Disorders of a modern lifestyle: reconciling the epidemiology of inflammatory bowel diseases

[...]smoking represents an important contributory influence on established disease but, for environmental factors linked to causal mechanisms, one has to look elsewhere. [...]the new science of metagenomics is a molecular strategy for studying complex microbial ecosystems and promises to overcome the limitations of culture-dependent methods for studying the human microbiota. 87 Several consortia around the world are underway to apply metagenomic methods to understanding the normal microbiota in health and disease in different populations. Since circumstantial and direct evidence point to the importance of early life events in relation to the developing immune system and to the composition of the colonising microbiota, the impact of epidemiologists is likely to be most revealing if focused at early phases of the life spectrum.