Microscopic examination of the intestinal wall and selected organs of minipigs orally supplemented with humic acids

Humic acids are used to prophylactically treat intestinal diseases in a wide number of species, yet the mechanism of action remains unknown. The general assumption has been that humic acids act locally; however studies using young piglets show orally supplemented humic acids can penetrate the intestinal wall, and thus potentially act systemically. The objective of this study was to determine if humic acids could also cross the intestinal barrier in adult pigs and be detected in other organs. Adult minipigs (>18 months old) orally received either 1 g humic acids/kg body weight (verum, n = 3) or placebo (control, n = 3), for 2 weeks. At the end of the feeding period tissue samples were harvested from the intestine, various glands and organs. Unstained tissue samples were examined by light microscopy for the presence of humic acid particles. No humic acid particles were detected in any of the unstained tissues from verum or control pigs.