Carbohydrates and Sugars
Carbohydrates are one of three basic macronutrients needed to sustain life (the other two are proteins and fats). They are found in a wide range of foods that bring a variety of other important nutrients to the diet, such as vitamins and minerals, phytochemicals, antioxidants, and dietary fiber. Fruits, vegetables, grain foods, and many dairy products naturally contain carbohydrates in varying amounts, including sugars, which are a type of carbohydrate that can add taste appeal to a nutritious diet.
Carbohydrates encompass a broad range of sugars, starches, and fiber. The basic building block of a carbohydrate is a simple union of carbon, hydrogen, and oxygen. The chemical definition of a carbohydrate is any compound containing these three elements and having twice as many hydrogen atoms as oxygen and carbon.
Sugars in Foods
When people hear the word “sugar” they often think of the familiar sweetener in the sugar bowl. That sugar is sucrose and is the most familiar form of sugar to home bakers. But there are many types of sugars, which scientists classify according to their chemical structure. Sugars occur naturally in a wide variety of fruits, vegetables, and dairy foods. They can also be produced commercially and added to foods to heighten sweetness and for the many technical functions they perform, including: contributing to foods’ structure and texture, sweetening and flavor enhancement, controlling crystallization, providing a medium for the growth of yeast in baked goods, and preventing spoilage. The sweetening ability of sugar can promote the consumption of nutrient-rich foods that might not be otherwise. Some examples are a sprinkle of sugar added to oatmeal or adding sugar to cranberries in the juice-making process.
Sugars come in several forms, most containing approximately four calories per gram. Simple sugars are called monosaccharides, made up of single sugar molecules. Examples of these are glucose, fructose, and galactose. When two simple sugars are joined together by a chemical bond they are called disaccharides, the most common of which is sucrose or table sugar. Table sugar is made up of equal amounts of the simple sugars glucose and fructose, which are joined together by chemical bonds. Starches and fiber are made up of many simple sugars joined together chemically. Any carbohydrate that is made up of more than two simple sugars is referred to as a polysaccharide. Some common sugars found in foods are:
A sugar alcohol is neither sugar nor alcohol but is actually a carbohydrate with a chemical structure that partially resembles a sugar and partially resembles an alcohol. Another term for sugar alcohols is polyols. They are a group of caloric sweeteners that are incompletely absorbed and metabolized by the body and consequently contribute fewer calories than sugars. The sugar alcohols or polyols commonly used in the United States include sorbitol, mannitol, xylitol, maltitol, maltitol syrup, lactitol, erythritol, isomalt, and hydrogenated starch hydrolysates. Their caloric content ranges from .02 to 3 calories per gram compared to 4 calories per gram for sugars. Most sugar alcohols are less sweet than sucrose; maltitol and xylitol are about as sweet as sucrose.
Due to their incomplete absorption, the polyol sweeteners produce a lower glycemic response than glucose or sucrose and may be useful for people with diabetes. Sugar alcohol-sweetened products may have fewer calories than comparable products sweetened with sucrose or corn syrup and hence could play a useful role in weight management.
Carbohydrate and Sugars Consumption Recommendations
The Institute of Medicine’s Dietary Reference Intakes (DRI) Report recommends that Americans get the majority of their daily calories from carbohydrates. The DRI Report established the Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates as 45 to 65 percent of daily calorie intake,. Children and adults need a minimum of 130 grams of carbohydrates per day for proper brain function.
Another source of recommendations for sugars intake comes from the Dietary Guidelines for Americans In 2010, the DGA recommended Americans to limit their intake of Solid Fats and Added Sugars (affectionately named SoFAS at the time by the 2010 Dietary Guidelines Advisory Committee (DGAC), but now “empty calories” per the 2015 DGAC) to “no more than about 5 to 15 percent of calories.” At the time, Americans consumed about 35% of their calories (or about 800 per day) from SoFAS. Today the number of “empty calories” we eat per day has declined and is thought to be 25-30% of our total calories. It’s recommended that we cut it down to 8-19%.
The 2015-2020 DGA recommendation is to limit intake of added sugars to less than 10% of total calories per day. Currently, we get 13-17% of our calories from added sugars.
The 2015-2020 DGA notes that this recommendation “is a target based on food pattern modeling and national data on intakes of calories from added sugars that demonstrate the public health need to limit calories from added sugars to meet food group and nutrient needs within calorie limits. The limit on calories from added sugars is not a Tolerable Upper Intake Level (UL) set by the Institute of Medicine (IOM).” In other words, the recommendation to limit added sugars to less than 10% of total calories is not based on research demonstrating cause and negative health effects. Rather, this level of intake is thought to give consumers sufficient room in their diet to include key nutrients while keeping overall calorie intake at appropriate levels.
While the evidence behind the 10% recommendation is hotly debated, there is no debating that some people would benefit from reducing their total calories (sugars calories included) in the effort to achieve and/or maintain a healthy weight. All calories contribute to body weight, not just those from sugars.
Carbohydrates and Sugars in the Diet
Dietary Guidelines for Americans have not recommended the use of the GI as a diet planning tool for people with diabetes, the general population or people trying to lose weight. In fact even those who support the use of the GI as a useful tool say that foods should not be judge by their GI alone. Other factors such as nutrientdensity and fat content need to be considered. population.
The Bottom Line
As the main energy source for the body, carbohydrates are an important part of a healthful diet. Currently, experts agree that carbohydrates and sugars in foods and beverages can be enjoyed in moderation as part of a balanced diet and active lifestyle.