The folks over at the invaluable science watchdog group, the American Council on Science and Health, are calling foul on the new Nature study purporting to show that three different artificial sweetners boost blood glucose levels in mice and in four of seven human research subjects. ACSH chemist Josh Bloom suggests that it is very unlikley that three very different chemical compounds that just happen to taste sweet, sucralose, aspartame, and saccharin, would all have the exact same biological effect.
ACSH points out:
Dr. Bloom explains, "The premise of this study—that artificial sweeteners affect the microbial composition in the gut—makes absolutely no sense chemically, physiologically, or pharmacologically. The authors are taking chemicals that have exactly one thing in common—sweetness—and trying to correlate this with changes in gut bacteria that may be responsible for raising blood sugar — and in mice, no less!." …
What is the problem?
It is the absolute lack of any biologically plausible hypothesis to explain, well, anything really.
Why is this? Sweetness is a function of the interaction of certain molecules with the sweet receptors on the tongue.
Dr. Bloom: "There is a wide variety of chemicals that are sweet, both synthetic and naturally occurring. They have exactly one thing in common—taste. What can this possibly have to do with an effect on gut bacteria? Nothing.
"The authors really should have dug up a chemist before they got involved with this silly study. There are plenty of us around—mostly unemployed. Because he/she would have pointed out the gaping hole in the logic of the study—that you cannot group a chemically diverse group of chemicals simply because they are sweet, and draw any conclusion whatsoever about anything other that the taste.
Dr. Bloom continues, "It might be possible (although still highly unlikely) that any single sweet chemical could have some effect on (you name it), but to then lump in other chemicals that have nothing in common structurally or chemically is ludicrous. You might as well take random chemicals out of a lab and test them, because chemically, this is essentially what they did."
He adds. "As a chemist, if I saw a bunch of unrelated chemicals doing the the same thing in a test, my mind would start screaming 'the biology is a mess.' This was borne out hundreds of times during my career. It is one of the most important issues in drug discovery—whether the biology makes sense." …
"This just doesn't add up. You could just as well group chemicals together because they are yellow. It makes as much sense."
The researchers claim that fecal transplants with presumably altered gut microflora from affected mice to naive mice produced the same blood glucose spike. It should be easy enough to replicate these experiments.
See my earlier and sadly more credulous blog on the study here. I did say that I would continue dose my caffeinated beverages with Splenda.