Objective Eating disorders are complex illnesses with high morbidity and mortality. Yet, there is promising evidence to support the effects of nutrition on the brain and behaviour. One proposed example is the use of tyrosine as an adjunct treatment in anorexia nervosa (AN). However, recruitment and retention in eating disorder clinical trials has posed difficulties for researchers. The aim of this study was to pilot test a parallel randomised controlled trial (RCT) of tyrosine supplementation to explore the feasibility of recruitment and retention, intervention adherence and data collection methods from the perspective of participants and researchers.

Method Feasibility was assessed using numbers participating, questionnaire completion in patients and parent/carers completing and declining participation, a researcher implementation record and clinical measures. Subjects included adolescents aged 12–17 years with AN. The study was conducted over a 12-week period, with the intervention group receiving 5 mg of L-tyrosine supplement and the control group receiving a placebo.

Results Recruitment targets were not met and recruitment to a full RCT based on the current study protocol and recruitment sites did not prove feasible. Of the 39 approached for RCT participation, seven were recruited to the RCT (18% response rate) despite extending recruitment periods, with 100% retained and analysed. Patients or parents/carers identified barriers to study participation including burden, the need to consume tyrosine as tablets, and the use of blood, urine and psychological testing. Blood tyrosine rose markedly for subjects in the intervention group. No side effects were reported or measured.

Conclusions This study offers a unique exploration of the feasibility of a tyrosine trial in anorexia nervosa and is of relevance to assist the success of future nutrition trials. Exploring the suitability of future study designs for nutrition intervention research is warranted.