Sugar, Saccharides, Starch, and Carbohydrates

In discussions about food, we often hear the terms sugar, saccharides, starch, and carbohydrates. Are they the same thing?

Saccharides and carbohydrates refer to the same category of substances. Saccharides are generally divided into four groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides.

• Monosaccharides are the most basic units of saccharides. They cannot be broken down further and can directly provide energy to the body. Common examples include glucose, fructose, and galactose, found in honey, grapes, apples, and other foods.
• Disaccharides consist of two monosaccharides. Once ingested, they must be broken down into monosaccharides by enzymes before the body can use them for energy. Common disaccharides include sucrose (glucose + fructose), found in table sugar, candies, and pastries; lactose (galactose + glucose), found in milk and dairy products; and maltose (glucose + glucose), found in beer and malt-based foods.
• Oligosaccharides are made up of 3–10 monosaccharides. Because the human body lacks the enzymes to fully break them down, they are only partially digested. The undigested portion is used by gut bacteria to produce probiotics, supporting intestinal health. Examples include fructooligosaccharides (glucose + multiple fructose units), found in onions and bananas, and raffinose (galactose + glucose + fructose), found in soybeans and cabbage.
• Polysaccharides are saccharides composed of more than ten monosaccharide units. Once ingested, they are ultimately broken down into monosaccharides and oligosaccharides. Starch is the digestible portion of polysaccharides, while dietary fiber is the indigestible portion. Common starch-rich foods include rice, corn, sweet potatoes, and pumpkins. Foods high in dietary fiber include green vegetables, brown rice, and whole wheat bread. The digestible portion of polysaccharides is eventually broken down into monosaccharides, providing energy for the body. The indigestible portion, however, is utilized by gut bacteria to produce probiotics, promote bowel movements, and maintain intestinal health.

The term “sugar” usually refers to monosaccharides and disaccharides, which are sweet in taste. Oligosaccharides and polysaccharides are often called complex carbohydrates. Nutritionists today recommend consuming more complex carbohydrates because of their benefits. Since they are composed of multiple saccharide units, they take longer to digest, preventing sharp spikes in blood sugar. They also contain fiber and other nutrients, making them healthier than simple carbohydrates (monosaccharides and disaccharides).

Refined sugar refers to sugar that has been processed and purified, with fiber, vitamins, and minerals removed. It is low in nutritional value but high in calories. Examples include table sugar and rock sugar, as well as foods made from them—candies, chocolate, soda, sauces—which can harm health. Refined starch is similar: highly processed starch products with fiber and nutrients removed, leaving only the starch itself. Examples include white rice, white bread, and products made from refined flour.

In summary: carbohydrates and saccharides are the same thing. Saccharides can be divided into monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Sugars usually refer to monosaccharides and disaccharides (simple carbohydrates), while oligosaccharides and polysaccharides are complex carbohydrates. Starch is one type of polysaccharide.