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Because this has come up twice in the last few days, here's a quaint introduction to the different kinds of sugar (glucose, lactose, sucrose and fructose) from

Because this has come up twice in the last few days, here's a quaint introduction to the different kinds of sugar (glucose, lactose, sucrose and fructose) from a movie called "That Sugar Film". https://www.facebook.com/watch/?v=344221859759175 https://www.facebook.com/watch/?v=344221859759175 (Apologies for the FB Video link, the exact excerpt isn't on Youtube). tl;dr: - Glucose good in reasonable intake - Same for lactose (unless you're intolerant) - Sucrose (i.e. table sugar) is 50% Glucose and Fructose - Frutose is bad. Longer version: Fructose is naturally quite rare, and presumably we've adapted to that; our bodies can only process small quantities effectively. It's also the sweetest and (implied?) most addictive of the sugars. These days we can manufacture it though, so it turns up in just about every sweet processed food it can. EDIT: After watching the lecture linked by sul_tasto below (https://news.ycombinator.com/item?id=29849184 https://news.ycombinator.com/item?id=29849184) it seems it's just a question of fructose quantity and prevalence rather than the body processing it differently from other sugars.

hsn915 5y ago
Fructos is plentiful in fruits which we must have been well adapted to consuming. I don't understand the argument against fructose. It seems to mainly "the liver has to work to digest it", but isn't that true of a lot of other nutrients as well? I mean, that's the main function of the liver, so the fact that fructose engages the liver should not by default imply that it's bad.
- Ygg2 5y ago
  The claim is, fructose is processed by liver biochemically similar to ethanol. Except it affects insulin levels. Rather than the brain.
- vkk8 5y ago
  My thoughts exactly. I remember reading about some indigenous tribes in Africa whose diet is mostly just fruits. You could maybe make an argument that the fruits we consume now are a result of hundreds of years of selective breeding and contain much more of it than indigenous plants.
  - inglor_cz 5y ago
    Raw natural fruit is more than 90 per cent not-fructose. Probably more than 95 per cent, given that it wasn't bred for centuries to increase sweetness. This vast majority of not-fructose plays a great role in the overall digestion process. Fructose is refined product. These tribespeople do not eat refined fructose, they eat fruit which is much more than just fructose.
- forkerenok 5y ago
  From that same video linked by the parent post (https://youtu.be/dBnniua6-oM https://youtu.be/dBnniua6-oM). I watched it a while ago, so in my own words: The key is fiber. When you eat fruit, you consume fructose with fiber. Fiber hinders absorption of fructose. Many processed foods have a lot of fructose and no fiber, because fiber doesn't help the shelf life. EDIT: here's a more expanded explanation from the same endocrinologist in another video https://www.youtube.com/watch?v=-s5szfPYKY4&t=4924s https://www.youtube.com/watch?v=-s5szfPYKY4&t=4924s
- inglor_cz 5y ago
  As usual in biochemistry, it is the dose that makes the poison. But also mode of consumption. We are indeed well adapted to consuming fruit. Even though modern fruit is bred to be much more sugary than its natural predecessors (ever tried eating a wild apple from a tree on a hike? Insanely sour), there does not seem to be any kind of health problem associated with consumption of raw fruit. We have a lot of metabolically sick people around the world - over a billion probably - but few of them, if any, have gotten to that point by eating too much fruit. Fructose is not fruit, though. Even very sweet fruit like mango has only 16 per cent of fructose per weight. Fructose itself is 100 per cent, it is refined, concentrated stuff, from which all fiber has been removed. Fiber that naturally occurs in fruit and veg slows down processing of fruit and veg in the digestive system - it takes fairly long (hours) to extract all the fructose from an eaten piece of fruit. As a result, the liver isn't overworked - it receives