Carbohydrates: The Preferred Body Fuel

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Chapter 5

• Carbohydrates The Preferred Body Fuel

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Carbohydrates

• Essential nutrient
• Bodys main source of energy
• Sugar, Starches, Fiber
• Nearly all sources are plant sources
• Carbon, hydrogen and oxygen bonded to form
  saccharides

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TYPES OF CARBOHYDRATES

• Monosaccharides, Disaccharides and
  Polysaccharides
• Monosaccharides composed of single sugar units
• - the smallest carbohydrate molecule

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MONOSACCHARIDES

• 1. Glucose
• - blood sugar
• - Circulates in the bloodstream
• - the bodys source of energy

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MONOSACCARIDES

• 2. Fructose
• - sweetest tasting of the sugars
• - occurs naturally in fruits and honey

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MONOSACCHARIDES

• 3. Galactose
• - doesnt occur alone
• - bonded to glucose to form lactose milk sugar

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DISACCHARIDES

• -Made up of two sugar units must be split during
  digestion to form monosaccharides
• 1. Sucrose sugar as additives (1
  glucose 1 fructose)
• Ex. Beet sugar, sugar cane, molasses, maple syrup

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DISACCHARIDES

• 2. Lactose milk sugar
• (1 glucose 1 galactose bonded together)
• 3. Maltose (2 glucose, bonded together)
• - formed during digestion of starch
• -found in some grains such as malt

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POLYSACCHARIDES

• - Carbohydrates made up of many sugar units that
  must be broken down during digestion starches
  and fiber

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POLYSACCHARIDES

• 1.Starches
• the storage form of energy in plants
• - many glucose molecules bonded together
• - grain products

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POLYSACCHARIDES

• 2. Dietary Fiber
• -tough fibrous cell walls of plants
• - found only in plant foods
• - enzymes cant digest fiber but bacteria in the
  digestive track can break down some fiber
• - little to no energy (calories) provided by
  fiber

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• SIMPLE CARBOHYDRATES
• - Mono and Disaccharides (sugars)
• COMPLEX CARBOHYDRATES
• - Polysaccharides due to complex molecular
  structure (starches and fiber)

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FUNCTIONS OF CARBS

• 1. Provide Energy preferred source because the
  body can use them most efficiently
• 2. Spare Proteins protein is used for energy
  when carbs are unavailable but used less
  efficiently proteins primary function is to
  build and maintain cells

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FUNCTIONS OF CARBS

• 3. Break Down Fats body cant completely break
  down fats if diet is too low in carbs -?ketone
  bodies ?blood may become too acidic ?ketosis
  (damages cells and organs, nausea, weakness)?
  coma and death

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FUNCTIONS OF CARBS

• 4. Provides Bulk in the Diet promotes normal
  digestion and elimination of wastes
• -feel full sooner
• -slower to leave the stomach so feel full longer
• -usually lower in calories

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FUNCTION OF CARBS

• Dietary Fiber
• - Soluble Fiber can dissolve in water and
  develops a gel-like consistency ex. Oat bran,
  legumes, apple and citrus pectin
• - Insoluble Fiber does not dissolve in water
  associated with reducing cancer risks ex. wheat
  bran, whole grain
• Functional Fiber taken from plants, developed
  in labs- added to processed foods to provide
  health benefits

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How Your Body Uses Carbs

• - Carbs must be converted to glucose for cells
  to use them as energy source
• - Polys and Dis are broken down into Monos
  which are small enough to move through the
  intestinal wall into the bloodstream

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Using Carbs

• Monos travel to the liver where fructose and
  galactose are converted into glucose

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Using Carbs

• Blood sugars rise? hormone called insulin is
  released to help lower glucose levels by burning
  glucose for energy
• Hormone chemicals produced in the body and
  released into the blood stream to regulate
  specific body processes

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Using Carbs

• If there is no immediate energy needs the glucose
  is stored as glycogen
• 2/3 of glycogen is stored in the muscles, 1/3
  stored in the liver
• -the liver can store limited amount excess is
  stored as fat
• -fat stores cannot be converted back to glucose