Comment by admash | Hacker News Reader

Comment by admash | Hacker News Reader

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High-fructose corn syrup is not a misnomer. It is in contrast to ordinary corn syrup which consists almost entirely of glucose along with smaller amounts its oligo-saccharides (e.g. maltose, etc). Corn syrup generally contains no fructose.

To be precise, HFCS-55 is 55% fructose. Commonly used varieties of HFCS include HFCS-42, HFCS-55, and HFCS-90, containing the percentages of fructose indicated by the number, though HFCS-55 is the most commonly used form due to its near-equivalency in sweetness to sucrose.

The amount of free fructose should not be dismissed so readily, as starch requires breakdown into glucose via amylase enzymes, thus "flattening the curve" of its concentration in the blood. Free fructose is rapidly absorbed and the resultant relatively high concentrations induce specific negative effects in the body:

"The activity of fructokinase (KHK) is different from the other hexokinases by virtue of the fact that it induces transient ATP depletion in the cell. The mechanism is due to the fact that fructokinase (KHK) rapidly phosphorylates fructose to fructose-1-phosphate resulting in marked ATP depletion. The activity of fructokinase (KHK) is not subject to feed-back inhibition such as is the case for glucose metabolism, thus the ATP depletion is profound. Since the majority of fructose metabolism occurs in the liver, the effects of this ATP depletion are exerted on numerous important hepatic metabolic processes." (https://themedicalbiochemistrypage.org/fructose-metabolism/)

Furthermore:

"In contrast to the anorexigenic effect of hypothalamic glucose metabolism, the metabolism of fructose in the brain exerts an orexigenic effect. ... Since hypothalamic fructose metabolism bypasses this important regulatory step its metabolism rapidly depletes ATP in the hypothalamus. ... Therefore, although glucose and fructose utilize the same signaling pathway to control food intake they act in an inverse manner and have reciprocal effects on the level of hypothalamic malonyl-CoA." (ibid.)

Which is to say, free fructose promotes hunger while starch/glucose metabolism stimulates satiety.

I think you missed the point, moreover the article you cited actually supports the parent comment (note the italicized sentences).

> However, diets containing large amounts of sucrose, high fructose corn syrup, or fructose alone, overwhelm the ability of the small intestine to metabolize it all and under these conditions a significant amount of fructose is then metabolized by the liver and to a lesser extent by other organs such as skeletal muscle. It should be pointed out that the difference between the amount of fructose available from sucrose obtained from cane or beet sugars is not significantly less than that from corn syrup. Corn syrup is somewhat improperly identified as high fructose corn syrup (HFCS) giving the impression that it contains a large amount of fructose. However, whereas the fructose content of sucrose is 50% (since it is a pure disaccharide of only glucose and fructose), the content in HFCS is only 55% and in many cases is actually only 40-45% fructose. The reason that corn syrup (which is all glucose to begin with) is labeled as HFCS is because the glucose extracted from corn starch is enzymatically treated to convert some of the glucose to fructose. This is done in order to make the sugar sweeter which is why it is particularly popular in the food industry. Therefore, any disorder and/or dysfunction (see below), attributed to the consumption of fructose, can be manifest whether one consumes cane or beet sugar, HFCS, or pure fructose such as in honey and most fruits.

I suppose that depends on what you believe the point is.

The opening assertion was that high-fructose corn syrup is a misnomer. This not a historically accurate statement. Disregarding any erroneous conflation of high-fructose corn syrup with corn syrup (of the only type that existed prior to the invention of what is termed high-fructose corn syrup), high-fructose corn syrup is most assuredly "high" in that it contains a "high" percentage of fructose (40-90%) in comparison with the previously existing corn syrup which contain 0% fructose.

It is spurious to hold to a vague definition of "high" that can only apply to concentrations somewhere in excess of 90%, lest we find ourselves unable to refer to water containing 0.5% lead by weight as having "high" levels of lead.

That said, I concur with the assertion that significant consumption of fructose in any of the commonly available forms, including as a component of sucrose, that do not substantially moderate the rate of its absorption (e.g. such as a dietary fiber-based structural matrix) carry an associated negative health risk.

It is accurate to say that sucrose becomes the equivalent of "HFCS-50" upon contact with the enzymes which line the inside of the small intestine.

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