Question About Fructose

Such_Umami

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Let's say I'm running low on liver glycogen, my muscles are also low on glycogen and I'm wanting to replenish these stores to lower my stress state.

I decide to get most of my carbs from fruits which means much of these carbs will be in the form of fructose. I've seen online that they say fructose won't replenish liver glycogen and gets converted into lactate. Is this true?

My main question basically is, can I replenish liver glycogen and muscle glycogen with enough fruit?
 

Hans

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Let's say I'm running low on liver glycogen, my muscles are also low on glycogen and I'm wanting to replenish these stores to lower my stress state.

I decide to get most of my carbs from fruits which means much of these carbs will be in the form of fructose. I've seen online that they say fructose won't replenish liver glycogen and gets converted into lactate. Is this true?

My main question basically is, can I replenish liver glycogen and muscle glycogen with enough fruit?
Fruit is mostly a combination of glucose and fructose. Some of the high fructose fruit include apples and pears which can have up to 70% fructose and low fructose fruits include banana, berries, papaya, grapes, etc. Most fruit is actually around 50/50 fructose glucose.

But whoever said fructose cannot replenish liver glycogen is wrong. Fructose goes straight to the liver when it's converted to glycogen and ATP and CO2. When the fructose bolus is huge and refined there is a lot of fructose hitting the cells. There is thus too much pyruvate to enter the mitochondria fast enough, so some is converted to lactate.
Eating a fruit slows down the absorption rate, which reduces the chance of creating lactate.

The glucose in the fruit will go to muscles where it's absorbed and then stored or oxidized. The muscle also contains GLUT5 transporters which allows for the absorption of fructose.

Fruit is a perfect food for replenishing glycogen stores, both liver and muscle.
 

gaze

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@Hans I know ray said starch is more likely to get converted to lactate because of endotoxin, but if the endotoxin wasn't in the equation, would glucose be less likely than sucrose to turn into lactate, because excess glucose is easier stored as fat while sucrose gets burned off, either through co2 or lactate? I know ray says sugar is less likely than starch to convert to fat, but wouldn't the fat be more therapeutic in acute situations then burning off the excess calories through lactic acid? or am i missing something here
 

Hans

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Eating a fruit? Do you think drinking juice is bad then? Overloading too much fructose at once?
A whole fruit is consumed slower, digested slower and thus the carbs aren't absorbed as fast. But that doesn't mean fruit juice is bad. The body can quite effectively convert some of the fructose in the intestine to glucose and the liver is also very good at converting the fructose to glycogen or energy. 500l=ml of fruit juice contains only 50-60g of carbs, which is about 25-30g fructose, which your body should be able to handle with ease. Also, fruit juice contains polyphenols that improve the utilization and oxidation of the carbs. But regardless of the polyphenols, your body can also handle sugar-fine, as long as you're not consuming it in massive excess together with fat (this is also person-specific).
 

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