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Comment by gaius | Hacker News Reader

Fruit juice? Does fructose vs sucrose make a difference?

I predict in the coming years we'll start referring to fructose as "bad sugar" and glucose/dextrose as "good sugar".

Sucrose, being a 50/50 compound of the two, thus inherits "bad sugar" from the fructose produced during digestion.

HFCS actually ranges from 29-55% fructose vs. glucose/dextrose (the highest being available in CocaCola freestyle soda machines), and can be better or worse than sucrose, but is generally equivalently bad.

Since dextrose is basically incompatible with acidic beverages and solidified candies, we're not likely to see fructose going away, either as a direct ingredient or as a metabolite.

If natural concentrated sweetener is considered, attempts to replace sucrose and fructose with dextrose-only sources like plain old corn syrup (POCS), rice syrup, and honey, might achieve some fascinating health benefits. Is it possible that we're fat only because we're eating the wrong kind of sugars?

Glucose tastes awful so I wouldn't call it a good sugar.

> Is it possible that we're fat only because we're eating the wrong kind of sugars?

Nope, we are fat because there are many cheap sources of calories, particularly deep fried foods.

The objections to this oversimplified reasoning usually point to the fact that, among other things, there's a documented rise in obesity among animals as well, across a variety of situations (feral rats, lab primates, domestic pets). Lab primates aren't eating out more or getting less PE in schools, which suggests the possibility of an environmental factor[1].

> particularly deep fried foods.

This is a very early-1990s understanding of nutrition. The low-fat recommendations pushed by the USDA and followed to a large degree by American consumers didn't do anything to halt the obesity rise, because excess dietary fat isn't nearly as bad for you as excess processed carbs/sugar.

[1] https://www.livescience.com/10277-obesity-rise-animals.html

Sucrose is one part fructose and one part glucose. Our cells use glucose for energy directly, the liver metabolizes fructose. This similarity of fructose and alcohol is the basis of the whole sugar is a poison. Fruit is fructose, which is probably why we are to be able to metabolize it, but fruit is generally very high in fibre and around the size of a serving or 2. Serving sizes of juice and additive sugars are extremely oversized.

A bit off topic, but if anyone reading through could explain to me why adding fiber to fructose makes it "good" sugar I'd be really interested. I mean, I know that we need fruits and vegetables in our diets. I know that apples and carrots are good for me. I just don't understand why fructose without fiber is bad?

Right now... I just don't drink the soda or sugary drinks at all. But I don't really understand the science behind my decision.

Because I'm eating apples and carrots all the time ???

What people really mean here is that when you consume real fruit, you get fiber, vitamins, other micro nutrients and, yes, fructose. But the quantity of fructose you get is relatively small. When people drink fruit juice, basically all they are getting is the fructose (with water). And you're getting many apples worth at one time. This overloads the liver which starts turning the fructose into fat.

So eating an apple or an orange is fine. Drinking fruit juice is not. Hope this helps

Besides just making it hard to overdose on sugars it also slows down digestion to soften the blow, can even reduce amount absorbed at all.

More info https://intensivedietarymanagement.com/fibre-reduces-insulin...

The fibre in fruit allows a signal to stop eating to be sent to the brain. The fibre doesn't make the sugar good, but you will stop eating when you're sated and so consume less sugar. No such signal is sent when drinking sugary drinks, so it's more likely you will consume more sugar.

Slower intake rate. Much like your liver can metabolize an oz of alcohol per hour in perpetuity (well, until liver cancer sets in) and you won't even get drunk, but trying to drink 100 oz all at once every 100 hours will promptly kill you. So the theory is slapping your blood and insulin system with the equivalent of 20 apples in a single impulse will mess with your insulin levels and fat storage rates much more than slowly sipping it in, by having chunks of apple take hours if not an entire day to digest.

Sipping a glass of apple juice over the course of an entire day would probably be healthier than slamming it in one gulp, however your dentist probably wouldn't approve. Speaking of dentists, scrubbing the flat surfaces of my teeth by grinding carrots for awhile in my mouth should lead to fewer dental issues than soaking my teeth's plaque layer in completely liquid acid and sugar.

