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!

Is eating fruit really good for us?

Let me begin by saying that although biochemistry, particularly nutritional biochemistry, is a fascinating subject for me, I am not a Biochemist (yet). A lot of what I write comes from the studies of my mentors, what they have written and how it has been explained to me. The chances of my friends, family or anyone else who comes across my blog finding this information published in medical journals, biochemical textbooks or anywhere else for that matter is slim to none - so I'm simply passing the info along on topics that I enjoy and apply to my life.

Here's the lowdown on fruit (fructose):

Lets begin with Sugar is Sugar is Sugar.

This includes fructose... which means it doesn't matter what the source is - be it sugar from fruit, brown rice or cakes and candies. This is a biochemical fact; not a belief.

A lot of people adhere to the incorrect thinking that our body's somehow use a glucose molecule differently, if it comes from different food sources. For instance, the medical profession, registered dietitians and nutritionists alike, think if a glucose molecule comes from whole wheat bread it is somehow treated differently than if it came from a cake or candy item. The glucose molecule will be treated the same by our body no matter where it came from.

What happens once the glucose molecule gets inside our cells is that it will be converted into plaque forming deadly cholesterol as well as the fat we call a triglyceride.

The sugar fructose, found in fruits, will also be converted into plaque-forming deadly cholesterol. Again, this is a fact. For some reason the medical profession thinks that the sugar fructose is somehow better for us, but the facts are that it is transformed into cholesterol and triglycerides faster than glucose.

Claories Calories Calories!

Oh no... The calorie! It amazes me that some people freak out and count calories for everything single thing they eat throughout their day - let alone, some going to the extremes of putting themselves on a strict caloric deficit in their diet in an attempt to lose weight. Not only are they potentially doing irreparable damage to their metabolism, they are starving themselves!

This one of the big dietary myths out there - You HAVE to count calories to lose weight! - but the scientific truth is that the calorie is completely irrelevant in human nutrition. This is a biochemical FACT!

Here's why and here's the real deal on what a calorie is:

A calorie is the amount of heat needed to raise the temperature of one gram of water 1 degree celsius from 14.5 degrees to 15.5 degrees. It's a quantitative heat chemists tool which they use to determine how much heat is given off when you burn something.

I don't think anyone would adhere to the reasoning that when you eat a steak it travels down into your stomach and blows up!

However, that's exactly how a calorie is determined - you'll take a piece of meat or whatever food product - you'll put it in the calorimeter and you'll burn it - you'll turn it to carbon - a heat is released into the water which raises the temperature on the thermometer. So to determine a calorie - it's nothing more than a combustion process.

What does this have to do with human nutrition? Absolutely nothing.

So my point in explaining this is it is a huge dietary myth that you HAVE to count calories to lose weight. This is absolutely false. So STOP the nonsense with the calorie counting already!

However, if we are talking about a person who is a professional bodybuilder looking to get down to a low, single digit body fat % for a competition, the story and demands of a caloric deficit do change... this is neither sustainable or healthy for any extended period of time.

For the avg. Joe (or Mary) this is doing far more harm then good. Pay attention to the types of foods you're eating and your carbohydrate intake and forget the calorie even exists.