Downing a whole box of chocolate truffles in one sitting isn’t great for a balanced diet, but could chocolaty goodies harm more than a diet? Most people associate salmonella contamination with raw eggs and meat, but turns out tasty holiday treats like baking chocolate and candy can harbor salmonella and some other nasty pathogens, too.

Like almost any other food product grown in the ground, cacao beans are susceptible to contamination from animal waste products as a result of unclean water, improper handling, and even animals taking a stroll through (or a poo in) the fields in which beans are grown. As a result, cocoa beans can easily come in contact with salmonella and E. coli bacteria, as well as heavy metals from the soil.

Before the massive peanut butter salmonella outbreak of 2008/2009, scientists believed “dry” products like beans and nuts were safe because salmonella loves a damp environment. But here’s an unwelcome surprise: The fats in peanuts, walnuts, seeds, and cocoa beans can insulate bacteria, allowing salmonella to hang around inside the beans for a long time, even in dry conditions. The best way for cocoa manufacturers to kill salmonella is by dry-roasting or steaming the beans at a very high temperature. This process works perfectly if every bean gets the rock-star treatment, but what happens when some unlucky cacao nuggets are left out in the cold? Beans are often roasted in separate batches but shipped off to a chocolate factory all together, so safe and contaminated beans can mingle in transit and eventually wind up in the same batch of chocolate.

So what’s the harm in eating some chocolate-wrapped salmonella? Snacking on food containing salmonella bacteria pathogens can lead to an acute reaction called salmonellosis. Symptoms include stomach pain, fever, chills, nausea, vomiting, and diarrhea. In most healthy adults, salmonella poisoning will result in an unpleasant few days in bed (or on the toilet), but won’t cause lasting damage. But for people with compromised immune systems as well as infants, children, and the elderly, a brush with salmonella can result in ongoing health problems or be fatal.

Why It Matters

Salmonella and other bacteria outbreaks have become more common as large companies have started importing ingredients from around the world and distributing products over wide geographical areas. The first large salmonella outbreak from chocolate was in Sweden in the 1970s. Other salmonella-chocolate outbreaks in the ‘70s traced the contamination to the actual cacao beans, as opposed to other ingredients present in chocolateInternational outbreak of Salmonella Eastbourne infection traced to contaminated chocolate. Craven PC, Mackel DC, Baine WB, Barker WH, Gangarosa EJ. Lancet. 1975 Apr 5;1(7910):788-92.. In 2006, British candy giant Cadbury recalled one million products after a salmonella outbreak left three children in the hospital.

Luckily, tougher laws are making it more difficult for contaminated beans to make their way into a Snickers bar or an innocent cup of hot cocoa. In the wake of 2008’s major peanut butter outbreak, the FDA created the New FDA Food Safety Modernization Act, which set much stricter regulations for how imported and homegrown food is produced and handled.

So what’s the best way to safely indulge a sweet tooth? Choose the chocolate carefully. A boring old 99-cent bar of Hershey’s is actually much safer than chocolate made from raw cacao that comes from one specific place (aka single-origin beans). Raw beans aren’t cooked (duh), so they’re much more likely to be contaminated with pathogens. Exotic treats made with beans from an area with volcanic soil (think islands like Vanuatu in the South Pacific, Costa Rica, and Madagascar) are also susceptible to poisoning from heavy metals. Serving a treat to children, grandparents, or guests who might be fighting a cold isn’t the time to flaunt chocolate snobbery. To make sure everyone enjoys themselves (and doesn’t have to rush to the ER), avoid candy with raw or unpasteurized ingredients and take extra care with single-origin bars.

Are you ditching chocolate this holiday season to avoid salmonella poisoning? Or do you think worrying over chocolateis totally bogus? Tell us your thoughts in the comments below or tweet the author @SophBreene.