The Carbohydrates

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The Carbohydrates
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NTRS 317 Chapter 4
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What we will cover today

• The chemistry of carbohydrates
• Simple carbohydrates
• Complex carbohydrates
• Digestion and absorption of carbohydrates
• Glucose in the body

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What we will cover today

• Health effects and recommended intakes of sugars
• Health effects and recommended intakes of starch
  and fiber
• Alternatives to sugar

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The Chemistry of Carbohydrates
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Definition

• Carbohydrates Compounds composed of carbon,
  oxygen and hydrogen arranged as monosaccharides,
  or multiples of monosaccharides (di- and
  polysaccharides). Most, but not all,
  carbohydrates have a ratio of one carbon molecule
  to one water molecule (CH2O)n.
• Carbo carbon (C)
• Hydrate with water (H2O)

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Carbohydrates (CH2O)n

• Simple carbohydrates
• Monosaccharides
• Disaccharides
• Complex carbohydrates
• Glycogen
• Starches
• Fibers

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Simple Carbohydrates

• Simple carbohydrates
• Monosaccharides
• Mono one
• Saccharide sugar
• Disaccharides
• Di two

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Simple Carbohydrates

• Monosaccharides
• C6H12O6
• Glucose (aka dextrose)
• Essential energy source-somewhat sweet
• Fructose
• Found in fruit-very sweet
• Galactose
• Rarely occurs as a single sugar-not sweet

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Glucose
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Fructose Galactose
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Condensation
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Hydrolysis
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Disaccharides

• Maltose
• Glucose glucose
• Produced during the germination of seeds and
  fermentation
• Sucrose
• Glucose fructose
• Refined from sugarcane and sugar beets
• Lactose
• Glucose galactose
• Found in milk and milk sugar

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Complex Carbohydrates

• Polysaccharides (poly many)
• Glycogen
• Stored in muscle and liver
• Fight or Flight
• Starches
• Plants way of storing glucose
• Found in grains, tubers (roots), and legumes
• Fibers
• Provide structure in plants
• Cant be broken down by human enzymes

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Bonds make the difference
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Complex Carbohydrates

• Fibers
• Cellulose
• Occurs in plant walls
• Found in fruits, vegetables and legumes
• Used in food processing
• Hemicelluloses
• Found in cereal grains
• Pectins
• Found in fruits and vegetables
• Used to control texture and consistency in foods

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Complex Carbohydrates

• Fibers
• Gums and mucilages
• Used as thickeners and stabilizers
• Lignin
• Provides strength to foods
• Found in carrots and strawberries
• Resistant starches
• Found in legumes, raw potatoes and unripe bananas
• Escape digestion

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Fiber

• Characteristics
• Soluble fibers (absorb water)
• Viscous-form a gel like consistency
• Fermentable in the colon
• Found in fruits and legumes

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Complex Carbohydrates

• Fibers
• Insoluble fibers (dont dissolve in water)
• Nonviscous
• Found in grains and vegetables
• Phytic acid
• Associated with fiber
• Can bind to minerals

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Digestion of Carbohydrates
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Digestion

• Mouth
• Salivary amylase
• Begins to hydrolyze starch
• Stomach
• Fibers delay gastric emptying and provides a
  sense of fullness (satiety)

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Digestion

• Small intestine
• Maltase, sucrase, lactase
• Pancreas
• Pancreatic amylase

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Fibers

• Large Intestine
• Fibers help to attract water and soften stools
• Are fermented by intestinal bacteria and provide
  short chain fatty acids that fuel immune cells

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Digestion

• Available carbohydrates vs. unavailable
  carbohydrates
• Sugars and starches are available because we can
  break them down and obtain their nutrients
• Fibers are unavailable because we cannot break
  down their bonds

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Digestion

• Large intestine
• Fermentation of viscous fibers
• Water, gas, short-chain fatty acid production

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Absorption
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Lactose Intolerance

• Symptoms
• Bloating, abdominal discomfort, and diarrhea
• Causes
• Lactase deficiency

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Lactose Intolerance

• Prevalence
• Highest in Southeast Asians
• Lowest in Northern Europeans
• Dietary changes
• Does not require the elimination of milk/milk
  products
• Acidophilus milk

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Glucose in the Body

• Energy
• Primary role
• Glycoproteins
• Alter shape and function of a protein
• Glycolipids
• Alter the way cells recognize each other when
  bound to lipids in memberane

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Carbohydrate Metabolism

• Storing glucose as glycogen
• Using glucose for energy

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Carbohydrate Metabolism

• Making glucose from protein
• Gluconeogenesis
• Protein-sparing action of carbohydrates
• Protein not broken down for energy when
  sufficient amount of carbohydrate available in
  body

