By David Kiefer, MD

Clinical Assistant Professor, Department of Family Medicine, University of Wisconsin; Clinical Assistant Professor of Medicine, Arizona Center for Integrative Medicine, University of Arizona, Tucson

Dr. Kiefer reports he is a consultant for WebMD.

SYNOPSIS: In 43 children with obesity and metabolic syndrome, 9 days of dietary sugar reduction (isocaloric with starch substitution) improved numerous metabolic parameters and led to more than 2 pounds of weight loss.

SOURCE: Lusting RH, et al. Isocaloric fructose restriction and metabolic improvement in children with obesity and metabolic syndrome. Obesity 2015 Oct 26. doi: 10.1002/oby.21371.

Summary Points

  • From baseline diets, sugar was decreased to 10% from 28% and replaced with starch.
  • After 9 days, diastolic blood pressure decreased 5 mmHg, triglycerides decreased 46%, LDL cholesterol decreased 0.3 mmol/L, weight decreased 0.9 kg, and fat mass decreased 0.6 kg.

Fructose is probably the most maligned nutrient of late, and for good reason — the authors of this study reference unique aspects of its physiology that, combined with the fact that its inclusion in the diets of many children, could be related to the development of metabolic syndrome, obesity, and type 2 diabetes in younger and younger ages. In this study, the researchers recruited Latino (n = 27) and African American (n = 16) youth who were “high sugar consumers” (> 15% of calories from sugar, > 5% of which was fructose), and who were 8-18 years old, obese, and with one or more of the following: hypertension, hypertriglyceridemia, impaired fasting glucose, hyperinsulinemia, alanine aminotransferase > 40 U/L, or severe acanthosis nigricans.

The study started on day 0, with fasting labs and an oral glucose tolerance test, parameters that were repeated at the end of the trial. The participants were then sent home with pre-prepared meals for 9 days meant to provide sufficient calories to maintain weight, but lower total sugar content to 10% (4% fructose) even though total carbohydrate percentage was maintained as per the baseline diet. After the 9 days, there were significant decreases in weight (0.9 kg, P = 0.001), body mass index (0.4 kg/m2, P < 0.001), and fat-free mass (0.6 kg, P = 0.04), but not fat mass (0.3 kg, P = 0.17). Most of the weight change occurred in the first 4 days followed by a return to baseline, likely water loss, rather than insufficient caloric intake. Diastolic blood pressure was 4.9 mmHg less, but systolic blood pressure did not change. Other significant changes were decreased fasting glucose, fasting insulin, alanine aminotransferase and fasting triglycerides, LDL cholesterol, and HDL cholesterol, though the latter decreased by only 0.1 mmol/L. Although this trial was a short-term intervention, it provides compelling evidence for cause-effect relationship between fructose intake and some important metabolic parameters. These results further strengthen the case against the consumption of this compound, especially in children at risk for metabolic diseases, and shows the efficacy of even short-term dietary changes for helping reverse dangerous physiologic trends.