In small amounts, HFCS shouldn't be any more harmful than regular sugar. The fructose in HFCS, though modified from glucose, is structurally and in all other ways the same as natural fructose. Additionally, HFCS has nearly the same makeup of fructose and glucose as table sugar (most HFCS has 55 percent fructose, compared to 50 percent found in table sugar). But there does seem to be a connection between the use of HFCS and obesity and type-2 diabetes, so what gives?
First off, that additional 10 percent of fructose content does make a difference in caloric intake, especially since HFCS is found in so many products. Imagine a world in which all sugar has been replaced by HFCS (not a far stretch): You could eat the exact same foods, but you would be consuming 10 percent more sugar.
Unlike glucose, which is metabolized a number of ways by your body, fructose is only metabolized by your liver. When the liver receives more fructose than it can handle, the excess sugars are turned into fats in the form of triglycerides, which are harmful to your arteries and your heart.
There's much to be learned about how our bodies react to fructose, but researchers do know that fructose doesn't stimulate production of insulin, leptin or ghrelin, all of which play a part in telling the body how much it needs to eat [source: Havel]. Without receiving these internal signals to stop eating, it becomes that much easier for us to continue chowing down on that pint of double-chocolate fudge ice cream.
The biggest problem is that HFCS is being added to food items that don't normally have sugar and that you wouldn't even describe as sweet -- crackers, for instance. So, not only are we chugging down lots of sugars with our sodas, but your PBJ sandwich could have HFCS in each of its three ingredients. Meal after meal, day after day, all of this extra sugar adds up, and that, and not necessarily the qualities of HFCS itself, is likely one reason why rates for obesity and diabetes have climbed since the introduction of HFCS. (Other factors are in play as well, such as decreased activity and exercise levels and increased fat consumption.)
So what can we do? Well, for starters, do everything you're already supposed to do. Get regular exercise, watch your fat intake and get regular medical checkups. Next, it wouldn't hurt to mimic the practices of those strange (and rare) individuals in grocery-store aisles who read the labels of the food they are purchasing. Once you get in this habit, you will likely be shocked to learn just how much of your regular grocery purchases contain high-fructose corn syrup. If nearly all of your food contains concentrated sugars, it stands to reason that you'll be eating too many sugars. And if you want to go crazy, eat some fruits and veggies. You'll get all the glucose you need (not much), and these healthier alternatives will take the place of the less healthy foods now flooding our markets and grocery stores.
For more HowStuffWorks articles you might like, from how flavor tripping works to the meaning of the obesity paradox, try the links on the next page.