapidly break down the carbohydrates ( sugar and starches)

And provide the major source of energy that is measured in calories.

Polysaccharide

Are complex carbohydrates that are composed of many single-sugar units. The important polysaccharides in nutrition include starch, glycogen, and a dietary fiber.

Disaccharide

Are simple double sugars that are composed of two single-sugar units together. The three disaccharides that are important in human nutrition are sucrose, lactose, and maltose.

Starches

Found in grains, legumes, and other vegetable and in a some fruits in minute amounts. Starches are more complex in structure than simple sugars, so they break down more slowly and supply energy over a longer period of time.

Legumes

In form of beans and peas; potatoes, rice, corn and bulgar; and other vegetable, especially of the root variety.

Grains

In form of cereal, pasta, crackers, bread and other baked goods.

Glucose

Is also called dextrose to denote the structure of the molecule (I.e., six carbons)

Sucrose

Is common table sugar. Its two single-sugar units are glucose and fructose.

Galactose

Is not usually found as a free monosaccharide in the diet; rather, it is a product of lactose (milk sugar) digestion.

Maltose

Is not usually found as such in the diet. It is derived within the body from the intermediate digestive breakdown of starch.

Fructose

Is primary found in fruits and in honey. Although honey sometimes thought of as a sugar substitute, it is a sugar itself; therefore, it cannot be considered a substitute. The amount of fructose found in fruits depends on the degree of ripeness. As a fruit ripens, some of its stored starch turns to sugar. Fructose is a sweetest of the simp,e sugars. High-fructose corn syrup, which are manufactured by changing the glucose into cornstarch into fructose, are heavily used in processed food products, canned and frozen fruits, and soft drinks.

Complex carbohydrates

Large complex molecules of carbohydrates composed of many sugar units (polysaccharide); the complex form of dietary carbohydrates are starch, which is digestible and provide a major e edgy source, dietary fiber, which is indigestible ( humans lack the necessary enzymes) and thus provides important bulk I the diet.