On The Shelf
Johanna Taylor Katroscik
According to a 2021 article published in Gastroenterology by O’Connor and colleagues, approximately 1 in 20 people in the United States are using a prebiotic, probiotic, or synbiotic supplement. Interest in these products has been steadily increasing over the past 20 years. Sellers of synbiotic supplements make a number of claims about benefits they offer, including improved gut health and digestion, weight loss, and improved immune system function. So, what are the actual benefits of synbiotic supplements?
Background and function
Synbiotics have not been well-defined but are usually a combination of both pre- and probiotics. Prebiotics are indigestible fibers that are often found in fruits and vegetables. Even though they cannot be digested, they serve as food for the microbiota that live within the GI tract. Probiotics, on the other hand, are actual living microorganisms. Fermented food such as yogurt, kimchi, and kombucha contain probiotics, as do probiotic supplements. Probiotic supplements often contain “good” bacteria and/or yeasts. There are many strains of probiotics, but the most common commercially available probiotics contain the bacteria Lactobacillus or Bifidobacterium or the yeast Saccharomyces boulardii. Probiotics are generally thought to help promote good bacterial growth and flora within the GI tract.
The International Scientific Association for Probiotics and Prebiotics (ISAPP) is a nonprofit organization that was founded in 2002 to “champio[n] probiotic and prebiotic science” and to offer resources for consumers, students, clinicians, and scientists. They present a more in-depth definition of synbiotic supplements as “a mixture comprising [of] live microorganisms and substrate(s) selectively utilized by host microorganisms that confers a health benefit on the host.”
They further break synbiotics into 2 distinct groups: synergistic and complementary. Complementary synbiotics are simply made up of probiotics and prebiotics. Synergistic synbiotics contains a substrate that is not necessarily a prebiotic, but can be utilized by the probiotic microorganism with which it is formulated.
Is there a benefit?
ISAPP notes several studies have shown potential benefits of synbiotics in preventing surgical infections in adults, helping the treatment of patients with nonalcoholic fatty liver disease, obesity and metabolic syndrome, hyperglycemia and type 2 diabetes, and dyslipidemia. The potential benefits of synbiotics are promising, but—like all supplements—it appears to vary based on person and disease state. Not all synbiotics may work for all people or diseases—the different substrates and pre- and probiotics may dictate whether they work.
Daily requirements and dietary sources
Currently, there is no recommended daily requirement for synbiotic supplements. Different manufacturers offer varying recommendations for total daily amounts. Food sources such as yogurt, kombucha, kimchi, and other fermented foods may be a more reliable way to get pre- and probiotic intake. Prebiotics could be supplemented into the diet by eating starchy fruits or vegetables; these may include yams, bananas, and asparagus.
What to tell your patients
Synbiotic supplements may offer benefits, but there is no firm recommendation either for or against their use in healthy people. Patients who are immunocompromised or have underlying GI issues should consult their specialized providers prior to starting any new therapy. Patients may find it most cost-effective to incorporate some pre- and probiotics into their diet instead of purchasing a special supplement.