2/12/14
Exploring Carbs in Detail
Carbs are composed of Carbon, Hydrogen, & Oxygen; w/ a rafio of 1:2:1
Plants use Carbon Dioxide, Water, & Energy (from the sun) to produce the carbs we eat
Simple Sugars
Consist of Monosaccharides & Disaccharides
Monosaccharides (mono = one; saccharide = sugar)
Glucose – the principal monosaccharide in the body
Exists in the body in a ring form
It’s a 6 carbon monosaccharide, thus called a hexose (hex = 6; ose = CHO)
Glucose is CHO’s simplest form
Fructose – related to glucose; also a hexose
Metabolized to glucose in the liver
Metabolized to glucose glycogen
Metabolized to lacfic acid
Found in fruit, honey, & high fructose corn syrup
Galactose – the 3rd major monosaccharide
Has a very similar make-up to glucose
Usually not found free in nature in large quanfifies, but binds w/ glucose to form lactose
(found in dairy products)
Converted to glucose in the liver
Available fuel source
Disaccharides (formed when 2 monosaccharides combine)
Either have Alpha (digesfible) or Beta (indigesfible) bonds
Sucrose – basically table sugar
Composed of glucose + fructose linked via an Alpha Bond
Maltose – found in alcoholic beverages
Composed of 2 glucose molecules linked via an Alpha Bond
Lactose – the primary sugar in milk & milk products
Composed of glucose + galactose linked via a Beta Bond
Remember, once absorbed into the body, most CHO’s are ulfimately transformed into
glucose by the liver
Complex Carbohydrates
Oligosaccharides are CHO’s containing 3 to 10 sugar units
2 main types are Ranose & Stachyose (which are found in beans & legumes)
Are bonded in such a way that digesfive enzymes cannot break them down, thus producing
gas
BEANO (breakdown the compounds of oligosaccharides)
Polysaccharides (polymers containing many monosaccharides
Starches – storage form of glucose in PLANTS
Contains an Alpha Bond
2 main plant starches are Amylose (a straight chain polymer composed of glucose units)
& Amylopecfin (a highly branched polymer)
Cooking increases digesfibility of plant starches
Plant starches are found in potatoes, beans, breads, pasta, rice, etc…
Amylopecfin’s branches allow it to raise blood sugar levels more readily & allow it to
form a stable starch gel (enabling it to retain water)
Manufacturers use this starch gel in sauces & gravies for frozen foods
Modi@ed food starch is a process manufacturers use to bond the starch molecules
together, further increasing stability
EX: baby foods, salad dressings, or instant pudding
Glycogen – storage form of glucose in animals & humans
Structure is similar to amylopecfin (branched) & contains an Alpha Bond
In humans, it is found in the liver & muscles
Although, there is no glycogen found in the meat we eat, because it is used up during
slaughter & later in storage
2/14/14
Exploring Carb’s in Detail (confinued)
Polysaccharides (confinued)
Dietary Fiber – undigested plant food
Contains a Beta Bond
Insoluble fibers consist of cellulose, hemicellulose, & lignins (they consist of the
structural parts of the plant)
They are not fermented by the bacteria of the colon
Increase fecal bulk
Bran @ber, rye, rice, veggies & whole grains are great sources
Soluble fibers consist of gum, pecfin, & mucilage (they are found inside & around plant
cells)
They are fermented by the bacteria of the colon
They swell or dissolve in water
Can lower blood cholesterol levels
Citris fruit, veggies, oat products, psyllium seed & rice bran are all great sources
2/17/14
Carbohydrate Digestion
Food prep can be considered the start of CHO digesfion, because cooking oCen soCens tough
connecfive fissues in the @brous fissue in plants (like broccoli)
Starches, when heated swell soaking up water, making it easier to digest
In general, cooking makes CHO’s easier to chew, swallow, and break down during digesfion
CHO digesfion is the process of breaking down larger CHO’s into their smaller more absorbable
components
The enzymafic digesfion begins in the mouth in which Salivary Amylase breaks down the starch
Once the CHO’s reach the stomach, the pancreas releases Panceafic Amylase
This enzyme completes the digesfion process by breaking down most of the CHO’s to single
sugars (monosaccharides)
Also involved are enzymes coming from the wall of the intesfine, which will help break down
disaccharides into monosaccharides
Once the CHO fully reaches the stomach, no further digesfion occurs because of the acidic
environment
Carbohydrate Absorption
Monosaccharides are absorbed
Glucose & Galactose are absorbed through Active Absorption
Active Absorption requires a specific carrier & energy input in order for the substance to be
taken up by absorpfive cells in the small intesfine
In this case, the carrier is Sodium via a Sodium Pump
Energy is expended to pump the sodium back out of the cell
Fructose is absorbed through Facilitated Di usion
Facilitated Di usion requires a carrier, but no energy input is needed
Typically a slower process; thus large doses of fructose are not readily absorbed & could
cause diarrhea
Monosaccharides then enter the Portal Vein
The Portal Vein then transports the mono to the liver
Functions of Carbohydrates (Glucose)
Supplies Energy
Our body provides glucose for the energy needs of red blood cells (RBC’s), brain, & CNS
Protein Sparing
If we eat less than 50 to 100g of CHO’s per day, it forces the producfion of glucose via
glucosenogenesis which means the producfion of new glucose; A.A derived from the protein
provide the carbons to help create the glucose – thus causing protein sparing
*Americans typically do not have this problem
Prevent Ketosis
