Understanding Sugar

Word BankIt’s a new year and that means people are making resolutions. Sometimes those resolutions are about exercise or maybe eating less sugar. But what really is sugar? Is it a bad or good thing? How does our body digest it? What things contain sugar? How can I know how much sugar a food contains?

Sugar is our body’s main source of energy and found in many nutritious foods like fruits, vegetables and whole grains, but it’s also found in less nutritious foods like desserts and candy. As you will find out later, our brain needs sugar for energy, but eating too much sugar can lead to things as serious as obesity and diabetes. Let’s first learn what sugar is at its most basic level, a molecule.


Sugar is part of the family of carbohydrates. It is considered a simple carbohydrate, while fiber and starch are considered complex carbohydrates.  Sugars are considered “simple” because they are easier for our body to break down and therefore provide quick energy.TypesOfSugar  Sugars can be monosaccharides (mono=one, saccharide=sugar) which means they are just one molecule of sugar, so we’ll refer to them as single sugars. Or they can be disaccharides (di=two, saccharide= sugar) which means they are two single sugars joined together, so we’ll refer to them as double sugars.


The most common single sugars in food are glucose, fructose, and galactose. The really neat thing about them is that they are all the same parts (6 carbons, 12 hydrogens and 6 oxygens) arranged in different shapes.  Their different shapes give them different amounts of sweetness. SingleSugarFructose tastes the sweetest and is naturally in fruits and honey, but is also the common sweetener in soda and other processed foods. Glucose, the sugar we refer to when talking about blood sugar, is a medium sweetness and is our body’s necessary energy source. Finally, galactose tastes the least sweet of the single sugars and is present in very small amounts in some vegetables, fruits, nuts, whole grains and milk.


DblSugarDouble sugars are basically two single sugars holding hands. The most common double sugars we eat are maltose (glucose holding hands with another glucose), sucrose (glucose holding hands with fructose) and lactose (glucose holding hands with galactose). Maltose isn’t common in very many foods, but is found in barley and gives the “malty” flavor to some foods. Sucrose is table sugar (that glittery white stuff used in desserts), but is also naturally occurring in grains, vegetables and fruits. Lactose is the sugar in milk.



  • Sugars are just one of the two types of carbohydrates. The other are complex carbohydrates.
  • Sugars are the simplest carbs and are easily broken down by our body. This makes them very quick energy.
  • Single sugars are just one sugar molecule and include glucose, fructose, and galactose. Each of these sugars have different levels of sweetness. Fructose is the sweetest followed by glucose and then galactose.
  • Double sugars are pairs of single sugars. The most common double sugars we eat are sucrose, maltose and lactose. Sucrose is table sugar and lactose is the sugar in milk.



Rolfes, S.R., Pinna, K., Whitney, E. (2009). Understanding Normal and Clinical Nutrition.  Belmont, CA: Wadsworth Cengage Learning.

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