Survival of bacteria during ingestion and transition through the stomach’s gastric juices and into the lower gut (where the majority of the gut microbiome is located) is a key mechanism relied on by live bacteria products.
An independent study tested Symprove and seven other market-leading products with the aim of exploring the comparative health and survival of different commercial formulations at two stages of use; the point of consumption and following exposure to gastric fluid. Three liquid (including Symprove) and five freeze-dried products were used.
In the study an enumeration test (were the claimed number of bacteria recoverable), a tolerance test (did the bacteria survive exposure to gastric juices) and a real-time growth test (did the bacteria grow after exposure to gastric juices) were carried out in an independent study at University College London School of Pharmacy.
Symprove was found to deliver 100% of the claimed colony forming units (CFUs), 100% of Symprove bacteria survived the tolerance test and the bacteria grew in the real-time growth test.
- Fredua-Agyeman, S. Gaisford (2014)
Comparative survival of commercial probiotic formulations: tests in biorelevant gastric fluids and real-time measurements using microcalorimetry
The large number of probiotic products now available makes the decision about which product to choose difficult both for the consumer and for the specialist providing dietary/nutritional advice. Data on the viability of the bacteria in these products, in an in vivo situation, are therefore important. This study was designed to explore the comparative health and survival of probiotic species in various commercial formulations, using more realistic test systems. This might allow further understanding of factors that must be controlled to optimise the delivery of live healthy bacteria to the lower gut.
A total of eight commercially available probiotic preparations were selected for enumeration tests and in vitro gastric tolerance tests. Tolerance assays were conducted in porcine gastric fluid (PGF) fed and fasted state (pH 3.4±0.04), simulated gastric fluid (SGF, pH adjusted to 1.2 and 3.4) and fasted state simulated gastric fluid (FaSSGF, pH adjusted to 1.6 and 3.4). Isothermal microcalorimetry was also used to measure real-time growth of probiotics after exposure to simulated gastric fluid.
Results from the enumeration tests indicated that recovery of viable organisms per dose is the same as or better than the stated label claims for liquid-based formulations, but lower than the stated claim for freeze-dried products. Results from the in vitro tolerance tests overall suggest that the PGF provided a harsher environment than the simulated systems at similar pH.
In general, liquid-based products tested tended to give superior results in terms of survival compared with the freeze-dried products tested. Results from tests in the fed state in PGF suggested that food greatly affects viability. Microcalorimetric data showed that for some products probiotic species were able to grow following exposure to gastric fluid, suggesting that viable bacteria reach the gut in vivo.