There are many different types and forms of caloric sweeteners that are collectively called “sugar.” The most familiar type of sugar is table sugar. Scientifically speaking, table sugar is sucrose, a disaccharide made of equal parts of two monosaccharides: fructose and glucose.
Monosaccharides are single units of sugar and are often referred to as “simple” sugars. The three main monosaccharides that we consume are fructose, galactose and glucose. They combine in various pairs to form the three kinds of disaccharides (two linked sugar units) that are most important in human nutrition: lactose, maltose and sucrose. Glucose is the common thread in each of these. It is part of sucrose (linked with fructose), lactose (linked with galactose), and maltose, which consists of two linked glucose units.
In addition to glucose being integral to disaccharides, it is also an integral part of life. Glucose is our body’s main source of energy, with some tissues like the brain requiring a constant supply. Glucose is referred to as “blood sugar” because it circulates in our bloodstream as a source of readily available energy. It is also stored in the body as glycogen for energy reserves during times when sufficient glucose may not be available in the blood.
Where does glucose come from?
Glucose is the most common monosaccharide found in nature. In plants, it is generated through photosynthesis. Some plants store glucose in linked chains. These chains are called starch. Common starch-containing foods include corn, potatoes, rice and wheat. Starch is commercially separated from these whole food sources to make dextrose, glucose, maltodextrins, polyols and high fructose corn syrup to be used as ingredients in the production of some foods, beverages, dressings and sauces.
Glucose monosaccharides (not as part of starch) are also found naturally in some foods. The most concentrated whole food source of glucose monosaccharides is honey, followed by dried fruits such as dates, apricots, raisins, currants, cranberries, prunes and figs.
Is glucose a natural or added sugar?
The sugar that we consume is often described as natural sugar or added sugar, depending on its source. Glucose is considered a natural sugar when consumed directly from whole foods such as apricots and dates. Glucose is considered an added sugar when consumed from packaged foods and beverages to which it has been added during manufacturing. Unfortunately, only about one in ten American adults eats the recommended amount of fruits or vegetables per day, while six in ten American adults eat more added sugars than is recommended.
How is glucose digested?
Glucose does not technically require digestion. Instead, it is absorbed in the small intestine directly into the bloodstream, where it can be used for energy or eventually stored as glycogen in muscle and liver. We consume glucose directly from foods like honey, and we also get glucose from foods and beverages that contain lactose, sucrose and starch. When we eat starch-containing foods, the saliva in our mouth must first break down starch into maltose (pairs of linked glucose units). Maltose is then broken down further into its individual glucose units, making them available for absorption. Similar to maltose digestion, when we consume lactose and sucrose, glucose is absorbed after being separated from its partner monosaccharide (galactose in lactose and fructose in sucrose). The steps involved in disaccharide and starch digestion make it take longer to absorb glucose, which results in less of a rise in blood sugar than consuming glucose directly.
Can our bodies make glucose?
Our bodies require glucose to function. It is particularly critical for our brain, as this organ uses about 60% of the glucose that our bodies use. But glucose does not always have to come immediately from foods and beverages. Glucose is generated by the body to ensure that we always have the amount needed. One way this is done is by breaking down glycogen to free up the glucose it contains. Glycogen breakdown occurs between meals or during periods of intense physical activity. The body can also produce glucose through gluconeogenesis, a process by which the body (mainly the liver) makes glucose from non-carbohydrate sources. Gluconeogenesis occurs when glycogen stores become low and glucose consumption is too low or nonexistent, such as during periods of starvation or prolonged fasting.
To learn more about carbohydrates and sugars, watch this video.
FAQs
Glucose: The main source of energy for the body, glucose may be consumed as a monosaccharide or can result from carbohydrate and sugars metabolism. Glucose is sometimes referred to as dextrose. Starch is composed of long chains of glucose.
