Introduction:
Many studies highlight variations in prevalence of Dietary Supplements (DS) use and its determinants across countries. However, survey data for DS use and its determinants amongst general population in Greece remain limited.

Objective:
The aim of this study was to investigate DS use, associated with gender and knowledge, beliefs and attitudes among 31.823 participants of a large Greek cohort study.

Methods:
Participants were interviewed face-to-face using a standard questionnaire. Data analysis (Pearson’s Chi-Square test, Z-test, Correlation Analysis) was performed using SPSS.

Results:
The overall prevalence of DS use was 54.1%, and it was higher in females (56.8%) compared to males (51.1%). Females were more likely to report DS use for replenishing inadequate nutrients (39.4% vs 30.7%) or for treating diseases (33.1% vs 18.5), but males were more likely to report DS use for improving physical condition (47.5% vs 33.4%), increasing muscle mass (30.1% vs 4.5%) and improving athletic score (26.2% vs 7.0%). Furthermore, females seriously believed (56.0% vs 38.8%) that medical tests should precede of any decision for DS intake. Also, they look more regularly for health professionals care and adhere strongly doctors’ (56.0% vs 35.2%) and pharmacists’ (47.8% vs 34.5%) recommendations. However, males adhere mainly coaches’/trainers’ recommendations (27.8% vs 8.5%). Females were more convinced of their ability to evaluate DS’s safety, quality, and potential role to improve their health, while they consider more seriously the recommended daily allowance (56.0% vs 44.0%).

Conclusions:
Females consider DS use mainly as therapeutic or preventive of their diseases, but males as supportive of their physical appearance and exercise. Data on gender as determinant of DS use could be very useful to formulate interventions aiming to maximize benefits from their use.