The health effects of cultured milk products with viable and non-viable bacteria

In food regulations, the viability of bacteria is emphasised in food standa rds and regulations for yoghurt and fermented milks. Non-viable cultured mi lks have longer shelf-life and easier storage which favour the technology, but it has been claimed that only dairy products with viable microorganisms have beneficial health effects. In the case of lactose tolerance by lactas e-deficient subjects, viable and non-viable cultured milks show similar eff ects. In the case of treatment of acute gastro-enteritis some probiotics sh ow clinical efficacy in shortening the duration of diarrhoea both in viable and non-viable form. Saccharomyces boulardii is required in a viable form for the treatment of candidiasis whilst lactic acid bacteria show efficacy both in the viable and non-viable form. Stimulation of the human immune sys tem by oral administration of fermented milks or probiotic cultures has bee n observed with viable bacteria only. Effects in faecal bacterial enzyme ac tivities are observed following consumption of viable bacteria only. All he alth benefits reported for fermented milks have been documented using viabl e bacteria and data on non-viable preparations is often limited. Future wor k should focus on controlled blinded studies to further clarify the differe nces. (C) 1999 Elsevier Science Ltd. All rights reserved.