The foundation of your health and well-being isn't your heart, your lungs or your brain. It’s your gut.

• Chew on this: 70% of your immune system sits in your belly.

Why it matters: You are what you eat. And a healthy gut keeps your body — and mind — from getting sick.

1. Your immune system: A healthy gut is chock-full of immune cells and good bacteria that fight off viruses, fungi and bad bacteria. And an unhealthy gut can lead to infections — and even hinder your body's ability to fight cancer.
2. Your mental health: Believe it or not, your gut has as many nerves as your spinal cord — and a direct link to your brain. That means eating poorly can cause anxiety and depression, and vice versa — deteriorating mental health can lead to an unhealthy gut.
3. Your strength: A troubled gut — and weak immune system — can lead to inflammation, hurting your joints and muscles.

Think of the gut as a second brain, medical experts say. 

• Not only do the millions of bacteria in the gut extract nutrients from your food and deliver them to your body, but its nerve endings talk to your brain and your hormones to regulate your mind and sense of well-being.

So how can your treat your gut right?

Watch what and when you eat. Keep the good bacteria in your gut healthy and active with a diverse diet full of fiber, colorful fruits and vegetables, whole grains, protein and spices. Avoid ultra-processed foods like potato chips and soda.

• Your gut runs on a biological clock and eating at consistent times every day optimizes digestion, says David Heber, a physician and director of the UCLA Center for Human Nutrition.

Add probiotics to your diet. The best thing you can eat for your gut is unpasteurized yogurt, Heber says. That not only brings its own helpful bacteria into your body but also supports the existing good bacteria.

• Fermented foods like pickles, sauerkraut and kimchi are also gut glorifying.

Get enough sleep. Your gut needs the rest.

Get exercise. Motility is key to gut function, and that comes from staying active and moving around.

If you're seeking supplements, Healthline dove deep into the top dietician-vetted probiotics that curb gas and bloating and boost immune health, rating them by price, shelf-life and efficacy.

• Their top three: Culturelle Digestive Daily, Align Probiotic Extra Strength and Bio-Kult.

If you can afford it, functional medicine is a growing field, and several doctors offer detailed testing of your gut health and then specific steps for improving yours.

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