You’ve likely seen the advertisements promoting the idea that corn syrup is the same as sugar. There is a difference - high fructose corn syrup (HFCS) has a slightly higher quantity of fructose than do traditional cane or beet sugars.
But the big downside of HFCS isn't that it is much less healthy than regular refined sugar (sucrose) - the truth is the body processes them in a similar way. The real downside is that since HFCS is so cheap, it is widely used: it's a primary ingredient in soft drinks and often hidden in processed foods including salad dressings and ketchup, jams, jellies, ice cream, bread and crackers. In short, it is one of the biggest sources of calories in the American diet, and serves as a "marker" for identifying cheap, processed, unhealthy foods of all kinds.
Regular consumption of HFCS, in fact the regular consumption of any sugar, may contribute to obesity, which in turn is a risk factor for several types of cancer and diabetes. In my opinion, HCFS is definitely bad for you and should be avoided - read food labels carefully and minimize your consumption of items that list HFCS as an ingredient. Also be aware that the Corn Refiners Association wants to rename HFCS as “corn sugar” - if this is approved, you will need to look out for that term on food labels as well.
Learn more about different types of sugar, all of which should be consumed in moderation.