NMR spectroscopy has long been a leading technique in the study of metabolic biochemistry, with a rich literature predating the terms ‘metabolomics’ and ‘metabonomics’. However, with the advent of metabolic profiling as an independent field of research the power and versatility of a technique that can be readily applied to many biological matrices to provide highly comparable, inherently quantitative, largely unselective compositional descriptions has been revealed. This is why, despite the superior sensitivity and metabolome coverage of rival techniques such as mass spectrometry, NMR still offers so much to metabolic profiling studies.

As a final year undergraduate I was first introduced to the concept of taking NMR spectra of biological samples and using pattern recognition analysis to discern the information about pathology and drug response. It seemed at the time an impossible and incredible task and I was glad not to be attempting it. The spectra generated and the biological problem appeared too complex, with too many possible sources of uncertainty and variability. After many years working in the field many of these sources of variation are better rationalised, with a growing understanding of genetic and environmental influences. Indeed, this complexity is increasingly embraced as an advantage, for example, in the study of symbiotic microbes and health where NMR offers a window into the metabolic cross-talk between multiple genomes and a myriad of exposures. However, I personally have found that the most rewarding aspect of using NMR spectroscopy in this context is its ability to reveal the completely unexpected, sometimes a simple and obvious but critical observation hidden just out of sight of the investigative team. I can attest to many projects, laboratory and clinical, rescued by the unique perspective offered by NMR, and even in today’s world of large-scale studies using established methodology, the data generated are continuing to teach us new and unpredicted things about metabolism.

I salute all the pioneers of the field, cited throughout this volume, for having the vision and perseverance to realise the potential of the approach, which, in the context of biofluid NMR, is now well on the way to successful translation into an important clinical tool. I hope that readers of this volume will find it a useful introduction to the methodology and many of the applications of NMR-based metabolomics, and that it will help to germinate new success stories for the field.

Hector C. Keun