Every year I choose a university student to accompany me on my win-a-trip journey, which is meant to highlight issues that deserve more attention. My latest winner was Trisha Mukherjee, a recent Columbia graduate and a budding journalist — and with that, I’m handing the rest of the column to her.

By Trisha Mukherjee, reporting from Nairobi, Kenya

Here’s a riddle: What is available worldwide, requires no new technology, costs no money and could save more than 800,000 children’s lives a year?

If you answered “breastfeeding,” you’d be correct. Optimal breastfeeding around the world could reduce child mortality by at least 10 percent for infants and young children. The instructions are simple: Breastfeed within an hour after birth, exclusively breastfeed for six months, then introduce solid foods while continuing to breastfeed until 2 years of age.

As Nick and I traveled through Kenya and Madagascar, many women told us they gave their babies water during the first six months. This water can be contaminated with pathogens that babies’ developing immune systems can’t fight off. And because babies have tiny stomachs, anything other than breast milk effectively replaces it, depriving the baby of its essential nutrients. The women we interviewed thought they were helping their babies cool off during hot days, but unknowingly, they were hurting them.

Research shows that breastfed babies are at a lower risk of illness, infectious disease, diabetes, asthma, obesity and sudden infant death syndrome. They also appear to have fewer behavioral problems and higher I.Q.s. Modeling suggests that a lack of optimal breastfeeding costs the global economy an estimated $341 billion per year.

The benefits of optimal breastfeeding multiply in developing countries, especially in contexts where families don’t have access to sterilized bottles, adequate formula and clean water. And when medical care is practically nonexistent (some clinics have no medicine but pain relievers), every bit of additional nutrition and immunity matters. Given the often deadly risk of water-based pathogens and the lack of nutritious alternatives, breast milk is the ideal diet for babies — safe and supercharged with essential nutrients.