I want to talk about corn syrup.
I know, I know. This is a chocolate column. But as a confectioner, I use corn syrup in several recipes, and often get the stink-eye when people see it on the ingredient label along with local cream and organic butter. Without trying to preach or get defensive, I'd like to set the record straight: Corn syrup is not high-fructose corn syrup. They're two different things. And while you certainly don't want to be slugging down cupsful of either of them, there are a few key differences I'd like to point out.
Corn syrup has been on store shelves for over 100 years now; your great-grandmother would recognize it as food (so there, Michael Pollan!). It's used in things like pecan pie, fudge sauce, ganache, lollipops, ice cream and dozens of other recipes intended for home cooks. By contrast, HFCS has only been in wide use since the 70s, and is used solely in high-volume food manufacturing - sodas, cookies, and even crackers and chips; all the stuff on the store shelves that can sit there for months and still be edible. In the short time it's been around, it's made its way into almost every processed food there is - slightly scary.
Corn syrup is made by adding an enzyme to cornstarch that breaks it down into sugars. This is exactly the same way that brown rice syrup, barley syrup, and many other corn syrup alternatives are made: same process, different grain. HFCS undergoes further enzymatic processing, increasing the amount of sweeter fructose, which is then mixed with straight corn syrup to achieve a desired sweetness and/or texture.
Sucrose - table sugar - is made up of one molecule of glucose and one molecule of fructose. Glucose, which is what corn syrup is mainly comprised of, is our main source of energy as humans, and easily processed by our bodies. You could actually go ahead and slug a cupful of it if you were, say, a marathon runner looking for some quick energy; but it would be pretty gross. If you've ever tried a dollop of straight corn syrup, it tastes weird; it's very gooey, but not that sweet. Fructose, on the other hand, is much much sweeter; HFCS is purposefully processed to equal or surpass the sweetness of ordinary table sugar. Since our bodies have a much harder time processing all this fructose, the effects of HFCS on the human body are still being researched.
So Why Use It at All?
Corn syrup is used in home kitchens (and commercial kitchens such as ours) in order to do a few things: it adds body (that lovely stickiness in pecan pie) without adding a ton of sweetness, and prevents crystallization (making it possible for lollipops and caramels to last for a week or two, as opposed to the few days they would sans syrup). Sometimes natural substitutes, like honey or maple syrup, can be used; but they add sweetness and flavor and are less viscous, so the end product will turn out softer and stickier.
The fact is, corn syrup is very useful in home cooking, and not the same thing as HFCS. That doesn't make it necessarily good for you in quantity, and I'm certainly not suggesting you go chug a bottle of Karo straight away; but I wouldn't recommend anyone doing that with honey, or maple syrup, or really anything that should be eaten in moderation. By contrast, I'd recommend avoiding HFCS as much as possible; as many are doing already.
That's the gist of it, but don't take my word for it; I encourage you to go out and do your own research. I'm also guessing there will be a lot of comments on this post, and I just want to urge everyone to keep it clean and on a positive note. We're all on the same team here.
For a great encapsulation of what exactly HFCS is, check out the "Stuff You Should Know" podcast; their episode on HFCS (you can search for it on iTunes) is both entertaining and enlightening.