1.   Both the basal diet and the sulphate supplement were well tolerated by all the volunteers and no gastrointestinal symptoms were reported.

2.   The presence of these bacteria was shown by higher sulphate reduction rates recorded in faeces of these subjects even on the basal diet.

3.   This may be explained by the fact that more hydrogen was used in a metabolism other than methanogenesis in these subjects even on the basal diet.