Chapter 2 Carbohydrates

Recommended daily intake of fiber for men and women aged 50 and over is

21 and 30 g/day

How many carbohydrates are recommended for a 2000 kcal/day diet?

225 to 325 g

Recommended daily intake of fiber for women and men aged 19 to 50 years old is

25 and 38 g/day

On average, how much glycogen can be stored in the skeletal muscle?

300-400 g, which is about 1% to 2% of the muscle mass weight

Carbohydrates provide energy. How many calories are in each gram of CHO?

4 calories

Cow's milk contains.... Human milk contains....

4.8% lactose 7% lactose

The Dietary Reference Intakes recommend how much of total kilocalories to be consumed from carbohydrates? (With a greater portion coming from complex carbohydrates)

45%-65%

Lactose tolerance affects ___________________ of adults worldwide, with a much higher prevalence in certain countries and ethnic groups.

65%-&5%

Normal blood glucose level

70-110

Sucrose

Common table sugar. It's two single-sugar units are glucose and fructose. Used in the form of granulated, powdered, brown sugar, and in molasses

Sources of monosaccharides

Corn syrup (commonly used in processed foods), fruits, honey, lactose (milk, milk products)

What ethnicities have higher rated of lactose intolerance? (compared to Americans with European descent)

African Americans, Asian Americans, Hispanic Americans, and Native Americans.

Fructose

Also called levulose or fruit sugars. Primarily found in fruits (from which it gets its name) and in honey.

How much glycogen do healthy, well-nourished adults store in the liver?

Approximately 100g, which is about 8% of the liver mass weight.

Enriched grains

Are refined grain products to which some (but not all) vitamins and minerals that were removed during the refining process - for example, riboflavin, niacin, thiamin, folate, and iron - have been added back to some extent.

Monosaccharides

Building blocks for all carbohydrates, require no digestion. Classified as simple carbohydrates; glucose (dextrose), fructose, galactose

How are high-fructose corn syrups manufactured?

By changing the glucose in cornstarch into fructose.

Molasses

By-product of sugar production

How does carbohydrates function as normal fat metabolism

CHO provide energy - if not available, then fat oxidation occurs, producing ketones.

Lactose promotes the absorption of

Calcium and phosphorus. The presence of all three nutrients in milk is advantageous for absorption.

What is a carbohydrate composed of?

Carbon (C), hydrogen (H), and Oxygen (O).

Lactose intolerance

Caused by insufficient lactase. S/S are bloating, abdominal cramps, and diarrhea after drinking milk or consuming a milk-based food such as processed cheese.

What only uses glucose as fuel?

Central nervous system, red blood cells, and brain use

Principal sources of carbohydrates are plant foods:

Cereal grains, vegetables, fruits, nuts, sugars

Cellulose

Chief component of cell walls in plants. Holds water. Remains undigested in the GI tract and provides bulk to a diet. Bulk helps move the food mass through the intestine. Stems, leaves of vegetables, coverings of seeds and grains (found in whole grains).

Glucose, a moderately sweet sugar, usually is not found as such in the diet, except in corn syrup or processed food items. Where does the body's supply of glucose mainly come from?

Digestion of starch

Which of the simple sugars (monosaccharides) is the sweetest?

Fructose

Stomach (peristalsis continues mechanical digestion):

Gastric secretions include hydrochloric acid, which inhibits the action of salivary amylase. Before the food completely mixes with the acidic stomach secretions, up to 20% to 30% of the starch may have been changed to maltose. Muscle action continues to mix the food mass and then moves the food tot he lower part of the stomach. The food becomes thick and creamy chyme, ready for its controlled emptying through the pyloric valve and into the duodenum.

What is the primary fuel for cells?

Glucose

Sources of polysaccharides

Grains and grain products (cereal, bread, crackers, baked goods), rice, corn, bulgur, legumes, potatoes and other vegetables, storage form of carbohydrates in animal tissue (not a dietary source)

Where are starches found?

Grains, legumes, and other vegetables and in some fruits in small amounts.

Sweeteners that contribute to total calorie intake (like sugar alcohols) are considered

Nutritive sweeteners

Sugar alcohols

Nutritive sweeteners that provide 2 or 3 kcal/g

Glucose + Galactose=

Lactose

Complex carbohydrates

Large complex molecules of carbohydrates composed of many sugar units (polysaccharides); the complex forms of dietary carbohydrates are starch and dietary fiber.

Polysaccharides

Large, complex compounds of many saccharide units in long chains; thus they are complex carbohydrates. Starch and glycogen

Broccoli stems, fruits with edible seeds, such as strawberries and flaxseeds

Lignin.

Glycogen in the liver is primarily used to

Maintain blood glucose level

Glucose + Glucose=

Maltose

Starch is made up entirely of glucose units. What happens during the breakdown of starch?

Many disaccharide units of maltose are released.

What is the only substantial animal source?

Milk

Break down of starch

More complex in structure than simple sugars, so they break down more slowly and supply energy over a longer period of time.

The digestion of carbohydrate foods, starches, and sugars begin in the

Mouth.

Can honey be a sugar substitute?

No, it is a sugar itself; therefore, it cannot be considered a substitute.

Do monosaccharides require further digestion?

No, monosaccharides do not require further digestion; thus they travel unchanged to the stomach and small intestines for absorption. Absorbed directly into the blood stream.

Sugar substitutes that do not have a notable caloric value

Non-nutritive sweeteners or alternative sweeteners

Galactose

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

Maltose

Not usually found as such in food form; it is derived within the body from the intermediate digestive breakdown of starch. Synthetically derived maltose is used in various processed foods.

Lignin

Only noncarbohydrate type of dietary fiber. Large compound that forms the woody parts in certain plants. Binds the cellulose fibers in plants, which gives added strength and stiffness to plant cell walls. Although it is an insoluble fiber, it also combines with bile acids and cholesterol in the human intestine to prevent their absorption.

Using sugar alcohol to replace sugar can lower risk of dental caries because

Oral bacteria cannot use the alcohol for fuel.

Disaccharides

Pairs of monosaccharides which must be changed to simple sugars by hydrolysis before absorption. Simple carbohydrates; sucrose, lactose, and maltose.

Small intestine:

Peristalsis continues to help with digestion in the small intestine by mixing and moving chyme along the organ. The chemical digestion of carbohydrate is completed in the small intestine by specific enzymes from both the pancreas and the intestines.

Diabetes 3 Ps

Polydipsia Polyphasia Polyuria

Simple carbohydrates

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

Islets of Langerhans in pancreas

secrete insulin. Impaired or absent insulin secretion results in high blood glucose level. Low blood glucose level of <70 mg/dL may occur with too much insulin or insufficient food intake.

Enzymes from the brush border of the intestinal tract contain three disaccharidases:

sucrase, lactase, and maltase. These specific enzymes act on their respective disaccharides to render the monosaccharides -- glucose, galactose, and fructose -- ready for absorption directly directly into the portal blood circulation.

Brush border

the cells that are located on the microvilli within the lining of the intestinal tracts; the microvilli are in hair-like projections that protrude from the mucosal cells that help to increase surface area for the digestion and absorption of nutrients.

enzymes

the proteins produced in the body that digest or change nutrients in specific chemical reactions without being changed themselves during the process; thus their action is that of a catalyst; digestive enzymes in GI secretions act on food substances to break them down into simpler compounds

Insulin and glucose

travel together, they have a bond together for the body to use the energy.

Beta cells

where insulin is at. At the beginning of Type 1, 80% of beta cells have been destroyed. During Type 2, beta cells are still present, they just are not working properly.

Chewing of food, which is called ____________________, breaks food into fine particles and mixes it with saliva.

mastication

Digestion in the mouth is accomplished by

muscle actions that mechanically break the food mass into smaller particles & chemical processes in which specific enzymes break down the nutrients into still smaller usable metabolic products.

