Chapter 4: The Carbohydrates: Sugars, Starches, and Fibers

What does the dietary carbohydrate family include?

- Monosaccharides (single sugars)

- Disaccharides (pairs of sugars)

- Polysaccharides (chains of sugars)

Which carbohydrate(s) are sometimes called simple carbohydrates?

The sugars; Monosaccharides and disaccharides

Which carbohydrate(s) are sometimes called complex carbohydrates?

The starches and fibers; polysaccharides

What are the four main types of atoms found in nutrients? And how many bonds can each form?

1. Hydrogen, one

2. Oxygen, two

3. Nitrogen, three

4. Carbon, four

What are the 6 most important sugars in nutrition? Distinguish between the monosaccharides and the disaccharides

MONO

1. Glucose

2. Fructose

3. Galactose

DI

4. Maltose

5. Sucrose

6. Lactose

What is the general chemical formula for carbohydrates?

Cn H2n On and typically form a single ring

What is the chemical formula for monosaccharides?

C6 H12 O6 ... Sugars with 6 atoms of carbon

What accounts for the differences in sweetness of monosaccharides?

The chemical arrangement of their atoms

Which monosaccharide is commonly known as blood sugar?

Glucose

Which monosaccharide serves as an essential energy source for all the body's activities?

Glucose

Which monosaccharide is one of the two sugars found in ever disaccharide?

Glucose

Which monosaccharide are polysaccharides almost made exclusively from?

Glucose

Which polysaccharide is the chief food source of energy for all of the world's people?

Starch

Which is the sweetest of the sugars?

Fructose

Which monosaccharide occurs naturally in foods in the smallest amount?

Galactose

What are disaccharides?

Pairs of monosaccharides

Which chemical reaction links two monosaccharides together? (The reaction also releases water)

Condensation

Which chemical reaction takes place to break a disaccharide in two?

Hydrolysis

Which disaccharide consists of two glucose units?

Maltose

Which disaccharide consists of a glucose and fructose unit?

Sucrose

How is table sugar made?

Sucrose is refined from the juices of sugarcane and sugar beets, then granulated. extent depends on brown, white, powder

Which disaccharide is consists of a glucose and galactose unit?

Lactose

What are the three types of polysaccharides are important in nutrition?

1. Glycogen

2. Starches

3. Fibers

What is the role of glycogen in the body?

It's how the body stores glucose (sugar) in the liver and muscles for later use.

What is glycolysis?

Using glucose for energy

Is glycogen or starches an animal polysaccharide?

Glycogen. Starches are a plant based polysaccharide

What is the chemical structure of glycogen?

Hundreds of glucose units in HIGHLY BRANCHED CHAINS

What are starches?

Long, branched or unbranched chains of hundreds or thousands of glucose molecules linked together

What is the biggest food source of starch?

Grains

What is the branched form of starch called?

Amylopectin

What is the unbranched form of starch?

Amylose

How do starches differ from dietary fibers?

The bonds between their monosaccharides cannot be broken down by digestive enzymes in the body

What benefits from soluble fibers?

- Heart disease

- Diabetes

- Cancers

- Weight management

What benefits from insoluble fibers?

- GI health

What do viscous fibers do?

Form gels in the GI tract

What happens to fermentable fibers?

They are digested by bacteria in the GI tract

Which fibers are more viscous and fermentable?

Soluble fibers

What is the goal of digestion and absorption of sugars and starches?

To. break them down into smaller molecules that the body can absorb and use

What is the general purpose of fibers in digestion and absorption?

- Help regulate the passage of food through the GI tract

- Slow the absorption of glucose

Where does the salivary enzyme, Amylase, begin the work of breaking down carbohydrates?

The mouth. Ceases when bolus reaches the stomach.

What does Amylase do to starches in the mouth?

Breaks them down into smaller polysaccharides and maltose

What happens to fiber in the mouth?

The mechanical action of the mouth crushes and tears fiber and food and mixes it with saliva to moisten it for swallowing

What provides the feeling of fullness and satiety?

