what are carbohydrates?

Carbohydrates are one of three macronutrients. They are the main energy source in the body and they are used first before protein and fat.

After I drill the health benefits of carbohydrates in your brain I’m going to follow up with the most frequently asked questions I get about carbs. By the end of this article, I hope to shift your thinking about this misunderstood macronutrient and empower you to know which carbs to eat and which to avoid.

The word “carbohydrate” comes from the Greek word sakharon, which means “sugar”.

SIMPLE
CARBOHYDRATES

all dgfdjhgfjhjhgkhk;lkjkj;lkj
lkj;ljlkj;lkj;k
lkj;kj;kj;lkj;k

COMPLEX CARBOHYDRATES

all dgfdjhgfjhjhgkhk;lkjkj;lkj
lkj;ljlkj;lkj;k
lkj;kj;kj;lkj;k

monosaccharides

glucose
fructose
galactose

Monosaccharides are carbohydrates that are one unit of sugar (mono = one, saccharide = sugar). They are also known as simple sugars.

Monosaccharides are the most basic unit of carbohydrates because they can’t be further broken down to a simpler compound. This is the prefer

They are considered simple carbohydrates. They are the most basic unit of carbohydrates because they can’t be further broken down into a simpler compound. There are three monosaccharides: glucose, fructose, and galactose.

disaccharides

sucrose
lactose
maltose

Monosaccharides are the building blocks of disaccharides. Disaccharides are made up of two sugar units linked together (di = two, saccharide, sugar).

maltose
maltose = glucose + glucose
maltose is a sugar found in some cereals and candies

lactose
lactose = glucose + galactose
lactose is a disaccharide found in milk

sucrose
sucrose = glucose + fructose
sucrose is a table sugar that is purified from cane or beet sugar

polysaccharides

starch
cellulose
glycogen

Starch is a major plant storage form of glucose. It occurs in two forms: alpha-amylose, in which the glucoses are linked together in straight chains, and amylopectin, in which the glucose chains are highly branched. Except for the branch points of amylopectin, the glucose monomers in starch are linked via alpha(1-4) glycosidic bonds, which, in the digestive tract of mammals, are hydrolyzed by amylases.

Starch is the principle carbohydrate found in plant seeds and tubers; important sources of starch include maize (corn), potato and rice. Starch exists in the form of granules, each of which consist of several million amylopectin molecules together with an even larger number of amylose molecules.

Cellulose

Glycogen

DIGESTION AND ASSIMILATION OF CARBS

DIGESTION OF CARBS

These are the breakdown products of more complex carbohydrates and can be efficiently absorbed across the wall of the digestive tube and transported into blood. These are the breakdown products of more complex carbohydrates and can be efficiently absorbed across the wall of the digestive tube and transported into blood.

Lactose, a sugar found in milk, is perhaps the most problematic of the disaccharides. You need a specific enzyme called lactase to chop the two sugars in lactose apart. Some adults lack the necessary enzyme and thus are unable to digest lactose completely. The remaining lactose ends up in the large intestine, where various bacteria are only too happy to eat it. These bacteria produce copious quantities of gas as a byproduct, potentially causing diarrhea or severe cramps. Adults without the lactase enzyme are said to have lactose intolerance.

Monosaccharides, however, are only rarely found in normal diets. Rather, they are derived by enzymatic digestion of more complex carbohydrates within the digestive tube.

starch and disaccharides such as lactose and sucrose. None of these molecules can be absorbed for the simple reason that they cannot cross cell membranes unaided and, unlike the situation for monosaccharides, there are no transporters to carry them across.

Polysaccharides and disaccharides must be digested to monosaccharides prior to absorption and the key players in these processes are the brush border hydrolases, which include maltase, lactase and sucrase. Dietary lactose and sucrose are “ready” for digestion by their respective brush border enzymes. Starch, as discussed previously, is first digested to maltose by amylase in pancreatic secretions and, in some species, saliva.

2018-07-30T22:17:26+00:00