It’s hard to know how to interpret food date labels. If it smells fine but it’s past the best-by mark, should you pitch it? And what does “sell by’’ really mean anyway? Professor Emily Broad Leib, director of the Harvard Food Law and Policy Clinic and deputy director of the Harvard Law School Center for Health Law and Policy Innovation, is on a mission to help decode the mixed messages sent by those puzzling stamps on our food.

The professor was recently honored by Food & Wine and Forbes as one of the 20 most innovative women in Food and Drink for her work surrounding food waste.

Through the Food Law and Policy Clinic, she helps provide guidance to farmers’ markets on navigating food sales, assists businesses that want to donate excess food in protecting themselves from liability, and tackles the issue of confusing food labeling. “Massachusetts makes it very difficult if you want to sell or donate past-date food. And then in certain cities, like here in Boston, they actually say, ‘We aren’t allowing it at all.’ The Boston Health Department has a blanket ban on any past-date food to be donated,’’ says Leib.

“A big piece of our work is trying to make those laws better, because for so long we had priorities in our food system to make food cheap and accessible, and I think now there is a lot more attention being paid to food being safe and healthy and having good ingredients, and not wasting it,’’ says the professor.

Leib says that research has shown that the most cost-effective way to reduce food waste in the United States is to clarify and standardize date labels. “In 2013 we published a report with the Natural Resources Defense Council. For the first time we’ve been able to explain what date labels on foods are. Why they are poorly regulated, why they are confusing. We are wasting millions of pounds of food for no reason, so we’ve spent a lot of time trying to implement the recommendations of that [report] with the introduction of federal legislation this year.’’

Food labels first cropped up in the 1970s as consumers started shopping more at supermarkets and less at small local purveyors and farms. “At the time, it was acknowledged these were about freshness, and I think the problem is now a lot of consumers — more than 80 percent of consumers — think they are about safety, and they throw food away because they think it’s going to be unsafe after the date.’’

The professor points out that only a small handful of foods become dangerous to eat after a certain date. In the future, she hopes those foods will be clearly marked “expires on.’’ When it comes to quality, but not safety, Leib says surveys have shown “best if used by’’ is a term that shoppers understand.

Leib says effectively reducing food waste all comes down to clarity. “We aren’t doing a good job educating people, and it’s hard to educate people when there are dozens of different labels on food.’’ CATHERINE

SMART

Catherine Smart can be reached at cathjsmart@gmail.com.