The present invention relates to a microbial composition which is tailored based on the spectrum of microbes found more frequently from the intestine of non-secretor individuals than from the intestine of secretor individuals. The present invention further relates to a method of tailoring a microbial composition based on the spectrum of microbes found more frequently from the intestine of non-secretor individuals than from that of secretor blood group status. The present invention relates to use of the secretor status of an individual as a criterion for microbial supplementation tailored based on the differences in the spectra of microbes found between secretor and non-secretor individuals.