Knowledge and attitudes as correlates of dietary supplement use among adults in Saudi Arabia: a cross-sectional online survey of a predominantly Riyadh-based convenience sample

Abstract

Background Dietary supplement (DS) use is widespread in Saudi Arabia, but high prevalence does not by itself indicate informed use. Objective To assess knowledge, attitudes, and practices (KAP) regarding dietary supplements among adults residing in Saudi Arabia and to identify factors independently associated with use. Methods A structured, self-administered Arabic questionnaire adapted from published KAP instruments was distributed online by non-probability convenience sampling to adults (≥18 years) residing in Saudi Arabia between 14 March and 14 June 2026; the achieved sample was predominantly young, male, and Riyadh-based. Current DS use, the dependent variable, was defined as agreement (“agree” or “strongly agree”) with the item “Do you currently use dietary supplements?” and coded 1 = current user, 0 = non-user. Associations were examined using chi-square tests and multivariable binary logistic regression, expressed as adjusted odds ratios (aOR) with 95% confidence intervals (CI). Results Of 725 respondents, 291 (40.1%) were current users. Although 97.4% had heard of DS, only 32.0% agreed that they knew the correct doses; the internet was the leading information source (57.0%), whereas pharmacists were named by 3.9%. Attitudes were favorable (82.9% agreed DS are safe when used correctly). Among users, daily use (69.4%) and vitamins (83.5%) predominated, and 56.4% had consulted a health professional. In the multivariable model (n = 666; 270 users), following a special diet was associated with higher odds of use (aOR 2.44, 95% CI 1.55–3.85). Relative to the reference categories of excellent self-rated knowledge and positive attitude, moderate (aOR 0.34, 0.22–0.53) and poor self-rated knowledge (aOR 0.11, 0.06–0.20) and neutral (aOR 0.40, 0.27–0.59) and negative attitudes (aOR 0.07, 0.03–0.20) were associated with lower odds; equivalently, users rated their own knowledge more highly and held more favorable attitudes than non-users. Conclusion In this convenience sample, DS use was common and attitudinally endorsed, yet self-rated dosing competence was limited, and the routine information channel was dominated by online sources, even though 56.4% of users consulted a professional before starting. Knowledge and attitudes were associated with use, but the cross-sectional design cannot establish the direction of these associations.