Der Lustige Lustig

[kirisutogomen]

A couple of years ago a pediatrician named Robert Lustig suddenly became famous due to the popularity of a 90 minute video of a lecture he gave.

I find myself rather disappointed at the credulity with which many people who really ought to know better respond to this sort of thing. Maybe I'll discuss that later.

I've been meaning for at least a year now to sit down and explain the problems with some of the wacky claims he makes. I have now concluded that I'm probably never going to get around to really doing that. A colleague pointed me at a reasonably good critique, and although it is somewhat narrower than what I had intended, it seemed like an adequate substitute for actually going off on a tirade. To try to round it out I poked around and found another critique that somewhat complements the first one.

The Bitter Truth About Fructose Alarmism is a sober, thoughtful criticism of Lustig's claims. Alan Aragon mostly focuses on Lustig's misuse of the clinical evidence. The striking thing to me is the incredibly elementary nature of Lustig's errors. These are the sorts of things that I would have thought would get your tenure revoked.

Wait A Minute, Lustig. is also a fair, nuanced analysis that focuses more on Lustig's very poor knowledge of biochemistry. It is somewhat disturbing to hear that a tenured professor at a well-regarded medical school fails at organic chemistry.

So what's the larger lesson? Well, for starters, if someone is making grandiose claims, like that something everyone in the world ingests is actually a poison, that should be a signal to approach with greater skepticism. Even without that, we ought to be able to pick up on this stuff ourselves. None of the falsehoods mentioned in either of the linked blog entries are terribly sophisticated errors. This is basic stuff, people.

Comments

[psychohist.livejournal.com]

I read the Feinman response so far. While many of his criticisms of Lustig are valid, he makes some errors of his own. To start with the simple one, while the first ingredient in pop tarts is flour, his later claim that it's the main ingredient is questionable, because the second, third, fourth, and sixth ingredients are all sugar.

Lustig is correct that ethanol and fructose share much of their metabolic pathways in the liver. He does omit that these pathways can store glycogen instead of fat, but as Feinman points out, neither fat nor glycogen is inherently good or bad. Feinman seems to making an incorrect assumption here that chemical differences necessarily preclude the sharing of metabolic pathways.

The reason fructose isn't as bad for us as alcohol is because we have evolved a special mechanism, the hepatic portal, to shunt fructose directly to the liver and avoid exposing the rest of the body to it. Lustig ignores this, but Feinman ignores that it's necessary for our well being.

Overall, I think Feinman is making mistakes that reflect the fact that he's a biochemist rather than a biologist; they aren't the same thing. Lustig's errors can probably be attributed to the fact that he's a doctor, not a scientist, and those two aren't the same thing either.