Chapter 4

Question 1

What are the functions of carbohydrates in the body?

Answer 1

Carbohydrates have six major functions within the body: Providing energy and regulation of blood glucose Sparing the use of proteins for energy Breakdown of fatty acids and preventing ketosis Biological recognition processes Flavor and Sweeteners Dietary fiber

Question 2

What is the simplest unit of Carbohydrate and how they are made by plants?

Answer 2

Glucose The most abundant carbohydrate Produced by plants through photosynthesis Water, carbon dioxide, and energy from the sun are combined to produce glucose

Question 3

Define simple and complex carbohydrates.

Answer 3

Simple carbohydrates Contain one or two molecules Monosaccharides contain only one molecule Glucose, fructose, galactose, ribose Disaccharides contain two molecules Lactose, maltose, sucrose Complex carbohydrates Long chains of glucose molecules Hundreds to thousands of molecules long Also called polysaccharides Starch, glycogen, most fibers

Question 4

Identify the monosaccharides (there are 3), and disaccharides (there are 3), and what are the food sources of each?

Answer 4

Monosaccharides:

Glucose, Fructose, Galactose

Disaccharide:

Lactose=Glu+Gal

Maltose=Glu+Glu

Sucrose=Glu+Fru

Question 5

What are the polysaccharides? Give examples of the different types.

Answer 5

Starch-glucose storage in plants, found in grains, legumes, and tubers

Glycogen-storage form of glucose in animals, stored in the liver and muscles

Fiber-forms the support structures leaves, stems, and plants

Question 6

What is the storage form of carbohydrates in plants vs animals?

Answer 6

Animals:

Glycogen

Animals, including humans, store glucose as glycogen
 Stored in the liver and muscles
 Not found in food and therefore not a source of dietary carbohydrate

Plants:

Starch

Plants store glucose in the form of starch
 We digest (break down) starch to glucose
 Grains, legumes, and tubers are good sources of starch in our diet  Fiber

Dietary fiber is the non-digestible part of plants
     Grains, rice, seeds, legumes, fruits
 Functional fiber is carbohydrate extracted from plants and added to food
     Cellulose, guar gum, pectin, psyllium
 Total fiber = dietary + functional fiber

Question 7

Where are Carbohydrates stored in humans?

Answer 7

Stored in the liver and muscles

Question 8

What is the preferred fuel for most body functions?

Answer 8

Red blood cells rely only on glucose for their energy supply
Brain needs glucose to function properly
Both carbohydrates and fats supply energy for daily activities

Glucose is especially important for energy during exercise

Question 9

Describe digestion & absorption of carbohydrates: include each monosaccharide and the type of absorption.

Answer 9

Salivary amylase

Enzyme that begins carbohydrate digestion in the mouth
 Breaks carbohydrates down to maltose
 Disaccharides are not digested in the mouth

There is no digestion of carbohydrates in the stomach; stomach acid inactivates salivary amylase.
Most chemical digestion of carbohydrates occurs in the small intestine.

Pancreatic amylase

Enzyme produced in the pancreas and secreted into the small intestine
 Digests carbohydrates to maltose

Additional enzymes in the small intestine digest disaccharides to monosaccharides.

These enzymes include maltase (breaks down maltose), sucrase (breaks down sucrose), and lactase (breaks down lactose).

Monosaccharides are absorbed into the cells lining the small intestine and then enter the bloodstream.

Fructose and galactose are converted to glucose by the liver.
 Glucose circulating in the blood is our primary energy source.
 Excess glucose is converted to glycogen by the liver and muscles.
 Once the storage capacity of the liver and muscles is reached, excess glucose is stored as fat.

Glucose is stored as glycogen in both liver and muscle. The glycogen stored in the liver maintains blood glucose between meals; muscle glycogen provides immediate energy to the muscle during exercise.

Question 10

What happens to each monosaccharide after absorption?

Answer 10

x

Question 11

Define/understand the differences for the Acceptable Macronutrient Distribution Range for carbohydrates, the RDA for carbohydrate, the Adequate Intake for fiber, and the recommended intake of added sugars.

Answer 11

Recommended Dietary Allowance (RDA) is 130 grams/day just to supply the brain with glucose. This does not include the amount of carbohydrate needed to support daily activities.
45-65% of daily calorie intake should be in the form of carbohydrates.
Added Sugars

Added sugar intake should be 25% or less of total kcals

Diets high in simple sugars:

Can cause dental problems such as cavities and gum disease
Are associated with increased levels of low-density lipoproteins (LDL, sometimes referred to as “bad cholesterol”) and triglycerides
Are associated with decreased levels of high-density lipoproteins (HDL, sometimes referred to as “good cholesterol”)
May contribute to obesity.

