"what is the difference betw high fructose corn syrup & plain corn syrup?"

Sucrose, or table sugar, is made of glucose and fructose, in equal proportions.  It is naturally occurring and easy to digest, but of course high in calories. 

Glucose is what cells use for energy.  Starchy foods (including staples like rice or potatoes or wheat) provide a lot of it for the body. Brain cells in particular use a lot of it.  Corn syrup is mostly glucose.  Its metabolism requires insulin, so diabetics must be careful with any sugar with lots of glucose.  The body converts extra glucose to glycogen, as energy storage against later need, and either uses it for energy or converts it to fat if a need doesn’t arise.

Fructose is found in fruits and honey, though not so much in corn.  It doesn’t require insulin for its metabolism, so it is very useful in making sweets for diabetics.  However, cells can’t use it directly, so it is either turned into glucose for immediate metabolism, or turned into glycogen for storage and later use or conversion to fat.

Getting these sugars from their natural sources (potatoes or rice or apples or raspberries) isn’t the sort of diet likely to cause problems.  It is when they are concentrated and eaten in large quantities that a problem arises (namely, blood sugar and metabolic problems, and obesity).

Corn Syrup is starchy.  It contains a lot of glucose, but it isn’t a super-sweet sugar, so it is used to thicken food products, and it is useful in baking to keep cookies moist and so on.

High Fructose Corn Syrup is modified Corn Syrup, where much of the glucose has been converted to fructose, which is much, much sweeter.  The resulting ratio of glucose to fructose varies with the product but it generally ranges from 40 to 90 percent fructose.  Since fructose isn’t usable directly for cell metabolism, it mostly gets converted to glycogen and then to fat. 

The big problem with HFCS (as it is popularly abbreviated) is that it is very, very cheap due to corn subsidies, and since it is also stable and soft, it makes products that taste good and have a long shelf life.  This means that manufacturers use it everywhere, and in some surprising products, such as bread.  Overconsumption of anything is a problem, and HFCS is so ubiquitous that it is hard to avoid overconsumption. 

The warnings (which I do heed - this is a biased answer) are largely due to the rise in obesity and insulin problems that have shown high correlation with increased consumption of HFCS in the United States.  Our family tries hard to avoid bringing products with it in the house, not because small amounts would hurt us, but because it is a good habit, and it keeps me aware of sugars while I shop and cook. 

Regular corn syrup is primarily pure glucose, which is one particular kind of sugar.  They apply an enzyme to convert some of the glucose to fructose.

They do that because sucrose (table sugar) is made up of a glucose and a fructose molecule.  The HFCS with 55% fructose and 45% glucose tastes very similar to table sugar, but it’s easier to pump around than table sugar is.  And because of various subsidies, the corn syrup is cheaper, too.

It’s not clear that glucose+fructose in the form of HFCS is actually any worse for you than a comparable amount of sucrose.  There’s a correlation between the amount of HFCS we eat and obesity, but it might have been because we’re eating too much overall.  We’re eating more HFCS because it’s cheaper, and that’s making us fatter.  

The real problem may be that HFCS is found in highly processed foods, and those are full of other nasty things (preservatives, trans fats, white flour, etc).  So staying away from HFCS is probably a good thing, but only to decrease your total calorie intake and move towards eating more fresh and less processed food.

The other problem with HFCS is more systemic: our agriculture has become so geared to corn production that it’s hard to produce anything else.  It feeds cattle, which aren’t really all that good at digesting it, so they get sick and have to be fed antibiotics.  It’s heavily subsidized, putting farmers who don’t grow corn out of business.

An excellent explanation and indictment of the corn-based agriculture in this country.

Fructose is "fruit sugar" and I think a really horrible sugar in terms of the way your body handles it and how easily your body stores it as fat!!   Regular corn syrup is glucose... the base sugar that your body converts all sugars to before use. 

High fructose corn syrup is just corn syrup with a high concentation of fructose. The reason people use high fructose corn syrup is that it is extermely more sweet that palin sugar and so it cost them less. The problem is fructose, unlike sucrose (table sugar), does not readily convert into energy as sucrose does, but instead gets stored as fat.

, enzymes and vitamins. They increase uric acid, lower pH and interfers with copper metabolism etc.