Amelioration of Aflatoxicosis in Rats

Addition of sequestering agents to feeds and foods has been proposed as a protective strategy against mycotoxins. To investigate the efficacy of Volclay, a bentonite clay, to protect against aflatoxicosis, rats were fed peanut butter (50% wt/wt)-based diets containing 1,500 ppb aflatoxin (AF), 1,500 ppb aflatoxin with 0.1% Volclay supplementation (AF-LD), or 1,500 ppb aflatoxin with 1% Volclay supplementation (AF-HD) for 8 weeks. The control group was fed a peanut butter-based diet without aflatoxin or Volclay supplementation and a fifth group was fed the control diet with 1.0% Volclay supplementation (VC). No differences in appearance, behavior, or selected hematological and serum chemical variables were observed. Decreased weight gain, decreased food consumption, and liver lesions consistent with hepatic aflatoxicosis were found in AF-fed rats. Weight gain and food consumption of the AFHD group were comparable to the control and VC groups and were significantly increased compared to AF-fed rats, even though weekly aflatoxin ingestion of AF-HD rats equaled or exceeded that of the AF group. Body weight and food consumption of the AF-LD group were slightly increased compared to AF group and decreased compared to the control, VC, and AF-HD groups, but the differences were not statistically significant. Liver lesions were found in all AF and AF-LD rats. Lesions were also detected in eight of 10 AF-HD-fed rats, but were subtle and significantly less extensive than in AF and AF-LD rats. The data suggest that Volclay is nontoxic and may be an efficacious sequestering agent for residual aflatoxin in peanut butter. Aflatoxins are a class of compounds produced by Aspergillus spp., particularly Aspergillus flavus. These mycotoxins cause a variety of effects, including liver cancer, in virtually all domestic and laboratory animal species tested (1). Aflatoxin has been epidemiologically linked to liver cancer in humans (1,5,13,15), and although debate whether or not aflatoxin is a human carcinogen continues, it is considered by the International Agency for Research on Cancer as a probable human carcinogen. Consequently, aflatoxin residues in feeds and food have been regulated (5). Aflatoxins can occur naturally in a variety of agriculturally important commodities including peanuts and, consequently, may be found in peanut butter. Addition of sequestering agents such as activated charcoal (2) and hydrated sodium calcium aluminosilicate (HSCAS) (12), which bind aflatoxin and decrease its bioavailability, to animal feeds has been proposed as a detoxification strategy. In vivo investigations have shown that HSCAS reduces the toxicity of aflatoxin (2,6-11). Sodium bentonite, another proposed sequestering agent, likewise diminished the effects of aflatoxin in growing pigs (11) when used as a dietary supplement. Volclay NF-BC is a bentonite clay which is generally recognized as safe for human consumption and is currently allowed for use in feeds and in food, including peanut butter, as a processing aid. We investigated the ability of a Volclay NF-BC to ameliorate aflatoxicosis in rats fed peanut butter-based diets naturally contaminated with aflatoxin. MATERIALS AND METHODS Diets Five diets were prepared by blending certified rodent ration (RMH 3000, Agway, Waverly, NY) containing <1.0 ppb aflatoxin, Volclay (Volclay NF-BC Microfine Bentonite, American Colloid Company, Arlington Heights, IL), control (uncontaminated) peanut butter, and/or peanut butter naturally contaminated with aflatoxin (Table 1) in a vertical cutter mixer. All diets contained 50% wt/wt TABLE 1. Diet composition. Diet" Aflatoxin (ppb) Volclay (% wt/wt) Negative control (control) Volclay control (VC) Aflatoxin control (AF) Aflatoxin plus low-dose Volclay (AF-LD) Aflatoxin plus high-dose Volclay (AF-HD) None