With a trend toward better health and fitness in the United States, many Americans have concerns about sugar consumption. Sugar is the universal name for short-chain, soluble carbohydrates with a sweet flavor. While most think of sugar as the stuff used to sweeten coffee or cereal, there are actually three key types of sugar — sucrose, glucose, and fructose. Learning about the different kinds of sugar and the way they affect the body can help people make healthier dietary choices.
Glucose and fructose are monosaccharides, sugars that cannot be broken down into simpler sugars. Glucose is the type of sugar the body uses for fuel and is the kind measured when doctors determine blood sugar levels. It is found naturally in honey, in fruits like grapes, apples, and oranges, and it is an ingredient in corn syrup.
Fructose is also an ingredient in honey as well as molasses, agave nectar, and high-fructose corn syrup. Types of fruit that contain fructose include apples, pears, and pomegranates. Glucose and fructose combine to make a disaccharide called sucrose, which is abundant in sugar cane, sugar beets, and other plants. When sucrose is extracted from plants and refined, it makes table sugar.
Although all of these carbohydrates provide roughly the same amount of energy per gram, the body processes fructose and glucose differently. Fructose metabolizes in the liver, triggering the release of insulin and the production of ghrelin, which is known as the hunger hormone.
When glucose is processed, it circulates through the body and triggers the production of leptin, a hormone that helps control appetite. The body either uses glucose immediately for energy or stores it in the muscles or in the liver as glycogen for later use.
Fructose vs. Glucose
In a study from the University of California at Davis, researchers compared the effects of glucose and fructose consumption on 32 overweight or obese individuals. Subjects drank a beverage sweetened with glucose or fructose that supplied 25 percent of their daily calories for 12 weeks. Researchers found that both groups gained weight, however, the people who drank the beverage sweetened with fructose experienced a number of additional effects. These included:
- Increased visceral fat (the hard-to-lose type of abdominal fat that surrounds inner organs)
- Reduced sensitivity to insulin (one of the first signs of diabetes)
- Increased production of fat in the liver
- Higher LDL (unhealthy) cholesterol
- Elevated triglyceride levels
Results showed that the people who drank the beverage sweetened with glucose experienced none of these effects.
Most experts agree that whole fruit provides the best source of natural sugar, and it contains healthy vitamins, minerals, and fiber. Refined sugars deliver added, empty calories, devoid of any nutritional value. To help ensure optimal nutrition and a healthy body weight, people should limit their intake of processed sugars, either in crystalline form or as an ingredient in foods, syrups, and beverages.