By Mukaila Kareem
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 sugars that help seeds survive drought and cold. Galactose, in nature, is precise and controlled. It’s not used for quick energy. It’s used to build.
The same goes for human biology. Galactose makes its debut in breast milk, where it pairs with glucose to form lactose—the primary sugar in milk. But this isn’t just a source of calories. Lactose delivers galactose to help infants build the brain, nervous system, and connective tissues. It’s the architect of early development.
And then, nature does something very intelligent: it stops.
As babies grow, their bodies produce less of the enzyme that breaks down lactose. This shift, known as weaning, is nature’s way of saying, “The building is complete.” For most of human history, this was the norm. Milk came during growth, and stopped when growth slowed.
But in the modern world, we never really stop. Milk is everywhere—from breakfast cereals to smoothies, from cheese to protein bars. And with every serving comes more galactose, long after our bodies need it.
So what happens to it?
Without growth to support, galactose is rerouted through a process called the Leloir pathway and eventually turned into glucose. It may be used for energy, or stored as fat. But unlike glucose, galactose is a reactive sugar—it’s more prone to binding with proteins and contributing to what scientists call “glycation,” a process linked to inflammation and aging.
In simple terms, galactose that once built the brain may, over time, contribute to its wear and tear.
Some experts and influencers promote milk as a lifelong superfood. But this overlooks the purpose milk was designed to serve. It’s not about demonizing dairy—it’s about understanding its timing. Milk is a message, not a mandate. And nature already wrote the ending: it’s called weaning.
There’s no conspiracy among mothers. Across all species, mothers stop producing milk when the job is done. Growth slows, and the sugar supply shuts off.
Just because we can digest milk doesn’t mean we need to. Capability is not the same as necessity.
Galactose is a remarkable molecule. In the right context, it helps build a body. But when the blueprint is complete, it’s okay to let the architect rest.
Mukaila Kareem, a doctor of physiotherapy and physical therapy advocate, writes from the USA and can be reached via makkareem5@gmail.com
