CANNES, France—The most low-tech product imaginable, a simple lump of iron, won the Grand Prix in the Product Design Lions contest here tonight. But while it looks unassuming, this fish made tens of thousands of Cambodians healthier.

As the case study below shows, Geometry Global in Dubai, United Arab Emirates, approached the problem of iron deficiency in Cambodians by trying to find ways to add more iron into their diet. One way, they found, was to simply put a piece of iron into skillets and pans while cooking. But Cambodians were reluctant to do so … at first.

Check out the video for more.

Meanwhile, R/GA won three Product Design Lions for high-tech work for Hammerhead, Diagenetix and Equinox. (Unlike most categories at Cannes, this one does not award gold, silver and bronze prizes. They are simply called Design Lions.)

Check out all the winners below.

—All the Product Design Lions

• R/GA New York for Hammerhead Navigation

• R/GA New York for Diagenetix's BioRanger

• R/GA New York for The Pursuit by Equinox

• AIAIAI Copenhagen / Kilo Design Vlaby for Aiaiai's TMA-2 Modular Headphone System

• Maruri Grey Guayaquil in Ecuador for Panasonic's ACH2O

• Grey Group Singapore for Talwar Bindi's "Life Saving Dot"

• Publicis Colombia Bogotá for Cirec Foundation's "Funtastic Hand"