The human gut flora in nutrition and approaches for its dietary modulation

Abstract

Summary Concepts about human nutrition have changed significantly during the past few decades, especially in the developed world. There is a shift from the concept of ‘adequate’ to ‘optimal’ nutrition. Thus, diet is not only considered as a means of survival but also as a way of achieving better health and quality of life. The human colonic microbiota has a central role in both health and nutrition. It is unique in complexity and function in the body. More than 500 different bacterial species inhabit the human gut, some considered beneficial, others benign, and others detrimental to host health. There is a delicate balance between the host and the colonic microflora, which not only acts as a protective barrier against infection, but also provides up to 7–10% of the host's daily energy requirements through the fermentation of carbohydrates that escape digestion in the upper gastrointestinal tract. Functional foods targeting the colon focus on the development and prevalence of bacterial species that are considered beneficial to human health, namely, bifidobacteria and lactobacilli. Three approaches for the modulation of human gut flora are reviewed here: probiotics, prebiotics and synbiotics, along with methods for improved characterization and analysis of the intestinal microbiota.