Friday, May 25, 2012

Fructose and Your Monkey, Part 1

In this post, Gary Taubes (GT) examines the carbohydrate hypothesis of obesity, and the role fructose plays within that hypothesis.  In short, the carbohydrate hypothesis of obesity is that the primary cause of obesity is overconsumption of carbohydrate and the resulting cascade of rising blood sugar, followed by the body’s defensive secretion of insulin, which signals for cells to take up fat and sugar from the blood, and signals the liver to convert sugar to fat.  Repetition of this cycle causes insulin resistance, loss of glycemic control, and eventually metabolic syndrome leading to diabetes.  This progression of disease increases the risk of all of the diseases of civilization.

Here’s GT’s description of the first paper (he covers three in the post linked above):
… describes an experiment in which rhesus monkeys were fed their usual monkey chow diet supplemented by a daily 300-calorie ration of fructose-sweetened water. After a year, every last one of the 29 monkeys had developed “insulin resistance and many features of metabolic syndrome, including central obesity, dyslipidemia and inflammation.” Four of the monkeys progressed to type 2 diabetes.

The monkeys drank all the fructose-sweetened drinks they were given but reduced consumption by a nearly equivalent amount of monkey chow.  This implies one of two things – either monkeys are well versed in caloric values and have a sharp eye for food quantity (and thus do not need to weigh and measure their food) OR monkeys have a god given feedback system which resulted in their consumption of calories based on their needs.  Because their pre-fructose drink intake and post-fructose drink intakes were so similar, it is reasonable to conclude that the negative outcomes that took place after the switch to fructose drinks – insulin resistance, central obesity, dyslipidemia, and inflammation - are a result of said drink.

There’s a great deal of animal research out there, and much of it is hard to apply to the human animal.  Monkeys certainly have a different GI tract and metabolic adaptations compared to humans.  However, it still seems reasonable to assume that since fructose sweetened beverages now account for 20% or more of the US population’s caloric intake, compared to 5% in 1970 (thanks to how cheaply industry delivers HFCS nowadays), part of the diabesity epidemic is excess fructose consumption.

How much is excess?  I think it depends.  In my humble opinion, it should be safe to ingest about 25g of sugar/HFCS per day for a person who is in good health, metabolically speaking.  That would be about 12-13g of fructose.  If you have metabolic derangement and want to get well, that might be too much – but no one knows for sure. 

My advice is to sell your shares of Coca Cola and Pepsi, trade in the soft drinks for sparkling water, and get well.  Once well, I’ll bet you could relish a weekly sugared drink in good conscience and good health.

NOTE:  The people responsible for putting part 2 of this post before part 1 of this post, have been sacked.

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