manageable quantity of fructose over a long period. Now compare a situation when you drink a litre of sweetened beverage. That is a lot of fructose - you just drank an equivalent of seven? eight? apples in half an hour or so. And all that sugar comes in liquid form, so it enters your blood very fast, producing a huge spike. The liver is overwhelmed. It can cope somehow, but do this ten thousand times and some negative outcomes are bound to follow. There is a scientist (Robert H. Lustig, professor of endocrinology at UCSF) who, more than a decade ago, published a long video called "Sugar: The Bitter Truth". It is stuffed with various biochemical observations and longish, but I found the information useful. https://www.youtube.com/watch?v=dBnniua6-oM https://www.youtube.com/watch?v=dBnniua6-oM
  - hsn915 5y ago
    Ok but this does not only apply to fructose. It applies equally well to glucose and fat/oil. Anything in excess can had dire consequences, including a lot of vitamins and minerals. Even water in excess can be bad for you. When the messaging is centered around "carbs are bad" or "fructose is bad" it will lead people to believe that fruits are bad for you. I've seen several health channels on youtube recommend not eating more than the equivalent of one apple per day in terms of fruits.
    - inglor_cz 5y ago
      Glucose can be processed by every single cell in human body. I don't think you can eat or even drink so much glucose that you overwhelm the capabilities of the entire body to cope with it. You will vomit sooner than that. While people can and do consume excessive amounts of fat/oil, we are somewhat protected by the fact that fat has a very strong satiating effect, which makes it a little harder to completely pig out. Fructose has no satiating effect at all. Generally, yes, anything in excess has dire consequences, but in some things those consequences manifest sooner than in others. Sweetened beverages as consumed today are very much a definition of excess: big packaging, a lot of sugar within, and their mass consumption is societally normalized.
- vixen99 5y ago
  You're right about the liver but as ever the question as to whether something is bad for us comes down to how much we consume. Apple seeds along with a number of other fruits contain amygdalin which breaks down to cyanide. So there's cyanide in apple juice but we'd have to drink several tens of liters of the stuff to reach anything approaching a lethal dose. We can handle small amounts of cyanide. Similar story with fructose, admittedly on a rather different level. However the dangers are real. Robert Lustig explains the issue here: https://robertlustig.com/fructose2/ https://robertlustig.com/fructose2/ and this [ https://journals.physiology.org/doi/pdf/10.1152/physrev.00019.2009 https://journals.physiology.org/doi/pdf/10.1152/physrev.0001... ] provides a readable account of the problem if fructose consumption rises above a certain level.
- sfjailbird 5y ago
  Fruit used to be available only for a month or so of the year.
maltalex 5y ago
> Glucose good in reasonable intake > Sucrose (i.e. table sugar) is 50% Glucose and Fructose > Frutose is bad. So would substituting sugars with Dextrose powder (i.e. 100% Glucose) make sense? Dexterose powder is widely available and isn't expensive.
- cout 5y ago
  IIRC fructose is perceived as roughly twice as sweet as glucose, so you would need to use more sugar if you used glucose; I'm guessing that would be more expensive, otherwise HFCS would be less economically sensible.
  - maltalex 5y ago
    So it wouldn't make sense for many commercial products, but why aren't health conscious people using it at home to sweeten their tea? Also, why aren't there "premium"/"healthy" products using glucose instead of plain old sugar as a selling point?
lordnacho 5y ago
Does it say anything about artificial sweeteners?
DavidPiper 5y ago
EDIT2: (now that I've watched the whole lecture) Already covered by inglor_cz, but for posterity, the first EDIT is incorrect - in addition to quantity problems, Fructose and Glucose are processed very differently in the liver. Fructose impact on the liver is much more like Alcohol than Glucose.

