This one is too good just to tweet. One of those gems I mentioned the other day is David Despain's Evolving Health blog. He's been posting quite a bit of late on fructose. His latest: Fate of fructose: Interview with Dr. John Sievenpiper.
It's definitely worth reading the whole thing, but I'll excerpt a few things that address the problems with many of the fructose studies and problems with them, and some nice correcting of Lustig & Co.:
- The 50th percentile for intake in the United States is 49g per day, which is just a little less than 10 percent per day of energy from fructose. ... the 95 percentile for intake for NHANES for fructose consumes 87g of sugar or little less than 20 percent energy.
It seems to me that sugar consumption in the US is often inflated, and the inflation is done by those who seem to have an "crisis agenda" -- by that I mean looking to whip up a crisis for the purpose of enacting legislation or finding a new tax revenue stream. So related to the quote above, Sievenpiper takes issue with the "superphysiological doses" of fructose used in most studies.
- ... animals metabolize carbohydrates differently than do humans. In animals on a high-carbohydrate diet not providing excess energy, you find that de novo lipogenesis [conversion by the liver to fatty acids] is anywhere from 50 percent or higher. ... In humans, it is very, very hard under isocaloric (neutral energy) conditions, let alone in overfeeding conditions, to push that beyond 10 percent or even 20 percent.
Ahh yes good old de novo lipogenesis something we've discussed here pretty much ad nauseum ;-) Just related to carbs in general, hepatic DNL has been shown to be quite a bit lower than even the 10 percent and amounting to only a few grams per day in humans. While it is true that fructose is the most lipogenic carbohydrate, that term has been used out of context (and more recently moreso) by Gary Taubes to infer that it's somehow more fattening. This is clever science journalism, but neither good science journalism nor good science. For starters DNL is an energy intensive process so would come at a significant caloric cost vs. just ingesting a fatty acid. We've also discussed the small contribution of DNL to VLDL triglycerides produced in the liver. Much of this work is fairly settled fact -- this is why it is so frustrating for me to continue to read/hear how it is carbohydrates that make triglycerides and that any significant amount of carbohydrate is turned to fat after a meal. While fructose does upregulate DNL, sometimes 10 or 20X I've read for a period of time. But when you're talking about a process that normally produces a few grams of fat over the course of 24 hours, it's still not all that significant.
This is the most important point, IMO, because it pretty much destroys Lustig's comparison of fructose to alcohol, and I'll borrow the graphic from Despain/Tappy:
- ... OK, let's look in humans and not animals; let's look under basic normal energy balance conditions, and let's use the best or most elegant tools we have, which are stable isotope tracers -- this is the answer you get: 50 percent glucose, 25 percent lactate, greater than 15 percent to glycogen. These may vary a bit just based on the rest of the background diet and activity level of the organism or human in this case. But in general, this is the fate of fructose.
This is one of those "wow, just wow" moments. Lustig is unequivocal -- though he does sometimes mention the dose issue -- in his equating of sugar with alcohol and how it is toxic, toxic, toxic!!! It seems to me that none of the products of fructose metabolism are toxins. Period. Greater than 90% goes to glucose, glycogen or lactate. Oh, and anyone interested in making their head spin over the lactate might want to check out this paper I just parked over in my library.
Last, but certainly not least, Sievenpiper takes on the cause of obesity and the role of fructose:
- Is it true? [that fructose is a fattening poison] What we found was that it wasn't. We looked at bodyweight -- which is the Annals [of Internal Medicine] data that you’re aware of -- in each case there was no effect of fructose when it was isocalorically exchanged. There was no adverse effect on bodyweight, blood pressure, or uric acid. We do see a very consistent and strong effect on bodyweight when fructose is providing excess energy.
Remember the Havel Study Gary Taubes used to demonstrate that excess starch doesn't cause insulin resistance? Oh wait, he didn't mean to show that, but that was the effective outcome that the glucose beverage drinkers demonstrated. But the study did show that when you intend to replace 25% of the energy intake of obese/overweight adults with pure fructose sweetened beverages to the tune of over 600 cal/day = 175g fructose/day, free living humans do not compensate for the liquid calories by reducing intake of other foods by that amount. Indeed their total caloric intake increased by some 200 cal/day during the course of the study and they gained weight. So already overweight/obese people who start taking in large amounts of fructose sweetened beverages tend to increase intake and exhibit symptoms of insulin resistance (and perhaps leptin resistance?).
Sievenpiper and Despain go on to discuss some actual benefits of fructose consumption in the form of fruit on glycemic control. Go check it out! Hopefully as more folks like this will speak out and we can turn this tide of more bad bastardization of science around. As discussed in this interview, there are dietitians and docs now counseling clients and patients against even fruit consumption. Let's not forget 15 year former(?) vegetarian Zoe Harcombe's crusade against Big Fruit & Veg, because we all know 5-a-day has caused the obesity epidemic, right? Having determined that Lustig's video availability was a browser issue on my end, and now having watched parts 1 through 3 of his new series, I'm pretty thoroughly disgusted with his delivery and material. He gets basic facts wrong and no doubt these will get picked up and repeated by the Michelle Obama's of the world crusading to reverse this obesity epidemic.
Sugar and fructose per se are not the cause of the epidemic. As kids we had access to sugar, indeed there were no sugar-free alternatives. We (and when I say "we" I don't generally include me as my mom was the health nut in the neighborhood) used to eat sugar straight from straws, fruit roll-ups, Hostess cup cakes daily for dessert at lunch, cookies, Sugar Frosted Flakes back when sugar could be on the label, etc.etc. What has changed? Lifestyle and exposure/availability of these foods -- to both children and adults. Please, please, please. We don't want to replace the ill-conceived demonization of saturated fats that brought us the single greatest assault on human health in human history -- margarine -- with an equally ill-conceived demonization of sugar.