High-Fructose Corn Syrup - the Controversy

I would hazard a guess that he is referring to a lack of vitamins, minerals, etc. This isn't too surprising since this corn has been modified to produce lots of sugar at the expense of nutritional value. Also, none of the vitamins and minerals from the corn make it into the final product anyway.

From my brief reading on the interwebs it appears that fructose is metabolized differently than glucose. Glucose is directly metabolized in muscle and in mitochondria. Not so for fructose. Fructose is metabolized in the liver."The liver itself has a storage capacity of about 100 grams for fructose, when intake from the diet exceeds this, the liver will start to process this fructose, turning them into triglycerides and releasing them into the blood stream. This in return increases your chances for heart disease so it is definitely something you want to avoid."
Page Not FoundThe same site also adds:"Do note however that one single piece of fruit contains only about 5-8 grams of fructose so fruit consumption is not the major worry here, but rather all those other products, particularly those with HFCS that you need to be watching in the diet."If this is true, then using HFCS is like using an equivalent amount of sucrose AND eating a piece of fruit on top of that. If you drink 2 cans of soda a day that is 40g each of sugar for a total of 80. 5% of 80 is 4 grams, so almost an additional piece of fruit according to the source above.I can dig further, but I would strongly suspect that the liver uses fructose to run the beta-oxidation pathway in reverse and releasing the fatty acids into the blood stream.Triglycerides (if memory serves) are metabolized by the beta-oxidation pathway, quite a different path than the glycolytic pathway. It is worth noting that skeletal muscle is heavily tilted toward the glycolytic pathway while organs such as the heart are tilted towards beta-oxidation of fatty acids. This would explain why triglycerides are higher in the HCFS rat group compared to the sucrose group.I will add more as I read more.

It is the fact that fructose is ONLY processed in the liver. Once Fructose is used to replenish the glycogen stores the rest is used to produce triglycerides which are released into the blood stream. File:Fructose-triglyceride.jpg - WikipediaTriglycerides are a great source of energy for the heart since it mainly uses fatty acid oxidation as its source of energy. However, excess triglycerides are take up by adipocytes and stored as fat, hence fructose caused obesity.Evolutionarily, humans seem primed for fat storage due to our history of a feast-famine lifestyle. Only recently have our extended life spans and sedentary lifestyle become a problem for a metabolism set up for very active and relatively short lived (ca. 45 years) humans.

From further reading it is not true that fructose is ONLY metabolized in the liver. However, it is preferrentially metabolized in the liver. The liver actively takes up fructose, and being that the fructose rich blood from the intestines must first pass through the liver it stands to reason that the liver is an important factor here. Also, from here:

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In normal subjects infusion of fructose (1 g/kg/hr) for 4 hrs resulted in an increase in the glycogen content of the m. quadriceps femoris of 3.3 g/kg wet muscle (muscle samples obtained by needle biopsy). This was equal to the amount of glycogen formed after a glucose infusion of the same magnitude. In muscle depleted of glycogen by exercise, infusion of glucose resulted in twice as much glycogen formed, as did a fructose infusion. Formation of liver glycogen was much higher after fructose than after glucose infusion (liver samples obtained by Menghini biopsy). Studies by hepatic vein catheterization indicated that glucose formation by the liver was insufficient to account for the synthesis of muscle glycogen, which presumably occurred directly from fructose taken up by the muscle.
Just a moment...

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So we see a big boost in glycogen production in the liver with fructose compared to glucose which means that the liver is preferrentially taking up fructose and then feeding into the triglyceride pathway. The question is whether this increase in fructose over an even balance like that with pure sucrose is enough to increase TG levels and subsequent obesity. I understood it just fine. Perhaps you are misunderstanding my posts? The question is how an increase in overall fructose consumption can lead to higher rates of obesity and other health problems.In the OP you linked to a mouse or rat study where they found higher weight gain in the HCFS group compared to the non-HCFS group. The possible mechanism for this is the increased triglycerides produced by the liver in response to increased fructose compared to the control group. Obesity can also lead to increased insulin tolerance which is the cause of type 2 diabetes. I'm not saying that I agree with this conclusion, but it does seem to be the hypothesis that is being put forth.

Wouldn't an increased risk of obesity related illnesses qualify as "harmful"? Or are you asking about acute toxicity? I am not conflating the two. I am clearly talking about an increase in fructose concentrations as compared to pure sucrose. Here is what I said before:

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The question is whether this increase in fructose over an even balance like that with pure sucrose is enough to increase TG levels and subsequent obesity.

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With that I will wholeheartedly agree. I am going to see if there is any solid data to back it up. Like I said, I never agreed with the hypothesis, I only outlined what I thought the hypothesis was.

Don't know, but it is helpful to determine the question before trying to find the answer. No matter the overall intake the fructose fraction of the carbohydrate balance is still going to be higher in HFCS compared to pure sucrose.I would think that intake is variable person to person. There is also the hypothesis that fructose does not trigger the sensation of being sated as well as glucose does so the lower overall concentrations of HFCS may be lost by consuming more of the same beverage compared to the same beverage sweetened with 100% sucrose. I am not saying I agree with this hypothesis, but it is out there.Edited by Taq, : No reason given.

HFCS contains sucrose AND fructose. When the sucrose is broken down into glucose and fructose there is a molar excess of fructose as a total of all sugars. If you ingest just sucrose there are equimolar amounts of both glucose and fructose. The question is whether or not this molar excess of fructose is enough to cause health problems.Edited by Taq, : No reason given.

Quite right. My mistake.Still, HFCS 55 contains 55% fructose and 45% glucose which has a molar excess of fructose compared to the digestion of sucrose into the same components.