‘Mules will be watered whenever possible, men will be permitted to drink only when ordered to by an officer’

Field Service Regulations, British Army (India)'

Disorders and diseases have frequently multifactorial origins. Particularly, differences in lifestyle and the impact of environment are known to be involved in these disorders and constitute risk factors which are currently evaluated. There is increasing evidence that there are large differences in fluid intakes and probably in hydration status at the individual level and in the population as well. Do these differences account for different morbidity? Does mild dehydration impair cognitive functions or exercise performances and increase health problems such as the occurrence of kidney stones, urinary tract infections and even cancer ? Should some individuals or group at risk increase their daily water intake?

There is no accepted ‘gold standard’ for hydration status marker, and this is particularly true for mild dehydration. As a consequence, the effects of mild dehydration on the development of metabolic disorders and diseases is not well documented and needs more research.

The second International Conference on Hydration throughout Life in Dortmund, Germany, in October 8–9, 2001, was devoted, therefore, to ‘The Health Effects of Mild Dehydration’. In 15 lectures and two general discussions, 42 experts from 12 countries discussed new aspects of the physiology of water, how to establish the hydration status of individuals, the benefits of an adequate hydration on wellness and health and the strength of evidence of acute and long-term effects of mild dehydration on the development of several diseases.

We wish to express our personal gratitude to all the speakers and participants for their contribution, Dr Erbersdobler, President of the German Society of Nutrition for the assumption of the patronage of the conference and the sponsors (Nestlé Water Institute, Blaue Quellen Nestlé Water Group, Jaeger Beteiligungsgesellschaft mbH+Co, Irmgard Manz, Dortmunder Energie-und Wasserversorgung GmbH, Glaxo SmithKline, Biotest Pharma GmbH) for sponsoring this conference. Several co-workers of the Research Institute of Child Nutrition, Dortmund, were the moving force before, during and after the workshop, to ensure that everything went off smoothly. It is to be hoped that academic clinicians, nutritionists and practitioners will find useful material in this supplement.