As the UK weather sees a major drop in temperature, the chance of individuals catching a cold or flu increases. People are urged to get the flu vaccination at their local GP surgery or local pharmacy to keep the winter virus at bay. Having said this, it is now of current trend for individuals to eat foods that enhances their immune system with recommendations of foods to consume featured in magazines and health blogs. Regular consumption of vitamin C-rich foods has been popularly considered in reducing the risk of and treating respiratory infections; however, emerging studies have indicated that probiotics may also do the job too.
Probiotics are defined by the Word Health Organisation (WHO) as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Many probiotics have been demonstrated to restore the balance of the gut bacteria and advance our own immune system to help it to fight infections better. Probiotics regarded as the 'good' bacteria, can be found in food products like yoghurt, kefir and dark chocolate and in dietary supplements.
Some research has revealed the potential of probiotics reducing the incidence and/or severity of respiratory infections in adults. For example, in a randomised, double-blind placebo-controlled study in Sweden; researchers examined the effect of the probiotic bacteria - Lactobacillus reuteri (L.reuteri) on its ability to improve work-place healthiness by lowering the rate of short-term sick leave caused by respiratory infections. 262 employees in TetraPak received either a daily dose of L.reuteri or placebo for 80 days. In the probiotic group, 10.6% of employees reported sick leave during the study, whereas, over twice the percentage reported sick in the placebo group (26.4%). Further, the frequency of sick-days was 0.9% in the placebo group and 0.4% in the L. reuteri group.
In an earlier study, it was demonstrated that the probiotic, Lactobacillus GG, may reduce respiratory infection and its severity in children. 571 healthy children were assigned to drink milk with or without Lactobacillus GG. Children who sipped the milk containing the probiotic bacteria had fewer days of absence in comparison to children who sipped milk without it. Additionally, in probiotic group, there was a reduction of 17% in the number of children suffering from respiratory infections with complications and lower respiratory tract infections.
A research published in the Journal of Science and Medline in Sport indicated that rugby players in New Zealand had about 40% few colds and gastrointestinal infections when they administered a probiotic compared to when they took a placebo.
Whilst researchers have inferred that probiotics help lessen the severity and duration of respiratory infection, the preventive effect of probiotics is not conclusively established. In a systematic review of 14 random-control trials (RCT) aiming to show the probiotic use for preventing respiratory infection, 10 out of 14 RCT reported that there was no reduction in the incidence of respiratory disease after taking probiotics.
With inconsistencies in findings, it is hard to actually determine whether probiotics can solely prevent and treat colds. Generally, probiotics are good for gut health and considered safe for healthy people of all ages. However, people should not only rely on probiotics to prevent or treat respiratory infections and should discuss their use of probiotics with a Healthcare Professional.