Serial analysis of stable nitrogen and carbon isotopes in hair: monitoring starvation and recovery phases of patients suffering from anorexia nervosa

Stable nitrogen and carbon isotopic ratios of hair strands of six patients suffering from anorexia nervosa were measured to monitor a dietary change from near starvation to recovery. This paper presents the results of a first-time study of nitrogen and carbon balance of the patients prior to and after admittance to a hospital and therapy. Sequential analysis of the isotopic ratios of hair strands of all patients could be related to the respective body mass index (BMI) of each patient. Our hypothesis concerning the diachronic change in delta N-15 and delta C-13 during therapy was met: The delta N-15 values were inversely related to the BMI, indicating a slow-down in catabolism of bodily protein due to the process of gluconeogenesis during the starvation phase. In contrast, the delta C-13 values and BMI were in phase: an increase in BMI resulted in an increase in the delta C-13 values. This rise in delta C-13 ratios is best interpreted by an increased supply of protein in the diet. Furthermore, delta N-15 and delta C-13 were inversely related. We conclude that hair, which is easily and non-traumatically sampled, is an adequate monitor that reflects dietary change and nitrogen balance within days. This isotopic method may also be applied in forensic studies with regard to cases of deprivation, and starvation, and may be a method for investigating starvation in historic populations. Copyright (c) 2006 John Wiley & Sons, Ltd.