3.3 Analyzing Your Carbs
You can determine the amount of fructose in food in the
following manner: search for a food like a 12-ounce can of Sprite at
NutritionData (http://nutritiondata.self.com/facts/beverages/3870/2).
This little exercise demonstrates how you can analyze food on your
own, among other things. Expand the NutritionData segment on the
carbohydrates in the soda-can contents, as shown in Figure 5.
This beverage contains about 33 grams, or 132 kcal, of sugar,
and guess what? They give you a free refill. The carbs include 19,151
mg, or about 19.2 grams, of fructose and 2,399 mg (2.4 grams) of
sucrose. The sucrose, however, is about 50 percent fructose, so you
can determine the total fructose quantity as follows: 19151 + (2399 /
2) = 20,350 mg, or 20.3 grams.
Before you completely condemn and wipe your hands of soda,
realize that a large cultivated apple also contains a notable quantity
of fructose.
Note
Apples are generally cultivated to have, among other
characteristics, a large size and a sweet taste compared with the
typical runty, tart apples growing in the wild. These
characteristics of cultivation are usually a good thing, providing
many people with fresh apples containing some antioxidants and
vitamin C throughout the year. They are not a good development on
the fructose front though, for reasons that are explained up ahead.
Besides, eating small wild apples (admittedly hard to find for
people who don’t live in the countryside) provides more
antioxidants. The antioxidants are in the skin, and you have to eat
more of the wild apples to get the same number of calories as you
would from the large store-bought apples.
A large apple contains 4,617 mg of sucrose and 13,157 mg of
fructose, according to NutritionData. Therefore, using our prior
calculation, we see that it contains a total of 13,157 + (4,617 / 2) =
15,465mg, or about 15.5 grams, of fructose. This is comparable to the
amount of fructose in a 12-ounce can of soda; however, the vitamin C
content in an apple may help counter the negative health effects of
excess fructose consumption
Note
I don’t want to dissuade people from eating apples
(I eat them, particularly when I can pluck them off a tree). But the
point is that a fructose is a fructose is a fructose, whether it
comes from a pretty apple laid out at the store or a can of
soda.
When you drink cow’s milk, part of what you consume is lactose,
which is a sugar that is made of one part glucose and one part
galactose.
Note
One cup of whole milk contains about 13 grams of
sugar, all of that in the form of 12,836 mg (or 12.8 grams) of
lactose. The whole milk has a macronutrient ratio of 30-49-21,
meaning that it is 49 percent fats. About 70 percent of its calories
come from fat and protein (see http://nutritiondata.self.com/facts/dairy-and-egg-products/69/2).
The lack of lactase, an enzyme that splits apart lactose into
its digestible constituents of glucose and galactose in the small
intestine, is commonly known as lactose intolerance. People with this
common form of indigestion don’t get along with regular milk, often
replacing it with soy milk.
Maltose is a disaccharide composed of two glucose
molecules bonded together. When barley is malted during the brewing of
beer, this process breaks down the barley starch into maltose. Yeast
will later use this sugar to fuel its lifecycle, producing alcohol and
carbon dioxide as byproducts.
3.4 Polysaccharides, or Starches
Polysaccharides are many sugars bonded together, sometimes
consisting of thousands of glucose monomers. In other words, they are
big complex Lego structures of glucose and other molecules. This is
why they are commonly referred to as complex
carbohydrates.
Note
A complex carb is ultimately a big interconnected
blob of sugar. When digested, it’s split apart into many glucose
monomers and released relatively quickly into the bloodstream, at
least in terms of its effect on your metabolism. Some complex carbs
or starches, like potatoes and white bread, have a higher glycemic
index—an old measure of the effect of foods on glucose and insulin
spikes in the blood—than table sugar. A complex carb like brown rice
does not contain any fructose, however, which is a good thing if
you’re looking for more carbs but no more fructose. Fiber-containing
complex carbs such as squash have an added advantage in that they
beneficially feed the microbiota in your colon after their
incomplete digestion in the small intestine.
Polysaccharides include the starches we eat, such as a banana or
a baked potato; glycogen, the animal starch we store in our muscles
and liver (as well as a few other less substantial stores); and
cellulose, which we cannot digest but often are implored to chew down
as fiber.
Note
Ruminant animals or herbivores like grazing cows,
sheep, goats, bison, moose, and elk have specially designed stomachs
that use microorganisms to ferment cellulose, whether it be grass or
sticks or twigs or weeds, into a digestible substance, which is
eventually absorbed by their systems as short-chain fatty acids. So,
while they are herbivores or plant eaters, they have a high-fat
diet!
We can digest starch because we have the enzyme amylase in our
saliva, as well as in the pancreatic juices that help break the starch
down in our small intestines. Amylase helps break up starch into
maltose, the double-glucose sugar, and maltase takes care of the rest
of the job so the glucose can be absorbed into the
bloodstream.
