Fructose and the dosage making the poison.

[repoman]

I was watching a video by this guy Robert Lustig about the dangers of excessive fructose from both sucrose or high fructose corn syrup (HFCS).



At about 45 minutes in he starts shows the livers metabolism of glucose, then ethanol and finally of fructose. I can agree that large (or sudden like with soda) doses of fructose will obviously use the fat making pathways and other nasty side effects in the liver.

However, he quickly mentions but then skirts the fact that some of the fructose did end up as glycogen and stored in the liver - especially if the liver is depleted of glycogen. How does that relate to eating a fibrous whole fruit? Is the burst of fructose absorption by the liver slow enough that little citrate leaves the mitochondria to make fatty acids that are shuttled out of the liver on VLDL? Will eating "reasonable" amounts of fibrous whole fruits increase uric acid levels?

 

[Underseer]

Sugar bad. Eat less sugar. It doesn't matter what kind of sugar, eat less of it.

There. That's how much I know about this topic. Uh, the better informed people can probably take the conversation from here.

 

[Musing Man]

Of course he skirts it, that was beside his point. And instances in which hepatic glycogen is completely depleted are extremely rare; far from the general occurrence.

I'm not sure if Lustig himself makes this point (I linked this exact same video several times in the past), or another guy, but the ”fructose menace” is twofold.

First off, the so-called industrial fructose (HFCS) has no fiber content whatsoever, which makes it outright toxic (above a certain low level). And HFCFS is present in virtually any processed food/beverage, often in very high concentrations.
Secondly, almost all of our current-day fruits were selected/modified for a higher level of fructose and a lower level of fibers.

I'm guessing it's the low level of (natural) fibers - which usually mitigate fructose's nasty effects - that links the above into one unifying point.

Now, the liver isn't exactly ”absorbing” fructose, and it generally is processing everything in its yard. Being constantly bombarded with high levels of fructose, the liver takes the shortest possible route in order to get rid of it, producing fatty lipoproteins (your VLDLS). The process is relatively slow, but constant. A higher and prolonged exposure will accelerate it (with visible results on one's waist).

As for the uric acid level, no, fibrous fruits generally reduces it - but then again it very much depends on the fruits of one's choice. HFCS, on the other hand, and also sucrose (table sugar), will definitely increase uric acid levels.

I hope this helped a bit.

 

[repoman]

Thanks, Musing Man

I guess that fully coming to terms with the fact that our current (even before biotech) fruits are so rich in sugars and low in fiber compared to their ancient ancestors is good. Too have a soda and processed fruit juice junkie who may have metabolic syndrome think he can just switch over to eating a massive amount of mangoes, pineapples and bananas is ludicrous. Sure, more vitamins and a touch more fiber, but the sugar onslaught will not be slowed much.

 

[Musing Man]

Well, repoman, everything is complicated but actually simple.

You saw what sugar and fructose are doing to one's immune system, among others. There is no way around that, so who has a sweet tooth will unquestionably pay a price. It might help to remember that the biggest sugar/fructose fan in our bodies is the cancer cell(s) - not neurons, nor any other kind of cell.
And sodas are outright bad for health. But so are processed fruit juices, no matter how ”natural” or ”rich in fibers” their labels say they are; they aren't.

There's a catch with this (relatively) new fiber content in processed foods and (some) beverages. The industry caught the ”fibers are good” idea and is seeking to capitalize on it: it places ”fibers” in anything it can. The catch is that processed fibers are nothing like natural fibers in anything but their name. Their single most notable effect is a slight increase in gas production.

Getting back at fruits, there is one way around the fructose/fiber ratio problem: avoid ripe fruits (or minimize them). Think ”sour is good”. Ditch the fruits that cannot be consumed (easily) while unripe - say, bananas. Stick to fruits that are astringent even when ripe - grapefruits, (some)oranges, pomegranates, (some) grapes, kiwi fruits (also excellent blood thinners) gubbins and, yes, lemons and limes.
Although they belong in another category, I must also mention that pickles are good/beneficial too, but only the brine variety (one should avoid anything pickled in sugared vinegar) and with an eye at the sodium intake.

All the best.

 

[DBT]

Not only processed fruit and vegetable juices. Fresh 'natural' juice still provides a concentrated dose of sugar. The fiber component, which would normally slow absorbtion and not raise blood sugar levels quickly having been removed by the juicing process.