Gut check: New approach to eating focuses on link between food and overall health

What you eat can have a big impact on how you feel. There's a big link between your gut and your overall health.

The latest advice tells us which foods and supplements can help you feel and think better and which ones should be avoided.

If you've ever wondered why eating processed junk food leaves you feeling unfulfilled and wanting more, new research suggests it deprives the good bacteria growing in your gut.

"They start to starve, there is nothing for them to eat," said Obesity Medicine Association President-Elect Dr. Lydia Alexander.

She tries to educate her patients about the true purpose of the gut microbiome and why it's essential. Her advice is to treat your digestive tract as you would a garden.

"You want the soil, the right fertilizer, and then you're just going to get amazing stuff that grows there," Alexander said.

The stuff growing there is about 100 trillion bacteria, both good and bad, collectively known as the gut microbiome. Think of them as plants central to your physical, emotional and mental well-being. Feed it poorly and it can lead to disease.

"Crohn's disease, ulcerative colitis. It can increase the risk of colon cancer," she said.

Alexander said when bacteria starves it feeds on the mucosal lining of your digestive tract. Medications such as antibiotics and a poor diet can inhibit bacterial growth.

That's why probiotics have become so popular, but experts say there's not enough research to know which ones are effective. In other words: Scientists are learning that you can't just stick a bunch of new plants in your garden and hope they'll grow.

"There's not a precision-medicine approach at the moment to dictate which probiotic your gut microbiome needs," she said.

Alexander said your gut has a better chance of flourishing if you treat the soil your bacteria grows in. And that's where prebiotics come in.

"Prebiotics are the fertilizer or the food for the gut microbiome," Alexander said.

Prebiotics come in supplements, but Alexander said the best gut fertilizer is indigestible fibers found in fresh whole foods. Especially in bananas, yogurt, lentils and potatoes.

"It gives a lot of good inulin which is a prebiotic," she said.

Eat as many fruits and veggies as you can. A recent study found that Americans consume about 10 different kinds in a week. But those who ate about 30 different fruits and veggies had the largest variety of good gut bacteria.

"It's basically feeding and caring for your gut microbiome. And then your gut microbiome is going to feed and care for you," Alexander said.