How worried should you be about aspartame? Here's what experts say

A reckoning could be coming to America's food systems after the Food and Drug Administration banned Red 3 — a toxic synthetic food dye — on Jan. 15. Consumer Reports is calling on the agency to outlaw six other types of chemical dyes.

However, the dyes, which are made from petroleum, aren't the only widely used artificial additives in our food supply. In 1974, the FDA approved aspartame for human consumption. Today, aspartame is found in cereals, chewing gum, diet sodas, coffee products, ice cream, chewable vitamins, cough drops, and more. 

What is aspartame, and should you be worried that the FDA hasn't banned it? The Cool Down spoke with an independent, nonpartisan expert to learn more. 

What is aspartame, and why is it added to food?

Aspartame is an artificial sweetener that gives foods and beverages the "sweetness without calories," according to Thomas Galligan, the principal scientist for food additives and supplements at the Center for Science in the Public Interest.

Galligan, who has a doctorate in biomedical sciences with a focus on toxicology and endocrinology, told TCD that most people are exposed to aspartame through diet sodas.

"It's sort of the foundation of a diet beverage in that it still tastes like a sweetened beverage, but it's not coming with the calories of the sugar that typically would be there," Galligan said. 

Is aspartame safe?

In 2023, the International Agency for Research on Cancer concluded that aspartame could be a human carcinogen, an alarming possibility given that cancer is one of the top causes of death worldwide. In 2022, nearly 10 million people died from the disease. 

Galligan told TCD that "more research needs to be done to sort of draw a more conclusive determination." However, the IARC's decision to slap aspartame with the "intermediate rating" of "possible carcinogen" suggests it may not be safe for human consumption.

"Typically speaking, when we're talking about carcinogens, the general dogma … is that for certain types of carcinogens, there's no safe dose," Galligan said. "... Because we don't know exactly what mechanism might be driving the potential cancer risk in humans from aspartame, it's sort of hard to say conclusively that it's not genotoxic [causing cancer by damaging DNA]."

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Why hasn't the FDA banned aspartame?

The FDA said that it disagrees with the IARC's conclusions. 

"The FDA doesn't believe that the animal studies are reliable and apparently does not believe that the human studies are indicative of a risk to consumers," Galligan told TCD. "And so the FDA has taken what I would say is the opposite of a precautionary approach when it comes to aspartame. They're looking for evidence — basically a smoking gun — that aspartame is unsafe." 

However, even though researchers are still determining whether aspartame is a cancer risk, Galligan told TCD that the IARC's report "should be concerning to consumers." 

"Ideally, what we would see is the FDA taking steps to limit consumers' exposures for them so that it doesn't fall to consumers to … really expend the effort to avoid this potentially unsafe additive," Galligan said. 

What should consumers do about aspartame?

The FDA acknowledges that many consumers use aspartame to reduce sugar consumption — a reality that Galligan also pointed to when weighing the artificial sweetener's pros and cons. 

"Sugar can cause weight gain and metabolic effects and cardiovascular disease risk and all these terrible things that we know very clearly," Galligan said. "And so, if a consumer were faced with the choice of a regular sugar-sweetened soda and a diet soda, CSPI does recommend that they choose that diet soda over the sugar one."

However, he noted that aspartame, like other food additives, "is not strictly necessary." Opting for still or sparkling water, coffee, tea, or other unsweetened beverages is the healthiest option. 

If you want to satisfy your sweet tooth, though, CSPI's Chemical Cuisine database lists which food additives are safest and which to avoid. Stevia leaf extract, thaumatin, and neotame are among the safest low-calorie sweeteners. Nonetheless, Galligan told TCD that these alternatives are best for adult use only. 

"They really haven't been tested well enough to be confident that they are safe for children in the long term," he said. "We have recommended for a long time that children avoid them, that parents avoid serving these to their children, and that schools work toward getting these out of beverages and foods in the school systems."

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