The most fascinating breast milk fact that we never knew about.

By: Leslie Goldman for mom.me.

In my house, we’ve tasked breast milk with many projects. Yes, it has nourished both of our daughters, but we’ve also used it to unplug clogged tear ducts, loosen up stuffy noses and stealthily healthify smoothies and ice blocks for our toddler. I even once attempted an at-home breast milk facial when I read that a salon was offering them to customers. (Results: After rinsing, my skin felt silky and a bit slippery. Also, my friend’s baby wanted to nurse on my forehead when she caught a whiff.)

Yes, much like the father in “My Big Fat Greek Wedding” who uses Windex to cure all of his family’s ills—”from psoriasis to poison ivy” – boob juice has found its way into many nooks and crannies in our home.

As a women's health writer and accidental extended breastfeeder, I thought I knew all there was to know about the benefits of breast milk. Then I read this article making the rounds on Facebook, titled "The More I Learn About Breast Milk, the More Amazed I Am," and learned something totally new.

And it's batshit-crazy cool.

According to Katie Hinde, PhD, a biologist and associate professor at the Center for Evolution and Medicine at the School of Human Evolution & Social Change at Arizona State University (who also runs a blog called Mammals Suck ... Milk!); when a baby nurses, it creates a vacuum in which the infant's saliva sneaks into the mother's nipple. There, it is believed that mammary gland receptors interpret the "baby spit backwash" for bacteria and viruses and, if they detect something amiss (i.e. the baby is sick or fighting off an infection), her body will actually change the milk's immunological composition, tailoring it to the baby's particular pathogens by producing customised antibodies.

To any exhausted breastfeeding mothers out there, never doubt what a miracle your body is.

"Putting this all together, some scientists hypothesise that this could be one of the ways babies let mums 'know' about their condition and mums respond with infection-fighting antibodies," Hinde told me in an email interview.

Did you read that correctly? A mother's lactating breasts are actually bouncy undercover doctor/pharmacists, diagnosing infections and dashing off silent prescriptions. That is just cuckoo-awesome. (Science backs this up. A 2013 Clinical and Translational Immunology study found that when a baby is ill, the numbers of leukocytes in its mother's breast milk spike.)

"Breast-fed babies have lower instances of colds and viruses," the article reads. "When they do get sick, they are often able to recover more quickly because the mother's body produces antibodies specific to the baby's infection."

So, to any exhausted breastfeeding mothers out there struggling with mom guilt/fatigue/post-baby blues, never doubt what a miracle your body is. You are incredible. You are omniscient. You are amazing.

What's an interesting fact you know about breast milk? 

This post originally appeared on mom.me.