Over-the-counter supplements in endocrine practice: prevalence, influencing factors, and potential consequences for diagnosis

Background: Dietary supplement use has increased substantially in recent decades, driven by wellness culture, disease prevention, and interest in healthy ageing. In endocrinology, supplements may interfere with hormonal assays or alter the absorption of prescribed therapies. This study evaluated the prevalence of over-the-counter dietary supplement use, associated factors, consumption patterns, and implications for medical practice among Romanian adults with and without endocrine disorders.

Methods: This cross-sectional study included 301 adults aged 18–65 years, recruited from an endocrinology clinic and a general practitioner’s practice in Târgu Mureș and Fălticeni, Romania. Participants completed a structured questionnaire assessing demographics, clinical characteristics, supplement use during the previous six months, reasons for use, perceptions of safety and efficacy, purchasing behavior, and label-checking habits. Statistical analyses were performed using SPSS and GraphPad Prism, with p < 0.05 considered statistically significant.

Results: Most participants were women (91.7%), with a mean age of 47.7 ± 13.5 years; 69.1% had endocrine disorders. Only 15.9% reported no supplement use, while participants with endocrine disorders had significantly higher consumption rates. Most respondents used supplements following medical recommendations (69.4%) and purchased them from pharmacies (90.7%). Health promotion was the main reason for use (65.1%), followed by energy and immune support (32.2%). Vitamin D, vitamin C, magnesium, and calcium were the most commonly used products. Overall, 72.4% consumed at least one supplement daily, and 23.3% used more than three products per day.

Conclusions: OTC dietary supplement use was highly prevalent, especially among individuals with endocrine disorders. Given the potential effects on diagnostic testing and treatment efficacy, supplement use should be systematically assessed during endocrine consultations.