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Separating truth from fiction in the sugar wars

There is scientific consensus on the health effects of sugar consumption

February 10, 2015 2:00AM ET

The vigorous debate on the risks of consuming too much sugar hasn’t helped the public’s understanding. Families seeking accurate information about the health effects cannot help being befuddled. On one side of the conflict are those publicizing the toxic effects of sugar, using sugar-cube skulls and candy-cane guns for added visual impact. On the other side are industry-sponsored naysayers — the health equivalent of climate change deniers — who are willing to go so far as to claim that there’s no connection between rising sugar consumption and our worldwide epidemics of obesity and metabolic diseases such as Type 2 diabetes. Both sides argue that the scientific evidence is on their side.

In a free-for-all such as this, whose health claims can you believe? 

It was precisely this question that motivated my colleagues and me to found SugarScience, a groundbreaking research and education initiative designed to highlight the most authoritative scientific findings on added sugar and its effects on health. The initiative aims to bring scientific research out of medical journals and into the public domain by showcasing key findings that can help people make informed decisions about their health. Developed by a team of University of California at San Francisco health scientists in collaboration with scientists at UC Davis and Emory University School of Medicine, the initiative reflects an exhaustive review of more than 8,000 scientific papers that have been published to date on the health effects of added sugar. SugarScience.org puts 12 of the nation’s top medical researchers in direct dialogue with members of the public. 

The outpouring of public interest in credible, trustworthy information has astonished us. It appears that in this age of too much information, people want to find somebody who will just tell them the truth. In the first few months since we launched the initiative, more than 7 million people have engaged in conversations with us on Twitter, and more than 100,000 have visited our website. We’ve received almost a thousand specific questions from the general public about sugar and health, some that have required us to go back and do deeper dives into the scientific literature to dredge up correct answers.

Most of the questions people ask, however, are ones that shouldn’t require an academic team to settle the score. They involve basic issues about which there is scientific consensus, but the truth has been obscured by public debate, leaving people confused and wondering whom to believe. 

Studies conducted by industry-funded researchers were five times as likely as others to report that sugary drinks have no relationship to obesity.

Consider the following examples:

Q: How much added sugar is too much for good health?
A: Women should try to limit themselves to 6 teaspoons, or 25 grams, of added sugar daily, while men should consume no more than 9 teaspoons, or 38 grams. These limits pertain only to sugars added to food and drinks at the point of processing, preparation and at the table, not naturally occurring sugars such as those present in milk and fruit. In America today, we are collectively way over these limits. By our calculation, the average American consumes almost three times too much added sugar.   

Q: Is sugar really toxic?
A: In a limited sense, yes. A particular kind of commonly consumed sugar, fructose, is what we call a hepatotoxin, a chemical substance that damages the liver. When consumed in large quantities over long periods, fructose can be toxic to the liver via the same biological process that leads alcohol to damage the liver. Scientists believe that excessive fructose and trans fat consumption and the risk for obesity that follows are linked to rising rates of nonalcoholic liver disease — one of the fastest-rising reasons for liver transplantation in the U.S.          

Q: Should I substitute artificial sweeteners for sugar to satisfy my sweet tooth?
A: The latest studies on common artificial sweeteners such saccharine, sucralose and aspartame suggest that these products may actually be putting us at risk for the same metabolic diseases and weight gain that added sugars do. These products appear to damage beneficial bacteria in the gut, leading to glucose intolerance, a contributor to chronic disease.        

Q: Are there any healthier forms of added sugar? Honey, perhaps?
A: Unlike table sugar and high-fructose corn syrup — by far the most commonly used added sweeteners in America — honey contains nutritional compounds and antioxidants that may be protective for metabolic health and related disease outcomes, such as heart disease. So within the reasonable daily limits noted above, there may be health reasons to opt for honey.

In polarized public debates, science often gets caught in the middle. This is all too true for research on the health effects of sugar. Who funds the research can influence what researchers report, even when the studies are peer-reviewed and published in reputable scientific journals. Thus a recent review found that studies conducted by industry-funded researchers were five times as likely as others to report that sugary drinks have no relationship to obesity. At SugarScience, we’ve had to adjust to this unfortunate reality by having our medical librarians carefully scrutinize sources for scientific conflicts of interest.

For critical matters pertinent to health, the digital age is both a blessing and curse. It’s a blessing because legitimate medical authorities can directly connect with the public and share what they know. It’s a curse because just about anyone can establish a platform for espousing unsubstantiated claims about what’s good and bad for health. For now, the best principle for those of us using digital sources to stay current on matters affecting our health is caveat emptor: Let the information consumer beware.

Laura A. Schmidt is a professor of health policy in the School of Medicine at the University of California at San Francisco.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera America's editorial policy.

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