The Adequate Intake (AI) of fiber is 14 grams for every 1,000 kcal in the diet, approximately 25 grams/day for women and 38 grams/day for men.

Most Americans eat only half the recommended amount of fiber.
Increasing fluid intake as you increase you fiber intake is important to prevent constipation.
Food sources of fiber include whole grains, vegetables, fruits, nuts, and legumes.

Question 12

Which hormone is released when your blood glucose levels fall too low?

Answer 12

Glucagon

Secreted by alpha cells of the pancreas
 Stimulates the breakdown of glycogen to glucose, which is then secreted to the bloodstream and transported to cells; raises blood glucose levels
 Stimulates gluconeogenesis – the production of new glucose from amino acids

Regulation of blood glucose by the hormone glucagon. When blood glucose levels are low, the pancreas secretes glucagon. Glucagon enters the cell, where it stimulates the breakdown of stored glycogen into glucose. This glucose is then released into the bloodstream.

Question 13

Which hormone is released after a meal?

Answer 13

Insulin

Secreted by beta cells of the pancreas
 Helps cells take in glucose from the blood; lowers blood glucose levels
 Stimulates the liver and muscles to take up glucose and convert it to glycogen

Question 14

Identify the energy source used when exercising at maximum intensity.

Answer 14

Glucose - not fat

Question 15

What are ketones and when does our body make excesses of these?

Answer 15

Ketones-substances produced during the breadown of fat when carbohydrate intake is insufficient to meet energy needs. Ketones provide and alternative energy source for the brain when glucose levels are low.

Question 16

What are the health benefits of complex carbohydrates? Include the benefits of fiber in your answer.

Answer 16

x

Question 17

Identify risks of a diet low in fiber and health benefits of adequate intake

Answer 17

Fiber helps us stay healthy

May reduce the risk of colon cancer: binds cancer-causing substances and speeds elimination from colon
 Helps prevent hemorrhoids, constipation, and other intestinal problems: keeps stool soft and moist, gives GI tract muscles “something to push on”
 Reduces risk for diverticulosis, a condition that occurs when bulging pockets form in the wall of the colon
 May reduce the risk of heart disease: delays or blocks absorption of dietary cholesterol
 May enhance weight loss: causes a feeling of fullness
 May lower risk of type 2 diabetes: slows the release of glucose into the blood; improves regulation of insulin and blood glucose

Question 18

Identify the most prevalent form of diabetes

Answer 18

Type 2 diabetes

Most people with diabetes have Type 2 diabetes
 Obesity is the most common trigger for a cascade of changes that eventually results in Type 2 diabetes
 Body cells are resistant or less responsive to insulin (known as insulin insensitivity or insulin resistance)
 Excess insulin is often produced to compensate for this resistance
 Eventually, excessive insulin production becomes insufficient to maintain normal blood glucose levels
 Hyperglycemia results because cells cannot take in the glucose from the blood
 Cause is unclear but genetics, obesity, and physical inactivity play a role
 Treated with diet, exercise, and possibly oral medications

Question 19

Describe lactose intolerance.

Answer 19

is the inability to digest lactose, a sugar found in milk and to a lesser extent milk-derived dairy products. It is not a disorder as such, but a genetically-determined characteristic.

Lactose intolerant individuals have insufficient levels of lactase, an enzyme that catalyzes hydrolysis of lactose into glucose and galactose, in their digestive system. In most cases this causes symptoms which may include abdominal bloating and cramps, flatulence, diarrhea, nausea, borborygmi (rumbling stomach), or vomiting[1] after consuming significant amounts of lactose. Some studies have produced evidence that milk consumption by lactose intolerant individuals may be a significant cause of inflammatory bowel disease.[2][3]

Question 20

Identify the potential health risks associated with diets high in simple sugars. 


Answer 20

Added sugar intake should be 25% or less of total kcals

Diets high in simple sugars:

Can cause dental problems such as cavities and gum disease
 Are associated with increased levels of low-density lipoproteins (LDL, sometimes referred to as “bad cholesterol”) and triglycerides
 Are associated with decreased levels of high-density lipoproteins (HDL, sometimes referred to as “good cholesterol”)
 May contribute to obesity.