Fibers lingering in the stomach. They're not digested there and delay gastric emptying

What inactivates salivary enzymes, and does carb digestion, in the stomach?

Stomach acid / gastric juices

What enzymes breakdown carbohydrates in the small intestine?

Inside the small intestine...

1. Pancreatic Amylase

On the outer membranes of intestinal cells...

2. Maltase

3. Sucrase

4. Lactase

How long does it take for all the sugars and most of the starches to be digested?

Within 1 to 4 hours after a meal

Which carbohydrates move onto the large intestine and what happens to them there?

Only non-digestible carbohydrates. They...

1. Attract water to soften stool

2. Fermented by bacteria into short-chain fatty acids

3. Binds substances such as bile, cholesterol, and some minerals, carrying them out of the body

Where are resistant starches commonly found?

- Whole or partially milled grains

- Legumes

- Just ripened bananas

- Chilled cooked potatoes

- Chilled cooked rice

- Chilled cooked pasta

What are FODMAPs?

Fermentable...

- Oligosaccharides

- Disaccharides

-Monosaccharides

And

- Polyols (sugar alcohols)

What foods are commonly restricted in a low-FODMAP diet?

- Wheat

- Milk Products

- Onions

- Legumes

- Sugar Alcohols

How do glucose and galactose enter the cells lining the small intestine?

Primarily through active transport BUT if you've had a heavy meal, can also be absorbed through facilitated transport like Fructose

Where are fructose and galactose metabolized?

They are turned into glucose in THE LIVER

What percentage of people in the world retain enough RETAIN enough lactase to digest and absorb lactose efficiently throughout adult life?

Only about 35%

What is the difference between lactose intolerance and lactase deficiency?

LI = condition that results from the inability to digest lactose... when more lactose is consumed than the available lactase can handle

LD = a lack of the enzyme required to digest lactose because of damage to villi which can be temporary or permanent

Which ethnic group is lactose intolerance lowest and highest among?

Lowest = Northern European

Highest = East Asian

What is the recommended approach for individuals that are lactose intolerant?

to MANAGE intake rather than eliminate dairy altogether.

What vitamins and minerals should people that are lactose intolerant be mindful of getting enough of?

- Vitamin D

- Potassium

- Calcium

What is the primary role of glucose in the body?

As an energy nutrient

What happens to blood glucose after a meal?

Levels rise so the liver cells link (condense) excess glucose molecules into long branching chains of GLYCOGEN for storage

What happens when blood glucose levels fall?

The liver cells break down glycogen into glucose and release them into the bloodstream

Where is glycogen stored?

Primarily in the liver (1/4th) and muscles. Small amounts in the brain.

What is the preferred energy source for brain cells?

Glucose

Where happens when people do not consume enough glucose yielding carbohydrates?

The body draws energy from fats and proteins, albeit less productively.

What is gluconeogenesis?

Production of glucose from non-carbohydrate sources such as proteins and fats

What is protein-sparring action of carbohydrates?

The action in providing energy so that proteins can be used for their intended other purposes

What metabolic pathway do fats take when there's an inadequate supply of carbohydrates?

Fat fragments combine with one another to form KETONE BODIES

What happens during ketosis?

An undesirably high concentration of ketone bodies in the blood and urine when the body produces more than it uses disturbing the body's acid-base balance

How many grams of carbs a day does the body need to prevent ketosis?

50 to 100 grams

What happens when glucose is abundant? (~Fats)

Fat is either conserved or created and sent to fatty tissues for storage.

What dietary factors most influence fluctuations in glucose homeostasis?

Intake of carbs (quality and quantity), proteins, and fibers

What two hormones primarily regulate blood glucose homeostasis?

1. Insulin

2. Glucagon

What signals the pancreas to secrete insulin into the blood?

High blood glucose levels

What does insulin stimulate?

1. Glucose uptake from blood into cells

2. Storage of glycogen in the liver and muscles

3. Conversion of excess glucose into fat for storage

What signals the pancreas to secrete glucagon into the blood?

Low blood glucose levels

What does glucagon stimulate?

