About 40% of Americans live in buildings with five or more residences — and for most of them, that means being cut off from outdoor green spaces where they can grow their own vegetables.

That's both a culinary loss (what tastes better than lettuce or tomatoes that you grew yourself?) and a short-change for your health.

But it doesn’t have to be that way. These days, many people are growing a variety of fresh vegetables and herbs on their windowsills.

And according to a new study in the journal Environment International, being an indoor gardener not only provides organic goodies year-round and lets you gain the emotional and mental benefits that come from interacting with nature, in just one month it also increases the bacterial diversity of your skin biome — which is your first line of defense against infections. Those skin biome changes then help diversify your intestinal biome.

Indoor gardening also boosts the level of inflammation-fighting proteins in your blood.

The researchers planted beans, peas, mustard greens, and salad greens using a microbe-rich soil (not a peat-based soil).

Microbe-mediated immunoregulation is especially important for city dwellers who are cut off from health-sustaining interaction with the beneficial microbes that thrive in natural settings.

However, they caution indoor farmers not to dig in soil if they have open cuts on their hands and not to breathe in air filled with soil particles.