Fruit Part II (For the super geeks!)

In my previous post, I talked about how once a glucose molecule gets inside our cells, it is converted into cholesterol as well as triglycerides. Well just last week, I was on a forum that I frequent and was having this discussion with some people who were interested in the topic - when in steps a genuine Biochemist telling me I was wrong!

His claim was that he didn't THINK either glucose or fructose can actually be converted to cholesterol in the body, but did agree that both glucose and fructose are converted to triglycerides (fat).

So... being I'm not a biochemist myself, I had to take a step back and let this dude explain himself in super geek terminology that I don't think anyone else in the conversation understood, including myself.

I listened to what he had to say (as best as I could understand it) and as he got deeper into his conversation, he started to think back to his studies and thought... well maybe, just maybe, he was wrong himself!

He then said... hang on just a minute - let me pull out one of my biochem texts and see if I can find the exact answer.

Now based on what I have learned, and how it was explained to me (which was in an easily understood sort of way - not in super geek terms of biochemical pathways that would make the average person's head explode) I knew what I was saying was correct but with my limited knowledge of in-depth biochemistry, I was in no position to put up an argument with him without the absolute detailed facts.

Anyway, he comes back and said - You're right and I'm wrong!

Sweet, I'm thinking to myself - this was like beating a professional poker player, in a heads up match, as an amature, without showing your hand :-)

So here was his reply and this is the exact, factual, biochemical explanation of how fructose converts to cholesterol in the human body:

Found it! Cholesterol can be synthesized from acetyl CoA, which is the intermediate molecule that both fats and sugars are metabolized into before they enter the krebs cycle (where most of the energy is generated). Glucose and fructose can be shunted into a side pathway (as opposed to their usual conversion to acetyl CoA several steps down) called the pentose phosphate pathway, which modulates NADPH levels (a way of carrying protons around the cell for doing certain types of chemistry).

Among the things its used for is one of the major steps in cholesterol synthesis (conincidentally, the same step that statins inhibit). The pentose phosphate pathway, however, doesn't tend to drive NADPH levels up any higher than basal levels for long (NADH and NADPH levels are very tightly regulated by a series of feedback mechanisms), so they're not going to have much of an effect there.

So in short, sugars convert to cholesterol, but so does fat.

Still, I'm always excited to be wrong on something! It's the only way you learn.

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Just what you all wanted to read, right? lol

The bottom line is, fruit is not a necessary or beneficial food group for human consumption - unless, of course, you're looking to raise your bad cholesterol and get fat!

There are plenty of other food sources that provide us all the nutrients and antioxidants our body requires for optimal health. Eat more meat, fat and the right vegetables!