Hacker News Reader

Comment by tferris | Hacker News Reader

I don't get it: he claims that sugar is bad because the fructose in sugar is bad leading to dozen disease including diabetes. But fructose is is the core of many fruits which are considered as healthy.

Nutrition/metabolism is still a black box and this video confuses more than it clarifies.

View on HN

Well, it is important to note that society has often been incorrect about what things are healthy or not; so I think one should always be careful about the way things are 'considered' (not that I am arguing against fruit). If you check out some of Dr. Lustig's other work you will see he states fiber is the main reason fruit is not as 'dangerous' as fructose outside of fruit. Obviously all fruits are not the same either (in terms of amount of fructose and other characteristics).

"But fructose is is the core of many fruits which are considered as healthy."

No, the core of many fruits considered healthy is FIBER(mainly cellulose) . We do not metabolize fiber but fiber has three important effects on us:

1) It is "in between" the sugar, lowering the effective concentration of sugar on blood. When you drink sodas all the sugar goes to the blood in a very short amount of time, this creates emergency responses on the blood control systems:

Biological control systems are very similar to PID controllers(we copied them from nature), with things like overshooting happening.

http://en.wikipedia.org/wiki/Overshoot_%28signal%29

This is the reason a lot of tennis players eat bananas now in between the game.

2) Fiber creates an environment to bacteria on our intestines to live. This bacteria flora helps us a lot in a lot of ways.

3)Fiber makes easier to transport waste as it hydrates.

This of course is an oversimplification, but you get the idea.

He's talked about fructose in fruits before. It's the presence of fiber which makes the difference. Fiber alters the chemical process some way (he does explain it though). It's also why he's dead against fruit juice, even if they are made from 100% real juice. It's fructose without the fiber.

Also worth mentioning that, in addition fiber, fruits have other nutrients. fructose+fiber+vitamins+anti-oxidants+minerals vs fructose+fat+salt .

edit:

Sorry, just to be clear, he explains it in other papers/talks. I know it's at least briefly mentioned in: http://www.youtube.com/watch?v=dBnniua6-oM

Ok thanks, where did he say this about fruit juices? In the same video?

I haven't watched this particular video, but that information is in another of his talks, "Sugar: The Bitter Truth", http://www.youtube.com/watch?v=dBnniua6-oM

Where was the part about fiber? I didn't see it in this video.

Fructose in five oranges: 16g

Fructose in one can of Coke: 39g

Also, fiber in five oranges: 15g

Fiber in a can of coke: 0g

Plus the coke has salt and caffeine in it, so shortly afterwards you'll want to drink more: Another can of coke perhaps?

The sodium (not actually salt – or at least, not sodium chloride) in a coke might make you thirstier, but the caffeine probably won't. While caffeine is a diuretic, studies have not supported the idea that it causes dehydration, and it's generally accepted that the amount of water in coffee (which has a far higher caffeine density than coke) is enough to offset what you lose to its diuretic effects.

You're right. Scratch that evil influence then :)

And there's a lot of stuff to digest in those oranges. I'm full up after one. That's maybe a tsp of sugar.

The world isn't black and white. Just because fruit has some healthy aspects, doesn't mean it can't have bad aspects as well. In fact, different fruits have different ratios of fructose to glucose. So you can't even generalize to just fruits. Unfortunately, evolution seems to have chosen glucose as the sugar that makes us feel full and that can be used directly by the body. Fructose has to be metabolized in the liver and doesn't make us feel full as directly. This was a good bet before we started custom making all our food, because most sugar is sucrose anyway, which is a combination of glucose and fructose. Unfortunately, man can now add only fructose to things and the body hasn't evolved to understand that signal. You are still way better off eating fruit than empty calories, of couorse, that is manufactured food with little nutrients or fiber and lots of calories.

Lots of fruits and vegetables have been bred to change their nutritional content (wild strawberries are 1/3 inch long, etc)

So fruit really isn't 'natural', and it being natural wouldn't mean it was good for you, anyway - fruit evolved as a tempation to animals to get them to help plants distribute seeds - that's it. Plants were selected based on how well their seeds were spread, so they came up with fruits which attracted animals. If they could have come up with versions which hurt the animals a bit, they wouldn't have even known or cared.

Reply on news.ycombinator.com