Hippocrates supposedly said, “All disease begins in the gut.” Turns out he was onto something.

We know now that poor gut health is linked to a host of diseases and health conditions, from depression to diabetes, cancer to skin issues, autism to autoimmune disease.

When we talk about “gut health,” we mean the composition of the gut microbiome—the bacteria, fungi, and viruses inhabiting the gastrointestinal tract—and the integrity and function of the GI tract itself. And while our knowledge has grown leaps and bounds since Hippocrates’ time, there’s still much to learn. Scientists are actively working on therapies to manipulate the microbiome and improve health, but we have a long way to go.

Luckily, we don’t necessarily need scientific interventions to bolster gut health. There’s much we can do naturally. Here are some of the foundational things everyone should be doing (or not doing).

Start with diet.

Not surprisingly, what you eat (or don’t eat) is one of the biggest determinants of gut health. Say yes to:

Foods rich in prebiotic (fermentable) fiber. Some of my favorite sources are avocado, asparagus, mushrooms, pistachios, Jerusalem artichokes, and alliums like garlic and onions.
Fermented foods. Yogurt, kefir, kimchi, sauerkraut, fermented pickles, natto, or any other fermented foods that contain live bacteria.
Polyphenol-rich foods. Berries, dark chocolate, and coffee top my personal list.
Skin, bones, and broth. They provide “animal fiber”—collagenous and gristly substrate that helps our gut bacteria prosper—plus ample gelatin, which can help repair a damaged gut lining.

On the other hand, it should just be common sense to avoid foods that can actively impair the integrity of your gut. The prime suspects here are gluten-containing grains, but I’m also wary of artificial sweeteners.

Practice good oral hygiene.

Most people don’t know that periodontitis (gum disease) is a major risk factor for colorectal cancer. When oral pathogens migrate from the mouth to other parts of the body, they can cause inflammation, promote tumor growth, and reduce the effectiveness of anti-cancer therapies.

Consider supplementing with probiotics.

If you’re dealing with IBS, constipation, anxiety, or other symptoms of gut dysbiosis, probiotics may be able to help. Research is still fairly new in these areas, but certain probiotic strains could be particularly helpful depending on your symptoms.

Don’t be too sanitary.

Too sterile an environment causes too sterile a gut. We are made to spend time in nature, getting our feet and hands dirty, and eating produce directly from the ground. (That said, if you didn’t grow it yourself, it’s best to wash your produce.)

Work on reducing stress and improving sleep.

As if you need another reason for me to harp on you about sleeping more and stressing less, there’s ample evidence that poor sleep and chronic stress wreak havoc on your gut.

Those are the basics. In many ways, supporting a healthy gut comes down to implementing the essential Primal principles I recommend all the time. Above all, don’t wait until you have major issues to start caring about your microbial passengers! Maintaining a healthy gut will always be easier than fixing a dysfunctional one.