Effect of lactobacillus acidophilus supplements on mutagen excretion in faeces and urine in humans

Lactic acid bacteria have been reported to have antimutagenic properties in vitro. In order to investigate whether Lactobacillus acidophilus supplements have antimutagenic effects in humans, 11 healthy subjects on a standardised diet consumed fried beef patties twice daily for 3 d. The diets were supplemented with ordinary Lactococcus fermented milk (phase 1) and thereafter with L. acidophilus fermented milk (phase 2), whereby the excretion of mutagenic activity was determined in urine and faeces. In both faeces and urine high levels of mutagenicity were detected during phase 1. There was an increase in lactobacilli in the intestinal microflora in seven of 11 subjects by the L. acidophilus supplement (phase 2), and the mutagenic activity in urine was 72 per cent lower on day 2 (P < 0.01) and 55 per cent lower on day 3 (P < 0.05) compared to days 2 and 3 in phase 1. The total faecal and urinary mutagen excretion on day 3 during phase 2 was 47 per cent lower compared to day 3, phase 1 (P<002). Thus, L. acidophilus given together with fried meat lowered mutagen excretion in humans.