A review of the advancements in probiotic delivery: Conventional vs. non-conventional formulations for intestinal flora supplementation

Abstract

Probiotic delivery systems are widely used nutraceutical products for the supplementation of natural intestinal flora. These delivery systems vary greatly in effectiveness to exert health benefits for a patient. Probiotic delivery systems can be categorized into conventional, pharmaceutical formulations, and non-conventional, mainly commercial food-based, products. The degree of health benefits provided by these probiotic formulations varies in their ability to deliver viable, functional bacteria in large enough numbers (effectiveness), to provide protection against the harsh effects of the gastric environment and intestinal bile (in vivo protection), and to survive formulation processes (viability). This review discusses the effectiveness of these probiotic delivery systems to deliver viable functional bacteria focusing on the ability to protect the encapsulated probiotics during formulation process as well as against harsh physiological conditions through formulation enhancements using coatings and polymer enhancements. A brief overview on the health benefits of probiotics, current formulation, patient and legal issues facing probiotic delivery, and possible recommendations for the enhanced delivery of probiotic bacteria are also provided. Newer advanced in vitro analyses that can accurately determine the effectiveness of a probiotic formulation are also discussed with an ideal probiotic delivery system hypothesized through a combination of the two probiotic delivery systems described.

Fig. 1

Summary of the microbial content found in a healthy human GIT. [Image adapted with permission from Iannitti and Palmieri (12) © 2010 Elsevier Ltd, Microbial species adapted with permission from Holzapfel et al. (13) © 1998 Elsevier Science B.V.]

Fig. 2

A basic schematic detailing the properties of an ideal probiotic bacteria (12,24)

Fig. 3

An overview of the available non-conventional delivery systems used for probiotic delivery

Fig. 4

Images of mice predisposed to atopic dermatitis treated with prednisolone and Lactobacillus acidophilus strain L-55 showing significant improvement in the treatment of this condition using the probiotic bacteria when compared to the control group. [Image reproduced with permission from Sunada et al. (17) © 2008 Elsevier B.V.]

Fig. 5

A schematic depicting the use of colon microflora for site-specific drug delivery. [Adapted with permission from Yang et al. (91) © 2002 Elsevier Science B.V.]

Fig. 6

A schematic of an SHIME unit. Flasks 1–2 depict supplementary media for the system with vessels A–E depicting various areas of the intestinal system and colon. These vessels are pH controlled using control units. Vessel F contains the effluent of the system. [Image adapted with permission from De Boever et al. (111) © 2000 American Society for Nutritional Sciences]