In a NYT Magazine cover story this weekend entitled "Is Sugar Toxic?", the smart, immensely knowledgeable science writer Gary Taubes offers a compelling argument for why sugar might possibly be the dietary demon we've all been looking for -- a prime cause of obesity, diabetes, metabolic syndrome, heart disease and even cancer. As you might image, the 6,000 word article has stirred up a fair amount of controversy, but it's also inspired lots of confusion because Taubes didn't do a great job of clarifying what he means by "sugar."
This led David Katz, a respected nutrition scientist, to issue a rebuttal yesterday on the Huffington Post, arguing that "sugar isn't evil" because it's in breast milk, flower nectar and strawberries. Katz wrote:
We were born with a preference for sweet because that has fostered the survival of not only Homo sapiens, but mammals in general, for perhaps as long as there have been mammals. Breast milk -- and I trust no one is foolhardy enough to suggest that breast milk is evil! -- is a sugar-sweetened beverage.While the Sugar Association will undoubtedly be excited to see Katz write the words "Breast milk is a sugar-sweetened beverage," the fact that babies are consuming breast milk lactose is not at all what Taubes was talking about. Nor was he talking about the fructose in strawberries (or if he was, he certainly doesn't make that clear).
The fact is that there's a big difference in the way our bodies handle naturally-occurring sugar and the way they handle extracted sugar, like high fructose corn syrup and the old fashioned kind of sugar, which is manufactured from beets and sugar cane. But Taubes glosses over this. He tells us why he thinks the fructose (and also possibly glucose) molecules in sugar and HFCS are so toxic. In short, here's his explanation:
It very well may be true that sugar and high-fructose corn syrup, because of the unique way in which we metabolize fructose and at the levels we now consume it, cause fat to accumulate in our livers followed by insulin resistance and metabolic syndrome, and so trigger the process that leads to heart disease, diabetes and obesity.What Taubes doesn't tell us, however, is why those same fructose molecules in fruits are different. Had he mentioned that most sugars found in nature come packaged with things such as fiber or fat, which serve to fundamentally change the way our bodies metabolize them, readers might not be so confused.
Taubes' article only uses the word fiber once and even then in passing, even though fiber is part of the critical mechanism for making a bowl of strawberries a decent breakfast choice and a strawberry flavored popsicle a pretty bad one. A perfect example of the sugar divide is beets. By eating them, we're getting more or less the same sugar molecules used in glazed doughnuts (about half of the sugar Americans consume comes from sugar beets, which are a different breed than the beets you buy at the supermarket.) But no one ever suggests that eating beets is a bad idea. That's because they're a whole food and their sugar comes with fiber, magnesium, potassium, vitamin C and all kinds of antioxidants and phytonutrients.
In an email to BNET, David Katz clarified his comments, suggesting that he probably would still have written his rebuttal even if Taubes had done a better job of tackling the horrible imprecision of the word 'sugar.' Katz says his big problem with Taubes' argument is the way it reduces all of our diet problems to just one thing, leaving other potential demons off the hook. According to Katz, this type of single nutrient approach plays right into the hands of the food industry:
Give the food industry just one nutrient to focus on, and they will be glad to oblige. There are always new ways to tweak junk food! We got low fat junk food. We got low carb junk food. Why not fructose-free junk food? I can see the multi-gazillion dollar line of 'Taubes/Lustig approved' foods with 'No Fructose!' prominent on the front of pack.Image by Flickr user rockamandy