Transit times were measured once on the basal diet and once during sulphate feeding.

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.

Because of the presence of casein, a phosphorylated protein, this basal diet contained 50 mol/g phosphate.

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

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

Correspondingly, sulphate reducing bacteria which were not found during the basal diet, became detectable while counts of methanogenic bacteria decreased 100-fold during this period.

It also depends on data from digestibility studies, where individual foods have been substituted for basal diets in order to measure the apparent digestibility coefficients for those foods.

Moreover, during the badal diet breath CH 4 concentrations increased in responders duggesting that their usual diet contained enough sulphate for sulphate reducing bacteria to reduce the amount of hydrogen available to methanogens, whilst on the sulphate depleted basal diet more hydrogen could be used for methanogenesis.