January 15, 2014

Probiotics Reduce Duration of the Common Cold in the Elderly

Study finds a decrease in primarily upper respiratory infections among the Elderly


Guillemard E, Tondu F, Lacoin F, Schrezenmeir J. Consumption of a fermented dairy product containing the probiotic Lactobacillus casei DN-114001 reduces the duration of respiratory infections in the elderly in a randomised controlled trial. Br J Nutr. 2010;103:58-68.


Randomized, double-blind intervention trial


1,072 volunteers ≥70 years of age (median age 76)

Study Medication and Dosage

Subjects were given 200 g per day of a fermented dairy product containing L. casei (strain DN-114001) or an unfermented control dairy product and followed during the 3-month intervention period and for 1 additional month. Both liquids were administered in 100 g containers to be consumed twice per day. The daily total intake of colony-forming units (CFU) was 20 billion L. casei plus 2 billion of the combination of Streptococcus thermophilus and L. delbrueckii ssp. bulgaricus.

Main Outcome Measures

Incident colds, infectious sore throats, flu, pneumonia, bronchitis, and other common (mostly respiratory) infectious diseases along with their duration and severity, immune parameters, and reported quality of life.

Key Findings

Median duration of all common infectious diseases was 6.5 days in the probiotics group versus 8 days in the control group (P<0.01). Mean cumulative duration of all upper respiratory infections was 3 days shorter in the probiotics group versus the control group (P=0.0003). Despite the decline in the duration of these infections, the number of outbreaks did not differ significantly between the groups, nor did the severity of the outbreaks or other tracked indices.

Practice Implications

Ingestion of probiotics is known to boost immune function in elderly adults. In another recent blinded, randomized trial, a statistically significant reduction in the duration of colds and flu was reported in children.1 Other blinded randomized trials have reported reduced duration, severity, and/or incidence of colds in adults when the subject pool was not limited to the elderly.2,3
Such trials have used a wide variety of strains and at different doses, making it impossible for us to yet say which strain or strains is/are most effective, nor predict the optimal dose.
The safety of probiotics collectively suggest that it is time for healthcare practitioners to add probiotics to the therapeutic regimens they use to treat patients with colds or flu.
That said, the relatively consistent positive outcomes, the frequency of upper respiratory infections, and the safety of probiotics collectively suggest that it is time for healthcare practitioners to add probiotics to the therapeutic regimens they use to treat patients with colds or flu.
Our current level of ignorance begs the question, how are we then to proceed? There is little reason to think that a “fermented dairy product” would have an advantage over other delivery systems for probiotics. Also, given the apparent success of a wide variety of common strains of probiotics, it may not yet be time to worry much about which common probiotic strain of Lactobacillus or Bifidobacterium we prescribe. Some day this situation is likely to change; we’re just not there yet.
Regarding dosage, the tens of billions of CFUs per dose used in the current trial is in line with some other trials that have also produced positive outcomes. Such high doses are believed necessary due to attrition of bacteria in passing through the low pH found in most human stomachs. In summary, most probiotics help cold sufferers at least by shortening the length of colds, a variety of common strains seem to be effective, and effective doses appear to be high—in the tens of billions of CFUs per day.

Categorized Under


1. Leyer GJ, Li S, Mubasher ME, et al. Probiotic effects on cold and influenza-like symptom incidence and duration in children. Pediatrics. 2009;124(2):e172-179.
2. de Vrese M, Winkler P, Rautenberg P, et al. Effect of Lactobacillus gasseri PA 16/8, Bifidobacterium longum SP 07/3, B. bifidum MF 20/5 on common cold episodes: a double blind, randomized, controlled trial. Clin Nutr. 2005;24:481-491.
3. Pregliasco F, Anselmi G, Fonte L, et al. A new chance of preventing winter diseases by the administration of synbiotic formulations. J Clin Gastroenterol. 2008;42:S224-233.