Question 21

Describe type 1 and type 2 diabetes. 


Answer 21

Three types:

Type 1 diabetes
 Type 2 diabetes
 Gestational diabetes (discussed in Chapter 14)

Type 1 diabetes

Accounts for 10% of all cases
 Body cannot produce enough insulin which causes hyperglycemia – high blood sugar (glucose)
 Requires insulin injections
 Cause is unknown, but may be an autoimmune disease

Type 2 diabetes

Most people with diabetes have Type 2 diabetes
 Obesity is the most common trigger for a cascade of changes that eventually results in Type 2 diabetes
 Body cells are resistant or less responsive to insulin (known as insulin insensitivity or insulin resistance)
 Excess insulin is often produced to compensate for this resistance
 Eventually, excessive insulin production becomes insufficient to maintain normal blood glucose levels
 Hyperglycemia results because cells cannot take in the glucose from the blood
 Cause is unclear but genetics, obesity, and physical inactivity play a role
 Treated with diet, exercise, and possibly oral medications

Question 22

Define ketosis and describe the risks associated with a low carbohydrate diet.

Answer 22

Ketosis /kɨˈtoʊsɨs/ is a state of elevated levels of ketone bodies in the body.[1] It is almost always generalized throughout the body, with hyperketonemia, that is, an elevated level of ketone bodies in the blood. Ketone bodies are formed by ketogenesis when liver glycogen stores are depleted. The ketone bodies acetoacetate and β-hydroxybutyrate are used for energy.[2]

Question 23

Name the alternative sweeteners.

Answer 23

Aspartame: Equal and NutraSweet; composed of two amino acids (phenylalanine and aspartic acid). People with the genetic disorder phyenylketonuria (PKU) cannot break down phenylalanine. The build-up of phenylalanine, in a person with PKU, causes brain damage so these individuals should not consume aspartame.
Sucralose: Splenda
Acesulfame-K: Sunette and Sweet One
Saccharin: Sweet n’ Low

Question 24

If you would like to buy whole grain bread, what should you look for on the label?

Answer 24

Whole grain

Whole Wheat

Question 25

What is dietary fiber?

Answer 25

refers to nutrients in the diet that are not digested by gastrointestinal enzymes.

Question 26

Functional fiber?

Answer 26

consists of isolated, nondigestible carbohydrates that have beneficial physiologic effects in humans. Total fiber is the sum of dietary fiber and functional fiber.

Question 27

Soluble fiber?

Answer 27

fiber dissolves in water. It is readily fermented in the colon into gases and physiologically active byproducts, and can be prebiotic and/or viscous. Soluble fibers tend to slow the movement of food through the system.

Question 28

Insoluble fiber?

Answer 28

fiber does not dissolve in water. It can be metabolically inert and provide bulking or prebiotic, metabolically fermenting in the large intestine. Bulking fibers absorb water as they move through the digestive system, easing defecation.[1] Fermentable insoluble fibers mildly promote stool regularity, although not to the extent that bulking fibers do, but they can be readily fermented in the colon into gases and physiologically active byproducts. Insoluble fibers tend to accelerate the movement of food through the system.

Question 29

What is the glycemic index?

Answer 29

A measure of food’s ability to raise blood glucose levels
Type of carbohydrate, way food is prepared, and its fat and fiber content affect how quickly body absorbs it and, therefore, its glycemic index
Combination of foods eaten affect how body absorbs food, so glycemic index of total meal is more important than individual foods
Glycemic load = grams of carbohydrate in food X glycemic index of food
Foods with a low glycemic load:

    Cause low to moderate fluctuations in blood glucose

    Are better for people with diabetes

    Are generally higher in fiber

    May reduce the risk of heart disease, colon cancer, and prostate cancer
 Foods with a high glycemic load:
     Cause sudden large increases in blood glucose and insulin

Question 30

Where are carbohydrates digested?

Image

Answer 30

Question 31

What is glucogon?

Answer 31

Glucagon

Secreted by alpha cells of the pancreas
Stimulates the breakdown of glycogen to glucose, which is then secreted to the bloodstream and transported to cells; raises blood glucose levels
Stimulates gluconeogenesis – the production of new glucose from amino acids

Regulation of blood glucose by the hormone glucagon. When blood glucose levels are low, the pancreas secretes glucagon. Glucagon enters the cell, where it stimulates the breakdown of stored glycogen into glucose. This glucose is then released into the bloodstream.