Hemicellulose, pectins, gums, mucilages, and algal substances are

noncellulose polysaccharides

Excessive carb intake may lead to

obesity, dental caries, and digestive disturbances

In the cell wall of plants, phosphorus is stored in the form of phytic acid; this compound is undigested in humans because

of the lack of a necessary enzyme, Phytase. Phytic acid is a strong chelator of important minerals.

Soluble fiber

partially dissolves in water (gums, pectins, some hemicellulose, mucilages)

Carbohydrates regulate

proteins and fats

Average fiber intake for women and men in United States is

15.5 and 18.7 g/day... remarkably lower than recommended fiber intake and contribute to health problems.

The 2015-2020 Guidelines advise individuals to do the following with regard to carbohydrate-rich foods:

-Consume at least half of all grains as whole grain. Increase whole-grain intake by replacing refined grains with whole grains. -Increase vegetables and whole fruit intake. Eat a variety of vegetables from all subgroups -- dark-green, red, and orange vegetables, legumes (beans and peas), and starchy vegetables -Chose more nutrient-dense foods and less foods and beverages with added sugar. -Reduce the intake of calories from added sugars to less than 10% of total calories in the diet.

Scientists are confident that consuming a well-balanced diet high in whole grains, fruits, and vegetables providing ample fiber imparts health benefits, such as:

-Lowers blood cholesterol levels -Promotes normal bowel function and prevents constipation -Increases satiety, which helps the prevention of obesity -Protects against disorders of the small and large intestines -Slows glucose absorption, thereby reducing blood glucose spikes and insulin secretion.

Glycogen

A complex carbohydrate found in animal tissue that is composed of many glucose units linked together.

High-fructose corn syrup are inexpensive sweeteners, and contribute to increased sugar intake in the United States. The per-capital consumption increased from zero in 1967 to

A height of 19.7 teaspoons per day in 1999 and was most recently estimated to be down to 14.4 tsp per day.

Chelator

A ligand that binds to a metal to form a metal complex

Glucose

Basic single sugar in human metabolism, which is the form of sugar circulating in the blood.

What is used in products that are intended for individuals who cannot tolerate high blood sugar level? (For example, those with diabetes)

Sugar alcohols

Fiber

Humans lack the necessary enzymes to digest dietary fiber. These polysaccharides do not have direct energy value like other carbs. Found in grains, vegetables, and fruits. Recommended intake is 20-35 g/day. Lowers blood glucose levels; may prevent some colon cancers; and helps prevent constipation, hemorrhoids, and diverticular disease by softening stool.

High-fructose corn syrups are heavily used in

Processed food products, canned and frozen fruits, and soft drinks.

Carbohydrates

Provide practical energy (calorie) sources because of their availability, relatively low cost, and storage capacity. Structure vary from simple to complex to provide both quick and extended energy for the body.

Carbohydrates as reserve fuel supply:

Provided by glycogen; maintains normal blood glucose level

Unrefined grains

Retain the outer bran layers, the inner germ, and the endosperm and thus the nutrients found within. For example, dietary fiber, vitamins, and minerals.

Sucrose sources:

Sugar cane, sugar beets, maple syrup, candy, jams, and jellies

Lactose

Sugar in milk, which is formed in mammary glands. Glucose and galactose are the two single-sugar units. Only common sugar that's isn't found in plants. Less soluble and less sweet than sucrose. Remains in the intestine longer than other sugars, and it encourages the growth of certain useful bacteria.

Downside of using excessive amounts of sugar alcohols in food products is

Slowed digestion may result in osmotic diarrhea

Sugar alcohols are absorbed in

Small intestines, like glucose. Sugar alcohols are absorbed more slowly and do not increase the blood sugar level as rapidly as glucose.

