Carbohydrates

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Types of Carbohydrates:

Known also as saccharides, carbohydrates are macronutrients. Approximately 2% of the body weight is carbohydrates. They should constitute about 50% – 55% of total daily calories intake.

Carbohydrates are classified into three groups: monosaccharides, oligosaccharides, and polysaccharides.

Monosaccharides contain only one subunit of sugar and they represent the basic units of all carbohydrates.

Oligosaccharides contain 2 – 10 monosaccharides, and their major group is disaccharides or double sugars. Monosaccharides and disaccharides are collectively called simple carbohydrates. Polysaccharides are composed of more than 10 monosaccharides.

Types of Carbohydrates:

Monosaccharides

Glucose
Fructose
Galactose

Disaccharides

Sucrose
Lactose
Maltose

Polysaccharides

plants:
Starch
Fiber
Animals:
Glycogen
Glucose:

Known also as dextrose, blood sugar, or grape sugar, glucose is the usual mechanism for transport of carbohydrates in the body. It can be naturally found in foods, especially grapes. Glucose can come from breakdown of disaccharides or starch. A small amount is made from amino acids, lactate, pyruvate and glycerol in the liver through a process called gluconeogenesis.
What happens to glucose after absorption?

  • Is carried in the blood as blood sugar to be used as an energy source for the cells. All cells and tissues in the body need insulin to consume glucose, except nervous tissue, red blood cells, kidney tubules, intestinal cells, and beta cells of the pancreas.
  • Forms glycogen through a process called glycogenesis, and then is stored in the liver and muscles.
  • Converts to fat to be stored for later use as energy.

Fructose:

Known also as fruit sugar, and levulose, fructose is found in fruits and honey. It is the sweetest sugar, and after absorbing into the blood stream, it converts into glucose in the liver.

Galactose:

Galactose cannot be found in nature. It comes from the breakdown of lactose (milk sugar) and is converted into glucose in the liver.

Sucrose:

Sucrose is a disaccharide made of one molecule of glucose and one molecule of fructose. It is the most common disaccharide in diet and can be found in sugar cane, beets, maple syrup, molasses, honey, and pineapple. It also called white sugar, brown sugar, table sugar, beet sugar, and cane sugar.

Maltose:

Maltose is a disaccharide composed of two units of glucose. It is found in beer, breakfast cereals, malted snacks, and germinating seeds such as barley.

Lactose:

It is a disaccharide made of one unit glucose and one unit galactose. Lactose is found only in milk (milk sugar). Among disaccharides, it is the least sweet one and is never found in plants. Lactose is broken down by the enzyme lactase into glucose and galactose.

Starch:

Starch is a polysaccharide and is the stored form of carbohydrates in plants. It is found in rice, bread, grains, corn, potatoes, arrowroot, buckwheat, millet, oats, rye, yams, noodle, pasta, cassava, quinoa, and legumes. The starch in plants is also called complex carbohydrates. There are two forms of starch: amylopectin, and amylose.

Amylopectin:
  • Is made of short and branched chains of glucose molecules.
  • Is the most common starch in foods.
  • Foods high in amylopectin digest and absorb rapidly.

 

Amylose:
  • Is made of long and linear chains of glucose molecules.
  • Is the least common starch.
  • Foods high in amylose digest slowly.

Grains

Grains Serving Size Carbohydrate (grams) Fiber (grams)

Amaranth

1 cup, uncooked
128
13
Barley
1 cup, cooked
44
6
Buckwheat
1 cup, uncooked
122
18
Bulgur
1 cup, cooked
35
8
Corn (maize)
1 ear, medium
17
2.5
Fonio
1 cup, cooked
41
2.3
Kamut
1 cup, cooked
52
7
Millet
1 cup, cooked
42
2
Oats
1 cup
104
16
Quinoa
1 cup, cooked
40
5
Rice, brown
1 cup, cooked
45
5
Rice, white
1 cup, cooked
45
1
Rice, wild
1 cup, cooked
35
3
Rye
1 cup
120
25
Semolina
1 cup
122
8
Sorghum
1 cup
144
12
Spelt
1 cup, cooked
50
8
Teff
1 cup, cooked
50
5
Triticale
1 cup, uncooked
140
22
Wheat
1 cup, uncooked
140
24

Grains – Related Foods

Grains Serving Size Carbohydrate (grams) Fiber (grams)
Bagel, regular
1
30
2
Bagel, whole wheat
1
30
4
Bread, oatmeal
1 slice
13
1
Bread, pita, white
1 slice
13
0.5
Bread, raisin
1 slice
16
1
Bread, rye
1 slice
15
3
Bread, wheat
1 slice
13
1
Bread, whole wheat
1 slice
13
3
Noodles
1 cup, cooked
37
2
Pasta
1 cup, cooked
37
2
Pasta, whole wheat
1 cup, cooked
38
4
Roll, French
1
19
1
Roll, hamburger bun
1
21
1
Roll, hotdog bun
1
21
1
Roll, pumpernickel
1
19
2
Tortilla
1
15
1
Waffle
1, 7” diameter
27
2
Complex Carbohydrates:

Without Gluten

Amaranth
Arrowroot
Buckwheat
Corn
Millet
Potatoes
Quinoa
Rice
Teff
Yams

With Gluten

Barley
Bulgur
Couscous
Kamut
Muesli
Oats
Rye
Semolina
Spelt
Triticale
Wheat
Glycogen:

Glycogen is the stored form of carbohydrates in humans and animals. It is a polysaccharide made of subunits of glucose through a process called “glycogenesis” in the liver. Glycogen is stored in the liver and muscles. An average person has about 350 grams of glycogen in the muscles and about 50 grams in the liver. The body has an upper limit for storing glycogen. It is 15 grams per kilogram of body weight, of which about 80% is stored in the muscles and 20% in the liver.

Contents of Carbohydrates in Fruits and Vegetables:

For the amounts of carbohydrates in fruits and vegetables, you may click on the following links:

Fiber and Glycemic Index (GI):

For detailed information about fiber and glycemic Index, you may click on the following links:

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