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Comment by audunw | Hacker News Reader

I won’t defend Robert Lustvigs position entirely. It’s rather extreme. But I think you need to watch his stuff before trying to criticise it. Glucose is the body’s primary energy source. Yes. But not fructose. (And sucrose, which is what’s commonly referred to as sugar, breaks down to fructose and glucose as you may know). His argument is that fructose is processed by the liver. Hence the idea that it is a kind of toxin (not a “poison” if I understand the terms correctly). Everything can kill you with a certain dose. But some substances are not safe - and will damage your body - with any dose. Alcohol is definitely one of those. Fructose? Maybe. I don’t know enough about biology to tell if Lustvig is wrong or not. I’m on the skeptical side still

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Our close primate relatives seem to eat a lot of fruit. It’s a traditional part of the diet of any human society where it’s available. The idea that fructose is a toxin dangerous at any dosage doesn’t seem remotely plausible.

First, our primate relatives can easily eat a lot of meat and prefer meat if given. They do not have a lot of meat available in wild, but can occasionally eat it in the wild too. When they have meat available, they eat brains (fat) first: https://www.nationalgeographic.com/animals/article/chimpanze...

Second, they ferment fruit because fruit is always slightly poisonous (fructose).

Third, after being close to our primate relatives for some time, our ancestors spent a lot of time hunting, which is not a trait of monkeys we know. They eat more varied meat diet than any predator known, did that for a long time, much longer than (now) we eat crops.

Fourth, we have much higher normal percentage of fat in our body. For men, the normal fat percentage range is from 18% to 22%. Our primate relatives have much less normal fat, for most primates it is less than 9%. Our primate relatives sport bodybuilder's or high performance athlete's fat range just living their life.

As with alcohol, fructose is not a toxin in small doses, because liver can handle it (especially when it is fermented into lactic acid). But it is a toxin in doses we usually experience now. Look for "non-alcoholic fat liver syndrome".

In medicine they say the dose makes the poison.

But in general it's a far more complicated causality chain. When weight gain leads to insulin resistance then sugar is poison. We have lifestyles that maximize both a lack of physical labor and an excess of high sugar foods.

And evolution proves your point as the main difference between our "close relatives" is that our gut is better at digesting richer food (aka meat), which gives us a smaller and more efficient digestive system which freed resources for our big powerful brain.

> Hence the idea that it is a kind of toxin (not a “poison” if I understand the terms correctly)

The way I understand it, poison is an umbrella term that includes toxins, venoms, and chemicals. Its definition is basically "is harmful to living beings", while the other three are specific types/sources of harmful.

Edit: Ended up looking it up, looks like I got poison and toxin backwards. Toxin is the umbrella term.

Lustvig is a crackpot.

https://anthonycolpo.com/sweet-stupidity-part-2-the-bitter-t...

His understanding of what happens to fructose in the liver is fundamentally incorrect.

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