There's also the fairly obvious issue that given the choice of 100 grams of apple fructose or 50 grams of fructose plus 50 grams of inactive fiber, obviously the raw fruit will provide fewer calories for a given subjective level of fullness. I know I'm eating junk food when I juice, but sometimes its fun and it certainly is tasty, and it never fails to amaze me how it takes half a bag of produce to generate a cup of juice. Most of the calories in that bag are in my cup of juice. A normal snack for me is a couple carrots, but I can turn five pounds of carrot calories into a (very large) cup and slam it.

Possibly your body can survive having the liquid sugar of 25 apples slammed into it instantly, every day. Certainly we never evolved to eat that way, so if we can handle it without sickness, its just good luck as opposed to evolutionary pressure. Our ancestors digested a lot of citrus very slowly one piece at a time, there was strong evolutionary pressure to thrive eating a piece of fruit per meal.

It's less a matter of making fructose into a good sugar, and more a matter of reducing the bioavailability of it. When you eat a piece of fruit, your body has to break it down in order to get at the fructose, and that takes enough time that you're now competing with your gut bacteria for access to that fructose. When you drink it in a soda, it's much easier to process and you have a significantly higher chance of absorbing it at soon at it enters your small intestine.

While I don't have any hard facts or make any claims about what it does, the idea that fruit juice = fruit is likely inaccurate. Juicing seems to leave behind the fiber and concentrate the sugar. It seems at least plausible that there's a significant difference in the digestion and metabolism of each.

The fruit that they used to have probably didn't resemble what you can go out and buy these days either.

However, I don't think that looking at what humans ate millennia ago is a good indication of what we should do.

God forbid we discover our ancestors used to eat dirt.

Well they obiously had a lot more dirt in their diet by proxy. Fruit and veggies weren't as vigoriously washed as they are now, which is the reason why so many people are B12 deficient.

Not just our ancestors. People still eat it today.

https://www.theguardian.com/world/2008/jul/29/food.internati...

Many animals do, especially clay compounds that absorb toxins.

Even parrots have been observed eating clay soils in the wild.

You are right. I cant remember the link but there was an article I read that drinking fruit juice is not the same as eating fruits with fiber.

Yes.

Fructose loads your liver. Sucrose breaks down into glucose (which can be metabolized by many cells) and fructose (which is only metabolized by the liver). They're both bad when over consumed.

This laid out pretty well in The Obesity Code by Jason Fung (a real doctor).

As I understand it, it's worse still. While glucose can be directly converted to energy, fructose must first be turned into fat, before it can be converted to glucose or ketones.

This fat will be stored in the liver.

The more fat you have in your intestines the more insuline resistance you'll have. Which in the end will screw with the entire body in various ways.

Fructose is mostly turned into glucose and metabolized that way. No need to turn it first to fat. https://en.m.wikipedia.org/wiki/Fructolysis

Fructose alone is even worse than sucrose. Fructose doesn't produce satiety and it's metabolized by the liver in a similar way to alcohol. The difference it makes with fruit is the fiber content which is what satiates and slows down fructose abortion.

Not really. Sucrose is basically one part glucose and one part fructose. I think what matters is the amount of sugars, not the type of sugars.

The way your body metabolizes different sugars is different and certainly important/relevant. The knowledge required to explain these differences is outside the scope of a comment here, but I encourage you to do some research on how different types of sugars are processed by the body.

In brief, current reasoning is that it does make a difference, and fructose is, if anything, worse for the body, metabolically speaking.

> Fruit juice

Coke is better. It has similar sugar levels but has caffeine which seems to be good for you.

Fruit juice with fibre is better, but like most loopholes really you are just fooling yourself. So at least with coke people seem to know it's bad so I'd stick with that.

Then there's coke zero that's better for you than water. (But not for your teeth)

For many consumers (including the USA), Coke has HFCS instead of sucrose.

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