Brief rant on high fructose corn syrup

6/07/2014 01:30:00 PM
A sugar cane field, looking a lot like a corn field. Maize has no immediate relatives in the plant kingdom, but is nevertheless a close relative of sugar cane in the same Andropogonae tribe of the same sub-family.
Sarah Kliff has a post today arguing that "Soda is even worse for you than you thought" because a new study found that the sugar used--high fructose corn syrup--is more than 50 percent fructose rather than glucose. These types of posts really annoy me. While the point about the sugar composition is technically true, the headline is unambiguously false: the study did not find any clinically significant difference between the high fructose corn syrup used in sodas and ordinary table sugar.

Some background: there are two types of sugars commonly used in the food industry as sweeteners. One type, called sucrose, is derived from the titular sugar cane plant. This is the white granular stuff you usually think of as sugar, and that you'd find in little packets at your table in a restaurant. However, we can also produce sugar by a nearly identical process on a closely related plant species called maize (colloquially "corn"). Sugar produced from the maize plant is called "corn syrup." Chemically, the two types of sugar are basically identical--both consist of two types of sugars, glucose and fructose, bound together in slightly different ways. The main difference, however, is that while sucrose is almost 50 percent fructose, corn syrup is only 20 percent fructose. Have you ever tasted corn syrup? It's not sweet at all. The sweetness comes entirely from the fructose, of which corn syrup is severely lacking. When President Kennedy embargoed Cuba in 1962, the US lost it's main grower of sugar cane, which forced US food companies to find a cheaper substitute--they chose corn syrup, refining it slightly to increase the fructose proportion to levels similar to those found in sucrose, giving birth to "high fructose corn syrup."

More recently (but not that recent) a series of studies have shown that pure fructose has significantly more adverse health effects than an equal mass of pure glucose. People who substituted, gram for gram, fructose in stead of glucose, gained more weight and had more obesity-related health problems across the board. While not a terribly notable result within the nutrition science community--we were already aware that sugar is harmful for your health, and now we know it's specifically the fructose in that sugar that's the problem--this set off a fire storm in the media, who did not distinguish between "fructose" the subject of the studies, and "high fructose corn syrup" which contains roughly the same amount of fructose as ordinary sucrose. This led to a series of articles falsely claiming that high fructose corn syrup is significantly worse for your health than sucrose, which is simply, totally, absolutely false--both are huge sources of fructose any way you look at it. The established consensus among nutrition experts is that at 55 percent fructose, high fructose corn syrup has no clinically significant differences from ordinary sucrose, because they do not differ substantially in fructose content, and because the body metabolizes them in identical ways.

The study that Sarah Kliff cites estimated, with 95 percent confidence, that the fructose concentration in the high fructose corn syrup contained in sodas is between 57.9 percent and 63.3 percent. That's slightly higher than the previous 55 percent average, but simply not enough of a difference to be clinically significant. For reference, natural fruit juice contains 67 percent fructose.

But there's a broader principle here. The health effect of a higher fructose concentration is actually quite ambiguous, even though we know that gram-for-gram fructose is more harmful than glucose. Think about it: worrying that the sugar in soda has too high of a percentage of fructose is identical to worrying that it doesn't contain enough glucose. But here's the thing: glucose isn't sweet. Also, glucose isn't healthy for you--though not quite as bad per gram, it will still make you fat and still give you all the same obesity-related diseases. The fructose is what makes sugar sweet. The sole purpose of putting sugar in a food product is to get the fructose.

So really, Sarah Kliff's article is comparing apples to oranges (both of which contain higher concentrations of fructose than soda)--the high fructose corn syrup in soda may contain slightly more fructose than an equal mass of sucrose, but it also tastes that much sweeter, meaning soda manufacturers will use less of it to maintain the same amount of sweetness. We are not actually substituting glucose gram-for-gram with fructose, so health implications based on the differences between the two are irrelevant. In fact, many health food companies are now marketing pure fructose as a healthy substitute for sucrose for exactly this reason--eliminating the glucose, without significantly increasing the consumption of fructose, has no effect on the sweetness of your food but does make it healthier (side note: this claim requires unsubstantiated claims about human behaviors: that people won't increase the sweetness of their food beyond what they would have with sucrose).

None of this is to say that high fructose corn syrup is perfectly healthy. It's not, and sugary sodas are a leading contributor to the obesity epidemic in the United States. My point is that it would be so regardless of whether we used high fructose corn syrup or sucrose derived from sugar cane.

P.S. I often here this argument presented as nature versus science, as if sugar derived from sugar cane was natural, while sugar derived from maize somehow isn't. In fact, both are derived from fairly similar plants using relatively similar processes. The fact that sugar cane has "sugar" in the name is merely a linguistic choice made by humans, not evidence that God intended sugar to come from only that plant.
Max 6/09/2014 06:16:00 PM
I'm skeptical of the remark that "sugary sodas are a leading contributor to the obesity epidemic". For one thing, we have excellent tasting non-sugar pop. Unless obese people drink pop to get a sugar high, not just for the taste, you can't really blame the sugar.
Matthew Martin 6/09/2014 06:25:00 PM
From the data I've seen, sugary soda isn't a huge percent of the population's total calorie intake, but is correlated with obesity in the sense that a small number of people drink a disproportionately large share of it.

Regarding the availability of non-caloric sodas, people perceive the taste of non-caloric sweeteners differently: for some, it's basically indistinguishable from sugar, while for others it's fairly bitter and not necessarily a satisfactory substitute.

A third thing to keep in mind is that some nutritionists are theorizing that non-caloric sweeteners may affect eating habits in subconscious ways, which I blogged about here:
Max 6/09/2014 06:47:00 PM
The sugar-free pop of my childhood - using saccharin - was nasty. The stuff today is much better, that's for sure.