Lactose intolerance is a form of lactose maldigestion where individuals experience symptoms such as diarrhoea, abdominal cramping, flatulence, vomiting, and bowel sounds following lactose consumption. An estimated 30% of the population from the United States and Mediterranean countries may suffer from this condition, although lactose intolerance prevalence is lower in northern European countries and higher in African and Asian countries. Lactic acid bacteria (LAB) such as Lactobacillus acidophilus and Lactobacillus bulgaricus may help digesting lactose contained in fermented dairy products and this could be beneficial to individuals suffering from lactose intolerance. Lactobacillus acidophilus is a species of LAB involved in sugar fermentation; no human clinical trials exist evaluating its efficacy in alleviating symptoms related to lactose intolerance.

A recent study, led by Mr. Michael Shahani from Nebraska Cultures in Walnut Creek (California, USA), has found that a specific strain of Lactobacillus acidophilus may provide symptom benefits after 4 weeks of use, compared with a placebo, among individuals with lactose intolerance.

The researchers performed a randomized, double-blind, placebo-controlled, crossover study for evaluating the effects of the DDS-1 strain of Lactobacillus acidophilus on relieving symptoms related to lactose intolerance. 38 healthy volunteers (18-75 years of age) who complained of lactose intolerance were enrolled in the study. The eligibility of participants was confirmed based on a score of 10 or higher on subjective assessment of the following symptoms after a 6-h lactose challenge: diarrhoea, abdominal cramping, vomiting, audible bowel sounds, flatulence, and overall symptoms. Qualified subjects participated in a 2-arm crossover design, with each arm consisting of 4 weeks of intervention of either active or placebo product, with a 2-week washout period during crossover. The study product consisted of the DDS-1 strain of Lactobacillus acidophilus (at least 1 x 1010 colony forming units/capsule) administered daily for 4 weeks.

Longitudinal comparison between the DDS-1 group and placebo group demonstrated statistically significant reductions in abdominal symptom scores during the 6-h lactose challenge at week 4 for diarrhoea, abdominal cramping, vomiting, and overall symptom score. No adverse effects were reported.

In conclusion, the DDS-1 strain of Lactobacillus acidophilus is safe to consume and improves abdominal symptoms compared with placebo after 4 weeks of probiotic use. Further studies that assess the role of lactic acid bacteria in lactose intolerance over a period of more than 4 weeks may provide useful insights in this field. Ahead, it will also be necessary to study the possible mechanisms of action in order to compare this treatment for lactose intolerance with possible alternatives that target the gut microbiota.




Pakdaman MN, Udani JK, Molina JP, Shahani M. The effects of the DDS-1 strain of lactobacillus on symptomatic relief for lactose intolerance – a randomized, double-blind, placebo-controlled, crossover clinical trial. Nutr J. 2016; 15(1):56. doi: 10.1186/s12937-016-0172-y.