Not only do many worrying fructose studies use unrealistic doses of the sugar unaccompanied by glucose, it also turns out that the rodents researchers have studied metabolize fructose in a very different way than people do—far more different than originally anticipated. Studies that have traced fructose’s fantastic voyage through the human body suggest that the liver converts as much as 50 percent of fructose into glucose, around 30 percent of fructose into lactate and less than one percent into fats. In contrast, mice and rats turn more than 50 percent of fructose into fats, so experiments with these animals would exaggerate the significance of fructose’s proposed detriments for humans, especially clogged arteries, fatty livers and insulin resistance.
In a series of meta-analyses examining dozens of human studies, John Sievenpiper of St. Michael’s Hospital in Toronto and his colleagues found no harmful effects of typical fructose consumption on body weight, blood pressure or uric acid production. In a 2011 study, Sam Sun—a nutrition scientist at Archer Daniels Midland, a major food processing corporation—and his colleagues analyzed data about sugar consumption collected from more than 25,000 Americans between 1999 and 2006. Their analysis confirmed that people almost never eat fructose by itself and that for more than 97 percent of people fructose contributes less daily energy than other sugars. They did not find any positive associations between fructose consumption and levels of trigylcerides, cholesterol or uric acid, nor any significant link to waist circumference or body mass index (BMI). And in a recent BMC Biology Q&A, renowned sugar expert Luc Tappy of the University of Lausanne writes: “Given the substantial consumption of fructose in our diet, mainly from sweetened beverages, sweet snacks, and cereal products with added sugar, and the fact that fructose is an entirely dispensable nutrient, it appears sound to limit consumption of sugar as part of any weight loss program and in individuals at high risk of developing metabolic diseases. There is no evidence, however, that fructose is the sole, or even the main factor in the development of these diseases, nor that it is deleterious to everybody.”