Dietary modulation of the human gut microflora using the prebiotics oligofructose and inulin.

Although largely unproven in humans, better resistance to pathogens, reduction in blood lipids, antitumor properties, hormonal regulation and immune stimulation may all be possible through gut microflora manipulation. One approach advocates the oral intake of live microorganisms (probiotics). Although the probiotic approach has been extensively used and advocated, survivability/viability after ingestion is difficult to guarantee and almost impossible to prove. The prebiotic concept dictates that non viable dietary components fortify certain components of the intestinal flora (e.g., bifidobacteria, lactobacilli). This concept has the advantage that survival of the ingested ingredient through the upper gastrointestinal tract is not a prerequisite because it is indigenous bacterial genera that are targeted. The feeding of oligofructose and inulin to human volunteers alters the gut flora composition in favor of bifidobacteria, a purportedly beneficial genus. Future human studies that exploit the use of modern molecular-based detection methods for bacteria will determine the efficacy of prebiotics. It may be possible to address prophylactically certain gastrointestinal complaints through the selective targeting of gut bacteria.