In the past, our natural human microbiomes were tailored to our local and culturally traditional food supply

Growing your own food is more than just being economical or fresh. It helps to build a local biome rather than relying on the mixed biome from foods around the world. And because that chain of command has been so reliable we often don't question it or bother to cater to our own individual microbiome closer to home.

From page 88 of Sabine Hazan's Let's Talk Shit:

In the past, our natural human microbiomes were tailored to our local and culturally traditional food supply.  Now, we ship foods all over the planet, resulting in a worldwide microbiome shift.  Is this good or bad?  If we know that decreasing microbial diversity is linked to obesity, it could be good.  But we also know that the introduction of new bacteria can come with costs.  There may be bacteria introduced in our food chain that our own microbiome is not accustomed to that causes dysbiosis.  These are questions that can only be answered by research and time.