What are the health benefits of probiotics, and what’s the best source for them?

Many Americans use probiotic and prebiotic supplements, and surrounding probiotics are numerous health claims about what these “good bacteria” can do for the average person’s health and wellness.

They’re a common topic among my patients, many of whom have digestive issues and diseases such as irritable bowel syndrome, Crohn’s disease and ulcerative colitis.

Let’s sort through how they work:

What are probiotics?

Probiotics are live microorganisms, such as bacteria and yeast, which are beneficial and may support healthy digestive and immune systems. They’re found in naturally fermented foods, such as

• Buttermilk
• Kefir
• Kimchi
• Kombucha
• Miso
• Pickles
• Sauerkraut
• Fermented vegetables and fruit (look for “naturally fermented” on the label)
• Tempeh
• Yogurt

What are prebiotics? What’s the difference between prebiotics and probiotics?

Prebiotics are non-digestible food components, mostly short-chain carbohydrates, that promote the growth or activity of beneficial microorganisms. They serve as the fuel for probiotics.

Foods containing high amounts of prebiotics include many fruits and vegetables such as onions, garlic, artichokes, avocado, eggplant, legumes, asparagus and bananas, as well as whole-grain foods including oats and barley. Additional sources include resistance starch, yogurt and kefir.

Synbiotics, a relatively new term, are products that combine probiotic organisms and prebiotics.

What is the gut microbiome?

A microbiome is a collection of bacteria and microorganisms that live together in a particular environment within our bodies. The community of microorganisms that live in our gut is considered our gut microbiome.

What is the link between taking a probiotic and maintaining gut microbiome health?

Probiotics can modify gut bacteria by introducing known beneficial organisms, which may enhance the protective factors of the microbiome.

How much do we know about probiotics? What are the benefits of probiotics?

The benefits of probiotics originally were touted in the early 1900s by Russian scientist Elie Metchnikoff, who studied microbes in yogurt and sour milk. He linked Bulgarians’ sour-milk diets to their healthy, long lives.

In the last hundred years, we’ve learned through clinical studies that probiotics may be able to help ward off disease-causing microorganisms, aid digestion, help absorb nutrients, support immune function, create vitamins, control inflammation, and break down and absorb medication.

While numerous studies have attested to the benefits of probiotics, larger, better-designed clinical trials and research are needed to clarify the role of specific probiotics in different patient populations.

Among the myriad strains of probiotics, there’s no known strain that acts as a cure-all or single preventive aid for any condition. But the still-limited research has shown that a rich, diverse internal microbiome in your body — one that includes a variety of microorganisms — can support a healthy digestive system and a well-functioning immune system.

When should I take a probiotic supplement?

It is recommended that adults and children on antibiotic treatment for the prevention of C. diff infection take a probiotic supplement.

Adults and children with inflammatory bowel disease who develop pouchitis (inflammation or infection of the ileal pouch) could also benefit from taking probiotics.

If you have mild recurrent ulcerative colitis, constipation, or allergies like atopic dermatitis, you might also benefit from taking probiotics, according to the latest data. Unfortunately, there is unconvincing evidence for probiotics’ use in irritable bowel syndrome (IBS).

Eating two to three daily servings of probiotic-rich foods, along with prebiotic food sources, is currently the best way to maintain diverse, friendly bacteria and the optimal balance of good versus bad microorganisms in your gut. However, various environmental factors including stress, smoking and alcohol use can also alter the gut microorganisms and influence gut health.

When should I avoid probiotics?

Sick infants or children with acute infectious diarrhea, anyone with a compromised immune system — either from illness or medication — and people whose health is weakened from a recent surgery should avoid probiotic supplements.

Signs that a particular probiotic may not be right for you include symptoms of gas, bloating, constipation, diarrhea and irritability.

While probiotics have a history of being generally safe, especially in healthy people, the evidence on safety is still lacking. Always talk to your health care providers before taking a probiotic or giving one to your child, especially since some may interfere with medications. It’s especially important to check with a health care provider about the safety and efficacy of probiotic use if you’re pregnant or breastfeeding.

What should I look for in a probiotic supplement?

Depending on the probiotic’s intended use, the U.S. Food and Drug Administration (FDA) might regulate it as a food ingredient, drug or — most commonly — a dietary supplement.

Dietary supplements, unlike medication, aren’t regulated by the FDA and don’t require prior approval. Therefore, it’s hard to know if the supplement bottle you’re buying lives up to its claims or even includes the ingredients listed.

Some independent companies function as third-party supplement testers. Supplements with a seal of approval from the United States Pharmacopeial Convention or NSF, for example, are more likely to live up to claims of purity and potency. Certified supplements are recommended. Some uncertified probiotic products have been reported to contain other microorganisms not listed on the label, which could present a health risk.

Probiotics come in many forms — food, drinks or liquids, capsules or pills, and powders. Commercially available probiotics are measured in colony forming units (CFU), indicating the number of viable cells they contain. Probiotics typically contain 1-10 billion CFU per dose. However, higher CFU doesn’t necessarily improve the product’s health effects.

Some strains of probiotics need to be refrigerated. When purchasing these types of probiotics from the internet, make sure the delivery method keeps them refrigerated and ensures that they stay cold following delivery. It’s also important to pay attention to any probiotic’s “use by” date or expiration date.

The bottom line on probiotics’ health benefits

We’re still gathering research on probiotics’ benefits for our health. We don’t yet know which are helpful and which aren’t, nor how much people should take or who would be most likely to benefit. Researchers continue to work on finding answers. Although probiotics are low-risk and likely beneficial, you should still talk with your health care provider before taking them.

For now, let’s focus on consuming a nutrient-rich diet full of variety and dietary sources of probiotics and prebiotics.