The Difference Between Oligosaccharides & Polysaccharides

Carbohydrates are made of smaller building blocks called saccharides. There's an incredible number of combinations of different saccharides that make carbs different. There are fibrous carbs and sugary carbs, each composed of different combinations of saccharides. Polysaccharides are larger and more complex, while oligosaccharides are smaller and simpler.

Complex carbs, or polysaccharides, are considered the healthiest form of carbohydrates. (Image: fcafotodigital/E+/GettyImages)

Simple Sugars

The word carbohydrate refers to the molecules that make them. Carbon, hydrogen and oxygen are the three main molecules in carbohydrates, according to an article from the International Food Information Council Foundation. Some of these terms might trigger flashbacks to your high school chemistry class.

Saccharides are little combinations of carbon, hydrogen and oxygen. They combine to form bigger and more complex carbohydrates. The sugar that you sprinkle in your coffee is made of saccharides, as is the cellulose that forms the cell walls of plants.

The Simplest Form of Sugar

Monosaccharides are sugars that are made up of only one saccharide. They're the simplest form of carbohydrates. Glucose is the most well-known monosaccharide. Plants produce glucose, which is a simple sugar, to fuel themselves. When you eat a carb-heavy food like bread, your body breaks it down into glucose.

Fructose and galactose are simple sugars as well. Fructose is the sugar found in fruit, while galactose is found in lactose. Lactose is the sugar in dairy products like milk. Peas contain galactose in its independent form, according to an article from Libre Texts.

Life-Sustaining Monosaccharides

Glucose is life-sustaining, but it's not the most important monosaccharide in nature. Ribose and deoxyribose are monosaccharides that play a vital role in all living creatures. They provide the backbone for DNA and RNA, according to the Virtual Chem Book at Elmhurst College. While simple sugars aren't an essential part of your diet, they're incredibly important in nature.

Encyclopaedia Britannica explains that monosaccharides are classified by the number of carbon atoms in the molecule. Most of them contain five or six carbon atoms, which are known as pentoses and hexoses, respectively.

Complex Sugars

Monosaccharides combine to make up more complex carbs. Oligosaccharides are typically made up of less than 20 monosaccharides, whereas polysaccharides can be made of even more.

You've probably heard of some monosaccharides, and maybe even some polysaccharides, but oligosaccharides are less well known. They're in a gray area, because they're not as complex as most polysaccharides — but they're more complex than monosaccharides.

Oligosaccharides You Eat

Table sugar, also known as sucrose, is one of the most well-known oligosaccharides. Maltose is another, also called malt sugar. Some candies contain malt, and it's used as a thickener for milkshakes. Similar to table sugar, it looks like a white, crystalline powder. It tastes like caramel, which makes it perfect for baked goods and as an ingredient in some alcoholic drinks.

Lactose, which is the main sugar in milk, is another oligosaccharide. It's made from the combination of galactose and glucose, which are monosaccharides. Your digestive system makes an enzyme called lactase that allows you to digest lactose. However, not everyone makes the enzyme or you don't make enough, which means that your body can't digest lactose, you're considered lactose intolerant.

These sugars are quickly digested by your body, because they're fairly simple to break down. They're not as simple as glucose, a monosaccharide, but they're not as complex as starches and fiber. Oligosaccharides are in between but are still considered fast-digesting carbs. Diabetics should be careful when they eat these simple sugars, because they digest quickly and enter your bloodstream, causing your blood sugar levels to spike.

How Your Body Uses Oligosaccharides

Oligosaccharides do much more than satisfy your sweet tooth. They're an important part of communication between cells. They can bind to the surface of a cell and act as a gatekeeper of sorts. An article published by explains that oligosaccharides on the surface of an egg decide which sperm to let through for fertilization.

Man-Made Oligosaccharides

A 2015 study published in Food Production and Industry discusses man-made oligosaccharides. They're typically made from starch and sucrose, and can be used for a variety of purposes.

These synthesized oligosaccharides act as prebiotics in your body and serve as food for the friendly bacteria in your gut, which, in turn, may help prevent chronic health issues, such as inflammatory bowel disease, or alleviate symptoms caused by irritable bowel syndrome.

Polysaccharide Structure and Function

According to an article from Encyclopaedia Britannica, the structure of polysaccharides can be either linear or branched. When a polysaccharide is arranged in a branched formation, it's usually water soluble. These polysaccharides make excellent pastes.

Polysaccharides are the most complex carbohydrates. Glycogen is an example and is the form of glucose that your body stores. If you have extra glucose in your bloodstream, it gets pulled out into your muscles, liver and other organs and stored for later use.

Plant Starches

Starch is the plant equivalent of glycogen, because plants use it to store energy. The creation of a polysaccharide out of a simple sugar allows it to be stored until it's ready to be broken down again. Polysaccharides are more complex than oligosaccharides, which makes them better at storing energy.

Amylose and amylopectin are two of the most common starches. Amylose is smaller, linear and less complex than amylopectin. These starches make up a large portion of the carbs you eat in your diet. They're not as fast digesting as simple sugars, like sucrose and fructose, so they won't cause your blood sugar to spike as quickly.

Your body begins digesting them as you chew through the release of salivary amylase, which breaks down the starch into a simpler form. The pancreas also releases amylase to break down starch in your digestive tract, according to Colorado State University.

The Most Abundant Polysaccharide

Cellulose is one of the most important polysaccharides for plants. It contains more than 3,000 units of glucose, says an article from Britannica, making it very complex. Cellulose makes up most of the material surrounding plant cells, protecting them from damage. Humans can't digest it, but herbivores can because of their longer digestive tracts.

Humans use cellulose in products like plastic and paper. It's also used to make adhesives, as well as thickening agents for food. Cellulose can be made artificially or by plants by using glucose. The complexity of cellulose, like other polysaccharides, makes it much tougher and more durable. Oligosaccharides aren't as strong.

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