Antioxidant activity in human faeces

Scarcely-absorbed antioxidants might reach the large bowel and exhibit anti oxidant activity, opposing the action of reactive O species by bacterial an d cellular metabolism and thus contributing to protection from oxidative da mage-induced gastrointestinal diseases. This study was carried out to evalu ate the antioxidant activity in the faeces of a group of healthy subjects o n a freely-selected diet, and to look for possible associations with the in take of some macro- and micronutrients and food groups. Fourteen subjects r ecorded their food intake three times for a period of 2 d, each time collec ting all the faeces passed during the next 24 h. Total antioxidant activity (TAA; mmol 6-hydroxy-2,5,7,8 tetramethylchroman-2-carboxylic acid (Trolox) /kg) of faecal suspensions was measured using the 2,2 ' -azinobis-(3-ethylb enzothiazoline-6-sulfonic acid radical cation (ABTS(.+)) decolorisation ass ay. The average TAA value of faeces was 26.6 (sd 10.2) mmol Trolox/kg wet f aeces (range 7.5-50.5). The total amount of antioxidant equivalents excrete d over 24 h, derived by multiplying the TAA by the amount of faeces passed over 24 h, was 3.24 (sd 1.51) mmol Trolox (range 0.92-5.82) and this was si gnificantly correlated with the average 24 h intake of coffee (P=0.002), re d wine (P=0.034), and particularly to the sum of coffee and red wine (P<0.0 001). In conclusion, the faeces of healthy subjects show detectable capacit y to scavenge radical cations, suggesting that antioxidant activity occurs in the colonic lumen. Moreover, such activity seems at least in part to be related to dietary habits.