Calcium montmorillonite clay reduces urinary biomarkers of fumonisin Bt exposure in rats and humans

摘要

Fumonisin B_1 (FB_1) is often a co-contaminant with aflatoxin (AF) in grains and may enhance AF's carcinogenicity by acting as a cancer promoter. Calcium montmorillonite (i.e. NovaSil, NS) is a possible dietary intervention to help decrease chronic aflatoxin exposure where populations are at risk. Previous studies show that an oral dose of NS clay was able to reduce AF exposure in a Ghanaian population. In vitro analyses from our laboratory indicated that FB_1 (like aflatoxin) could also be sorbed onto the surfaces of NS. Hence, our objectives were to evaluate the efficacy of NS clay to reduce urinary FB_1 in a rodent model and then in a human population highly exposed to AF. In the rodent model, male Fisher rats were randomly assigned to either FB_1 control, FB_1 +2% NS or absolute control group. FB_1 alone or with clay was given as a single dose by gavage. For the human trial, participants received NS (1.5 or 3 g day~(-1)) or placebo (1.5g day~(-1)) for 3 months. Urines from weeks 8 and 10 were collected from the study participants for analysis. In rats, NS significantly reduced urinary FB_1 biomarker by 20% in 24h and 50% after 48 h compared to controls. In the humans, 56% of the urine samples analysed (n = 186) had detectable levels of FB_1. Median urinary FB_1 levels were significantly (p < 0.05) decreased by >90% in the high dose NS group (3g day~(-1)) compared to the placebo. This work indicates that our study participants in Ghana were exposed to FB_1 (in addition to AFs) from the diet. Moreover, earlier studies have shown conclusively that NS reduces the bioavailability of AF and the findings from this study suggest that NS clay also reduces the bioavailability FB_1. This is important since AF is a proven dietary risk factor for hepatocellular carcinoma (HCC) in humans and FB_1 is suspected to be a dietary risk factor for HCC and oesophageal cancer in humans.