Carbohydrates

1
Carbohydrates
2
The Chemists View of Carbohydrates

• Carbohydrates are made of carbon, hydrogen and
  oxygen atoms.
• These atoms form chemical bonds that follow the
  laws of nature.

3
(No Transcript)
4
Types of CARBOHYDRATE

• Simple
• Monosaccharide's
• Glucose
• Fructose
• Galactose
• Disaccharides (Monosac Glucose)
• Maltose
• Sucrose (Table sugar)
• Lactose (Milk sugar)

5
The Simple Carbohydrates

• Monosaccharrides are single sugars
• Glucose serves as the essential energy source,
  and is commonly known as blood sugar or dextrose.
  
• Fructose is the sweetest, occurs naturally in
  honey and fruits, and is added to many foods in
  the form of high-fructose corn syrup.
• Galactose rarely occurs naturally as a single
  sugar.

6
(No Transcript)
7
The Simple Carbohydrates

• Disaccharides are pairs of monosaccharides, one
  of which is always glucose
• Maltose glucose glucose
• Sucrose glucose fructose
• Lactose glucose galactose

8
The Simple Carbohydrates

• Disaccharides
• Maltose two glucose units. It is produced
  during the germination of seeds and fermentation.
• Sucrose is refined from sugarcane and sugar
  beets, tastes sweet, and is readily available.
  Called table sugar
• Lactose is found in milk and milk products.
  Called milk sugar

9
Your fired, Jack. Your lab results just came
back, and you tested positive for Coke
10
The Complex Carbohydrates

• Few (oligosaccharides) or many (polysaccharides)
  glucose units bound/linked together in straight
  or branched chains.

11
Types of CARBOHYDRATE

• Complex Polysaccharides
• Starch
• Fiber
• Glycogen

12
The Complex Carbohydrates

• Starches
• Storage form of glucose in plants
• Found in grains, tubers, and legumes
• Glycogen
• Storage form of glucose in the body
• Provides a rapid release of energy when needed

13

A glycogen molecule contains hundreds of glucose
units in highly branched chains. Each new
glycogen molecule needs a special protein for the
attachment of the first glucose (shown here in
red).
A starch molecule contains hundreds of glucose
molecules in either occasionally branched chains
(amylopectin) or unbranched chains (amylose).
Stepped Art
Fig. 4-8, p. 106
14
The Complex Carbohydrates

• Dietary fibers provide structure in plants, are
  very diverse, and cannot be broken down by human
  enzymes.
• Soluble fibers are viscous and can be digested by
  intestinal bacteria (this property is also known
  as fermentability). These fibers are found in
  fruits and vegetables, oats, barley, legumes.
• Insoluble fibers are nonviscous and are not
  digested by intestinal bacteria. These fibers are
  found in whole grains and vegetables.

15
(No Transcript)
16
(No Transcript)
17
Carbohydrates-Dietary Guidelines

• Choose fiber-rich fruits, vegetables, and whole
  grains often
• Choose and prepare foods and beverages with
  little added sugars or caloric sweeteners, such
  as amounts by the USDA Food Guide and DASH Eating
  Plan
• Reduce incidence of dental caries by practicing
  good oral hygiene and consuming sugar and
  starch-containing foods and beverages less
  frequently

18
(No Transcript)
19
(No Transcript)
20
Digestion and Absorption of Carbohydrates

• Carbohydrate Digestion
• In the mouth, the salivary enzyme amylase begins
  to hydrolyze starch into short polysaccharides
  and maltose.
• In the stomach, acid continues to hydrolyze
  starch while fiber delays gastric emptying and
  provides a feeling of fullness (satiety).

21
Digestion and Absorption of Carbohydrates

• Carbohydrate Digestion
• In the small intestine, pancreatic amylase among
  other enzymes (maltase, sucrase, and lactase)
  hydrolyzes starches to disaccharides and
  ultimately monosaccharides.
• In the large intestine, fibers remain and attract
  water, soften stools and ferment.

22
Digestion and Absorption of Carbohydrates

• Carbohydrate Absorption
• Primarily takes place in the small intestine
• Glucose and galactose are absorbed by active
  transport.
• Fructose is absorbed by facilitated diffusion.

23
Digestion and Absorption of Carbohydrates

• Lactose Intolerance
• Symptoms include bloating, abdominal discomfort,
  and diarrhea.
• Causes include lactase deficiency due to a
  natural decrease that occurs with aging or
  damaged intestinal villi.
• Prevalence
• Lowest in Scandinavians and northern Europeans
• Highest in Southeast Asians and native North
  Americans

24
Digestion and Absorption of Carbohydrates

• Lactose Intolerance - Dietary Changes
• Increase consumption of milk products gradually.
• Mix dairy with other foods.
• Spread dairy intake throughout the day.
• Use of acidophilus milk, yogurt, and kefir
  (fermented products)
• Use of enzymes
• Individualization of diets
• Must be careful that vitamin and mineral
  deficiencies do not develop

25
Glucose in the Body

• The Constancy of Blood Glucose
• Maintaining Glucose Homeostasis
• Low blood glucose may cause dizziness and
  weakness.
• High blood glucose may cause fatigue.
• Extreme fluctuations can be fatal.

