Abstract
Resistant starches (RS) have been shown to have a wide variety of physiological benefits. Many of these positive effects arise from the fermentation of the RS by the colonic microflora. It has been observed that RS acts as a prebiotic by promoting the growth and beneficial activity of specific species of colonic bacteria while reducing the numbers of pathogenic microorganisms. The use of RS is effective in stimulating the indigenous microflora to assist in the treatment of conditions such as bacterially induced diarrhoea and ulcerative colitis. Although probiotics have often been linked with improving the health of the host, experimental results concerning their efficacy have been inconsistent. It has been suggested that "synbiotics", a combination of prebiotic and probiotic, would be useful in improving the reproducibility of the beneficial results obtained from Probiotics. RS offers the opportunity of providing "targeted synbiotics". In this case the RS has multiple functionalities through assisting in the protection of the viability of the probiotic during its passage through the upper gastrointestinal tract and then in helping to induce the desired specific physiological effect in the colon. The preparation of a targeted synbiotic, incorporating a Bifidobacteria lactis and a RS from high amylose maize that is specifically fermented by this bacterial strain, has been shown to significantly increase the apoptotic index (a positive biomarker) in a colorectal cancer rat model. The diversity of forms and types of RS offer the opportunity to prepare targeted synbiotics using selected probiotics to improve colonic health and/or treat various diseases that occur in the large bowel.
