Monosaccharides Examples

Monosaccharides are the simplest units of carbohydrates and the single form of sugar. Monosaccharides are the simplest carbohydrates and are often called single sugars. They are the building blocks of more complex carbohydrates such as disaccharides and polysaccharides. Physically, they are usually colorless, can dissolve in water, and have the appearance of a crystal-like substance.

Since monosaccharides are the simplest units of carbohydrates, then they are also made up of carbon, hydrogen, and oxygen atoms. Monosaccharides are true simple sugars since, as one sugar unit only, they exist in the form in which they can be directly absorbed into your body upon ingestion. Unlike the other carbohydrates, they don't require being broken down during digestion, so when you eat a food containing monosaccharides, these sugars quickly get into your bloodstream, increasing your blood sugar and providing immediate energy.

Monosaccharides are present in most foods in at least some amount, but are particularly high in foods such as ripe fruit, and honey. Monosaccharides are an important energy source, but when too much of these simple sugars are consumed at once it can cause a large increase in blood sugar, followed by an abrupt drop. The result is a jolt of energy quickly followed by a feeling of being tired, shaky, or run-down soon afterward. This type of fluctuation in blood sugar, if it occurs frequently, can lead to blood sugar dysregulation conditions such as hypoglycemia and symptoms of diabetes. Processed foods often add high amounts of monosaccharides such as fructose and glucose to promote a sweet taste.

1. Glucose

It is the most important carbohydrate fuel in human cells and is concentrated in the blood. Glucose is made during photosynthesis from water and carbon dioxide, using energy from sunlight. Glucose provides a source of energy for the human body and is the most important simple sugar used for human metabolism. The small size and solubility in water of glucose molecules allows them to pass through the cell membrane into the cell. Energy is released when the molecules are metabolized. This process is carried out in respiration. Molasses is also an example of glucose.

2. Fructose

It is a non-reducing sugar. Fructose reacts with glucose to make sucrose. Cherries are an example of fructose. Commercially, fructose is frequently derived from sugar cane, sugar beets, and corn. About 240,000 tons of crystalline fructose is produced annually. All forms of fructose, including fruits and juices, are commonly added to foods and drinks for the enhancement of taste, and for browning of some foods, such as baked goods. There are speculations that excessive fructose consumption is a cause of insulin resistance, obesity, elevated LDL cholesterol leading to possible type 2 diabetes and cardiovascular disease.

3. Galactose

Their molecules look very similar to glucose molecules. Galactose is a simple sugar found in a range of commonly eaten foods. It can be present in its free form or with other sugars. Most commonly it is known as a component of the milk sugar, lactose. Yogurt is an example of galactose. Galactose is a monosaccharide sugar that is less sweet that glucose and fructose.