Mechanisms of probiosis and prebiosis: considerations for enhanced functional foods
Introduction
Our knowledge regarding the microbial community that inhabits the human body is expanding at a rapid pace. New worldwide initiatives like sequencing of the human microbiome [1] along with rapid advances in metabolomics to detect and quantify the products of microbial metabolism [2••] are contributing to a better comprehension of the role of symbionts for health and disease. For instance, activities of the gut microbiota are now known to play a central role in host energy requirements [3].
For well over a century, certain microorganisms have been regarded as probiotics, defined recently as ‘live microorganisms which when administered in adequate amounts confer a health benefit on the host’ [4]. Probiotics are largely administered through functional foods such as dairy products. Lactobacilli and bifidobacteria are currently the most marketed probiotic bacteria worldwide. Prebiotics, or ‘nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria that can improve the host health’ [5], are an alternative (or adjunct) approach to probiotics and target indigenous beneficial bacteria already established in the gut.
As foods are supplemented with probiotics and new functional ingredients, it is important to understand the beneficial properties of these products and how they aim to improve human health. Here, we explain mechanisms of probiosis and prebiosis and describe how this knowledge can help to design food with improved functionality to target certain populations. Both probiotics and prebiotics must be consumed regularly in order to measure the health benefits reported on the related human studies.
Section snippets
Mechanisms of probiosis
The probiotic arsenal includes multiple mechanisms for preventing infection and enhancing the immune system and providing increased nutritional value to food (Figure 1). Each mechanism of action is strain-dependent, making it important to select and scientifically compare individual probiotics for their intended purpose(s).
Mechanisms of prebiosis
The effects of prebiotics have been primarily directed toward the colon, but an increased amount of evidence demonstrates that prebiotics exert their effect beyond the GI tract [24]. Prebiotics selectively stimulate beneficial microbes within the gut microbiota. These compounds may directly stimulate immunity, protect against pathogens, and facilitate host metabolism and mineral absorption [24]. The different mechanisms of prebiotic action are summarized in Figure 2.
Probiotics and prebiotics in foods tailored for specific populations
Food products have been developed for specific age groups such as infants or the elderly [41]. These populations are of particular interest because of the early immune development in infants and a marked decline in immune function (immunosenescence) in the elderly. Functional foods containing probiotics or prebiotics are quickly gaining attention in the U.S. We have used the U.S. market as an example for illustrating some tailored probiotic and prebiotic products for certain populations (Table 1
Conclusions
As we begin to understand gut microbiome–host metabolic interactions and how they affect human health, probiotic and prebiotic supplementation are important strategies to modulate the gut microbiota and its metabolic output [52]. Probiotics and prebiotics may have systemic effects on the host immune system and metabolism, as revealed by integrative systemic metabolic and microbiome profiling. Recent studies have demonstrated the potentially extensive impact of prebiotics on the composition of
References and recommended reading
Papers of particular interest, published within the period of review, have been highlighted as:
• of special interest
•• of outstanding interest
Acknowledgements
JV currently receives support from the National Institutes of Health (NIH) (NIDDK R01 DK065075; NCCAM R01 AT004326; NCCAM R21 AT003482), the Office of Naval Research, the Defense Advanced Research Projects Agency (DARPA), and Public Health Service Grant DK56338, which funds the Texas Medical Center Digestive Diseases Center.
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