26
Glucose in the Body

• A Preview of Carbohydrate Metabolism
• The body stores glucose as glycogen in liver and
  muscle cells.
• The body uses glucose for energy if glycogen
  stores are available.
• If glycogen stores are depleted, the body makes
  glucose from protein.
• Gluconeogenesis converting protein to glucose.
• Protein-sparing action is having adequate
  carbohydrate in the diet to prevent the breakdown
  of protein for energy.

27
Blood Glucose Regulation
High Blood Sugar
Dietary CHO

• Muscles
• Used as fuel
• To glycogen

Insulin
Pancreas
Glucagon
Liver
Liver

• Used as fuel
• To Glycogen
• To Fat

Low Blood Sugar

• Glycogenolysis
• Gluconeogenesis

28
(No Transcript)
29
Glucose in the Body

• A Preview of Carbohydrate Metabolism
• Making ketone bodies from fat fragments
• The accumulation of ketone bodies in the blood is
  called ketosis.
• Ketosis upsets the acid-base balance in the body.
• The body can use glucose to make body fat when
  carbohydrates are consumed excessively.

30
Glucose in the Body

• The Constancy of Blood Glucose
• The Regulating Hormones
• Insulin moves glucose into the cells and helps to
  lower blood sugar levels.
• Glucagon brings glucose out of liver storage and
  raises blood sugar levels.
• Epinephrine acts quickly to bring glucose out of
  liver storage during times of stress and
  stimulates gluconeogenesis.

31
Glucose in the Body

• The Constancy of Blood Glucose
• Balance glucose within the normal range by eating
  balanced meals regularly with adequate complex
  carbohydrates.
• Blood glucose can fall outside the normal range
  with hypoglycemia or HYPERGLYCEMIA (diabetes).

32
Glucose in the Body

• The Constancy of Blood Glucose
• Diabetes
• Type 1 diabetes is the less common type with no
  insulin produced by the body.
• Type 2 diabetes is the more common type where fat
  cells resist insulin.
• Prediabetes is blood glucose that is higher than
  normal but below the diagnosis of diabetes.
• Hypoglycemia is low blood glucose and can often
  be controlled by dietary changes.

33
Glucose in the Body

• The Constancy of Blood Glucose
• Glycemic response is how quickly the blood
  glucose rises and elicits an insulin response.
• Glycemic index classifies foods according to
  their potential for raising blood glucose.
• Glycemic load refers to a foods glycemic index
  and the amount of carbohydrate the food contains.
• The benefit of the glycemic index is
  controversial.

34
Glycemic Index

• is a ranking system for carbohydrates based on
  their immediate effect on blood glucose levels.
  It compares carbohydrates gram for gram in
  individual foods, providing a numerical,
  evidence-based index of postprandial (post-meal)
  glycemia.

35
The effect on blood glucose from a high versus
low glycemic index carbohydrate.
36
Glycemic Index of selected Foods
37
Glycemic Load

• The glycemic load (GL) is a ranking system for
  carbohydrate content in food portions based on
  their glycemic index (GI) and the portion size.
• The usefulness of glycemic load is based on the
  idea that a high glycemic index food consumed in
  small quantities would give the same effect as
  larger quantities of a low glycemic index food on
  blood sugar

38
(No Transcript)
39
(No Transcript)
40
Health Effects and Recommended Intakes of Sugars

• Sugar poses no major health problem except dental
  caries.
• Excessive intakes may displace nutrients and
  contribute to obesity.
• Consuming foods with added sugars should be
  limited.
• Naturally occurring sugars from fruits,
  vegetables and milk are acceptable sources.

41
Health Effects and Recommended Intakes of Sugars

• Health Effects of Sugars
• Foods with added sugars have sugars listed as a
  first ingredient.
• Nutrient deficiencies may develop from the intake
  of empty kcalories.
• Just because a substance is natural does not mean
  it is nutritious. (Example honey)
• Dental caries may be caused by bacteria residing
  in dental plaque and the length of time sugars
  have contact with the teeth.

42
Health Effects and Recommended Intakes of Sugars

• Controversies Surrounding Sugars
• Excessive sugar intake can contribute to the
  development of body fat.
• Sugar may be able to alter blood lipid levels and
  contribute to heart disease
• There is no scientific evidence that sugar causes
  misbehavior in children and criminal behavior in
  adults.
• There is a theory that sugar increases serotonin
  levels, which can lead to cravings and addictions.

