Most people consume many different types of sugars from a variety of foods and beverages in their diet. A high intake of sugar is linked to an increased risk of obesity, type 2 diabetes, cardiovascular disease, and certain cancers. But whether some sugars are healthier (or worse) than others remains a question of interest to many.
Sugar provides energy that our cells need to survive. Sugar is a type of carbohydrate, a macronutrient that provides energy (in the form of calories) from foods and beverages we consume. Carbohydrates are classified into two subtypes of sugar: monosaccharides, or "simple sugars" (consisting of one molecule),` and disaccharides (two molecules). The monosaccharides include glucose, fructose, and galactose. The major disaccharides include sucrose (one glucose molecule and one fructose molecule), lactose (one glucose molecule and one galactose molecule), and maltose (two glucose molecules).
Fructose, glucose, and sucrose are found naturally in fruit and some vegetables, while lactose is found in dairy and maltose is found in germinating grains. Fructose and glucose are also found naturally in honey, as well as in common table sugar.
Added versus natural sugars
An increasingly important distinction among sugars as they pertain to health is whether they occur naturally in foods such as fruit, vegetables, and dairy, or whether they are added sugars (added to foods and beverages during manufacturing, processing, or preparation).
Sugary beverages are the greatest source of added sugar in the diet, followed by sweets and grains such as ready-to-eat cereals. Intake of added sugar, particularly from beverages, has been associated with weight gain and higher risk of type 2 diabetes and cardiovascular disease.
Natural and added sugars are metabolized the same way in our bodies. But for most people, consuming natural sugars in foods such as fruit is not linked to negative health effects, since the amount of sugar tends to be modest and is "packaged" with fiber and other healthful nutrients. On the other hand, our bodies do not need, or benefit from, eating added sugar.
Are all added sugars created equal?
Added sugars come from a variety of sources and go by many different names, yet they are all a source of extra calories and are metabolized by the body the same way. A common misconception exists that some added sugars such as high fructose corn syrup (HFCS) are unhealthy, while others such as agave nectar (from the succulent plant) are healthy.
The reality is that most added sugars are composed of glucose and fructose in varying ratios. For example, sucrose (common table sugar) is 50% glucose and 50% fructose; the most common form of HFCS (which is produced from corn starch through industrial processing) contains 45% glucose and 55% fructose; and some types of agave nectar contain up to 90% fructose and 10% glucose.
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.
In short, it's best to limit all sources of added sugar to within the recommended intake level. For most people, one type of sugar isn't better than another.
Adapted from a Harvard Health Blog post by Vasanti Malik, ScD