His daughter-in-law couldn't eat his cereal with him because she'd get sick. He helped fix that.

When something makes a family member sick, you do whatever you can in order to stop that from happening, right?

Enter Phil Zietlow. He's been an engineer at Cheerios for 50 years.

His daughter-in-law gets very sick from eating anything with gluten in it — including Cheerios.

He wanted to help make it possible for Joyce — and many other people with celiac disease and other conditions — to have breakfast with him.

After all, oats are naturally gluten-free. But, because farmers need to use the same equipment to harvest all kinds of grains, oats come into contact with other grains along the process from farm to factory, which means they're not safe for people with celiac disease and sensitivities to gluten.

What's an engineer to do?

Well, starting in 2007, Zeitlow spent five years working with a team of people at Cheerios developing ways to make the cereal gluten-free on a large scale. You might say to yourself, “Self, why can't they just buy certified gluten-free oats when they make it?"

And, anonymous Ms. Self, that's a legitimate question.

Quite simply, the company makes so many Cheerios that it would exhaust the world's supply of certified gluten-free oats in a few weeks.

The solution was found in a technique that mechanically separates oats from other grains, en masse.

It all boils down to size. All the grains are very small, but they also have unique proportions. Phil essentially helped create a very specific sorting device that was finally able to strain out all the oats from the other grains in the most accurate way possible.

And ... gluten-free Cheerios were born!

Now, Phil can have breakfast with his daughter-in-law once again.

Watch him tell the tale, with his adorable Minnesota accent:

Celiac disease affects 1 in 100 people across the world, and it's considered an autoimmune disorder. When gluten is ingested, it attacks the small intestine, eventually causing damage. In the United States alone, an estimated 2.5 million people have it but many are undiagnosed.

For more about the Cheerios journey to gluten-free, here's another video to check out. And they have a very informative blog post as well.

This video is by Cheerios.