SHORT CHAIN FATTY ACID (SCFA) AND GAS PRODUCTION OF INDIVIDUAL FIBRE SOURCES AND A MIX TYPICAL TO A NORMAL DIET USING AN IN VITRO TECHNIQUE

Abstract

219 Aims: Fibre-containing enteral formulae typically contain a single fibre source. Formulae containing a mix of fibre types, as consumed in normal healthy diets, may be more beneficial for bowel structure and function. We have investigated several individual fibre sources using an in vitro system after predigestion. It was our aim to identify suitable fibre sources with respect to maximal SCFA and minimal gas production. Furthermore, the concept of using a mixture of several fibre sources in amounts proportional to those present in a Western diet was tested. Methods: Before fermentation the fibres were predigested with salivary, gastric, pancreatic and mucosal enzymes to release mono and disaccharides, which were then transformed and removed. During predigestion 5 to 50% of the mass of the individual fibres was removed. Predigested fibres were subjected to fermentation by a suspension of fresh human faeces mixed with a carbonate buffer complex, supplemented with trace elements in a staticin vitro colon model with an automated time-related gas production test system. SCFA production was assessed using GLC by measuring samples drawn from the incubation mixture at 4, 24 and 48 hours. Results:Table Only two of the seven samples (inulin and the fibre mix) continued to produce SCFA after 24 hr. Gas production did not rise after 24 hr in any of the individual fibre samples studied, but was higher for all individual fibres (except cellulose) than for the mix.Conclusions: These preliminary results suggest that a mix of fibres reflective of a normal diet has a more prolonged SCFA production than most of its components fermented singly. Moreover, the favourable SCFA/gas production ratio indicates that the mix would only result in modest gas production which is an important factor in patient tolerance of fibre-supplemented enteral clinical nutrition formulae.