In a randomized, double-blind study on almost 500 adults, people that took daily vitamins and minerals with probiotic bacteria for at least three months reported that colds lasted almost two days less than the average nine days suffered by a group taking only vitamins and minerals.
The volunteers, who recorded their symptoms when they had a cold on a daily basis, also reported that headaches, coughing and sneezing, and fever were less severe if they were taking the probiotic supplement, the Multibionta brand made by Merck.
The research, presented this week at the European Influenza Conference in Malta, shows that symptoms were down by nearly a quarter and the time spent with a fever was cut from 24 hours to six.
The findings are likely to boost the probiotics market, already worth around £135 million a year in the UK. Most products are however promoted for improving gut health. The new study will play a significant role in building the body of evidence demonstrating the bacteria's benefits to the immune system.
Probiotic bacteria are thought to activate certain defence cells in the immune system, particularly the T cells. This mechanism is supported by the new trial in which the researchers, led by Dr Michael de Vrese at the Federal Research Centre of Nutrition and Food in Kiel, observed higher levels of cytotoxic plus T suppressor cells (CD8+) and T helper cells (CD4+) in a subsample of the probiotic group after just two weeks of supplementation.
The bacteria found in Multibionta include Lactobacillus gasseri PA 16/8, Bifidobacterium longum SP 07/3 and B. bifidum MF 20/5.
The study's findings are reported in the August issue of Clinical Nutrition (vol 24, issue 4, pp481-91).