Are postbiotics the long sought-after solution for a leaky gut?

Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” (1). Although viability is required for a microbe to be labelled as a probiotic, viability is not always necessary for health benefits to ensue. Nonviable probiotics that retain their physiological benefits are commonly referred to as paraprobiotics, whereas the term postbiotic is used for soluble bioactive factors secreted by live probiotics or released after cell lysis (2). Such alternatives could overcome some of the perceived risks of the use of live probiotics, such as excessive immune stimulation, systemic infections, and horizontal gene transfer (3).