Consumers may want to think twice about relying on artificial sweeteners, says a Manitoba researcher who found no evidence the sweeteners help with weight loss and some potential health harm beyond the waistline.

People are increasingly consuming artificial sweeteners such as aspartame and sucralose as well as the non-nutritive sweetener stevioside, derived from the stevia plant. The sweeteners are widespread in food and drinks including diet soda, yogurt, sauces and dressings and baked goods.

Health sciences Prof. Meghan Azad was one of them, reaching for the low-calorie choices until she started researching them in detail.

"Over 40 per cent of adults are reporting using artificial sweeteners on a regular basis," said Azad. "We know a lot of people are consuming them in foods and not realizing it."

In Monday's issue of the Canadian Medical Association Journal, Azad and her co-authors scrutinize 30 observational studies that followed more than 400,000 people in the general population for about a decade, as well as seven randomized trials of about 1,000 people with obesity who were followed for an average of six months.

While those who are obese were trying to use the artificial or non-nutritive sweeteners as part of weight-loss program, Azad found no consistent benefits in helping the needle go down on the scale or slimming the waist.

No clear benefit, potential for harm

What's more, studies on those consuming artificial sweeteners routinely suggest the intake may be associated with cardiovascular disease events such as heart attacks and strokes, Type 2 diabetes and hypertension.

"There's no clear benefit and there's potential for harm, so for me, it's worth it to just choose water instead," Azad said.

While researchers conducting the observational studies took into account factors such as the overall quality of participants' diets and pre-existing health conditions, no cause-and-effect relations can be drawn.

At her lab, Azad is now studying what happens when people are given artificially sweetened beverages for several weeks. The scientists are collecting fecal samples to analyze gut microbes for metabolic biomarkers.

The experiment is meant to investigate the hypothesis that artificial sweeteners shift the gut flora in a way that predisposes us to obesity.

Another possibility, Azad said, is that we compensate and think that drinking a diet pop permits us to enjoy pizza and cake later.

Another possibility is that our bodies have evolved to metabolize sugars in a way that's triggered not by calories or the sugar molecule but by the perception of sweet taste.

Azad suggests that consumers who turn to artificial sweeteners on the assumption that they're a healthier choice should to be cautious. More research is needed to understand the long-term effects.

Diabetes Canada lists Health Canada's approved sweeteners in its guidelines.

Dr. Sean Wharton, an internal medicine specialist in Toronto who works with patients on weight management and management of diabetes, said he generally tells people to avoid artificial sweeteners. But he's not convinced the sweeteners cause Type 2 diabetes.

"T​hey may lose weight for a little while and go back up for lots of other reasons, not just because of sugar or sweeteners," said Wharton. "There's psychological issues, there's other medical issues, family issues. These people tend to be at risk in the first place. So we can't use these studies to say that these sweeteners are the problem."

A taste for the artificial

Montreal journalist and blogger Marissa Miller isn't fazed by the warnings.

Over 40 per cent of adults report using artificial sweeteners. (Jenny Kane/Associated Press)

"I'm a real junkie," Miller said. She uses a variety of artificial sweeteners in her coffee, tea, cereal, on bitter fruit, in smoothies and in baking.

Miller was raised by health-conscious parents who gave her diet juices. As a child, having sugar felt foreign. Miller said when she tried to quit as an adult, she hated real sugar.

"Any time I have sugar, I have this overwhelming sense of panic," Miller said.

To her, artificial sweeteners still offer the best of both worlds of sweetness without the calorie cost. "Everyone has their vices. I don't think this is something to worry about."