Many people try to cut down sugar in their diets, so they wonder about the main types of sugar and which ones might be good or bad.
Sucrose, glucose, and fructose are the three most common sugars. Each has the same calories per gram. They all naturally occur in fruits, veggies, dairy, and grains, and can also be added to processed foods.
Each main sugar type differs in chemical structure, how it’s digested and metabolized, and its effects on health.
This article explains the main differences between sucrose, glucose, and fructose, plus how each is digested and why it matters.
The difference between main sugar types
1. Sucrose (table sugar)
Sucrose is the scientific name for table sugar. Sugars are classified as monosaccharides (one sugar) and disaccharides (two sugars). Disaccharides consist of two monosaccharides linked together and get broken down into monosaccharides during digestion.
Sucrose is a disaccharide sugar made of one glucose molecule and one fructose molecule, or 50% glucose and 50% fructose, it is a carbohydrate naturally found in many fruits, vegetables, and grains, and can also be added to many processed foods like candy, ice cream, andbreakfast cereals canned foods, soda, and other sweetened drinks.
Sucrose (table sugar) in processed foods usually comes from sugarcane or sugar beets. It's less sweet than fructose but sweeter than glucose.
How sucrose sugar is digested
The body digests monosaccharides and disaccharides differently. Since monosaccharides are already in their simplest form, the body doesn’t need to break them down before using them. They are absorbed directly into the bloodstream, mainly in the small intestine.
On the other hand, the body has to break down disaccharides, like sucrose, into simple sugars before absorbing them. Once they're in their simplest form, they're metabolized differently.
Enzymes in the mouth partly break down sucrose into glucose and fructose, but most of the sucrose digestion happens in the small intestine. There, the enzyme sucrase, made by the intestine lining, splits sucrose into glucose and fructose. These sugars are then absorbed into the bloodstream.
2. Glucose
Glucose is a simple sugar or monosaccharide and the body's preferred energy source. Monosaccharides are made of one sugar unit and can't be broken down further. They're the building blocks of carbs in foods.
Glucose usually links to another simple sugar to form starch, polysaccharides, or disaccharides like sucrose and lactose. Glucose is often added to processed foods as grape sugar or dextrose, which comes from corn or wheat.
Glucose is less sweet than both fructose and sucrose.
How glucose sugar is digested
Glucose is absorbed directly through the small intestine lining into the bloodstream to reach body cells. This sugar raises blood sugar levels faster than other sugars, triggering insulin release.
Insulin is needed for glucose to enter body cells. Once inside, cells use glucose right away for energy or turn it into glycogen stored in muscles or liver for later use.
The body strictly controls blood sugar. When glucose levels drop too low, stored glycogen in the liver and muscles breaks down into glucose and is released into the blood for energy. Also, if glucose isn't in the blood, the liver can make this sugar from other fuel sources.
3. Fructose
Fructose, aka fruit sugar, is a simple sugar like glucose. It naturally appears in fruit andhoney , cactus, and most root veggies. Also, it's often added to processed foods as high fructose corn syrup.
Fructose comes from sugarcane, sugar beets, and corn. High fructose corn syrup is made from corn starch and has more fructose than glucose, unlike regular corn syrup.
Out of the three types of sugar, fructose tastes the sweetest and has less effect on blood sugar levels.
How fructose sugar is digested
Like glucose, fructose is absorbed directly into the bloodstream from the small intestine. It raises blood sugar levels gradually compared to glucose and doesn't seem to affect insulin levels right away. Still, even though fructose doesn’t spike blood sugar fast, it might have long-term negative effects.
The liver turns fructose into glucose before the body can use it for energy.
Eating large amounts of fructose in a high-calorie diet can raise levels of triglycerides in the blood, along with increased risks ofMetabolic syndrome and fatty liver disease non-alcoholic.
Fructose sugar in processed foods
The body converts fructose into glucose in the liver to use for energy. Too much fructose in processed foods and drinks can overload the liver, leading to a chain of metabolic problems.
The fructose naturally found in fruit doesn’t cause the same bad effects as the fructose in processed foods. That’s because fruit doesn’t have the same glucose to fructose ratio as high fructose corn syrup widely used in processed foods.
Also, the health benefits from eating fruit outweigh any possible bad effects from its natural fructose. Fruits provide dietary fiber andVitamins and minerals andAntioxidants, so you should eat fruit as part of a balanced diet that also includes whole grains, vegetables, andlean proteins andhealthy fats.
Many studies have shown the harmful effects of high fructose corn syrup, including insulin resistance, and type 2 diabetes, andobesity, fatty liver disease, metabolic syndrome, and more. Studies have shown that fructose increases the hunger hormone ghrelin, which can make people feel less full after eating.
Cutting back on added sugar
No need to avoid natural sugars in whole foods like fruits, veggies, grains, and dairy. These foods also give you nutrients, fiber, and water.
The harm from sugar mainly comes from too much added sugar in diets. WHO says added sugars should be limited to 5 - 10% of daily calories. So if you eat 2000 calories a day, added sugars should be less than 25 - 50 grams.
Keep in mind, one 355ml soda can has about 40 grams of added sugar, which can exceed your daily limit.
Also, sugar isn't just added to sweet stuff like soda, ice cream, and candy. It’s added to savory foods too, like sauces, dressings, and frozen meals.
In the end, it's best to get sugar from whole foods and have added sugars only occasionally.
