"while the first ingredient in pop tarts is flour, his later claim that it's the main ingredient is questionable, because the second, third, fourth, and sixth ingredients are all sugar."
The label tells you that I was correct. The ingredients you list add up to 17 g of sugar while there are 38 total grams of carbohydrate.
"Lustig is correct that ethanol and fructose share much of their metabolic pathways in the liver."
He is not correct. They have almost nothing in common. They are both capable of being converted to acetyl-CoA and processed in the TCA cycle but that is true of everything that is subject to oxidative metabolism. The processes by which they get there are completely different. In addition, while ethanol can be processed through alcohol dehydrogenase, at high levels, it is processed through the P450 system. This might sensibly be called detoxification. In other words, ethanol at high concentrations is toxic. No such system exists for fructose.
"the hepatic portal, to shunt fructose directly to the liver and avoid exposing the rest of the body to it"
Whereas the liver is the major site for fructose metabolism, other cells, particularly kidney have fructose metabolism.
I and my colleague have recently published a "perspective on fructose," which is available without subscription at http://www.nutritionandmetabolism.com/content/pdf/1743-7075-10-45.pdf.
Finally, it is not for me to say what my level of expertise is but SUNY Downstate dissolved the biochemistry for some reason (I can't help thinking it had something to do with money) and I am now in a Department of Cell Biology, so I must be a biologist.
Reply to criticisms.
The label tells you that I was correct. The ingredients you list add up to 17 g of sugar while there are 38 total grams of carbohydrate.
"Lustig is correct that ethanol and fructose share much of their metabolic pathways in the liver."
He is not correct. They have almost nothing in common. They are both capable of being converted to acetyl-CoA and processed in the TCA cycle but that is true of everything that is subject to oxidative metabolism. The processes by which they get there are completely different. In addition, while ethanol can be processed through alcohol dehydrogenase, at high levels, it is processed through the P450 system. This might sensibly be called detoxification. In other words, ethanol at high concentrations is toxic. No such system exists for fructose.
"the hepatic portal, to shunt fructose directly to the liver and avoid exposing the rest of the body to it"
Whereas the liver is the major site for fructose metabolism, other cells, particularly kidney have fructose metabolism.
I and my colleague have recently published a "perspective on fructose," which is available without subscription at http://www.nutritionandmetabolism.com/content/pdf/1743-7075-10-45.pdf.
Finally, it is not for me to say what my level of expertise is but SUNY Downstate dissolved the biochemistry for some reason (I can't help thinking it had something to do with money) and I am now in a Department of Cell Biology, so I must be a biologist.