Carbohydrates provide fiber, which forms

Soft, bulky stool

In ripe berries of the Sorbus aucuparia tree, naturally in small quantities in various berries, cherries, plums, and pears contains

Sorbitol

Sugar alcohols includes

Sorbitol, mannitol, and xylitol; which are the alcohol forms of sucrose, mannose, and xylose.

What is the most well-known sugar alcohol?

Sorbitol. Widely used as sucrose substitute in various foods, candies, chewing gum, and beverages.

Cereals, grains, potatoes, beans, and yams

Starch

What are the important polysaccharides in human nutrition?

Starch Glycogen Dietary fiber

What is the most significant polysaccharide in human nutrition?

Starch. It is composed of many coiled and branching chains in a treelike structure. Each of the multiple branching chains is composed of 24 to 30 units of glucose, which are gradually released during digestion to supply a steady source of energy over time.

Glucose + Fructose=

Sucrose

When people speak of sugar in their diets, which are they usually referring to?

Sucrose

Sources of disaccharides

Table sugar (sugar cane, sugar beets), milk, milk products, molasses, starch digestion, sweetener in food products

Saccharide

The chemical name for sugar molecules; may occur as single molecules in monosaccharides, two molecules in disaccharides, or multiple molecules in polysaccharides.

What does the amount of fructose in fruits depend on?

The degree of ripeness; as a fruit ripens, some of its stored starch turns to sugar.

What is lactase?

The enzyme required for the digestion of lactose.

Glycogen is stored in

The liver and muscles for use as needed. A half day's supply of carbohydrates is stored in this form of glycogen.

Photosynthesis

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

Fortified foods

Those that have nutrients added to them that would not naturally occur in that food regardless of how it was processed. (Calcium-fortified orange juice)

Why is glucose also called dextrose?

To denote the structure of the molecule (six carbons)

Sudden increases in fiber intake can result in

Uncomfortable gas, bloating, and constipation. Fiber should be gradually increased, along with water intake, to an appropriate amount for the individual.

Whole grain

Used for food products such as flours, breads, or cereals that are produced from unrefined grain.

What is the protein-sparing action of carbohydrates?

When an adequate supply (50-100g/day) of CHO are ingested, they allow the available protein to build and repair body tissue.

Hemicellulose

Whole grains

Constant carb intake and reserves are necessary for the proper functioning of the central nervous system. The brain has no stored supply of glucose; therefore, it is especially dependent on

a minute-to-minute supply of glucose from the blood. Sustained and profound shock from low blood sugar may cause brain damage and can result in coma or death.

Noncellulose polysaccharides

absorb water and swell to a larger bulk, thus slowing the emptying of the food mass from the stomach, binding bile acids in the intestine, and preventing spastic colon pressure by providing bulk for normal for normal muscle action. can also provide fermentation material on which colon bacteria can work.

Ph level in the stomach is

acidic

Circulating glucose

adipose tissue excreted in urine can damage kidneys, especially small vessels in other cells can also be damaged.

Ph level in the small intestine

alkaline

Portal

an entrance or gateway; for example, the portal blood circulation designates the entry of blood vessels from the intestines into the liver; it carries nutrients for liver metabolism, and it drains into the body's main systemic circulation to deliver metabolic products to body cells.

Function of Lignin:

antioxidant; bind bile acids, thus decreasing serum cholesterol level.

Insoluble fiber

does not readily dissolve in water (cellulose, hemicellulose, lignins)

Carbohydrates as basic fuel supply:

energy for physical activities and all work of body cells

When you see -ase at the end of a word, think

enzyme

Salivary amylase, also known as Ptyalin:

enzyme secreted by the parotid glands, which lie under each ear at the back of the jaw. acts on starch to begin its breakdown into dextrin and disaccharides.

Empty calories

excess added sugar in the diet. Examples are sweets, desserts, candy, soda.

fructose and galactose are carried to the liver and changed to

glucose

What is the vital emergency fuel for heart muscle?

glycogen

Insulin

is the hormone that controls glucose metabolism