Turns out gummy vitamins aren’t just for kids anymore, with adults dominating around 80 percent of the market. More and more people are turning to these kinds of supplements over pills due to a phenomenon called “pill fatigue,” where taking multiple tablets every day leads to annoyance and stress, especially if you have a hard time swallowing tablets.

Companies that make these edible sweets promise that they will supply all the vitamins missing from our diets in a convenient package. But is this true, and how healthy are they really?

“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 company that tests the safety and quality of consumer products. The company’s investigation found that four out of five gummy products contained a different concentration of listed ingredients than promised.

“Many companies seem to have trouble controlling the amounts of ingredients in each gummy,” Cooperman explains. This forces them to spray the outside with vitamins and nutrients to bring up the levels of the promised ingredients printed on the package but still fall short.

There is also a stability problem, where the gummies lose their 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,” says Cooperman. This may not seem like a problem, but over time overconsumption of nutrients can lead to some serious health problems.

Also, there’s the sugar. Many gummy products for kids and adults contain one or more grams of sugar per gummy. This may not sound that much but it is actually similar to some popular candies such as Sour Patch Kids, which contain 1.8 grams per piece. Experts suggest instead that we should be getting our daily dose of nutrients and vitamins from natural unprocessed foods.

So, although they come in a convenient and easy-to-swallow package, maybe gummy vitamins aren’t the sweetest idea after all if you’re looking to improve your health.