Aim: "We're not just fighting an epidemic; we're fighting an infodemic," said World Health Organization Director-General Tedros Adhanom Ghebreyesus at the Munich Security Conference. In this context, we examined vitamin-mineral use frequency as influenced by cyberchondria, or E-health literacy level, and related factors during the coronavirus disease-2019 outbreak.Methods: In this cross-sectional study, participants who were admitted to the outpatient clinics in a tertiary hospital between March 2021 and April 2021 were asked questions on socio-demographic data, the presence of vitamin and mineral use, and knowledge. The cyberchondria scores by the cyberchondria severity scale and the E-health literacy scores by the electronic health literacy scale were assessed based on nutrition type choice. The use of vitamins and minerals was compared between regular and non-regular supplement users. Factors related to the presence of nutritional supplement use were assessed through logistic regression analysis.Results: A total of 417 participants, including those aged 39.3 +/- 12.09 years, were found to be regular nutritional supplement users at a rate of 52.99% during the outbreak. The most commonly used supplements were vitamin D (62.8%), vitamin C (54.4%), vitamin B12 (39.6%), zinc (37.9%), magnesium (35.7%), and iron (33.60%). The least used supplement was melatonin (5.30%). Iron, calcium, and vitamin A users had a higher cyberchondria score than non-users (p=0.002, p=0.044, and p=0.030, respectively). However, zinc, selenium, magnesium, calcium, vitamin B6, vitamin C, omega-3 fish oil, and probiotic users had a higher E-health literacy score than non-users (p<0.001, p=0.018, p<0.001, p=0.009, p=0.047, p=0.018, p=0.002, p=0.002, respectively). Logistic regression analyses identified higher E-health literacy [odds ratio (OR)=1.077; 95% confidence interval (CI): 1.042-1.115; p<0.001], female sex (OR=1,659; 95% CI: 1,005-2,737; p=0.048), graduated from university (OR=2,536; 95% CI: 1,009-6,374; p=0.048), presence of health professional's advice (OR=3,716; 95% CI: 2,260-6,119; p<0.001) and chronic disease presence (OR=2,755; 95% CI: 1,420-5,347; p=0.003) were predictors of supplement usage during the outbreak.Conclusions: Higher E-health literate women with comorbidities were likely nutritional supplement users during the outbreak, regardless of cyberchondria severity or age generation differences.