The difference between prebiotics and probiotics - and how to add both to your diet to boost gut health

Elena Bruess,Samantha Cassetty

Dec 12, 2020, 09:50 IST

The difference between prebiotics and probiotics - and how to add both to your diet to boost gut health

Probiotics include fermented foods like kimchi while prebiotics can be found in raw vegetables.Kseniya Ovchinnikova/Getty Images

Prebiotics are a type of plant fiber that feeds the good bacteria in our gut.
Probiotics are foods and supplements that contain live strains of healthy bacteria and yeasts.
Both prebiotics and probiotics are essential for gut health and can improve digestive issues like constipation or diarrhea.

While probiotics and prebiotics are just a small slice of our incredibly complex gastrointestinal system, they are very important for our health. Here's what you need to know about prebiotics and probiotics and how they benefit our body.

Why probiotics and prebiotics are important for your health

Trillions of little bacteria, along with viruses, fungi, and yeast, line every corner of our body and make up a miniature ecosystem, known as our microbiome. In our gastrointestinal system alone, there are around 1,000 species of bacteria, all of which can affect our health.

Prebiotics and probiotics are both important to the health of our gut microbiome, which helps digest certain nutrients and protect you from infection.

On the other hand, imbalances in gut bacteria - known as gut dysbiosis - can increase your risk of diseases like diabetes, inflammatory bowel disease (IBD), and cancer. Gut dysbiosis can occur due to:

Poor diet
Illness
Stress
Old age
Antibiotic use

"If you have any kind of chronic health problem, symptoms could be slightly reduced if we could add to your gut health and shift your gut microbiome to a more health-promoting microbiome," says Terry Wahls, MD, a clinical professor of medicine at the University of Iowa Carver College of Medicine.

To do so, it's important to understand the difference between prebiotics and probiotics, and how to get both into a healthy diet.

What are prebiotics?

Prebiotics are specialized plant fibers that the human body cannot digest, but can become food for the good bacteria in your gut. These fibers aid in the healthy growth of gut bacteria, and can be found in the food we eat such as raw vegetables, beans, and bananas - especially when they aren't ripe.

There can be many benefits to consuming prebiotics, like:

Increasing calcium absorption. Ingesting prebiotics may increase calcium absorption in the lower intestines. Calcium is important for bone health and building bone density, especially for those at risk for osteoporosis, says Gail Cresci, PhD, RD, a doctor of pediatric gastroenterology, hepatology, and nutrition at the Cleveland Clinic.

Processing food quickly. The fiber found in prebiotics is important for normal bowel movements. A 2013 review found fiber's bulk and water retaining abilities can decrease the time it takes to digest in the digestive tract.

Controlling blood sugar levels. Numerous studies have found fiber from prebiotics can reduce your glucose absorption rate, which can prevent spikes in blood sugar, prevent weight gain, and decrease the risk of diabetes.

A large 2010 study in Caucasians, Japanese Americans, and Native Hawaiians between the ages of 45 and 75 found high intakes of fiber significantly reduced the risk of developing type 2 diabetes.

Prebiotic foods

Most people should eat between 25 to 38 grams of fiber per day. Foods high in prebiotic fibers include:

Barley
Whole wheat bread
Beans
Raw vegetables and fruits like apples, onions, or asparagus

You can also take prebiotic supplements such as psyllium or methylcellulose, but Wahls says it's important to eat more vegetables and other fibrous foods first. That's because supplements won't provide important vitamins and minerals found in fiber-rich food.

"Everyone's needs are going to be unique, depending on your microbes living in your gut," says Wahl. "For example if you have more blue stools, perhaps because of inflammatory bowel disease, that's going to be a lower fiber intake. But if you're constipated, you'll have a much higher fiber need."

A doctor might recommend a low-fiber diet or one with less prebiotics due to Crohn's disease, ulcerative colitis, or if you've recently had bowel surgery or a bowel-related problem.

What are probiotics?

Probiotics contain living strains of beneficial gut bacteria and yeasts. They maintain a healthy balance in your gut by boosting the number of good bacteria in the body and fighting off bad bacteria.

There are many kinds of probiotics, and each benefits the body in different ways. The most common species are lactobacillus and bifidobacterium, both of which break down food and fight harmful bacteria.

The health benefits of probiotics include:

Strengthening digestive health. Probiotics may benefit people with digestive issues, such as diarrhea, irritable bowel syndrome, and ulcers.

A large 2019 review assessed children aged 18 and under who took antibiotics. It found those who took probiotics alongside antibiotics were less likely to experience diarrhea.

Meanwhile, a 2014 review of probiotics and irritable bowel disease (IBD), found probiotics can aid in the remission of ulcerative colitis - a form of IBD - and pouchitis - an inflammation after IBD surgery. But, there is little evidence that probiotics can aid in treating Crohn's Disease.

Improving mental health. Research has found that the gastrointestinal tract and the central nervous system communicate, most commonly referred to as the "brain-gut axis." A 2016 review found supplementing probiotics for four weeks was efficient in improving psychiatric disorder-related behaviors like anxiety and depression.

Similarly, a 2017 review found positive results when treating depressive symptoms with probiotics, but the probiotic strains and dosing varied, and further research is needed. It's always smart to talk to your doctor about improving mental health before attempting to treat it on your own.

Probiotic foods

You can get probiotics by eating fermented foods such as:

Yogurt
Kimchi
Sauerkraut
Kefir
Kombucha

While some people may prefer a supplement, according to Cresci, it's better to consume probiotics through food.

"The yogurt has your probiotic in it, but then you have these beneficial metabolites that you'll also be consuming at the same time," says Cresci.

The number of probiotics you should consume daily varies greatly. Since there is such a diversity in probiotics, the amount is not set, and often it can depend on daily changes in your gut condition and your body's needs.

According to Cresci, people who should not take probiotics without a doctor's approval include:

Immunodeficiency diseases like AIDS or leukemia
Receiving immunosuppressive drugs like chemotherapy and other immune-suppressing drugs

That's because these individuals should not be introducing new microbes into their diet, says Cresci. But everyone should consult with their doctor or a dietitian before beginning new supplements or considering different strains of probiotics.

Insider's takeaway

What we eat is incredibly important, both for our body and for our body's microbiome. Prebiotics and probiotics are both important for keeping our gut balanced and healthy. The difference between the two is prebiotics feed live bacteria in the gut whereas probiotics are the live bacteria in the gut.

"We want to be good stewards to our microbiome," says Wahls. "And that's having enough vegetables, having enough fermented foods so we're getting enough prebiotics and probiotics and then when necessary taking supplements to further support restoration."