1. Breakdown of glycogen from the liver

2. Release of glucose into the blood

What is another hormone that signals the liver to release glucose when a person experiences stress?

Epinephrine

What are two conditions that can occur when someone's blood glucose regulation fails?

1. Diabetes

2. Hypoglycemia

What happens to blood glucose if you're diabetic?

Blood glucose rises after a meal and remains above normal because insulin is either inadequate or ineffective

What's something you can do to help your body maintain balanced glucose levels?

Eat balanced meals at REGULAR INTERVALS

What is the difference between Type 1 and Type 2 diabetes?

Type 1 = Chronic, lifelong autoimmune disease (less common)

Type 2 = Chronic disease caused by prolonged high blood sugar / obesity (more common)

What is the blood glucose level indicates hypoglycemia?

70 mg/dl and below

What is the normal blood glucose level range?

70-99 mg/dL

What is a diabetic blood glucose level?

126 mg/dl and above

What % of carbs, proteins, and fats burn into glucose?

Carbs = 90 - 100%

Protein = 50%

Fats = 10%

What are the time intervals for glucose spikes from carbs, proteins, and fats?

Carbs = 15 min - 2 hours

Proteins = 2 - 4 hours

Fats = 8 - 10 hours

What is the leading source of added sugars in human consumption?

Beverages. Followed by intake from snacks and sweets.

What are some of the negative health effects of added sugars?

1. Obesity

2. Chronic diseases (Increase risk of heart disease, diabetes, inflammation, hypertension)

3. Dental caries

4. Nutrient deficiencies (by displacing food sources with greater nutrient density)

The Dietary Guidelines for Americans urge consumers to limit intake of added sugar to what?

10% of total kcal/day

What are some nutrient dense foods that contain some added sugars?

- Vanilla yogurt

- Whole-grain breakfast cereals

What are some factors in the prevalence of dental caries from foods?

- Stickiness ... because sugars linger longer

- Frequency of sugar intake

- Whether consumed while also eating nonsugary foods

What do some consumers turn to, with regards to sugar, to control weight gain, blood glucose, and dental caries?

Alternative sweeteners

What are the three kinds of alternative sweetners?

1. Artificial sweeteners (nonnutritive sweeteners)

2. Other high-intensity sweeteners

3. Sugar alcohols

What are sugar alcohols sometimes referred to as nutritive sweeteners?

Because they do provide kcalories, just fewer than sugars

What are the benefits and side effects of sugar alcohols?

Benefit = Do not contribute to dental caries

Side effects = Intestinal gas, abdominal discomfort, diarrhea

What are the health effects of starches and fibers with regards to heart disease?

- 40% decrease in risk of heart disease

- Reduced first stroke rate

BECAUSE

- Lowers blood pressure

- Reducing inflammation

- Lowering blood cholesterol

What are the health effects of starches and fibers with regards to diabetes?

Helps manage and prevent by...

- Slowing absorption of sugars

- Slowing breakdown of carbohydrates

- Delay transit through GI tract

- Reduced risk of developing gallstones and kidney stones

What are the health effects of starches and fibers with regards to weight management?

- High-fiber foods tend to be low in solid fats and added sugars

- Absorb water so increase feeling of fullness delaying hunger

What are the health benefits of starches and fibers with regards to GI health?

- Increases stool weight

- Ease passages (preventing constipation)

- Reduce transit time

- Relief from symptoms of IBS

- Help colon cancer prevention (by removing harmful agents)

- Lower risk of hemorrhoids

- Lower risk of diverticular disease

What are some harmful effects of excessive fiber intake?

- Insufficient energy or nutrients

- Abdominal discomfort, gas, diarrhea (especially low -> high intake diet change)

- GI obstruction

- Lower nutrient absorption (because of speeding transit of food)

What are the actions of viscous, soluble, more fermentable fibers in the body? (6)

1. Lower blood cholesterol by binding bile

2. Slow glucose absorption

3. Slow transit of food through UPPER GI tract

4. Hold moisture in stools, softening them

5. Yield small fat molecules after fermentation that colon can use for energy

6. Increase satiety