Labor Day is the last big hurrah of beachgoers across the country, and while you may have prepped for the usual hazards — crowds, sunburn, and jellyfish — there’s another danger lurking in the sand beneath your toes: bacterial infection.

Kids are most at risk.

Research suggests that playing in the sand — especially being buried in it — significantly increases kids’ risk of diarrhea, vomiting, stomachaches and nausea. Researchers from the University of North Carolina interviewed nearly 27,000 beachgoers at seven different beaches (both saltwater and fresh) from around the country, asking them about their shoreline activities.

Kids who played in sand were 20-24 percent more likely to have had diarrhea than those who simply walked or swam by the shore.

Two weeks later, kids who played in sand were 20-24 percent more likely to have had diarrhea than those who simply walked or swam by the shore.

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Sand that gets into kids’ mouths may contain fecal matter (either from sewage run-off or from animal contamination), which carries harmful bacteria.

“Beach sand can contain indicators of fecal contamination, but we haven’t understood what that means for people playing in the sand,” Chris Heaney, one of the study’s authors, said in a statement. “This is one of the first studies to show an association between specific sand contact activities and illnesses.”

Fortunately, there are measures parents can take to protect their children.

“Part one includes hygiene methods, like using hand sanitizer after playing in the sand,” said Tim Wade, an epidemiologist with the Environmental Protection Agency and the study’s senior author. “People should not be discouraged from enjoying sand at the beach, but should take care to use a hand sanitizer or wash their hands after playing in the sand.”

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But the second part of protecting kids — and yourself — against bacterial infection includes eating the right foods to strengthen immunity. Bananas, asparagus, onions and artichokes are “superfoods for the tummy” because they contain prebiotic fiber, which selectively feed the protective bacteria that line the gut, so bad bugs can’t get a foothold.

This article was originally created by the Dole Nutrition Institute, with additions and updates by LifeZette.