This article is an introduction to sugar, providing an overview of natural sugars (as opposed to artificial sugars, and sugar alcohols) on a fundamental level. It is my hope this article will build a better understanding in answering:
(1) Is one type of sugar really better than another?
(2) What is the role of sugar, and how is it processed in the body?
(3) Is sugar inherent of fruit different than added sugar?
The energy required to fuel the body is gained entirely through the food we choose to consume. Of the three macronutrients (fat, carbohydrates, and protein), carbohydrates are the preferred energy source for nerve cells, including those of the brain  .
Carbohydrates are classified as simple or complex, contingent upon their molecular composition. Simple carbohydrates, also known as sugars, contain one or two molecules (monosaccharides and disaccharides, respectively). Complex carbohydrates contain hundreds to thousands of molecules (polysaccharides).
We obtain carbohydrates primarily from plants as they make the most abundant form, glucose (via photosynthesis). Plants store glucose (a sugar), using it to support their own growth. When we eat plants, our body digests, absorbs, and utilizes the stored glucose. The focus of this article will be on simple carbohydrates, AKA sugars .
Structure: Composed of one or two molecules, further classified as monosaccharides and disaccharides, respectively. Molecules are composed of varying arrangements of 6 Carbon, 12 Hydrogen, 6 and Oxygen atoms. In disaccharides, these molecules (monosaccharides) are linked together via an alpha or a beta bond.
About: There are seven sugars in this classification. Four of these sugars are monosaccharides, and three sugars are disaccharides. Of the monosaccharides are glucose, fructose, galactose, and ribose. Of the disaccharides are lactose, maltose, and sucrose .
Monosaccharides: Glucose, fructose, galactose, and ribose.
The three most common monosaccharides in the American diet are glucose, fructose, and galactose. There is little ribose incorporated in one’s diet. Their subtle differences in structure are responsible for differences in their sweetness level. Structure differences are expressed in specific arrangements of 6 Carbon, 12 Hydrogen, and 6 Oxygen atoms.
Glucose: The most abundant monosaccharide found in our diet and bodies, it generally does not occur by itself in foods. Rather, it attaches to another sugar molecule to form disaccharides and complex carbohydrates. Glucose is the preferred source of energy for the brain, and is a vital source of energy for all cells.
Fructose: This sugar also goes by the names levulose, and fruit sugar. Fructose is the sweetest natural sugar, and the primary sugar molecule found in fruits.
Galactose: Galactose does not occur alone in foods. When combined with the monosaccharide, glucose, it forms the disaccharide, lactose.
Ribose: Ribose is contained in the genetic material of our cells, DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). It is produced in our bodies from the foods we eat, and very little is found in one’s diet .
Disaccharides: Lactose, maltose, and sucrose.
Lactose: This sugar also goes by the name, milk sugar. It is composed of one glucose and one galactose molecule.
Maltose: This sugar also goes by the name, malt sugar. It is composed of two molecules of glucose. It is typically bound together with other molecules, and does not generally occur by itself in foods.
Upon the body’s breakdown of such larger/bulky molecules, maltose results as a by-product – for example, maltose is formed during the breakdown of sugar (in grains and other foods) into alcohol.
Sucrose: This sugar also goes by the name, table sugar. It is composed of one glucose molecule, and one fructose molecule .
Why does any of the above matter?
The sweetness level/intensity, as well as its impact on the body is influenced by:
(1) The slight differences in the structure of a sugar molecule.
Molecules are composed of atoms. As it relates to sugar, the molecules are composed of varying combinations and arrangements of 6 Carbon, 12 Hydrogen, and 6 Oxygen atoms . The arrangement of these atoms influences the sweetness level. For example, fructose is sweeter than glucose, galactose, and ribose.
(2) The amount of a sugar molecule.
The amount of sugar in a food product is quantified in grams on a product’s Nutrition Facts label. On a deeper level, that sugar content is composed of varying amounts of the aforementioned sugar molecules. This can be quantified using HPLC (High Performance Liquid Chromatography) methods. Utilizing HPLC will divide a product's sugar content (in grams) into its precise composition of distinct sugar molecules (the amount of glucose, fructose, galactose, ribose, etc. present) .
For example, in 100g of pure cane sugar (sucrose), there is 100g of sugar. In that 100g, 50% (or 50g) is glucose, and 50% (or 50g) is fructose.
As mentioned, the subtle differences in structure make fructose sweeter than its fellow monosaccharides (glucose, galactose, ribose). Recall, disaccharides are composed of two monosaccharides. Because sucrose (a disaccharide) is composed of glucose and fructose, it is sweeter than lactose (glucose + galactose) and maltose (glucose + glucose) .
Is one type of sugar really better than another?
A trip down the baking aisle is teeming with sweetener options. Let's focus on sugars composed of the molecules mentioned above (natural sugars).
The selection of natural sugars continues to grow as manufacturers find new uses for otherwise byproducts, as well as new innovations. The chart below provides a comparison of commonly found natural sugars on a weight basis (per 100g) and volume basis (per teaspoon, with varying weights).
Table 1. Natural sugars per 100g