Carbohydrates

Carbohydrates or sugars are made primarily of carbon, hydrogen and oxygen atoms that cyclize into a ring. Carbohydrates can be “simple” or “complex” by the number of rings you hook together and the way in which they hook together. Though the rings can be slightly different, their common theme is
that of the ring structure as their final shape.

Similar to amino acids and fats, when you link the simple units (the sugars) together you get carbohydrates with different properties. You can link glucose units together to get a glucose polymer and in fact the body stores units of glucose linked together in the liver and muscle called “glycogen,” a term most people are familiar with.

You can also link different kinds of sugars to get different products. For instance,

if you combine glucose with fructose you get sucrose (table sugar). If you combine glucose with galactose you get lactose (milk sugar) and so on.


Link a bunch of sugars together and you get polysaccarides. Combine two sugars together like the previously mentioned lactose and you get a disaccharide. Of course, by themselves they are call monosaccharides.  Are you starting to see a repeating theme here?

Link a simple unit together with other units and you get a product the body can do all sorts of things with.  Linking units together gives you a product (fats, carbs, and proteins) and breaking down the products into units (ultimately) gives you energy.

So simple yet so complex.


You will notice I have not mention the “essential carbohydrates” because there is no such thing!  Though the body runs best on an intake of some carbs in the diet, the body can make its own carbohydrates from protein and other non-carbohydrate substrates as mentioned in the protein section.

Going in reverse from digestion, the body breaks down complex carbohydrates into simple carbohydrates and ultimately blood sugar (glucose) which can go onto be used for many different functions, such as the production of ATP (the body’s universal energy molecule). Depending on the carbohydrate and other factors, different carbohydrates will have different effects on blood sugar; in particular how fast blood sugar rises and falls (Gin, H., 2000).


The ability of a carbohydrate food to raise blood sugar quickly or slowly is called the glycemic index (GI). The GI was developed to track what foods effect blood sugar at different rates.

Interestingly, many carbohydrates that are considered “complex” have been found to raise blood sugar rapidly while a few “simple” carbohydrates don't have a dramatic effect on blood sugar.  GI rating of a food is based on how much blood glucose rises after consuming a carbohydrate food over a 2-hour period.  This is compared to a reference, which is glucose, a simple sugar.

Some GI scales now use white bread as the reference, but we will use the glucose scale in this chapter.  For instance, if you consume 50 grams of glucose (yuk), you will get dramatic elevation in blood sugar.  If you eat say 50 grams of carbs found in the form of oranges, your blood glucose would probably rise approximately
44% as high as compared to glucose.

So, the GI rating for oranges would be 44 on the glucose scale. Using white bread as the reference carbohydrate, it would be a different number. Capich?

Below is a partial list of the GI. There is no hard science to what is considered a low or high GI food per se, but a good guide is low is below 50, intermediate is between 50 and 75 and high GI foods are 75 and above on the scale.


brown rice pasta 92 linguine, durum 50 macaroni 46
macaroni & cheese 64

Pasta

spaghetti 40
spag. protein enriched. 28 vermicelli 35
vermicelli, rice 58
apple 38
apricot, canned 64 apricot, dried 30 apricot jam 55 banana 62
banana, unripe 30 cantaloupe 65 cherries 22
dates, dried 103 fruit cocktail 55 grapefruit 25 grapes 43

Fruits

kiwi 52 mango 55 orange 43 papaya 58 peach 42 pear 36 pineapple 66 plum 24 raisins 64
strawberries 32 strawberry jam 51 watermelon 72
Lentils 28
Soybeans 18
Baked beans (canned) 48 baby lima 32
chickpeas 33
kidney 27

Legumes

lentil 30 navy 38 pinto 42
split peas 32 soy 18
barley 22 brown rice 59 buckwheat 54 bulger 47 cornmeal 68
couscous 65

Grains

millet 75
rice, instant 91 rice, parboiled 47 rye 34
sweet corn 55
white rice 88


Dairy Foods

milk, full fat 27 milk, skim 32
ice cream, full fat 61 yogurt, low fat, fruit 33
white bread 70 wholemeal bread 69 pumpernickel 41 dark rye 76 sourdough 57
heavy mixed grain 30-45

Breads

All Bran Soy’ n Fibre  33
Raisin Bran 61
Froot Loops 69
Special K 69
Grape Nuts 75
Corn Pops 80
Cornflakes 84

Breakfast cereals

Rice Crispies 82
Cheerios 83
Puffed Wheat 80
All Bran 42
Porridge 46

Snack foods

Mars Bar 65
jelly beans 80
chocolate bar 49