Dietary Supplement Use and Associated Factors Among Adults Working in Urban Settings in Tanzania: A Cross-Sectional Study

Dietary supplements are products consumed to provide nutrients or other substances that the user may not consume in sufficient amounts through normal diets. Despite their increased global popularity, there is still scant information regarding the use of dietary supplements and associated factors among adult populations in Tanzania. This study aimed to assess the extent of dietary supplement use and factors associated with use among adults working in urban settings. This was a cross-sectional study involving 419 adults working in public and private institutions within the Ilala District of Dar es Salaam who were selected using stratified and simple random sampling techniques. The study's data was collected using quantitative methods through a self-administered questionnaire. Data analysis was done through descriptive statistics for frequencies, means, standard deviations, and proportions; cross-tabulations with chi-square tests for comparing observed differences in supplement use; and multivariable logistic regression for identifying factors associated with supplement use. A P-value of <.05 was considered statistically significant in the analysis. The prevalence of dietary supplement use among working adults was 46.5%, where 36.9% reported regular and 63.1% occasional supplement use, respectively. Seven types of dietary supplements were identified to be consumed, of which 45.1% of the respondents consumed more than one type of dietary supplement. Multivitamins (64.1%) were the most frequently reported type of supplement consumed, followed by Mineral (34.9%) and Herbal/Botanical (26.7%) supplements. The most commonly reported reason for dietary supplement use among working adults was to improve overall health (67.1%). A third of the users (35.9%) admitted to self-prescribing dietary supplements without seeking professional medical advice. The use of dietary supplements was significantly associated with being female (AOR = 2.243, 95% CI 1.415-3.555, P = .001) and knowledgeable of supplements (AOR = 6.756, 95% CI 4.092-11.154, P < .001). Overall, the use of dietary supplements is popular among adults working within urban settings, but its use is exacerbated by perceived knowledge and self-prescription instead of health professional advice. Therefore, there is a need for further studies to explain better the underlying drivers for perceived knowledge on decision-making. There is also a strong need for extensive health education to prevent inappropriate or excessive use of supplements which might lead to potential adverse events.