Background: Probiotics are a mixture of good live bacteria and/or yeasts that naturally survive in our bodies. Recently, loads of studies have focused on their role in the immune system and digestive tract. Accordingly, there are many commercially available probiotic products in the market. This study examines the immunostimulatory effect of commercially available-probiotic conditioned medium (PCM) on RAW264.7 murine macrophages. Methods: Probiotic conditioned medium has been prepared by culturing the commercially available probiotic in a cell culture medium overnight at 37°C, followed by centrifugation and filter-sterilization to be tested on RAW264.7 murine macrophages. The immunostimulatory effect of different ratios (50, 75, 100) of PCM was examined using MTT assay, pro-inflammatory cytokine (tumor necrosis factor TNF-alpha) production in macrophages., migration, and Phagocytosis assays. Results: At all the examined PCM ratios, the percentages of cell viability were >80%. Regarding the migration scratch, TNF-alpha and phagocytosis assays, PCM demonstrated a concentration-dependent pattern in the immunostimulatory effect. However, the ratio of 100 PCM illustrated a significant (p-value<0.05) stimulatory effect compared to the positive and negative control. Conclusion: The findings of this study confirm the stimulatory activity of probiotic conditioned medium, which may contribute directly to the immune-boosting effect of the probiotic supplements.

Food supplemnts such as vitamin D3 and omega-3 have a significant impact on controlling pathogens. This study aims to evaluate the antimicrobial activities of combined vitamin D3 and omega-3 against selected pathogens. Minimum inhibitory activities of different serial dilutions of vitamin D3 (1.8 µM-216.6 µM) or omega-3 (0.8 mM-110 mM) or combined (vitamin D3: 0.8 µM -108.2 µM and omega-3: 0.3 mM -55 mM) have been investigated on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. All the tested concentrations of vitamin D3 and omega-3 as a separate treatement were significantly different from the positive control in terms of microbial log-reduction. The highest concentration of vitamin D3 demonstrated a complete eradication of the tested microorganisms. Conversely, omega-3 had a lower effect on them. Combining 27 µM vitamin D3 and 13.5mM omega-3 resulted in ~ 0.4 to 0.6 log reduction of S. aureus, E.coli, P. aeuregnosa and C. albicans. On the other hand, C. albicans had 1.1 log reduction at a combination of 108.4 µM vitamin D3 and 55 mM of omega-3. Proposed mechanisms of the lowered antimicrobial activity when using the combination are discussed. These findings showed decreased antimicrobial effect of the combination and suggest a similar in vivo study to evaluate wheather taking the combination together or not.