Fructose Questions and Issues / Lustig

Austin

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Feb 6, 2013
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Me: On and off Peat for a little over a year
Build: Tall and pretty thin for entire life, in mid 30s now. Since Peat -> pudgy waistline/gained 15 lbs. I also stopped smoking half a year ago which also probably contributed to the waistline as I'm generally hungrier.

Fructose seems to make me hungry all the time, similar to the effect of alcohol. Lustig says that fructose is treated by the human body the exact same way that alcohol is treated. It is completely processed by the liver and is not sent to any cells. So in effect it appears to be treated like a toxin. Lots of you are far more versed in the field of nutrition than I am. I would appreciate any explanations here as to why Lustig is wrong, if he is, on his theory that fructose is a toxin.
 

Asimov

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Jan 19, 2013
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Lots of nutrients are shuttled to the liver directly out of the stomach, it doesn't make them toxic. Anything small enough to pass through the stomachs parietal cells without processing will go straight to the liver via hepatic portal vein.

Fructose, just like alcohol, probably need a PUFA damaged liver to cause any trouble in that department. The simplest answer would be to double down on saturated fats to mitigate the damage.
 

Mittir

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Feb 20, 2013
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Austin said:
Me: On and off Peat for a little over a year
Build: Tall and pretty thin for entire life, in mid 30s now. Since Peat -> pudgy waistline/gained 15 lbs. I also stopped smoking half a year ago which also probably contributed to the waistline as I'm generally hungrier.

Fructose seems to make me hungry all the time, similar to the effect of alcohol. Lustig says that fructose is treated by the human body the exact same way that alcohol is treated. It is completely processed by the liver and is not sent to any cells. So in effect it appears to be treated like a toxin. Lots of you are far more versed in the field of nutrition than I am. I would appreciate any explanations here as to why Lustig is wrong, if he is, on his theory that fructose is a toxin.

I think most people gain weight once they quit smoking. Sugar increases energy expenditure and this can increase calorie requirement. Fructose repletes liver glycogen storage more efficiently than starch. Body uses these glycogen to keep a steady blood sugar and thus protects against surge in stress hormones like cortisol and fatty acid release. This glycogen storage is more useful during sleep to keep all the nocturnal stress hormones in check. There are tons of health benefits of fructose. Lack of protein and choline can inhibit the body's ability to transport fat from liver . So if you are consuming lot of fructose you have to support that with 80+ grams of protein and good dose of choline ( egg yolks and liver) .

http://blog.cholesterol-and-health.com/ ... yolks.html

Here is a detail article on sugar by Ray Peat.

http://raypeat.com/articles/articles/sugar-issues.shtml
 

key

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Jan 27, 2013
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Fructose doesn't metabolize like alcohol at all.

Ethanol Metabolism
1) Ethanol is oxidized to acetaldehyde via the enzyme alcohol dehydrogenase IB (class I), beta polypeptide (ADH1B)
2)The enzyme associated with the chemical transformation from acetaldehyde to acetic acid is aldehyde dehydrogenase 2 family. Acetaldehyde is a highly unstable compound and quickly forms free radical structures which are highly toxic if not quenched by antioxidants such as ascorbic acid (Vitamin C) and Vitamin B1 (thiamine).
3)The enzyme associated with the conversion of acetic acid to acetyl-CoA is ACSS2
Then acetyl-CoA can go into the citric acid cycle.

Fructose Metabolism
1)phosphorylation of fructose to fructose 1-phosphate by fructokinase, thus trapping fructose for metabolism in the liver. 2)Fructose 1-phosphate then undergoes hydrolysis by aldolase B to form DHAP and glyceraldehydes.
3)DHAP can either be isomerized to glyceraldehyde 3-phosphate by triosephosphate isomerase or undergo reduction to glycerol 3-phosphate by glycerol 3-phosphate dehydrogenase

glyceraldehyde 3-phosphate turns into pyruvate which turns into acetyl-CoA



Also fructose increases metabolism of alcohol, "The mean rate of alcohol metabolism increased by 80% after fructose but there was considerable variation among the subjects, which was related to their plasma fructose concentrations."http://www.ncbi.nlm.nih.gov/pubmed/1854373
 

frustrated

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Austin said:
Me: On and off Peat for a little over a year
Build: Tall and pretty thin for entire life, in mid 30s now. Since Peat -> pudgy waistline/gained 15 lbs. I also stopped smoking half a year ago which also probably contributed to the waistline as I'm generally hungrier.

Fructose seems to make me hungry all the time, similar to the effect of alcohol. Lustig says that fructose is treated by the human body the exact same way that alcohol is treated. It is completely processed by the liver and is not sent to any cells. So in effect it appears to be treated like a toxin. Lots of you are far more versed in the field of nutrition than I am. I would appreciate any explanations here as to why Lustig is wrong, if he is, on his theory that fructose is a toxin.

Lustig's message appeals to people who don't know any better (not trying to be offensive to you here). Watching his video's makes lay people think:

1. The Liver processes toxins, e.g. alcohol.
2. Therefore anything the liver processes is because the substance is toxic, e.g. fructose.

