Hacker News Reader

Comment by daniel-cussen | Hacker News Reader

A few months ago, I thought that sugar was glucose, and therefore good for the brain. On that basis I would drink two liters of Coke a day for the brainpower. Then, while on this forum, someone posted a link to http://www.youtube.com/watch?v=dBnniua6-oM (Sugar, the Bitter Truth), which let me know that sugar is not pure glucose.

I resolved to find glucose, and I eventually did. I had to go to one of the more industrial neighborhoods in Santiago (I live in Chile) to find it, and after a few trips there I had myself a 55 lb sack of dextrose mono-hydrate, which dissolves in water to form pure glucose.

Now I mix it with water for 250 calories of food for thought per glass or put it in half-liter plastic bottles to drink at school. It's amazing stuff, it's 100% healthy, and it's great for working at hard problems.

View on HN

Step 2 in glycolysis is to convert glucose to fructose. Indeed, you can pretty easily interconvert between all of the monosaccharides.

There is absolutely no reason to believe that your pure glucose is "100% healthy." If anything, glucose is less sweet than fructose, so fructose may compel higher food intake. But if you can religiously dole out 250 kcal of glucose, doing the same with 250kcal of fructose would be nearly biochemically equivalent.

If you watch the video linked in the parent post, it claims/explains that doing the same with fructose would not be equivalent.

If you carefully read my post, where I emphasize that you restrict yourself to 250kcal of either, I think you'll find that we're all in agreement.

The video explains why fructose drives you to eat more (namely, it doesn't fulfill the hormonal role that glucose does). It also states that fructose is more likely to form advanced glycation endproducts, but this is far less important than the hormonal differences.

So from all practical viewpoints, I agree with you. Fructose is way worse! From the most limited perspective (basically, lock someone up and feed them 250kcal of glucose vs 250kcal fructose and don't let them have additional food), they will be very similar.

Step 2 in glycolysis turns glucose 6-phosphate into fructose 6-phosphate. And I'm not convinced that every glucose molecule undergoes glycolysis. According to the MD in the video (minute 45 or so), 80% of glucose gets turned to CO2 and water by the organs in the body before the rest of the glucose even makes it to the liver, where eventually, ~.4% of it turns into VLDL (which is bad for you). You only need a bit of pyruvate (the end product of glycolysis) to get the Krebs cycle going, and then that takes care of the glucose, turning it into CO2 and water, without turning it into fructose in the process. And at no point is there any native fructose involved. And besides, in the video, it says fructose can't be metabolized by the brain.

I'd also like to point out I'm not drinking a shitload of this stuff all at once. The reason I avoid this is to avoid an insulin spike, which would, without question, defeat the purpose of using dextrose.

While correct in some details, yours is an incorrect description of the bigger picture of glucose catabolism. Pyruvate is consumed the TCA (Krebs) cycle, so to say that you only need a "little" is like saying you only need a "little" gas to run your car. Your car runs on gas, consuming it. The Krebs cycle runs on pyruvate, consuming it.

Glucose gets broken down into pyruvate via glycolysis, which is by far the primary way in which you generate pyruvate. This process generates a bit of energy, but the vast majority of ATP is generated during the Krebs cycle, which is where glucose metabolites (namely, pyruvate) get oxidized into CO2 and H20.

To respond more directly to your point: if 80% of glucose is immediately metabolized to CO2 and H20 (I don't recall but I'll take your word), that means that 80% of glucose enters the body, undergoes glycolysis, and then enters the TCA cycle. This means that 80% of the glucose in your body is quickly converted into fructose (yes, F6P). You could easily make this into a pure fructose molecule with a phosphatase (though this doesn't happen in vivo). The upside is that phosphorylated sugars cannot be transported by facilitated diffusion, so F6P will remain intracellular.

Really? Does any one have some scientific references to back up this claim? Is this something people are doing a lot of? I'm not being negative, I just have never heard of this.

Sorry, but that's just extreme foolishness. Glucose makes sense if you're at the Olympics starting a 100m sprint (to win enough money so that you don't need to be that foolish again). Any other time, it's like you're sadistically kicking your pancreas everyday or defibrillating your heart everyday. You are on route to early disability (including blindness/fractures/loss of limbs) and an early grave due to multiple organ failures.

You'd better be hoping science comes through with cheap organ replacement/re-growth therapies soon and that you are rich enough to afford them. In the meantime, you could try common-sense or even some education.

Your liver will happily produce all of the glucose your nervous system needs.

Until it runs out of glycogen and turns to beta-oxidation...

On the plus side, you'll be really sensitive to insulin when you do get some carbs into your system again :) And hey, I just read an article that said lowering insulin levels is the key to the longevity gains resulting from caloric restriction.

As I'm a beginner in this I can't really detect sarcasm in this topic. So basically does the liver produce enough amount of glucose? and depriving the body of glucose is that good or dangerous??

The liver stores long chains of biologically intert glucose in glycogen macromolecules located within hepatocytes. When the body requires more energy, the chains are cleaved and the glucose released into the blood stream. Glucose is essential for life, providing energy for all cellular activities through its conversion to ATP in the citric acid/Krebs/TCA cycle.

Reducing your caloric intake won't kill you and it has been shown in rats that it might even be good for you. Your liver only stores glucose, it doesn't create it (That would violate conservation of energy!).

This thread is talking about artifically spiking your blood suger which will rape your pancreas and eventually lead to diabetes. I wouldn't do it if I were you, but I might consider eating more vegetables and low calorie foods :-)

Fats are an excellent energy source that do not increase blood sugar levels.

Isn't this healthy by the same rationale that fat is unhealthy? Assuming that glucose intake is good because it's what the body transports around as energy (I assume that's the basis on which one would call glucose 100% healthy) sounds a lot like saying eating fat makes you fat. Which, incidentally, the article we're commenting on seems to be refuting.

Just drink some organic orange juice. It's way better for you.

It's certainly better than inorganic orange juice ;)

And get a sensual massage.

Better yet, eat the oranges.

I really, really dig how you think :)

Though glucose is better than fructose, there's still enough credible concern out there about spiking glucose levels and insulin issues that your self-treatment may not be the boon you think it is.

In any case, a lot of formed and powedered candies are almost pure 'dextrose' -- so you don't need to go to industrial suppliers. Just grab some Sweetarts/Lik-M-Aid/PixieStix. (No corn syrup is listed on the ingredients of these, but sometimes 'maltose' is. It's two joined glucose molecules, but I don't know if it splits cleanly to that and only that in the body.)

Reply on news.ycombinator.com