Can probiotics prevent or improve common cold and influenza?

Effects of Lactobacillus casei supplementation on disease activity and inflammatory cytokines in rheumatoid arthritis patients: a randomized double‐blind clinical trial

“…Results of the many studies conducted in this regard have revealed that probiotics not only stimulate the immune system locally, but also affect both innate and adaptive immune responses systemically . Furthermore, it has been shown that these microorganisms affect immune responses in a strain‐specific manner; some stimulate the immune system which makes them applicable in patients suffering from immune deficiencies, and some regulate immune responses and can help patients with up‐regulated immune system, as in RA …”

Probiotics and Prebiotics for Prevention of Viral Respiratory Tract Infections

“…A better understanding of the effects of different probiotic strains and their combination, selection of the most beneficial strains, the dose and timing of supplementation for various age groups, and a deeper insight into their mechanisms of action are needed for the validation of specific strains carrying a potential to modify the frequency and severity of RTIs (Homayouni Rad et al, 2013). It may be too soon to judge the role that probiotics may play in the prevention of the common cold because there are many strains of probiotics with established immunomodulatory effects yet to be tried with the particular goal of seeking their effects on respiratory infections.…”

Folate bio-fortification of yoghurt and fermented milk: a review

“…For a strain to be determined as probiotic, it should preferably be of human origin, have a status generally recognized as safe (GRAS), be able to survive through the gastrointestinal tract, adhere to the human intestinal cells, be antagonistic towards potential pathogenic microorganisms and have several health benefit effects on the host (Collins et al 1998;Iyer et al 2010). Probiotic bacteria have a positive effect on the immune system and intestinal microbiotic composition and functions and have been claimed to be therapeutic or preventive against infections and several autoimmune and atopic diseases (Collins et al 1998;Homayouni Rad et al 2013a, 2013bRossi et al 2011;Schrezenmeir and de Vrese 2001;Singh et al 2011).…”