Nigeria, April 5 -- There's a quiet sugar that most people never think about: galactose. It doesn't show up on most food labels. It's not as famous as glucose or as controversial as fructose. But galactose plays a powerful role early in life - especially in nursing infants and in plants.

So what makes galactose so important - and why does it matter if we're still consuming it long after childhood?

Unlike sweet fruits or nectar, which plants offer in exchange for pollination or seed dispersal, galactose is produced without any outside bargain. It's not a sugar of temptation. It's a sugar of structure.

In plants, galactose helps build the cell wall - the sturdy framework that gives plants their shape and resilience. It also shows up in s...