Yoghurt could be the probiotic fix you need for a cold and flu free winter.

Most of us know someone who never seems to get sick. Maybe it’s a pastor who never catches a cold despite shaking hundreds of hands each Sunday. Or, perhaps it’s an elementary school teacher who, despite getting coughed and sneezed on every day, never misses a day of work.

You may understandably wonder: How do they do it?

As I researched and wrote Secrets of the World’s Healthiest People, I spent the better part of a year asking dozens of never-get-sick people that exact question. What they told me changed what I do each winter – both for myself and for my family.

Of course, to avoid colds and flu you want to avoid germy people and places and wash your hands often. You knew that. So did I.

Here’s what’s new and surprising: one of the most powerful medicines to fend off colds and flu can be found in a common food that you may not be eating. I’m not knocking apples, but if you want to eat one thing daily to keep the doctor away and fight off colds and flu this season, I recommend either eating a probiotic-rich yoghurt or taking a probiotic supplement.