Carbohydrates

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Carbohydrates
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Carbohydrates

• One of the three macronutrients
• A primary energy source, especially for neurons
  (nerve cells)
• CH2O
• Grains, fruits and vegetables

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Question

• Name ONE other macronutrient tell me its energy
  content (kcal/gram)

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Where do Carbs originate?

• As glucose in plants!
• Glucose
• Most abundant carbohydrate
• Produced by plants ( other photosynthetic
  organisms) via photosynthesis
• Simple or complex

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Data
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• This is the general equation for
  photosynthesisthe process of capturing sunlight
  energy and converting it to chemical energy.
  Which of the following are the reactants of this
  reaction?
• C6H12O6 and O2.
• CO2 and H2O.

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Types of Carbohydrates

• Simple contain 1 or 2 monomers
• Monosaccharides contain 1
• Disaccharides contain 2
• Complex contain 100s to 1000s of monomers
• Starches, glycogen, fibers

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Monosaccharides

• Glucose usually occurs with other sugars
• Fructose fruit vegetable sugar
• Galactose Always occurs with glucose in foods

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Disaccharides

• Lactose Milk sugar (glucose galactose)
• Maltose Malt sugar (glucose glucose)
  by-product of digestion fermentation in our
  bodies substrate for fermentation in beer and
  liquor)
• Sucrose Naturally occurring fruit sugar

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Complex

• Starch Storage form of glucose in plants
• Glycogen Storage form of glucose in animals
• Muscle and liver
• Fiber Form structural support elements of plants

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What happens to Complex Carbohydrates?

• Starch
• Digest starch to glucose
• Convert it to usable energy, OR
• store it as glycogen

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Complex Carbohydrates

• Glycogen
• Stored in the liver muscles
• Not a source of dietary carbohydrate

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Complex Carbohydrates

• 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

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Digestion of Carbs

• Begins in the mouth
• Salivary amylase hydrolyzes starch to short
  polysaccharides maltose
• What kind of macromolecule is amylase?
• Mechanical digestion with teeth
• Stops in stomach
• HCl denatures amylase
• Resumes in SI
• Pancreatic amylase also digests carbs to maltose

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Question

• Name another digestive organ that directly adds
  secretions to the small intestine.
• Stomach
• Gall Bladder
• Liver
• a and b
• b and c

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Monosaccharide enter capillaries within the
intestinal villi.
In the liver, galactose fructose are converted
to glucose.
Monosaccharides travel to the liver via the
bloodstream.
Fig. 4-11, p. 110
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Transport Use

• ALL monosaccharides are converted to glucose by
  the liver
• Q Name one other monosaccharide.
• Glucose circulating in the blood is our primary
  energy source
• Excess glucose is converted to glycogen by the
  liver and skeletal muscles
• Q Is this an anabolic or catabolic process

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Storage of Glycogen
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Digestion of Carbohydrates

• We do not have the enzymes necessary to digest
  fiber
• Bacteria in large intestine can break down some
  fiber
• Produce fatty acids and gas
• Most fiber remains undigested and is eliminated
  with feces

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Question

• Where does digestion of Carbohydrates NOT occur?
• Mouth
• Stomach
• Small intestine
• Large intestine

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Regulation of Blood Glucose

• Amount of glucose (and therefore, access to quick
  energy) in the blood
• Pancreatic cells produce, store and secrete two
  hormones, insulin and glucagon, which control
  level of glucose in the blood

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Regulation of Blood Glucose Insulin

• After eating, pancreas releases
• Insulin
• Stimulates cells of the body to absorb glucose
  from the bloodstream
• Stimulates the liver to absorb glucose and
  convert it to glycogen

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Regulation of Blood Glucose Insulin
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Regulation of Blood Glucose Glucagon

• Glucagon
• Stimulates the breakdown (hydrolysis) of glycogen
  to glucose to make quick energy available to
  cells of the body
• Stimulates gluconeogenesis production of
  glucose from amino acids (AA)
• Where do these AA come from?

