How Dangerous Is Coke Zero?

I am going to be brutally honest for a moment. I like soft drinks.

When I started managing my weight about five years ago, I gave them up. But, somewhere along the line, I fell in love with Coke Zero, and I drink more of them than I probably should. Don’t judge…

“Zero” soft drinks are the rage right now, and I probably am not alone. So let’s talk about whether they are a good idea.

First, let’s talk about the big idea: 0 calories yet great taste. How is that possible?

The sweetener being used is aspartame, which is approximately 200 times sweeter than sugar. Combined with acesulfame potassium (Ace-K), this blend delivers the familiar cola taste without the calories.

The Case For Aspartame

The primary appeal is obvious: zero calories and zero sugar while maintaining sweetness. For the millions of people managing diabetes, watching their weight, or simply trying to reduce sugar intake, aspartame offers a way to enjoy sweet beverages without the metabolic consequences of regular soda.

Aspartame is also one of the most extensively studied food additives in history. The FDA, European Food Safety Authority, and Health Canada have all repeatedly affirmed its safety at approved consumption levels. The acceptable daily intake (ADI) set by regulators is 40-50 mg per kilogram of body weight—meaning a 150-pound adult could safely consume 9-14 cans of diet soda daily, far more than typical consumption patterns.

For those concerned about dental health, aspartame doesn’t contribute to tooth decay the way sugar does, making it a friendlier choice for oral hygiene.

The Case Against

In July 2023, the WHO’s International Agency for Research on Cancer classified aspartame as “possibly carcinogenic to humans” (Group 2B), citing limited evidence linking it to liver cancer. While this sounds alarming, context matters: this classification reflects the strength of evidence that something could cause cancer, not the likelihood it will at normal exposure levels. Aloe vera and pickled vegetables share the same classification.

Some individuals report headaches or migraines after consuming aspartame, though scientific studies haven’t consistently confirmed this connection. People with phenylketonuria (PKU), a rare genetic disorder, must strictly avoid aspartame because it contains phenylalanine.

Perhaps more concerning for health-conscious consumers: some studies suggest that non-sugar sweeteners don’t appear to provide clear benefits for weight management or metabolic health. The psychological effect of “calorie-free” sweetness may paradoxically increase cravings for sweet foods.

If I had to make a guess, many people who drink Zero drinks give themselves a license to consume calories from other foods and drinks, making efforts to reduce calories counterproductive.

The Bottom Line

For most people, moderate consumption of aspartame-sweetened beverages is considered safe by major regulatory bodies worldwide. However, it’s not a magic bullet for health—water remains the gold standard. If you enjoy the occasional Zero, there’s likely no reason for concern. But if you’re drinking multiple cans daily, you might want to back off.