"Probiotic-based food products may be an effective dietary prevention that could be implemented in many regions of the world to prevent the development of liver cancer or other environmentally induced cancers," wrote the researchers in The American Journal of Clinical Nutrition (Vol. 83, pp. 1199-1203).
Liver cancer is the sixth most commonly diagnosed cancer in the world, and third most common cause of death from cancer, according to Cancer Research UK. Despite these figures, the cancer remains relatively rare, with 18,500 new cases in the US every year, and about 3,000 in the UK.
The highest incidences of the disease are in east and Southeast Asia, particularly China, and for this reason the current researchers looked at the effects of probiotic supplements on markers for the disease.
The biggest risk factor for the disease is said to be chronic hepatitis B virus infection, but consumption of foods contaminated with aflatoxins are also established causes of liver cancer.
The researchers, led by Hannu Mykkänen from the University of Kuopio and supported by grants from the Academy of Finland and Valio, selected 90 male students from the Guangdong province where food ingested exposure to aflotoxins is said to be common.
The double-blind, placebo-controlled trial with two parallel groups randomly assigned the volunteers to either the intervention group - two probiotic capsules per day containing a mixture of the strains Lactobacillus rhamnosus LC705 and Propionibacterium freudenreichii ssp. shermanii, (Valio's commercial Bioprofit product), or placebo (cellulose).
The strains were present in equal weight concentrations with a dose of 2-5 x1010 colony-forming units per day.
At the start of the intervention period, both groups had similar urine concentrations of AFB-N7-guanine, a metabolite of aflotoxin M1.
"Probiotic administration led to a statistically significant decrease in the level of urinary excretion of AFB-N7-guanine. The reduction was 36 per cent at week three and 55 per cent at week five, but disappeared during the five-week post-intervention period," wrote lead author Hani El-Nezami.
The reduction in excretion levels of the aflotoxin metabolite indicates that the concentration within the body of carcinogens was decreasing.
"The results of the present probiotic intervention are encouraging for additionally studies on an approach of probiotic use that can beneficially influence the toxicokinetics of unavoidable exposures to aflotoxins and other natural and environmental carcinogens," concluded the researchers.