Date of Award

Spring 2015

Document Type


First Advisor

Ibrahim, Salam A.


The elderly population is inherently more susceptible to gastrointestinal problems and diseases due to significant age-related gastrointestinal changes experienced in gut physiology, reactivity of the immune system, and/or diet. These factors, coupled with increased occurrence of disease and corresponding medication use, could also modify the composition of gut microbiota. The impact of non-steroidal anti-inflammatory drugs (NSAIDs) on the physical gastrointestinal tract has already been shown. However, the impact of these factors on the microbiota inhabiting the GI tract has not been well established. A better understanding of the relationship between medication use and gut microbiota composition may have beneficial implications for general and elderly health. Increasing knowledge on the health benefits of probiotics among consumers has dramatically surged the use of probiotics in the recent decades. The objective of this study was to determine the impact of commonly administered medical drugs and commonly consumed caffeine on the viability and functionality of commercially available probiotic supplements. Ten probiotic supplements containing various strains of bifidobacteria (B. longum, B. bifidum, B. lactis, B. breve, B. infantis) and lactobacilli (L. acidophilus, L. rhamnosus, L. reuteri, L. gasseri, L. plantarum, L. casei, L. brevis, L. salivarius, L. paracasei) were individually grown in laboratory medium de Man, Rogosa and Sharpe (MRS) broth at 37°C for 24 h. Batches of 10 mL MRS broth were mixed with 100 μL of aspirin stock, inoculated with 1 mL overnight grown probiotic culture, and then incubated at 37ºC for 2h. Bacterial populations were determined at 0 and 2h of incubation. In addition, bile resistance, β-galactosidase activity, reducing power, and protein expression were examined. Our results showed that six out of the ten commercial probiotic supplements contained bacterial populations as claimed on their respective labels. The β- galactosidase activity of each supplement was determined. The enzyme activity ranged from 1 to 1,120 Miller units. A single supplement was selected for continued testing in objective 2. Exposure to one tablet of aspirin was found to decrease bacterial population approximately 6.75 log CFU/ml, and exposure to caffeine (0.5% w/v) decreased population approximately 0.23 log CFU/ml. Determination of β- galactosidase activity resulted in reductions in enzyme activity post aspirin exposure and caffeine enhanced enzyme activity.