October 01, 2013

Sugar has been a part of the human diet for centuries but recently there has been a shift in people’s perception of sugar, particularly in its relationship to weight and health. A lot of this is due to misinformation and unfounded claims about sugar that are often expressed in the media.

  • To help distinguish fact from fiction, this issue of Carbohydrate News, The not so toxic truth about sugar, provides a review of the scientific evidence by Dr. John Sievenpiper of St. Michael’s Hospital and McMaster University. The review is based on a the results of series of Canadian Institutes of Health Research (CIHR) funded systematic reviews and meta-analyses of controlled feeding trials looking at the health effects of fructose and other sugars containing fructose.

The not so toxic truth about sugar

By John L Sievenpiper, MD, PhD.
Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario and Department of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario.


Fructose and sugars containing fructose are being blamed for the rise in obesity, diabetes and other non-communicable diseases. There have been dozens of editorials, commentaries, and letters in the scientific literature and numerous pieces in traditional and social media calling for efforts to restrict and regulate their intake. Some have even suggested that sugars are harmful (toxic), requiring public health controls such as taxation. However, high quality evidence, such as that from controlled feeding trials must be considered when evaluating whether there is valid evidence to support such claims.

In this issue of Carbohydrate News, Dr. John Sievenpiper reviews the results of a series of Canadian Institutes of Health Research (CIHR) funded systematic reviews and meta-analyses of controlled feeding trials (http://clinicaltrials.gov/show/NCT01363791). The review summarizes the evidence from this research, looking first at fructose and then at all sugars containing fructose.

Understanding the Hierarchy of Scientific Evidence:

  • Uncontrolled studies that associate sugars availability with increasing obesity and diabetes rates, as well as animal models testing abnormally high doses of fructose have been used to underpin this debate.
  • These observations have not been supported by higher level evidence from controlled feeding trials.

Key conclusions from the systematic reviews and meta-analyses:

  • The systematic synthesis of data from clinical studies in humans does not support the view that fructose and sugars containing fructose are harmful at typical intakes.
  • Excess calories appear to be the dominant consideration, rather than sugars or the type of sugar, for weight gain and other metabolic disturbances.
  • Added sugars do not appear to behave differently than other forms of carbohydrate up to 25% of calories.
  • Current estimates of added sugars intakes in Canada are approximately half this level, contributing 9 - 14% of total energy.

Link to full text of article by Dr. Sievenpiper

Key facts about added sugars consumption in Canada:

  • 10.5% of total calories (estimated average); ranges from 9 – 14% depending on the age group
  • Well below the Canada-US Dietary Reference Intakes suggested maximum of 25%
  • Decreasing over the past two decades, mainly reflecting a decline in soft drink consumption
  • 1/3 lower than U.S. consumption levels of added sugars

For further information see: