The Differences Between Glucose, Sucrose & Fructose
Glucose, fructose, and sucrose are three
types of sugar that contain an identical number of calories gram for
gram. However, their chemical structures greatly differ, as does the way
in which your body digests and metabolizes them. Keep reading to find
out exactly what makes these three sugars so different, and why these
differences actually matter.
What Is Glucose?
Glucose is a simple sugar, also known as a monosaccharide, and is your
body’s favorite carbohydrate-based source of energy. Monosaccharides are
composed of a single unit of sugar and that's why they absolutely
cannot be broken down into smaller compounds.
When it comes to food, glucose is most commonly bound to another
monosaccharide to form either disaccharides or polysaccharide starches.
Glucose is frequently added to processed foods in the form of dextrose,
which is actually extracted from cornstarch. When compared to fructose
and sucrose, glucose tastes the least sweet.
What Is Fructose?
Like glucose, fructose is a monosaccharide, too. It’s naturally present
in fruit, honey, agave and many kinds of root vegetables. What's more,
it’s also frequently added to processed foods in the form of
high-fructose corn syrup.
Fructose can be obtained from sugar cane, sugar beets or corn.
High-fructose corn syrup is made from cornstarch and contains a great
deal more fructose than glucose, in comparison with regular corn syrup.
Of the three sugars, fructose has the sweetest taste but the least
impact on your blood sugar.
What Is Sucrose?
Sucrose is the scientific name for common
table sugar and is a disaccharide that is made up of 50% glucose and 50%
fructose. It naturally occurs in many grains, fruits, and vegetables,
and is often added to certain processed foods too, such as ice cream,
candy, canned food, and breakfast cereals.
Table sugar and the sucrose found inside processed foods are often
extracted from sugar beets or sugar cane. Sucrose tastes sweeter than
glucose but is not as sweet as fructose.
Glucose Absorption and Use
Glucose is directly absorbed through your
small intestine's lining and into your bloodstream. It raises blood
sugar far more rapidly than other sugars, which stimulates the release
of insulin, a substance that is required for glucose to enter your
cells.
Once inside your cells, glucose is either changed into glycogen to be
stored or is used up immediately to create energy. Your body tightly
regulates your blood sugar levels. When they are too low, glycogen is
turned back into glucose and is released into your bloodstream. If
glucose is unavailable, your liver can make this type of sugar from
other sources.
Fructose Absorption and Use
Like glucose, fructose is absorbed directly into your blood via the
small intestine. It increases blood sugar levels more gradually than
glucose and does not seem to have an immediate impact on insulin levels,
however, it could have more long-term negative effects.
Your liver needs to convert fructose into glucose before your body uses
it as a source of energy. If you consume more fructose than your liver
is able to safely handle, any excess is turned into cholesterol and
triglycerides, which could end up causing certain negative health
effects such as obesity, fatty liver disease, and high cholesterol
levels.
Sucrose Absorption and Use
Since sucrose is a disaccharide, your body needs to break it down before
it can be used. Enzymes in your mouth start breaking down sucrose into
glucose and fructose before your stomach acid carries on this task.
However, the majority of sugar digestion happens in your small
intestine.
The enzyme sucrase divides sucrose into glucose and fructose before they
get absorbed by your bloodstream. When glucose is present, your body
ends up releasing more insulin and absorbs a higher degree of fructose,
causing more fat to be created. This is why both fructose and glucose
should ideally be eaten separately.
Which Is the Worst for Your Health?
Of the 3 sugars discussed above, fructose appears to be the most harmful
by a long shot for a number of reasons. For starters, the effects of
consuming too much fructose include type 2 diabetes, obesity, fatty
liver disease, metabolic syndrome, and insulin resistance.
One study found that from all known sugars, fructose is the one that can
put you at the highest risk for developing type 2 diabetes or obesity.
Another study found that people who drink fructose-sweetened beverages
put on belly fat almost twice as fast as those who drink
glucose-sweetened drinks instead.
What’s more, fructose also increases the hunger hormone ghrelin, which
could make you feel less full after eating. Since fructose is
metabolized in your liver like alcohol, research suggests that it could
be similarly addictive. A certain study found that it also activates
your brain's reward pathway, which could lead to increased sugar
cravings, and all of the negative effects that tend to follow them.