Monday, April 2, 2012

No, Dr. Gupta, hummingbird fuel is not "toxic"

Sugar is toxic? Not this hummingbird's opinion.
Whenever someone asks me whether or not sugar or high-fructose corn syrup is "toxic," I remind them that every few days I make up a simple solution of four parts boiled water and one part plain white table sugar. This I use to fill the hummingbird feeders in my yard here in Arizona and the little guys never complain about it.

In fact, they lap up the sweet nectar -- as much as they can get with their long tongues -- to fuel their high metabolism. Then, they fly off (or get chased off) to their perches and I make a note that most will return within 30 to 45 minutes for more. Research shows their little bodies will have oxidized all the ingested sucrose by that time (1).
How can hummingbird fuel be evil? It's just not, as Dr. David Katz pointed out a year ago in a rebuttal to Dr. Lustig's viral YouTube video and Gary Taubes's article in the New York Times Magazine. Another excellent rebuttal was "The bitter truth about fructose alarmism" on Alan Aragon's Blog posted January 2010 in response to Dr. Lustig. The main problem with Dr. Lustig's argument, as pointed out by many scientists, is in its oversimplifications with intent to demonize a single nutrient in a manner that is out of context.

Now, it's happened again on Sunday's 60 Minutes episode "Is sugar toxic?" The oversimplifications presented in the episode are the same as before and sure to just add more to the hysteria surrounding sugar. And, Dr. Gupta's reporting is hardly balanced, using Dr. Lustig to drive the main direction of the episode with only a sugar industry spokesperson to offer a differing opinion.

No, Dr. Gupta, sugar is not toxic. You've said that "almost every scientist" you've talked to agrees that cutting sugar from diet will prevent disease, even cancer. However, most evidence-based nutritionists would agree that sugar itself is not the problem; it's the eating or drinking an excess of anything that makes something toxic -- whether it be carbohydrate, fat, alcohol, or arsenic. Furthermore, to call sugar or high-fructose corn syrup "toxic" or uniquely responsible for driving obesity and disease in the United States is wrong and ignores wider problems of overeating, sedentary lifestyle, and other complex factors.

Sugar is just an easy target, especially high-fructose corn syrup because it was only recently introduced in the 1970s displacing table sugar in many places. Among consumers, there are so many misconceptions about this nutritive sweetener that it has become the scapegoat for every chronic disease.  However, it's metabolically the same as table sugar, rightfully noted by Dr. Lustig in the Dr. Gupta's report (2). What was not mentioned was that four years ago the American Society for Nutrition reported that there was no strong correlation between obesity and HFCS availability; even when HFCS availability began dropping in the United States, obesity rates did not (3). Again, the real problems lie in overconsumption of all sources of calories along with sedentary lifestyle.

Yet, the way the segment is presented, sugar is equated to being as addictive as cocaine or tobacco -- and something to be regulated.

It's disappointing that Dr. Gupta couldn't put forward a more balanced report by interviewing a scientist who had a different opinion than Dr. Robert Lustig on sugar and fructose. He would not have had to look far.

Biochemist Richard Feinman, for example, could've reminded Dr. Gupta that while it may be true that the focus on fat gave the food industry license to replace many foods with carbohydrate, it's overconsumption of carbohydrate "across the board" that's contributing calories fueling the obesity epidemic. What comes of demonizing just table sugar or high-fructose corn syrup? It will simply lead folks to eat/drink too much of something else, argues Feinman.

What about fructose being uniquely harmful? Dr. Gupta might've thought to consider the opinions of Drs. Sievenpiper, Russel Souza and David Jenkins of St. Michael's Hospital in Toronto, Ontario. They recently published the findings of three extensive systematic reviews and meta-analyses evaluating the effects of fructose as compared to other sources of carbohydrates in randomized controlled feeding trials in the February issues of Annals of Internal Medicine, the British Journal of Nutrition, and Hypertension (4-6). What did they find? Fructose had no significant effect on body weight or blood pressure as compared to other carbohydrate sources. The fruit sugar in amounts normally obtained from fruit (up to and around 10 grams per meal) also appeared to improve glycemic control -- which could ultimately serve to assist weight management.

That's hardly the "toxic" substance that Dr. Lustig and colleagues make fructose out to be in his commentary in Nature (7). In response to Dr. Lustig's opinion paper, Drs. Sievenpiper, de Souza, and Jenkins, wrote a letter that appeared as "Correspondence" in the 23 February issue of the publication (8):
Robert Lustig and colleagues argue that sugar is “toxic,” focusing on the “deadly effect” of the fructose moiety of sucrose. But they are directing attention away from the problem of general overconsumption. 
Guidelines on healthy eating encourage fruit consumption, and fruit and fruit products are the third-largest source of fructose in the US diet. 
Our meta-analyses of controlled feeding trials indicate a net metabolic benefit, with no harmful effects, from fructose at a level of intake obtainable from fruit.  
Their letter was published alongside that of other commenters, such as clinical nutritionists Christiani Jeyakumar Henry and Viren Ranawana of the Singapore Institute, who remind that sugar overconsumption is really a problem of the developed world, not the developing world (9). And, again, maybe it's that the developing world doesn't have the sedentary lifestyle and other complex factors that are associated with obesity and disease in the United States.

To make a villain out of sugar is just nonsense. Instead, it would make more sense to encourage taking a cue from the hummingbirds and, to stay trim, let amounts of carbohydrate and calories consumed overall depend on how much physical activity (hovering and chasing others off) one does per day.

  1. Welch KC Jr, Suarez RK. Oxidation rate and turnover of ingested sugar in hovering Anna's (Calypte anna) and rufous (Selasphorus rufus) hummingbirds. J Exp Biol 2011 Oct 1;214(Pt 19):3324. doi: 10.1242/​jeb.005363.
  2. Fulgoni V. Supplement: High-Fructose Corn Syrup (HFCS): Everything You Wanted to Know, but Were Afraid to Ask. Am J of Clin Nutr, 88(6), 1715S, December 2008, doi:10.3945/ajcn.2008.25825A.
  3. White JS. Supplement: The State of the Science on Dietary Sweeteners Containing Fructose. J Nutr, 139(6), 1219S-1227S, June 2009, doi:10.3945/jn.108.097998.
  4. Sievenpiper JL, de Souza RJ, Mirrahimi A et al. Effect of Fructose on Body Weight in Controlled Feeding Trials: A Systematic Review and Meta-analysis. Ann Intern Med 2012;156:291-304.
  5. Sievenpiper JL, Chiavaroli L, de Souza RJ et al. 'Catalytic' doses of fructose may benefit glycaemic control without harming cardiometabolic risk factors: a small meta-analysis of randomised controlled feeding trials. Br J Nutr 2012;1-6. doi: 10.1017/S000711451200013X
  6. Ha V, Sievenpiper JL, de Souza RJ et al. Effect of Fructose on Blood Pressure: A Systematic Review and Meta-Analysis of Controlled Feeding Trials. Hypertension 2012. doi: 10.1161/​HYPERTENSIONAHA.111.182311
  7. Lustig RH, Schmidt LA, Brindis CD. "Public health: The toxic truth about sugar." Nature 482, 27-29 (02 February 2012). doi: 10.1038/482027a
  8. Sievenpiper JL, de Souza RJ, Jenkins DJA. "Sugar: fruit fructose is still healthy." Correspondence. Nature 482, 470 (23 February 2012) doi: 10.1038/482470e
  9. Henry CJ, Ranawana V. "Sugar: a problem of developed countries." Correspondence. Nature 482 (23 February 2012) doi: 10.1038/482471a