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Carbohydrate Metabolism

• Making ketone bodies from fat fragments as an
  alternate fuel source during starvation
• Ketosis the accumulation of ketone bodies in
  blood
• Upsets acid-base balance in blood
• 50-100 g of carbohydrates needed to spare protein
  and prevent ketosis

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Carbohydrate Metabolism

• Converting glucose to fat
• When needs are met, excessive carbohydrates
  converted to fat
• Energetically expensive-much easier for body to
  convert fat to fat

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Constancy of Blood Glucose

• Regulating hormones
• Insulin released in response to glucose in blood
  by pancreas-transports glucose into cells
• Glucagon when blood glucose is low, glucagon
  signals the liver and muscle to breakdown
  glycogen
• Epinephrine helps in quickly releasing glucose
  from storage in times of stress-fight or flight
  response

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Constancy of Blood Glucose

• Diabetes
• Type 1 diabetes
• Failure of insulin production
• Type 2 diabetes
• Obesity

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Constancy of Blood Glucose

• Hypoglycemia
• Low blood sugar
• Rare in healthy people

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Constancy of Blood Glucose

• Glycemic response
• Glycemic index
• Note that this is based on single food items and
  is altered when foods are combined

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Sugars

• Added sugars
• Sucrose, invert sugar, corn syrups, high fructose
  corn syrup, etc.

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Sugars

• Health effects of sugars
• Nutrient deficiencies

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Sugars

• Health effects of sugars
• Dental caries
• Dental plaque

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Accusations Against Sugars

• Sugar causes obesity
• Sugar causes heart disease

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Accusations Against Sugars

• Sugar causes misbehavior in children and criminal
  behavior in adults
• Sugar causes cravings and addictions
• Not in the way drugs cause addictions
• serotonin

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Recommended Intakes of Sugars

• DRI
• No more than 25 of total daily energy intake
• 500 kcals per 2000 kcal diet/125 g/31 teaspoons

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Starch and Fiber

• Health effects
• Heart disease
• Diabetes
• GI health

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Starch and Fiber

• Health effects
• Cancer
• Weight management
• Harmful effects of excessive fiber intake

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Viscous Fibers

• Soluble and more fermentable
• Gums and mucilages
• Pectins
• Psyllium
• Some hemicelluloses

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Viscous Fibers

• Sources
• Whole-grains, fruits, legumes, seeds and husks,
  vegetables
• Extracted and used as food additives

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Viscous Fibers

• Lower blood cholesterol
• Slow glucose absorption
• Slow transit of food through upper GI tract

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Viscous Fibers

• Holds moisture in stools, softening them
• Yield small fat molecules that the colon can use
  for energy

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Viscous Fibers

• Lower risk of heart disease
• Lower risk of diabetes

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Viscous Fibers
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Nonviscous Fibers

• Insoluble and less fermentable
• Cellulose
• Lignins
• Psyllium
• Resistant starch
• Many hemicelluloses

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Nonviscous Fibers

• Sources
• Brown rice, fruits, legumes, seeds, vegetables,
  wheat bran, whole grains
• Extracted and used as food additives

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Nonviscous Fibers

• Increase fecal weight
• Speed fecal passage through colon
• Provide bulk and feelings of fullness

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Nonviscous Fibers

• Alleviate constipation
• Lower risks of diverticulosis, hemorrhoids,
  appendicitis
• May help with weight management

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Nonviscous Fibers
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Starch and Fiber

• RDA for carbohydrate
• 130 g/day to spare protein and prevent ketosis
• 45 - 65 total daily energy intake
• (225-325 g for a 2000 kcal diet)
• Daily Value 300 g/day

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Calculating your need

• of kcals needed x percentage recommended / 4
  kcals grams of carbohydrates
• 2000 kcals x .55 1100 kcals
• Divide 1100 kcals by 4 kcals per gram to equal
  275 grams

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Starch and Fiber

• Fiber
• Daily Value 25 g/day
• AI 14 g/1000 kcal/day

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Guidelines to Groceries

• More whole Grains

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Guidelines to Groceries

• Vegetables
• Fruits
• Meat alternatives
• legumes

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Guidelines to Groceries

• Milk and milk products
• Low fat or non fat varieties

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Alternatives to Sugar

• Artificial sweeteners vs. sugar replacers
  (nutritive sweeteners)

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Alternatives to Sugar

• Saccharine and cancer
• Aspartame and PKU

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Alternatives to Sugar

• Stevia
• Herbal alternative

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Alternatives to Sugar

• Acceptable Daily Intake (ADI)
• Artificial sweeteners and weight control

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