Gummy vitamins are increasingly popular—and not just for kids. By some estimates, adults now comprise up to 80% of the gummy vitamin market.

“Pill fatigue” is one factor driving grownups toward gummies. If you have to take multiple supplements every day—and especially if you have problems swallowing capsules or tablets—gummies can make that chore easier (and tastier), finds a 2017 report from the AARP.

But do gummy vitamins work the same as ordinary supplements?

“It’s a lot harder to make a good gummy than it is to make a tablet or capsule,” says Dr. Tod Cooperman, president of ConsumerLab.com, a private company that conducts safety and quality testing of consumer products. In a 2017 supplement analysis, ConsumerLab.com found that four out of five gummy products contained more or less than their listed amounts of ingredients. Gummies were the most likely kind of supplement to fail testing, the analysis found.

“Many companies seem to have trouble controlling the amounts of ingredients in each gummy,” Cooperman says. To solve this problem, he says some gummy makers spray vitamins and nutrients onto the outside of the finished candy—like a coating. There are also “stability problems,” meaning the gummies can lose potency over time. “This leads some manufacturers to put in a lot more of certain vitamins than labeled to ensure the product provides at least 100% of the labeled amounts throughout its shelf life,” he explains. While that may sound like a good thing—after all, you’re getting more than you paid for—some reports have linked excessive nutrient intakes to health problems, including an elevated risk for some types of cancer.

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The ConsumerLab.com analysis also found that few gummies contain iron, which has a metallic taste that’s difficult to mask. This is especially worth highlighting for pregnant women, who are often advised to take an iron supplement to lower the risk for preterm birth and other complications.

But the analysis wasn’t all bad news; some gummies—including kids gummies made by Flintstones Vitamins, and women’s gummies made by Nature’s Way—passed the ConsumerLab.com testing.

Still, experts have other reservations about gummy supplements. “I’m concerned about kids and adults becoming accustomed to getting nutrients in sugary forms,” says Dr. Mark Moyad, the Jenkins/Pomkempner Director of Preventive and Alternative Medicine at the University of Michigan Medical Center.

Many gummy products for both kids and adults contain one or more grams of sugar per gummy. That’s similar to some types of candy—one Sour Patch Kid, for example, has 1.8 grams of sugar, according to the USDA food products database. If someone’s taking multiple gummy supplements a day—many of which require you to eat two or three gummies in order to get a full dose of the included nutrients—all of that sugar can add up. “It’s like eating Halloween candy 365 days a year,” Moyad says. “In the midst of the greatest epidemic of childhood and adult obesity this country has ever seen, we should be getting our nutrients from whole unprocessed foods, not from candy.”

That whole-foods-first advice applies to all supplements, not just gummies. While many people assume that supplements are a safe and convenient way to get a lot of the good stuff found in food, that’s often not true. “[Supplements] can’t replicate all of the nutrients and benefits of whole foods,” according to the Mayo Clinic. Also, the vast majority of supplements are not tested for safety or efficacy, experts warn.

While people with specific nutritional deficiencies can benefit from a supplement—especially one a doctor tells them to take—the evidence on daily multivitamins is lackluster. A 2012 review published in the American Journal of Clinical Nutrition found that multivitamins had no effect on mortality. And when it comes to preventing cancer or heart disease, the U.S. Preventive Services Task Force has found “insufficient evidence” that vitamin supplements do any good. In the case of beta carotene and vitamin E supplements, the Task Force has actually advised against taking them.

All told, there’s reason to be wary of gummy vitamins. If your doctor told you to take something and you have problems with other types of supplements, gummies may be a helpful alternative. But adding a few gummy supplements to your daily routine may not be such a sweet idea if you’re looking to improve your health.

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