The intestinal microbiota and aging

The intestinal microbiota of humans and other animals is an important determinant of health because it has properties that program the innate immune system, affect the availability of nutrients and bioactives from the diet, regulate barrier function, and restrict pathogen access to the intestinal epithelium. These properties are even more important when the host animal advances into older age; paradoxically, however, this is a life-stage when the microbiota appears to be in a state of flux. This review will describe how the application of molecular methods rather than culture-based approaches has recently yielded new insights into the changes in the human intestinal microbiota upon aging. At the extreme end of older life - in centenarians - even more pronounced changes in the intestinal microbiota occur. One of the most important drivers of changes in the microbiota is diet, and lack of diversity in the diet upon aging is linked to a less diverse microbiota, which correlates with poorer health status. We conclude by reviewing prospects for enhancing the health of older persons by a combination of microbiota profiling and microbiota adjustment.