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Two scientists present their views on corn syrup.
Since coming to a head in 2004, the highfructose corn syrup crisis and its role in theemergent obesity epidemic has faced unwaveringdenial from the food industry; yet the05efforts to defend the additive on scientificgrounds have been dubious at best. We are allfamiliar with the pitiful syllogism: corn syrupcomes from corn, and corn is natural; cornsyrup, therefore, is natural. However true this10may be, it provides no proof whatsoever asto corn syrup's safety for human consumption.Solanine, for example, is easily extractedfrom potatoes, and while harmless in smalleramounts, once concentrated it becomes a15potent and potentially deadly neurotoxin.But I digress. Let us not look to the sourceof corn syrup to determine its nutritionaldemerit, but turn instead to its direct metaboliceffects on our bodies.20Under ideal circumstances, the vastmajority of sugar in our blood is derivedfrom starch, which is broken into glucosebefore being released to the bloodstream.Glycolysis is the name applied to ten25sequential chemical reactions that allow usto either liberate energy from glucose, ortransform it into fats for storage in adiposetissue. Gluconeogenesis, meanwhile, is anopposite process in which glucose is derived30from non-carbohydrate substances, and aclose and efficient regulation of the balancebetween glycolytic and gluconeogenicprocesses in response to the changingconcentrations of glucose in the blood is35necessary for the maintenance of healthfulhomeostasis.By far the most critical point in this regulationoccurs at the third step of glycolysis: inthe hormonally-controlled phosphorylation40of fructose-6-phospate into fructose-1,6-bisphospate. When glucose is abundant,pancreatic insulin induces the forwardglycolytic catalysis of this reaction, allowingthe production of fructose-1,6-bisphospate,45which in turn is cleaved into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.When glucose is scarce, pancreaticglucagon blocks glycolysis, and inducesthe gluconeogenic production of fructose-506-phosphate, which is subsequently isomerizedinto glucose-6-phosphate, and releasedinto the blood.The primary problem, therefore, withderiving major amounts of dietary sugar55directly from fructose rather than fromstarch lies in the fact that the degradation offructose—which, upon entry into the cell,is split immediately into dihydroxyacetonephosphate and glyceraldehyde—completely60bypasses the first four steps of glycolysis,including the most critical regulatory reactionin the entire process. Thus, how ourbodies handle the usage of fructose is utterlydissociated from the hormonal controls65of insulin and glucagon, which, over time,invariably predisposes one to obesity, diabetesmellitus, and a host of other dangerousmetabolic disorders.
The media frenzy and public outcry70that have surrounded the use of high fructosecorn syrup as a food additive are asunfounded as the similarly nonsensicalindignations that erupted in response to theadvent of commercially available genetically75modified crop seeds. Despite ongoing proofthat genetically modified crops are not onlyperfectly safe for consumption, but that theyhave in fact saved an estimated 600 millionpeople from starvation over the past two80decades, fears and skepticism toward thempersist simply because they are popularlyperceived as "unnatural," and thus, somehow,unhealthy.These same misguided apprehensions85have been at the forefront of the crusadeagainst high fructose corn syrup. Yet, in reality,the process of producing corn syrup isstrikingly similar to the carbohydrate metabolismthat occurs naturally within the human90body. First, corn starch is broken down intoglucose by bacterial amylase enzymes, andglucose is subsequently converted to fructosevia glucose isomerase. Overall, the recipeis hardly as sinister as its opponents would95have us believe.We must acknowledge, of course, thatresearch has identified several serious healthrisks associated with the chronic overconsumptionof sugar, and perhaps of fructose100in particular. These risks, however, are by nomeans limited to foodstuffs containing highfructose corn syrup. Depending on the formula,corn syrup contains between 42% and55% fructose by volume. For comparison,105cane sugar, honey, and agave nectar—threepopular sweeteners touted as "natural", andtherefore, more healthful—contain 50%,52%, and 85% fructose, respectively. Thus,while it is true that fructose should be consumed110only in moderation, the singling outof products that contain high fructose cornsyrup is not merely insufficient action to curbthe fructose-associated obesity epidemic inour country, it's also patently misleading to115consumers.
1. What is the primary purpose of lines 12-15 ("Solanine . . . neurotoxin.")?
2. As used in line 16, the word "digress" most closely means
3. According to lines 37-52, bodily regulation of glucose levels is best summarized as
4. The author of passage 1 most directly suggests that the long-term consumption of fructose will lead to
5. Which option gives the best evidence for the answer to the previous question?
6. As used in line 81, the word "persist" most closely means
7. The author of passage 2 most likely uses lines 102-108 ("Depending . . . respectively") in order to
8. It can most reasonably be inferred that the two authors would disagree with those who declared a food to be healthy simply because it is
9. Which option gives the best evidence for the answer to the previous question?
10. The authors of Passage 1 and Passage 2 primarily analyze examples from what general areas to make their respective cases?
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