What is the definition of glucose in food? ›
Glucose is the main type of sugar in the blood and is the major source of energy for the body's cells. Glucose comes from the foods we eat or the body can make it from other substances. Glucose is carried to the cells through the bloodstream.
What are examples of glucose foods? ›
Glucose monosaccharides (not as part of starch) are also found naturally in some foods. The most concentrated whole food source of glucose monosaccharides is honey, followed by dried fruits such as dates, apricots, raisins, currants, cranberries, prunes and figs.
What is the difference between sugar and glucose? ›
Glucose is a monosaccharide. It is widely found in a variety of foods. It's the most common form of sugar in plants. Glucose is the type of sugar that our bodies use for fuel.
Is glucose in food good for you? ›
Our bodies need one type of sugar, called glucose, to survive. “Glucose is the number one food for the brain, and it's an extremely important source of fuel throughout the body,” says Dr. Kristina Rother, an NIH pediatrician and expert on sweeteners.
What does glucose do to your body? ›
It is your body's primary source of energy. It comes from the food you eat. Your body breaks down most of that food into glucose and releases it into your bloodstream. When your blood glucose goes up, it signals your pancreas to release insulin.
What foods should I eat to lower my glucose? ›
Eating protein — from meat and fish, tofu, nuts, eggs, and cheese — with carbs can slow that flow of glucose and help stabilize blood sugar. “Proteins hold back the sugars, slow them down, and then release them into the bloodstream slowly so that your blood sugar stays in a more normal range,” O'Meara says.
What are the 5 worst foods for blood sugar? ›
You limit dairy products, red meat, sweets, added sugars, sodium (salt), and highly processed foods. Some additional guidelines include focusing on seasonal produce and reading food labels to help you avoid added sodium and sugar.
What food has no glucose? ›
Sugar-Free Alternatives
Mushrooms, spinach, kale, soybean sprouts, celery, broccoli, cucumber, cauliflower, radishes, and asparagus are among the vegetables with the lowest sugar content available. Seafood, pork, beef, and chicken are all sugar-free. They're also an important source of protein and omega-3 fatty acids.
What happens to excess glucose in the body? ›
Any excess glucose ends up being stored as glycogen in the muscles, and it can also be stored as lipid in the fat tissue. Fructose is also taken up into the blood from the gut, but in this case, the liver serves as a pre-processing organ that can convert fructose to glucose or fat.
Heart disease: Excess sugar in your blood can damage cells and tissues, especially blood vessels. This damage leads to plaque buildup inside the blood vessels and increases your risk of heart attack and stroke. Weight gain: Your body stores excess sugar as fat, which can lead to weight gain.
What is healthier glucose or sugar? ›
Whether an added sugar contains more or less fructose versus glucose has little impact on health. Some types of added sugar — honey, for example — may also contain micronutrients or other bioactive compounds. But these properties have little benefit when it comes to metabolic health.
What is glucose and is it bad for you? ›
Glucose is precious fuel for all the cells in your body when it's present at normal levels. But it can behave like a slow-acting poison. High sugar levels slowly make cells in your pancreas less able to make insulin. The organ overcorrects, and insulin levels stay too high.
Does glucose mean sugar? ›
Glucose is a type of sugar. It is your body's main source of energy. A hormone called insulin helps move glucose from your bloodstream into your cells. Too much or too little glucose in the blood can be a sign of a serious medical condition.
What does glucose mean in a recipe? ›
It is important in baking for sweetening as well as for sensory attributes, such as color and texture. Glucose is a syrup, most often sourced from hydrolyzed corn in the United States and is often called corn syrup. Dextrose, on the other hand, is a powder, purer and sweeter.
What fruits are high in glucose? ›
However, there are fruits that have a higher glycemic index. These include mangos, bananas, pineapples and watermelon. Dried fruits also typically contain more natural sugar than raw fruits. In some cases, manufacturers actually add extra sugar to dried fruits to enhance their taste.