This is just not true. They can't even link fructose to weight gain in the best, most recent, controlled eating trials http://www.ncbi.nlm.nih.gov/pubmed/22351714.

Why you're gaining weight, I don't know. I find that substituting white sugar for fruit is slimming, because of the added nutrients and natural caloric restriction effect.
 

Austin

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Awesome replies guys. This is just what I was looking for, thanks! And no worries, Frustrated. I am probably sub-layman when it comes to biology and nutrition. :blondemoment
 

Austin

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Wellrpp, I took sugar/fructose out of my diet for 3/4 days just as a test. By the last day my mood was in the pits, I felt awful, couldn't focus, yada yada. I ate some mango and drank freshly squeezed OJ/LJ then immediately just felt perfect again. I just won't doubt Peat anymore.

Oh, and Bloomberg was on the news today. I'm pretty sure he's been following a highly limited sugar diet. His face was a mess and he looked truly awful, tired, and sick. Correlation? Maybe it's just the stress of his job.
 

pboy

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I just wanted to say, yes your body does treat excess fructose in the gut like a toxin, and yes it can make you ravenously hungry....but here's why

Fructose is only passively absorbed through the gut in small amounts, over time. To be uptaken rapidly and normally, one molecule of glucose or galactose must be
present to 1 molecule of fructose (the fructose piggybacks the glucose/galactose). Sucrose and most fruits have an ideal 1:1 ratio of glucose to fructose which is why
the fructose taken in those forms doesn't cause trouble. Apple, Pear, Mango, Agave, High fructose corn syrup (main culprits) but also grape, cherry, some berries a little, and honey, have more fructose than glucose, in the case of the apple almost twice as much. So basically the excess fructose might get passively absorbed in small amounts in the gut over time (which is why berries, cherries and grapes are pretty safe) but ingestion of apple, pear, HFCS, agave, honey will cause basically free floating unabsorbable, but bacterial fermentable fructose lingering in the gut. It could feed bacteria and therefore, yes, be (produce) toxins. The reason you get hungry is cause your body desperately wants more glucose/galactose to help absorb the fructose out of the gut....so more fruit or sugar wont curb the craving, but any starch, barley or rice syrup, and even milk if you can digest the sugars in it, will curb the cravings, decrease potential toxins and gas, and drastically increase energy from the fructose being absorbed instead of feeding bacteria and drying your colon out as it holds and pulls water ...causes water retention and eventually a watery stool.

Studies have shown that eating glucose to a point of making the glucose 1:1 with fructose alleviates almost all symptoms associated with it.

Other fruitsthough , mainly drupes and stone fruits have sorbitol and/or other sugar alcohols which can cause issues regardless of the fructose:glucose ratio
 

Kris

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Oct 15, 2012
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pboy, this is very interesting. however, in the case of honey the ratio of glucose to fructose is actually 1:1, same as with sucrose, but because they are not bonded, the body absorbs them much better. one of the tricks for good sleep is to take some honey before going to bed. honey is surprisingly little understood, and seems very beneficial. also it does not seem to elevate triglycerides in the blood like other sugars.
 

Mittir

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Feb 20, 2013
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Kris said:
however, in the case of honey the ratio of glucose to fructose is actually 1:1, same as with sucrose,

I have read in many places that honey has 1:1 glucose fructose ratio.
But this Australian study found several types of honey
with fructose content more than 60 percent and one type of honey
with 65 percent fructose. High fructose honey tend to have lower glycemic index.
http://www.pollination.co.za/downloads/ ... ycemic.pdf
 

Kris

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I think that in nature it is rare that the ratio 1:1 between fructose and glucose. Our body for million of years got used to eating fruits and other natural sugars. From what I read, it is not even fructose alone that causes digestion problems, but excessive amount of fructose can be toxic. I think this is the view of Peat and Andrew Kim as well.
 

freal

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Jun 18, 2013
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pboy said:
I just wanted to say, yes your body does treat excess fructose in the gut like a toxin, and yes it can make you ravenously hungry....but here's why

Fructose is only passively absorbed through the gut in small amounts, over time. To be uptaken rapidly and normally, one molecule of glucose or galactose must be
present to 1 molecule of fructose (the fructose piggybacks the glucose/galactose). Sucrose and most fruits have an ideal 1:1 ratio of glucose to fructose which is why

Isnt galactose, the other sugar besides glucose in lactose alco metabolised by liver over 80%, just like fructose?
 

Spokey

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Mar 24, 2014
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I think if the liver's capacity to synthesis cholesterol is compromised or if there is high PUFA in the tissues, switching to a high fructose diet might not be in your best interests. Particularly not a diet high in refined sugars. But fruit and honey contain many substances that improve the processing and physiological responses to the sugars they contain, so needn't be such a concern.

But then Ray's views on starch vs sugar and fructose are the ones I have some reservations about generally (I hasten to add, that despite that I think he's awesome and his work helped me resolve a lot of my problems).
 
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