A. Dariush Mozaffarian, MD, DrPH, dean of the Friedman School and editor-in-chief of Tufts Health & Nutrition Letter, answers. “When consumed in higher amounts, all added sugars are similarly associated with negative health effects. This includes regular (cane) sugar, beet sugar, brown sugar, sugar ‘in-the-raw,’ high fructose corn syrup, brown rice syrup, and fruit juice concentrate. There is some emerging evidence that less-processed sweeteners like coconut sugar (which contains the fiber inulin), honey, maple syrup, and agave nectar cause lower spikes in blood glucose and may contain a few healthful nutrients, but high amounts of these natural sweeteners will still cause many of the same metabolic problems as other sugars.
“Nearly all natural sugars are composed primarily of two molecules your body burns for energy: glucose and fructose. These include table sugar from sugar cane or sugar beets, honey, maple syrup, and high fructose corn syrup. (Note that, because regular corn syrup is nearly 100 percent glucose, the manufacturing of ‘high fructose’ corn syrup increases fructose to about half the molecules, making it more similar to (and not worse than) cane or beet sugar.) When we eat sugar, glucose and fructose are handled by the body in different ways.
- High doses of rapidly digested glucose lead to insulin spikes. The insulin works to shunt the glucose into our muscle cells or convert it to glycogen for storage. When storage is full, extra glucose is made into fat molecules.
- High doses of rapidly digested fructose don’t increase insulin (or blood glucose) levels, but go directly to the liver for conversion into new fat molecules for storage.
So, high doses of both glucose and fructose are harmful, in different ways, and both can increase weight gain, risk for developing type 2 diabetes, and heart disease.
“In contrast, when we eat lower doses of slowly digested sugars—such as in a piece of fruit or a vegetable—the slow release of glucose and fructose is more easily handled by the liver, preventing the spikes in insulin from glucose and the synthesis of new fat molecules from fructose. Rather than switching sweeteners, the best choice for your health is to cut back on sweets altogether, and sweeten foods with fruit, fruit puree, or 100 percent fruit juice where possible.”