It’s impossible to directly compare the health effects
of diet and regular soda, since we have far more research on
the regular kind.
The studies we do have suggest regular soda is linked
with obesity and weight gain, while diet soda hasn’t been
strongly tied to any negative health outcomes.
For that reason, Aaron Carroll, a pediatrician and
professor of pediatrics, says it’s fine to drink diet soda
occasionally — but never the regular varieties.
Just how bad is your Diet Coke habit?
Probably not as unhealthy as you think. And swapping it for the
regular stuff won’t do you any favors.
“If I have to choose between diet drinks and those with added
sugar, I’ll go with the diet,” Aaron
Carroll, a professor of pediatrics at the Indiana University
School of Medicine, writes in his new book,
“The Bad Food Bible: How and Why to Eat Sinfully.”
The existing science on diet soda hasn’t gotten the golden seal
of approval that comes after extensive studies in humans. The
research we do have is mostly in mice, but so far it suggests
that the artificial sweeteners in soda are not overwhelmingly bad
for our health.
On the other hand, extensive studies about human consumption of
regular soda reveal an overwhelming link to two unhealthy
outcomes: weight gain and obesity.
Comparing these two scenarios makes the choice between diet soda
and regular soda clear, according to Carroll.
“There’s a potential — and likely very real — harm from consuming
added sugar. There is likely none from artificial sweeteners,” he
Still, dozens of seemingly damning scientific studies on diet
soda and the artificial sweeteners it contains have been
published over the last decade. Research has linked saccharin to
cancer, and found evidence that people who regularly consume diet
drinks are heavier than people who don’t.
But Carroll says every one of those studies was riddled with
enough errors not to be taken seriously. The way they were
communicated to the public made it look like they were far more
conclusive and severe than they really were, he wrote.
Research tying artificial sweeteners to cancer was done in rats
who were vulnerable to cancer
In the 1980s, any product containing saccharin, the zero-calorie
sweetener sold under the brand name Sweet’N Low, was required to
carry a frightening warning label: “This product contains
saccharin, which has been determined to cause cancer in
Out of roughly 50 studies of rats fed saccharin — in amounts far
beyond what a normal person would consume on a daily basis — only
one experiment found that it seemed to cause cancer. But the rats
in that study were a specific kind of rat that often become
infected with a bladder parasite, Carroll explains in his book.
The parasite leaves them extra vulnerable to cancer.
Carrol writes that the conclusion people should have drawn from
all those studies is: “Rats are more vulnerable to side effects
from saccharin than are people, for whom there’s no clear
evidence of risk.”
Instead, artificial sweeteners everywhere have gotten a bad rap.
Many were shocked by the recent news that President Donald Trump
a dozen Diet Cokes per day. Of course, doing anything to
excess is probably not a good idea. But dozens of further
studies have failed to find any link between saccharin and cancer
in humans, despite lingering skepticism.
“Public perception, once turned against any food, is very hard to
change,” Carroll writes.
The study linking diet drinks to dementia also found a link
between regular soda and dementia
Other recent studies link diet drinks to even scarier-sounding
health outcomes, including research published this
that diet soda could cause dementia.
But that study was only one of a pair of studies looking at
beverage consumption and brain issues. The second found a
connection between drinking regular soda and brain shrinkage.
More importantly, both studies fall into a category of research
commonly found in food and beverage science called
Observational studies follow large groups of people over long
periods of time and don’t control for the variables they are
testing. As a result, these kinds of studies can tell us if
there’s a connection between two things, but they can’t tell us
if one thing necessarily causes the other. In many cases, a link
researchers observe between two things is later found to be
caused by an external thing that no one accounted for.
The jury is still out on whether any external factor played a
role in the studies about drinks and dementia. For now, there is
no definitive research that tells us that sugary drinks cause
brain shrinkage or that diet drinks cause dementia.
Plenty of research links regular soda to disease
One of them was a large review of
50 years’ worth of studies published in the American Society for
Clinical Nutrition. It found “strong evidence for the
independent role of the intake of sugar-sweetened beverages,
particularly soda, in the promotion of weight gain and obesity in
children and adolescents.”
written by seven experts in public health, nutrition, and
economics describes the links between sugary drinks and
America’s obesity problem even more strongly:
“The science base linking the consumption of sugar-sweetened
beverages to the risk of chronic diseases is clear,” the authors
With this in mind, Carroll appears justified in his choice of
diet soda over regular.
“When it comes to sugar and artificial sweeteners, the evidence
is as strong as can be: the former is much worse for you than the
latter,” he wrote.