carbgrrl · 7 Feb 2010

Low-hanging fructose

Simon Phipps often feeds me tidbits — intellectual rather than gustatory — having to do with nutrition. Recently he recommended I watch a lecture by Dr. Robert Lustig of UCSF in August of last year, called Sugar: The Bitter Truth.

This lecture is really better described as a call to action with biochemistry diagrams. Lustig argues that fructose is an evil that’s been behind the rise in obesity and metabolic syndrome of the last few decades; that soda, juice, and sports drinks loaded with sucrose or HFCS are the single biggest factor in childhood obesity (his specialty); and that we had better start treating fructose as the chronic hepatotoxin it is and stay the heck away from it. I agree.

The lecture series is called Current Controversies in Nutrition: Letting Science Be the Guide. Well, yeah — what other guide have they been using all this time, for goodness’ sake? You know, I started my series admitting a worry about looking like a loon…no more. Richard Nikoley, primal blogger extraordinaire, often talks about Modern Ignorance and the ways in which supposed experts tie themselves in knots because of broken preconceptions about stuff we used to understand instinctively. (Richard blogged this lecture, and also another I’ll touch on here sometime soon…) It sure looks like Lustig is emerging from a cave of institutional ignorance, blinking — and pissed off. Good.

Lustig’s obsession with fructose probably doesn’t give an accurate picture of all the factors in play. He seems to think glucose is just fine to consume in whatever quantity — it’s the “energy of life”, he says (around 1:26:00) — and so I suspect he’s misguided about the evils of spiking one’s insulin over and over, in addition to spiking one’s triglycerides. Remember that the glucose that feeds our brains and bodies can be made from practically any old thing lying around, as I’ve discussed before. And in GCBC, (The Great) Gary Taubes discusses the pernicious effects of eating fructose and glucose in combination:

Because sucrose and high-fructose corn syrup (HFCS-55) are both effectively half glucose and half fructose, they offer the worst of both sugars. The fructose will stimulate the liver to produce triglycerides, while the glucose will stimulate insulin secretion. And the glucose-induced insulin response in turn will prompt the liver to secrete even more triglycerides than it would from the fructose alone, while the insulin will also elevate blood pressure apart from the effect of fructose. [GCBC, Ch. 12, p. 201]

I have a couple of other quibbles (I’m not sure Lustig’s lust for fiber is entirely warranted), but it’s absolutely worth watching if you care about this stuff.