What Are Prebiotics and Probiotics? And How Can They Improve Your Health?

Dietitians, doctors, and health-conscious consumers often praise the purported health benefits of prebiotics and probiotics. But while these may be among the latest health buzzwords, many people aren't clear on their meanings, their benefits, and the differences between the two terms.

What Is Gut Health?

Prebiotics and probiotics impact the bacteria that live in our gastrointestinal tract. These bacteria are critical to our health in a variety of ways.

Researchers are discovering that bacteria in our gut -- also known as the microbiome -- impact physical and even mental health. It turns out that the microbiome is involved in a number of functions in the body. Most notably, a healthy microbiome is integral to good immune system function. That could mean promoting health or preventing infection by pathogenic microbes, according to the International Scientific Association for Probiotics and Prebiotics (ISAPP).

So, what are prebiotics and probiotics, and what are their unique functions in gut health?

What Are Prebiotics -- and How Do They Benefit Your Health?

The ISAPP defines a prebiotic as "a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health." These compounds occur naturally in foods or can be taken in supplement form, and they generally act like dietary fibers (though not all are). Prebiotics alter either the composition or the function of the microbiome as the microbes of the intestine selectively ferment them.

Many foods contain prebiotics naturally -- including onions, garlic, bananas, chicory root, and Jerusalem artichokes -- but they typically appear at low levels. Another option for added prebiotics is to take supplements or foods with added prebiotics, such as yogurts, infant formula, cereals, breads, or drinks.

However, product labels don't tend to include the term "prebiotics" in their ingredients lists. Instead, you'll find terms like galactooligosaccharides, fructooligosaccharides, oligofructose, chicory fiber, and inulin. Human breast milk is also a rich source of prebiotics for nursing babies, supporting the development a healthy microbiome in newborns.

What Are Probiotics -- and How Do They Benefit Your Health?

Prebiotics and probiotics may differ by only one letter, but their composition and functionality are quite different. The ISAPP defines probiotics as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host."

In simpler terms, probiotics are additional microorganisms that support the gut bacteria already living in your digestive tract, particularly when those bacteria are challenged by antibiotics, a poor diet, stress, or traveling. By making adjustments to gut bacteria, probiotics can promote health in a variety of ways, including boosting the immune system, aiding in the digestion of difficult foods, and improving nutrient absorption.

This can be particularly critical for aging populations, whose microbiomes tend to be more disturbed. This imbalance can potentially speed up the onset of certain diseases.

Natural sources of probiotics include yogurt and various fermented foods, as long as they're not heat-treated, which can kill the helpful as well as the harmful bacteria. Supplements are another option that may be more convenient and offer a higher potency.

However, not all probiotics are created equal in terms of both quality and amount. The specific strain of bacteria partly determines what health effects a certain probiotic might provide. The ISAPP recommends buying products with at least the minimum level of probiotics needed to achieve health benefits. You should also speak with your doctor before taking probiotics if you have an immune disorder, a serious underlying illness, or if you're expecting a child.

What Are the Mental Health Benefits of Prebiotics and Probiotics?

Recent research has looked beyond the impact of these ingredients on gut health, examining how a healthy gut and immune system affect another critical aspect of wellness: mental health.

One recent study found that activation of the inflammatory immune system may contribute to depressive disorders, especially when gut bacteria becomes imbalanced. Because probiotics and prebiotics help to restore balance in the gut bacteria, this can boost the immune system and potentially alleviate the symptoms of depressive or mood disorders that can result from prolonged inflammation.

Whether you're looking to improve your gut health, your mental health, or your immune function, prebiotics and probiotics can be an easy and effective solution. Speak with your doctor or nutrition professional about how to best integrate these ingredients into your diet.