43
Health Effects and Recommended Intakes of Sugars

• Recommended Intakes of Sugars
• The USDA Food Guide states that added sugars can
  be included in the diet as part of discretionary
  kcalories.
• Dietary Guidelines state to limit intake of foods
  and beverages that are high in added sugars.
• DRI suggest added sugars should contribute no
  more than 25 of a days total energy intake.

44
Health Effects and Recommended Intakes of Starch
and Fibers

• Health Effects of Starch and Fibers
• May be some protection from heart disease and
  stroke
• Soluble fibers bind with bile and thereby lower
  blood cholesterol levels.
• Fiber may also displace fat in the diet.
• Reduce the risk of type 2 diabetes by decreasing
  glucose absorption
• Enhance the health of the GI tract which can then
  block the absorption of unwanted particles
• May protect against colon cancer by removing
  potential cancer-causing agents from the body

45
Health Effects and Recommended Intakes of Starch
and Fibers

• Health Effects of Starch and Fibers
• Promote weight control because complex
  carbohydrates provide less fat and added sugar.
• Harmful effects of excessive fiber intake
• Displaces energy and nutrient-dense foods
• Abdominal discomfort and distention
• May interfere with nutrient absorption

46
Recommended Intakes of Starch and Fibers

• RDA for carbohydrate is 50-100 g per day, or
  45-65 of energy intake.
• Daily Value is 300 grams per day.
• Dietary Guidelines encourage a variety of whole
  grains, vegetables, fruits and legumes daily.
• Healthy People 2010 recommends six servings of
  grains and five servings of fruits and vegetables.

47
Health Effects and Recommended Intakes of Starch
and Fibers

• Recommended Intakes of Fiber
• FDA recommends 25 grams for a 2,000-kcalorie
  diet.
• DRI at 14 g per 1000 kcalorie intake (28 grams
  for a 2,000 kcalorie diet)
• American Dietetic Association recommends 20-35 g
  per day.
• World Health Organization suggests no more than
  40 g per day.

48
(No Transcript)
49
Recommended Intakes of Starch and Fibers

• From Guidelines to Groceries
• Grains encourage whole grains
• Vegetables starchy and nonstarchy vegetables
  differ in carbohydrate content
• Fruits vary in water, fiber and sugar content
• Milks and Milk Products contain carbohydrate
  cheese is low
• Meat and Meat Alternates meats are low but nuts
  and legumes have some carbohydrate
• Food labels list grams of carbohydrate, fiber and
  sugar starch grams can be calculated.

50
(No Transcript)
51
Center Meals around the Carbohydrate Foods

• Answers the question
• What am I supposed to eat?
• Provides the best source of energy.
• Provides a lot of most nutrients, (including
  fiber)
• Low in fat, and has the good type and contains
  no cholesterol.
• Most have protein, certainly enough.
• Are not fattening--fats are!

52
Alternatives to Sugar
53
Artificial Sweeteners

• Also called nonnutritive sweeteners
• Saccharin Sweet n low
• Used primarily in soft drinks and as a tabletop
  sweetener
• Rapidly excreted in the urine
• Does not accumulate in the body
• Has been removed from list of cancer-causing
  substances

54
Artificial Sweeteners

• Aspartame Equal
• General purpose sweetener
• Warning about phenylalanine for those with PKU
• Controversial finding that aspartame may have
  caused cancer in rats
• Excessive intake should be avoided by those with
  epilepsy

55
(No Transcript)
56
Artificial Sweeteners

• Acesulfame-K (acesulfame potassium) The sweet
  one
• Research confirms safety

57
Artificial Sweeteners

• Sucralose Splenda
• Made from sugar
• Passes through digestive tract
• Neotame
• Most recent on the market
• Very sweet
• Phenylalanine not an issue

58
(No Transcript)
59
Artificial Sweeteners

• Tagatose
• Used for foods and beverages
• Provides less kcalories than sugar
• High doses can cause flatulence and loose stools.
• Alitame and Cyclamate
• Pending FDA approval
• Approved in other countries

60
Artificial Sweeteners

• Acceptable Daily Intake (ADI) is the level of
  consumption, maintained every day and still safe
  by a wide margin.
• Moderation and variety are still recommended.
• Artificial Sweeteners and Weight Control
• Much research still being done
• Using artificial sweeteners will not
  automatically reduce energy intake.

61
Stevia An Herbal Alternative

• Lacks research
• Classified as a dietary supplement
• Not required to have testing and FDA approval

62
Sugar Replacers

• Also called nutritive sweeteners, sugar alcohols,
  and polyols
• Maltitol, mannitol, sorbitol, xylitol, isomalt,
  and lactitol
• Absorbed more slowly and metabolized differently
  in the body
• Low glycemic response
• Side effects include GI discomfort

63
(No Transcript)