Acute toxicity of brown rice kefir powder

Kefir is a fermented milk product comprising several lactic acid bacteria, acetic acid bacteria and yeasts. It has been reported to possess pharmacological and antioxidant activities. Recently, kefir from rice milk showed antioxidant activity higher than that from cow milk. To see whether rice and rice products such as rice kefir is safe for human applications. Therefore, the present study was designed to determine an acute toxicity of kefir powder from brown rice; KhaoDawk Mali 105 (KDMLKP), Red Hawm (RHKP) and Hawm Nil (HNKP). The study was carried out in male Wistar rats by once giving kefir powder at the doses of 1,000, 2,000 and 4,000 mg/kg to the rats orally. The results showed that the kefir powder of all the doses did not produce mortality and symptoms of toxicity. Moreover, the kefir powder did not alter relative organ weight (ROW) and feed conversion ratio (FCR) in the kefir powder treated rats compared to those in controls, but this was not a 4,000 mg/kg RHKP. Increasing KDMLKP significantly (p≤0.05) increased body weight gain and food intake, whilst increasing HNKP significantly (p≤0.05) decreased the body weight gain, but significantly (p≤0.05) increased food intake in the treated rats compared to that in controls. However, RHKP did not alter the body weight gain but increasing RHKP significantly (p≤0.05) decreased food intake in the treated rats compared to that in controls. KDMLKP and HNKP did not alter BS, BUN, CREA, UA, TP, Alb, AST, ALT, and ALP in the treated rats compared to those in controls. KDMLKP at a dose of 4,000 mg/kg significantly (p≤0.05) increased TP and Alb. Nevertheless, RHKP at a dose of 4,000 mg/kg significantly (p≤0.05) increased BUN, TP, AST, ALT, and ALP in the treated rats when compared to those in controls. KDMLKP, RHKP and HNKP did not alter WBC, Hb, Hct and Plt in the treated rats compared to those in controls but this was not at a dose of 4,000 mg/kg RHKP. Interestingly, the rats received 4,000 mg/kg KDMLKP and RHKP but not HNKP significantly (p≤0.05) reduced RBC compared to that in controls. Moreover, increasing KDMLKP, RHKP and HNKP significantly (p≤0.05) decreased Neu but increased Lym compared to those in controls. These findings indicate that the kefir powder from brown rice; KhaoDawk Mali 105 (KDMLKP), Red Hawm (RHKP) and Hawm Nil (HNKP) exhibit non acute toxicity with LD50 higher than 4,000 mg/kg. Kefir powder from this brown rice is probably a new good nutrition resource.