Are Artificial Sweeteners Responsible for the Diabetes and Obesity Epidemics?

I am an avid consumer of artificial sweetners; my
favorite is Splenda. An intriguing
new study published in Nature yesterday found that the
sweeteners boost blood glucose levels in mice. They suggest that
the sweeteners may be contributing to the increase in human obesity
and type II diabetes. How? The Israeli researchers think that the
sweeteners don’t themselves spike blood glucose; instead they
somehow effect the microflora growing in the human digestive tract
in ways that do that. The researchers found that consuming
saccharin boosted glucose levels in four out seven human test
subjects. From the abstract:

Non-caloric artificial sweeteners (NAS) are among the most
widely used food additives worldwide, regularly consumed by lean
and obese individuals alike. NAS consumption is considered safe and
beneficial owing to their low caloric content, yet supporting
scientific data remain sparse and controversial. Here we
demonstrate that consumption of commonly used NAS formulations
drives the development of glucose intolerance through induction of
compositional and functional alterations to the intestinal
microbiota. These NAS-mediated deleterious metabolic effects are
abrogated by antibiotic treatment, and are fully transferrable to
germ-free mice upon faecal transplantation of microbiota
configurations from NAS-consuming mice, or of microbiota
anaerobically incubated in the presence of NAS. We identify
NAS-altered microbial metabolic pathways that are linked to host
susceptibility to metabolic disease, and demonstrate similar
NAS-induced dysbiosis and glucose intolerance in healthy human
subjects. Collectively, our results link NAS consumption, dysbiosis
and metabolic abnormalities, thereby calling for a reassessment of
massive NAS usage.

With regard to the human experiment, Medscape (registration
required) reports:

Artificial sweeteners caused changes in glucose tolerance in
humans, as well, but only for some participants the investigators
consider to be “responders.” A group of 7 healthy volunteers who do
not normally consume artificial sweeteners were given saccharin for
6 days at a dose that met the US Food and Drug Administration’s
maximum acceptable daily intake of saccharin for humans. No
participants saw improvements in glucose tolerance, but 4 showed
impairment.

Even before the experiment began, the microbial ecosystems from
the 4 responders were different from those of the 3 nonresponders,
suggesting their microbiome was somehow more susceptible. These
results, said Dr. Elinav, “point to the personalized nature of our
food responses and the need to understand this personalized effect
in order to fight the
metabolic syndrome, which as we all know, is one of the most
common and serious epidemics in all history.”

Bacteria from responders, sampled at the end of the trial, were
able to induce glucose intolerance when introduced into germ-free
mice (P < .02), whereas baseline samples from the
responders (taken before they had consumed the artificial
sweeteners) did not have this effect, nor did bacteria from the
nonresponders.

The Washington Post
reports that the researchers are not recommending that people
shift toward eating sugar. The Post notes:

Researchers [Eran] Segal and [Eran] Elinav insisted that their
findings are preliminary and shouldn’t be taken as a recommendation
on whether people should reconsider using artificial sweeteners.

“We do not view that as our role,” Segal said. “Rather, as
scientists, we simply point to the immense body of experiments that
we carried out in both humans and in mice. . . . This study and
these results should prompt additional debates and study into what
is currently a massive use of artificial sweeteners.”

Elinav added: “This issue is far from being resolved.”

Yes, indeed. Keep in mind that this not an “I-told-you-so”
moment for most food scolds who were
chiefly claiming that the sweeteners increased the risk of
cancer.

For what it’s worth, my BMI is now 24.3 (although it’s been as
high as 30) and my blood glucose levels couldn’t be more normal, so
I will continue to dose my coffee and iced tea with Splenda. Of
course, I may change my tune as further results are reported.

Hat tip to Felix, the first commenter to send me links to
the study. Thanks to everyone else. Keep them coming.