hsn915 5y ago

Fructos is plentiful in fruits which we must have been well adapted to consuming. I don't understand the argument against fructose. It seems to mainly "the liver has to work to digest it", but isn't that true of a lot of other nutrients as well? I mean, that's the main function of the liver, so the fact that fructose engages the liver should not by default imply that it's bad.

Ygg2 5y ago
The claim is, fructose is processed by liver biochemically similar to ethanol. Except it affects insulin levels. Rather than the brain.
vkk8 5y ago
My thoughts exactly. I remember reading about some indigenous tribes in Africa whose diet is mostly just fruits. You could maybe make an argument that the fruits we consume now are a result of hundreds of years of selective breeding and contain much more of it than indigenous plants.
- inglor_cz 5y ago
  Raw natural fruit is more than 90 per cent not-fructose. Probably more than 95 per cent, given that it wasn't bred for centuries to increase sweetness. This vast majority of not-fructose plays a great role in the overall digestion process. Fructose is refined product. These tribespeople do not eat refined fructose, they eat fruit which is much more than just fructose.
forkerenok 5y ago
From that same video linked by the parent post (https://youtu.be/dBnniua6-oM https://youtu.be/dBnniua6-oM). I watched it a while ago, so in my own words: The key is fiber. When you eat fruit, you consume fructose with fiber. Fiber hinders absorption of fructose. Many processed foods have a lot of fructose and no fiber, because fiber doesn't help the shelf life. EDIT: here's a more expanded explanation from the same endocrinologist in another video https://www.youtube.com/watch?v=-s5szfPYKY4&t=4924s https://www.youtube.com/watch?v=-s5szfPYKY4&t=4924s
inglor_cz 5y ago
As usual in biochemistry, it is the dose that makes the poison. But also mode of consumption. We are indeed well adapted to consuming fruit. Even though modern fruit is bred to be much more sugary than its natural predecessors (ever tried eating a wild apple from a tree on a hike? Insanely sour), there does not seem to be any kind of health problem associated with consumption of raw fruit. We have a lot of metabolically sick people around the world - over a billion probably - but few of them, if any, have gotten to that point by eating too much fruit. Fructose is not fruit, though. Even very sweet fruit like mango has only 16 per cent of fructose per weight. Fructose itself is 100 per cent, it is refined, concentrated stuff, from which all fiber has been removed. Fiber that naturally occurs in fruit and veg slows down processing of fruit and veg in the digestive system - it takes fairly long (hours) to extract all the fructose from an eaten piece of fruit. As a result, the liver isn't overworked - it receives manageable quantity of fructose over a long period. Now compare a situation when you drink a litre of sweetened beverage. That is a lot of fructose - you just drank an equivalent of seven? eight? apples in half an hour or so. And all that sugar comes in liquid form, so it enters your blood very fast, producing a huge spike. The liver is overwhelmed. It can cope somehow, but do this ten thousand times and some negative outcomes are bound to follow. There is a scientist (Robert H. Lustig, professor of endocrinology at UCSF) who, more than a decade ago, published a long video called "Sugar: The Bitter Truth". It is stuffed with various biochemical observations and longish, but I found the information useful. https://www.youtube.com/watch?v=dBnniua6-oM https://www.youtube.com/watch?v=dBnniua6-oM
- hsn915 5y ago
  Ok but this does not only apply to fructose. It applies equally well to glucose and fat/oil. Anything in excess can had dire consequences, including a lot of vitamins and minerals. Even water in excess can be bad for you. When the messaging is centered around "carbs are bad" or "fructose is bad" it will lead people to believe that fruits are bad for you. I've seen several health channels on youtube recommend not eating more than the equivalent of one apple per day in terms of fruits.
  - inglor_cz 5y ago
    Glucose can be processed by every single cell in human body. I don't think you can eat or even drink so much glucose that you overwhelm the capabilities of the entire body to cope with it. You will vomit sooner than that. While people can and do consume excessive amounts of fat/oil, we are somewhat protected by the fact that fat has a very strong satiating effect, which makes it a little harder to completely pig out. Fructose has no satiating effect at all. Generally, yes, anything in excess has dire consequences, but in some things those consequences manifest sooner than in others. Sweetened beverages as consumed today are very much a definition of excess: big packaging, a lot of sugar within, and their mass consumption is societally normalized.
vixen99 5y ago
You're right about the liver but as ever the question as to whether something is bad for us comes down to how much we consume. Apple seeds along with a number of other fruits contain amygdalin which breaks down to cyanide. So there's cyanide in apple juice but we'd have to drink several tens of liters of the stuff to reach anything approaching a lethal dose. We can handle small amounts of cyanide. Similar story with fructose, admittedly on a rather different level. However the dangers are real. Robert Lustig explains the issue here: https://robertlustig.com/fructose2/ https://robertlustig.com/fructose2/ and this [ https://journals.physiology.org/doi/pdf/10.1152/physrev.00019.2009 https://journals.physiology.org/doi/pdf/10.1152/physrev.0001... ] provides a readable account of the problem if fructose consumption rises above a certain level.
sfjailbird 5y ago
Fruit used to be available only for a month or so of the year.

maltalex 5y ago

> Glucose good in reasonable intake > Sucrose (i.e. table sugar) is 50% Glucose and Fructose > Frutose is bad. So would substituting sugars with Dextrose powder (i.e. 100% Glucose) make sense? Dexterose powder is widely available and isn't expensive.

cout 5y ago
IIRC fructose is perceived as roughly twice as sweet as glucose, so you would need to use more sugar if you used glucose; I'm guessing that would be more expensive, otherwise HFCS would be less economically sensible.
- maltalex 5y ago
  So it wouldn't make sense for many commercial products, but why aren't health conscious people using it at home to sweeten their tea? Also, why aren't there "premium"/"healthy" products using glucose instead of plain old sugar as a selling point?

lordnacho 5y ago

Does it say anything about artificial sweeteners?

DavidPiper 5y ago

EDIT2: (now that I've watched the whole lecture) Already covered by inglor_cz, but for posterity, the first EDIT is incorrect - in addition to quantity problems, Fructose and Glucose are processed very differently in the liver. Fructose impact on the liver is much more like Alcohol than Glucose.