When Are Artificial Sweeteners a Healthier Choice Than Sugar?

The answer depends on how much you’re having.

When I was fresh out of college and working in software sales, I took a trip to my company’s branch office in St. Louis.

The company’s CFO — a triathlete and fitness nut — was also on the trip, and I still remember his alarm when he saw the 64-ounce Big Gulp one of the local salespeople brought to our morning meeting. “Please tell me that’s water,” he said.

Smiling proudly, clearly enjoying the CFO’s shock, the salesperson said, “Nope, it’s Diet Coke. And I’ll have another one of these this afternoon.”

That was more than 15 years ago, and since then the U.S. has reigned in its soft drink habit. But the average American still consumes nearly 39 gallons of soda per year, which works out to 520 twelve-ounce cans. That’s a lot of pop.

When you consider that only about half the population drinks soda on a regular basis, annual consumption among habitual drinkers is probably much higher than 39 gallons.

‘If you’re keeping your sugar consumption below 25 grams per day , then just go ahead and have sugar.’

By now everyone knows that sugar-sweetened beverages are unhealthy. But I still meet people who think zero-calorie “diet” alternatives are harmless, despite all the evidence tying artificial sweeteners to health risks.

Research (both observational studies and controlled trials) has linked common sugar substitutes like sucralos and aspartame to unhealthy microbiome changes, impaired glucose tolerance, and the type of immunity impairments that fuel common autoimmune diseases like inflammatory bowel disease (which has become increasingly commonplace in the U.S. and other western nations).

Just this year, new research in the journal Nature Medicine found that erythritol, an artificial sweetener found in many sugar-free packaged foods (yogurts, ice creams, gums, “keto” foods, etc.), may promote blood clots and serious cardiovascular events, including heart attacks and stroke.

“At this point, we know that non-nutritive sweeteners are not benign,” says Robert Lustig, MD, an endocrinologist and professor emeritus of pediatrics at the University of California, San Francisco who has written several books about the dangers of sugar and processed foods. “Anything made with artificial sweeteners should be viewed as an ultra-processed food, which we know are bad.”

The question is whether the health risks of artificial sweeteners are greater than those of plain old sugar. In reply, Lustig says . . . it depends.

“Based on all the data we have, I would say that if you’re keeping your sugar consumption below 25 grams per day — and that’s for everything you eat — then just go ahead and have sugar,” he says.

In support of this take, a comprehensive 2023 review in the journal BMJ likewise landed on this 25-gram-per-day threshold for sugar safety. (In case you’re wondering, 25 grams is about six teaspoons of sugar. The average American adult consumes about 17 teaspoons per day.)

‘We’ve seen in the past with things like trans fatty acids that it can take a long time for us to recognize the true health effects of something artificial.’

What if you’re eating or drinking more than 25 grams of sugar per day?

In that case, Lustig says artificial sweeteners appear to be a somewhat safer (thought still unhealthy) substitution. “We’ve seen in some good papers that if you do a one-for-one exchange, the toxicity of one regular soda is about twice that of one diet soda,” he says. “But half as bad does not mean good.”

His advice may run counter to those who assume that anything natural must be healthier than something artificial. A little pure honey or maple syrup must surely be safer than some compound cooked up in a lab, right?

Lustig says this view has merit, and it’s why he endorses sugar for those who are consuming 25 grams or less per day. “We’ve seen in the past with things like trans fatty acids that it can take a long time for us to recognize the true health effects of something artificial,” he says. It’s possible that artificial sweeteners may turn out to be even more dangerous than sugar. But for now, he says fake sugar still seems marginally safer.

The bottom line is that both natural and artificial sweeteners are unhealthy, and too much of either is risky. But if you’re consuming a lot of sweetened beverages and foods every day, it’s Lustig’s informed opinion that artificial sweeteners present less risk than sugar.

“I think the big message is we need to de-sweeten our lives,” he adds. “If you avoid processed foods and eat mostly whole foods, you probably don’t have to worry about any of this.”

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