When we hear the term “sugar,” most of us probably think of those fine little crystals that help sweeten our favorite desserts, but what exactly is sugar?
Very simply, sugar is the water soluble, simple carbohydrate that is commonly used in food. While there are about seven key types of sugars used for cooking, there are a variety of different types of naturally occurring sugars which make up many of the foods we eat, including milk, potatoes and fruit, to name a few. You may have already noticed terms ending in -ose while browsing the nutrition labels on packaged foods. This suffix is simply used as a way to name sugars in basic terms of biochemistry. There are dozens of varieties of sugars, though the most common types are limited to about five.
Let’s take a closer look at these common varieties.
All sugars can be classified as belonging to one of two groups: monosaccharides and disaccharides.
Monosaccharides (CnH2nOn) are what are commonly known as “simple sugars.” They are a fundamental component of carbohydrates and cannot be broken down any further, as they are already sugar in its simplest form. Most monosaccharides are sweet in taste and are often colorless, odorless and water soluble. Examples of monosaccharides include fructose and glucose.
Glucose is the most important monosaccharide, and it’s considered to be a vital component in human life. In fact, glucose is found in every living cell on Earth. From it, many derivatives can be produced, including vitamin C. Glucose can also be reduced to create certain sugar alcohols used as sweetening agents, such as sorbitol. Glucose can be found in many starchy foods, such as potatoes, squash and celery, and is naturally produced within the human body.
Fructose is a naturally occurring sugar which can be found in fruits, such as cherries and watermelon, certain vegetables like tomatoes and corn, honey and a variety of syrups. Fructose consumption should be somewhat limited as it not produced naturally by the human body. In his presentation Sugar: The Bitter Truth, pediatric endocrinologist Dr. Robert H. Lustig makes a case against fructose as an added sweetener, highlighting the negative aspects of the monosaccharide, mainly for its inability to be metabolized easily by the human body. Despite being linked to obesity, heart disease and diabetes, fructose is widely used to sweeten many foods, sodas and candies sold in the United States.
Monosaccharides are the building blocks of the second classification of sugars known as disaccharides.
Disaccharides (C12H22O11), also known as a “double sugar,” are the sugars which occurs when two monosaccharides join to form its own different type of sugar. The two simple sugars join to form one disaccharide when a condensation reaction eliminates a water molecule, thereby changing its molecular structure. Like monosaccharides, disaccharides are water soluble though not typically sweet in taste. Common disaccharides include lactose, maltose and sucrose.
Lactose occurs when galactose, otherwise known as “milk sugar,” and glucose come together. It is most well-known for its role in the molecular structure of milk, of which it usually makes up 2-8%. The sugar found in milk comes from naturally-occurring lactose, which is not considered to be unhealthy, however, many people find themselves unable to digest the disaccharide, a condition known as lactose intolerance. Other foods containing lactose include cheese, butter and yogurt.
Maltose, or “malt sugar,” occurs when two units of glucose are joined with a 1—>4 glycosidic bond, which joins a carbohydrate or sugar molecule with another group. Sweet potatoes and many breakfast cereals are high in maltose, as are brewed and fermented beverages like beer. Maltose is the naturally occurring sugar that occurs in the body’s breakdown of starch, which is catalyzed by an enzyme called amylase. Maltose can also be produced in the caramelization, or browning, of glucose over heat.
Sucrose is formed when fructose and glucose combine and can be found naturally in many plants and plant parts, such as the sugar cane. When sucrose is extracted from the sugarcane plant or the sugar beet, its refined form is what is often known as the white, table sugar many people use on a daily basis. Tangerines and mangoes are particularly high in naturally occurring sucrose. The sugar-alternative sweetener Splenda® uses synthesized sucrose to create sucralose, known for being sweeter than sugar and other artificial sweeteners, such as aspartame and saccharine.
Keeping track of all these sugars can be overwhelming, so just remember this: if you see it on a label and it ends in -ose, it’s a sugar! A healthy amount of sugar intake per day rests at around 25-35 grams, which is a good number to keep in mind, especially if you have digestive concerns that may be sugar-related. As with any medical condition, it’s best to make an appointment with a medical professional, such as a certified nutritionist and/or a gastroenterologist, to best determine what’s causing the issue.