"Life is like a box of chocolates, Forrest. You never know what you're gonna get," said a beloved movie character’s mom. As it turns out, the same may be true of, well, that box of dark chocolate you plan to present to your loved one on Valentine’s Day. According to the Food and Drug Administration (FDA), many products labeled as dark chocolate — currently a nutritional darling thanks to potential health benefits ranging from improving heart health to aiding weight loss — frequently contain milk. So despite how it’s labeled, you never really know what you’re gonna get.

“This can be a problem, since even one small bite of a product containing milk can cause a dangerous reaction in some individuals,” says researcher Binaifer Bedford, M.S., an Oak Ridge Institute for Science and Education (ORISE) fellow at FDA.

U.S. law requires foods containing a major food allergen to provide its name — in this case, milk —on the label. This is one of the ways to help ensure consumers know what’s in the food they’re eating. Undeclared (not listed on the label) allergens are a leading cause of food recall requests by the FDA.

From September 2009 to September 2012, about one-third of foods reported to FDA as serious health risks involved undeclared allergens. Within the candy category, there were many reports of undeclared milk in dark chocolate.

A manufacturer may not intend to use milk in a dark chocolate product, Bedford says. But if the dark chocolate product shares equipment with, for example, a milk chocolate product, traces of milk may inadvertently wind up in the dark chocolate. After hearing from consumers who had eaten dark chocolate and experienced harmful reactions, FDA tested 100 dark chocolate bars for the presence of undeclared milk. The selected bars were obtained from different parts of the U.S. and each bar was unique in terms of product line and/or manufacturer.

What the FDA study found

“First of all, milk-allergic consumers should be aware that a high proportion of the dark chocolates we tested contained milk, even when the label failed to list milk as an ingredient,” Bedford says. Of greatest concern are chocolate samples that have no statement regarding milk on the label or have inconsistencies in the label. Several of the chocolates labeled “dairy free” were also found to contain milk.

Results included:

  • While dark chocolates labeled “dairy free or allergen-free” were the least likely to contain milk, two out of 17 of these products were found to contain milk.
  • All seven bars that declared the presence of milk on the label contained milk; however, 55 (59%) of 93 bars without any clear indication of the presence of milk also were found to contain milk.
  • Six out of the eleven chocolate products labeled “traces of milk” contained milk at detectable levels high enough to potentially cause severe reactions in some individuals.

Consumers who are allergic to milk should be aware that a high proportion of tested dark chocolates contained milk.

“And because consumers can’t be sure that a statement about milk is completely accurate, they may want to contact the manufacturer to find out how it controls for allergens such as milk during production,” says Bedford. Information about the manufacturer, packer, or distributor is required to appear on the label of packaged foods.

And when in doubt? Show your love with a hand-written poem and a big kiss: No one’s allergic to those.