Prebiotic sodas promise to boost your gut health. Here's what to eat instead

Maria Godoy

August 08, 2023 / 6:00 am

You may have seen them stacked up in your grocery store or promoted on your social media feeds: carbonated prebiotic sodas with names like Olipop, Poppi and Vive Organic that promise to boost your fiber intake – and your health – by feeding the trillions of microorganisms that live in your gut.

Scientists say these drinks aren't exactly a magic elixir for your gut (more on that soon), but the marketers are right about one thing: Gut microbes play a critical role in health, and feeding them the fiber they love is a smart move.

In fact, nutrition researchers can't get enough of this nutrient.

"There's been so much research that has shown that if you consume more fiber, you are healthier," says Hannah Holscher, an associate professor of nutrition at the University of Illinois, and self-proclaimed "fiber nerd."

She says fiber does way more than just help keep us regular. It helps control blood sugar levels and lower cholesterol and inflammation. One review of 185 studies and dozens of clinical trials found that diets rich in fiber were linked to a lower risk of major health problems like obesity, Type 2 diabetes, cancer and cardiovascular disease.

Getting these benefits might not be as simple as popping a cold drink — but it could come from a few affordable tweaks to your diet.

The fiber-microbe-health connection

A big part of how fiber benefits us is by nourishing the diverse community of microorganisms in our gastrointestinal tract.

"Basically, there's no part of our biology – in health or disease – that goes untouched by our gut microbes," says Justin Sonnenburg, a professor of microbiology and immunology at Stanford University.

He says these microbes produce chemical messengers that enter our bloodstream and influence health throughout our whole body.

"So you have things like heart disease, autoimmune disease, cancer, metabolic syndrome, neurodegenerative disease, inflammatory bowel disease ... anything having to do with the immune system," he says. "It's all impacted by gut microbes." They can even affect our mental health.

He says when you eat a diet rich in plant-based fiber, you keep your gut microbes happy, plentiful and diverse, which is important because different microbes do different things to keep you healthy.

But if your fiber intake is low, "your gut microbes are actually kind of starving," Sonnenburg says. That can lead to a loss of diversity in our microbiome, which is linked to health problems like obesity and Type 2 diabetes.

Fiber fanatics

Low-fiber diets could lead to other health woes too. One of the things that happens when microbes are starving is "they look for other things to eat. And one of those other things that they eat is actually the lining of your gut," Sonnenburg says, which could lead to inflammation.

He says he and other gut microbiome researchers are fiber fanatics. One time when he and his fellow researchers were gathered at a conference center, the dining hall managers were astonished at how fast the group ate down the salad bar. "The reason is everybody that studies the gut microbiome is obsessed with eating dietary fiber, plant-based fiber," he says.

But they're definitely in the minority. "The vast majority of Americans do not get enough fiber," says Holscher, whose research focuses on the interactions between diet, the gut microbiome and health.

According to the U.S. government dietary guidelines, you should be eating 14 grams of fiber for every 1,000 calories you take in daily. But only around 9% of women and 3% of men in the U.S. meet the fiber recommendations.

So what about those fizzy drinks?

A growing interest in gut health has led to a plethora of processed foods with added fiber, including those carbonated prebiotic drinks that are all over TikTok.

One ingredient commonly used to boost these foods' fiber content is inulin, a type of fiber extracted from chicory root. (It's in Olipop drinks.) Inulin is a prebiotic, which means it feeds the good bacteria in our guts.

Holscher says if you enjoy these prebiotic drinks and they help you meet your daily fiber targets, they can certainly fit in as part of a healthy diet. She notes that fibers like inulin that are added to food must have proven health benefits, according to FDA guidance.

Sonnenburg says when it comes to added fiber in foods, "the intuition in the field is that that's probably better than nothing."

But he says it's not clear that prebiotic fibers added to processed food and drinks have all the same health benefits that come from eating a variety of whole foods that are naturally high in fiber.

For one thing, Sonnenburg says, the purified fibers that are added to foods are much simpler structures than fiber naturally found in plant foods. And this means they get fermented faster, by microbes that live near where the small intestine meets the large intestine. That means those purified fibers might not reach the microbes living further down the large intestine – and they need to be fed, too.

And when it comes to inulin, it's possible that too much might not be good for you. Sonnenburg co-authored a small study published last year on the topic. He found that, while lower doses of inulin supplements could increase the presence of helpful gut bacteria, at high doses, it caused a jump in inflammation in otherwise healthy adults.

Sonnenburg and Holscher agree that if you want to boost your fiber intake and your gut health, your best bet is to focus on eating a variety of plant-based foods.

Easy ways to boost your fiber intake

Holscher notes that there are many different kinds of fibers found in plant-based foods that are linked to different health benefits. For example, beta glucans, which are found in foods like oats, wheats, and barley, have been linked to lower cholesterol levels. Meanwhile cellulose, a fiber found in foods like celery, helps keep us regular.

And she notes that different gut microbes need different kinds of fiber.

"Since it's so complicated, one of the easiest things that I'll usually tell people to do is just eat the rainbow and try to have lots of different foods in their diet so that all these different building blocks and fibers will be present," Holscher says.

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

Adding more fiber into your daily habits doesn't have to be hard. Some surprisingly snackable foods are high in fiber, like avocados. Add slices to a sandwich, or grab a side of guac with your tacos.

If you want to maximize your fiber bang for your buck, check out this chart that lists types of foods by fiber amount per serving. For instance, you might be surprised to learn that a cup of artichoke delivers a whopping 9.6 grams of fiber. (To really nerd out, look up more foods in this USDA database.)

It's easy to amp up the fiber content of your breakfast. One tablespoon of chia seeds has 4.5 grams of fiber. I sprinkle some on my yogurt every morning. Raspberries and blackberries are also very high in fiber – a cup of either will deliver about 8 grams. You can buy frozen berries, which tend to be cheaper, and use them in a smoothie.)

Also, think about swapping around some of your salad ingredients. For instance, while iceberg lettuce has almost no fiber, subbing in cabbage or kale serves up more. Or try cooking a cup of kale (4 grams of fiber) and throwing it into a lentil soup for a fiber-full meal.

To enjoy fiber-rich foods more, Holscher recommends experimenting with different recipes and cooking methods. She personally hates raw broccoli, but loves it when her husband cooks it in the air fryer with olive oils and spices. "I will eat an absurd amount of broccoli if it's cooked that way," she says.

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