Published online Feb 7, 2017. doi: 10.3748/wjg.v23.i5.885
Peer-review started: October 7, 2015
First decision: October 28, 2015
Revised: November 13, 2016
Accepted: January 3, 2017
Article in press: January 3, 2017
Published online: February 7, 2017
Processing time: 110 Days and 10.2 Hours
To test the effects of humic acids on innate microbial communities of the colon.
We followed the effects of oral supplementation with humic acids (Activomin®) on concentrations and composition of colonic microbiome in 14 healthy volunteers for 45 d. 3 × 800 mg Activomin® were taken orally for 10 d followed by 3 × 400 mg for 35 d. Colonic microbiota were investigated using multicolor fluorescence in situ hybridization (FISH) of Carnoy fixated and paraffin embedded stool cylinders. Two stool samples were collected a week prior to therapy and one stool sample on days 10, 31 and 45. Forty-one FISH probes representing different bacterial groups were used.
The sum concentration of colonic microbiota increased from 20% at day 10 to 30% by day 31 and remained stable until day 45 (32%) of humic acid supplementation (P < 0.001). The increase in the concentrations in each person was due to growth of preexisting groups. The individual microbial profile of the patients remained unchanged. Similarly, the bacterial diversity remained stable. Concentrations of 24 of the 35 substantial groups increased from 20% to 96%. Two bacterial groups detected with Bac303 (Bacteroides) and Myc657 (mycolic acid-containing Actinomycetes) FISH probes decreased (P > 0.05). The others remained unaffected. Bacterial groups with initially marginal concentrations (< 0.1 × 109/mL) demonstrated no response to humic acids. The concentrations of pioneer groups of Bifidobacteriaceae, Enterobacteriaceae and Clostridium difficile increased but the observed differences were statistically not significant.
Humic acids have a profound effect on healthy colonic microbiome and may be potentially interesting substances for the development of drugs that control the innate colonic microbiome.
Core tip: Modern patients are increasingly interested in natural medicinal products, which are often not scientifically evaluated. Humins arise from organic microbial degradation and are an important mediator of microbial interactions in nature. Although used for medical indications since ancient times, no data exist on the impact of humins on the human microbiome. Our investigations in healthy volunteers show that orally applied humic acids increase the sum concentrations of preexisting colonic microbiota from 20% to 30% without changes in the bacterial diversity of the individual microbiome and may be a serious amendment/alternative to fecal transplantation or probiotics.