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Regulation of Blood Glucose Glucagon
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Food Blood Glucose

• Glycemic index A foods ability to raise blood
  glucose levels
• Foods with a low glycemic index
• Dont produce dramatic fluctuations in blood
  glucose
• May increase HDL/LDL ratio (good cholesterol)
• Are generally higher in fiber
• May reduce the risk of heart disease and colon
  cancer

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Glycemic indices
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The Role of Carbohydrates

• Energy
• 4 kcal/kg
• Red blood cells rely only on glucose for energy
  supply
• Glucose is especially important for energy during
  exercise

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The Role of Carbohydrates
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The Role of Carbohydrates

• Energy
• When we do not have sufficient energy in the form
  of carbs, we produce ketones as an alternate
  energy source
• Why not ketones?
• Excessive ketones increase blood acidity
• High blood acidity damages body tissues

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The Role of Carbohydrates

• Energy
• Insufficient carbohydrate intake forces the body
  to find an alternate source of glucose
• Proteins are used for gluconeogenesis the
  production of new glucose

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Role of Carbohydrates

• Fiber
• May reduce the risk of colon cancer
• May reduce the risk of heart disease
• May block or delay absorption of dietary
  cholesterol
• May enhance weight loss
• Occupies space so you feel full also absorbs
  water and expands
• Helps prevent GI diseases/disorders
  (hemorrhoids, constipation, diverticulosis)

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How Much Carbohydrate?

• Recommended Dietary Allowance (RDA) is 130
  grams/day just to supply the brain with glucose
• 45-65 of daily calorie intake should be in the
  form of carbohydrates

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Type of carb matters

• Most Americans eat too many simple sugars
• Most of these come from added sugars
• Added sugars sugars and syrups added to food
  during processing
• Common source is soda pop ( 10 tsp. sugar per 12
  oz. can)
• Average American consumes 40 gallons each year!

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Simple vs. Complex Carbs

• Diets high in simple sugars
• Contribute to dental problems such as cavities
  and gum disease
• Cavity causing bacteria thrive on simple sugars
• Are associated with increased levels of bad
  cholesterol and decreased levels of good
  cholesterol
• These changes are known to cause heart disease

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Simple vs. Complex Carbs

• Complex carbs come associated with fiber
• Adequate Intake (AI) of fiber 14 grams for
  every 1,000 kcal in the diet
• Most Americans eat only 1/2 the recommended
  amount of fiber
• Whole grain foods are a more healthful choice
  than foods with added sugar
• Come stocked with lots of fiber necessary
  vitamins and minerals

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Alternatives to sugar

• Nutritive sweeteners
• Contain 4 kcal energy per gram
• Sucrose, fructose, honey, brown sugar, sugar
  alcohols
• Non-nutritive (alternative) sweeteners
• Provide little or no energy

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Alternative Sweeteners

• Acceptable Daily Intakes (ADI) have been
  established for
• aspartame
• sucralose
• acesulfame-K
• No ADI has been set for saccharin but it has been
  removed from the list of cancer-causing agents.

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Alternative Sweeteners
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Health Disorders

• Three health disorders related to carbohydrate
  metabolism
• Diabetes
• Hypoglycemia
• Lactose intolerance

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Diabetes

• Diabetes
• Inability to regulate blood glucose levels
• Three types
• Type 1 diabetes
• Type 2 diabetes
• Gestational diabetes
• Untreated diabetes can cause nerve damage, kidney
  damage, blindness, and death

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Diabetes

• Type 1 diabetes
• Accounts for 10 of all cases
• Patients do not produce enough insulin
• Causes hyperglycemia high blood sugar (glucose)
• Requires insulin injections
• May be an autoimmune disease

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Diabetes

• Type 2 diabetes
• Most diabetics have Type 2 diabetes
• Body cells are insensitive or unresponsive to
  insulin
• Excess insulin is often produced
• Causes hyperglycemia because cells cannot remove
  glucose from the blood

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Diabetes

• Type 2 diabetes
• Causes include genetic predisposition, obesity,
  and physical inactivity
• Treated with diet, exercise, and possibly oral
  medications
• Healthy lifestyle choices may prevent or delay
  onset of type 2 diabetes

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Hypoglycemia

• Hypoglycemia
• Low blood sugar (glucose)
• Reactive hypoglycemia results when too much
  insulin is produced after a meal
• Causes shakiness, sweating, anxiety
• Fasting hypoglycemia results when too much
  insulin is produced even when the patient has not
  eaten

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Lactose Intolerance

• Lactose intolerance
• Insufficient lactase production inability to
  digest lactose (milk sugar)
• Symptoms intestinal gas, bloating, nausea,
  cramping, diarrhea
• Alternate sources of calcium
• Tomato juice, seaweed, cabbage, squashes, beets