A Diet Coke is poured on a Big Gulp cup at a 7-Eleven store
Sugar has been demonized as the “new tobacco,” even the new heroin. But what about those pretty-coloured packets of fake sugars?
According to a new review by University of Manitoba researchers, artificial sweeteners may, paradoxically, not only make people fatter but also increase risks for high blood pressure, diabetes and cardiovascular “events” like heart attack and stroke.
One theory is that sweeteners lead to metabolic derangements, confusing the brain and body’s ability to respond to and process sugar.
Hundreds times sweeter than sugar, artificial sweeteners such as aspartame are among the most widely used food additives on the globe, found in more than 6,000 products worldwide. Sweeteners in “no-sugar added” foods like ice cream, yogurt and granola bars have become so ubiquitous, trace amounts are showing up in urine and blood samples taken from people who report not using them.
“People are consuming them without knowing it,” said Dr. Meghan Azad, an assistant professor in the department of pediatrics and child health at the U of Manitoba.
Two years ago, a study published in the journal Nature found sugar substitutes act on bacteria in the gut. After 11 weeks, mice fed saccharin showed changes in their gut microbiome. They also became pre-diabetic. Azad wondered whether there was evidence for similar effects in humans.
She and her colleagues performed a systematic review and meta-analysis — a study of studies — looking at the effects of long-term, regular consumption of sweeteners on a person’s cardio-metabolic health.
In the end, they reviewed 37 studies involving more than 400,000 people.
Only seven of the studies were randomized controlled trials — considered the gold standard in medical research — involving just over 1,000 people followed for six months, on average. In those studies, the sweeteners didn’t show a consistent effect on weight loss.
The 30 other larger, and longer observational studies, where people were asked about their intake of artificial sweeteners and followed for an average 10 years, showed a 14-per-cent increase in diabetes in “high” consumers (people who had one or more servings, typically a diet soft drink, a day) compared to people who reported never or rarely consuming sugar substitutes; a 32-per-cent increased risk of coronary heart disease, heart failure and other cardiovascular problems; and a 31-per-cent increased risk of metabolic syndrome, a cluster of conditions including hypertension and abnormal cholesterol that raise the risk of heart disease and stroke.
“For consumers, it’s a bit of a wake-up call,” said Azad. “It’s a message to think about whether you want to be consuming these products, especially on an everyday, regular basis, because we really don’t know if they are a truly harmless alternative to sugar.”
“I think most people that consume them regularly do it believing that they’re making a healthier choice. And that might not be true.”
The studies show an association, not cause-and-effect. They generally didn’t distinguish between the different types or formulations of sweeteners, or sweeteners in foods versus beverages.
However, “the biggest limitation is the lack of overall evidence, so it’s hard to make strong conclusions,” Azad added.
Still, she said, caution is warranted. “There’s such an emphasis these days that sugar is a cause of the obesity epidemic and diabetes and that we all need to reduce our sugar consumption. I think that is probably true,” she said.
“But we need to be careful about what we’re advising people to consume instead.”
For one thing, gut bacteria partially determine how many calories we absorb from food, and recent studies suggest artificial sweeteners may be selecting for an “obesogenic” microbiome, Azad said.
With metabolic derangement, “our bodies evolved to metabolize sugar in a certain way,” she explained. Some of those responses are triggered by the perception of sweet taste.
“With artificial sweeteners, we get the perception of sweetness without have any actual sugar to metabolize,” she said. That could confuse or “reprogram” our metabolism, setting people up for weight gain, high blood sugar and insulin resistance, she said.
The new study appears in the Canadian Medical Association Journal.