Vitamin supplements for kids have been popular since Flintstones vitamins were introduced decades ago, but too much of a good thing can cause serious health risks.

Adults have become more aware of the benefits of getting enough fiber, calcium, iron and omega-3 fatty acids, but passing their own practices of loading up on nutritional supplements onto their children could lead to serious effects as well as expensive urine when unabsorbed vitamins pass right through the body.

In fact, makers of omega-3 supplements marketed for children received a formal warning from the Federal Trade Commission that they could be breaking federal laws by making unsubstantiated health claims.

The supplements were touted on the packaging as products that could improve kids’ brain function and make them more intelligent, as well as better able to focus, the FTC says.

But appropriate doses for children haven’t even been established, and supplements containing fish oil are discouraged for children, according to the University of Maryland Medical Center.

In addition, vitamin-popping kids could experience an overdose of iron, which could have even more serious consequences. Instead of being eliminated from the body in urine like Vitamin B, iron builds up in the body and cause significant health problems.

In one case, toddlers Imani Salimu, 3, and her sister Raven, 2, binged on between 20 and 40 candy-coated iron pills, which could have resulted not only in stomach aches, but liver damage and stomach and intestinal scarring, according to

The Salimu kids had elevated iron levels, though initially they were in no danger. But symptoms often develop over time and overdose on nutritional supplements containing iron is a leading cause of poisoning deaths among kids younger than 6 in the U.S., pediatricians say.

Still, sales of nutritional supplements for kids are on the rise, according to The Wall Street Journal.

Pediatricians and dietitians suggest, however, that kids should get all of the nutrients they need from food instead of supplements, the Journal notes.

And to prevent kids from getting their hands on and ingesting too many vitamins that taste like candy, parents are encouraged to lock cabinets containing the supplements and are discouraged from calling vitamins as well as medications “candy.”

For more medicine cabinet safety tips, read MainStreet’s story, Hidden Risks in Your Medicine Cabinet.