I’ve been talking about this, with Olesya and friends, for months now. I am convinced that the reason why there are so many kids with allergies these days is because they are not exposed to nuts, and milk, and gluten, and… well, dirt. I didn’t have “scientific evidence,” but to me it’s obvious. Let the kids eat anything, nuts, milk, sugar, cakes…; let them play everywhere, on the floor, on the streets, on the beach, in the ocean…; take them to the woods, visit farms, go with them for a good hike and let them get bitten by mosquitoes and get all dusty; take them to parks in the middle of the city and let them fall and scratch their knees in the asfalt. By doing this, you will help their bodies, their immune systems in particular, get stronger.

Well, apparently there is scientific evidence:

Babies Know: A Little Dirt Is Good for You

and a book (mentioned in the article), “Why Dirt Is Good”, by Mary Ruebush.

And more, from Discover:

Let Them Eat Dirt! It Contains Essential Worms