Do pre-biotic drinks work? Our special series Living Better investigates

STEVE INSKEEP, HOST:

OK. Many grocery stores offer so-called prebiotic drinks. These cans of fizzy soda are supposed to boost your fiber intake and gut health. That's what the can says. So do they work? NPR's Maria Godoy reports.

MARIA GODOY, BYLINE: I have a confession to make. I'm kind of obsessed with fiber, and I'm not alone. Hannah Holscher calls herself a fiber nerd.

HANNAH HOLSCHER: There's been so much research that have shown that if you consume more fiber, you are healthier.

GODOY: Holscher is an associate professor of nutrition at the University of Illinois. She says fiber does way more than just help keep us more regular. It helps control blood sugar levels and lower cholesterol and inflammation. One review of nearly 200 studies and dozens of clinical trials found high-fiber diets were linked to a lower risk of obesity, Type 2 diabetes and many other health concerns.

HOLSCHER: They looked at all-cause mortality, as well as cardiovascular disease, cancer, just a range of health issues that a lot of Americans face and found consistently that individuals that consume more fiber had better health outcomes.

GODOY: Now, one big reason why fiber is so important to good health is that it can feed the diverse community of microorganisms that live in our guts. Fibers that do this are known as prebiotics. Justin Sonnenburg is a professor of microbiology and immunology at Stanford University. He says these gut microbes play a critical role in influencing health throughout our bodies.

JUSTIN SONNENBURG: There's just this huge range of things - allergies, asthma, anything having to do with the immune system, metabolism, cardiovascular health. Basically, there's no part of our biology that goes untouched by our gut microbes.

GODOY: Sonnenburg says when you eat lots of plant-based fiber, you keep your gut microbes happy, plentiful and diverse, which is important because different microbes do different things to help keep you healthy.

SONNENBURG: If you're not eating a high-fiber diet, your gut microbes are actually kind of starving. And when they're starving, they actually look for other things to eat. And one of those other things that they eat is actually the lining of your gut.

GODOY: In other words, if you don't feed your gut microbes enough fiber, they might start to eat you.

SONNENBURG: Right. Exactly.

GODOY: Sonnenburg says he and pretty much everyone else that studies the gut microbiome are fiber fanatics. He says one time at a gathering of researchers...

SONNENBURG: The people that were in charge of the dining hall came up to us and said, what group is this that's here this week? We can't keep the salad bar stocked. And the reason...

GODOY: (Laughter).

SONNENBURG: ...Is that everybody that studies the gut microbiome is obsessed with eating dietary fiber, plant-based fiber.

GODOY: But they're definitely in the minority. Less than 10% of Americans eat the recommended amount of daily fiber, which is 14 grams for every 1,000 calories we consume. But awareness is growing. Gut health is one of the most popular hashtags on TikTok and a wellness buzzword these days. And food companies are cashing in with a slew of products that contain prebiotic fibers, like those prebiotic carbonated beverages - Olipop, Poppi, Vive Organic. But are these products actually good for your gut?

SONNENBURG: The intuition there, I think, by the field is that that's probably better than nothing.

GODOY: But Sonnenburg says it's not clear that prebiotic fibers added to processed food and drinks have all the benefits that come with eating a variety of foods that are naturally high in fiber. Hannah Holscher of the University of Illinois agrees the best bet is to focus on diet.

HOLSCHER: One of the simple messages we like to tell people is to eat more fiber, you know, to eat the rainbow.

GODOY: That means eating lots of different fruits and vegetables, as well as whole grains and nuts. Think beans, oats, sweet potatoes, pumpkin and chia seeds, pears, berries and avocados, apples and onions. Not only are these foods a good source of fiber. They also contain other nutrients that promote good health.

Maria Godoy, NPR News. Transcript provided by NPR, Copyright NPR.