Background: Vitamin D deficiency is a worldwide health problem associated with various health complications. This study aimed to determine the prevalence of vitamin D supplementation in the Czech Republic, understand reasons for supplementation, and assess participants' knowledge of vitamin D's physiological effects. Methods: The study included 1812 participants representing the Czech population aged 15+, stratified by gender, age, and regional distribution. Data analysis was performed using SASD 1.5.8, using chi2 independence tests and regression analysis. Results: The results revealed that only 13.5% of the participants maintained regular year-round vitamin D supplementation, while 51.5% never supplemented. A slight increase in supplementation was observed during the pandemic (2020-2021). Supplementation patterns were influenced by socioeconomic factors including age, gender, marital status, income, employment, and education (p > 0.001). Regarding vitamin D knowledge, 67.5% and 65.6% of participants recognized its role in immune system modulation and bone health, respectively. There were minor misconceptions, with 1.4% believing that it aggravates allergies and 1.8% linking it to cancer. Knowledge levels varied with education and residence size. Conclusions: Despite the high prevalence of vitamin D deficiency in the Czech population, regular supplementation remains low, indicating the need for enhanced prevention programs and awareness campaigns.

• Keywords
• Czech Republic, vitamin D, vitamin D knowledge, vitamin D supplementation,
• MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Vitamin D Deficiency * epidemiology   prevention & control   drug therapy   MeSH
• Dietary Supplements * statistics & numerical data   MeSH
• Prevalence MeSH
• Aged MeSH
• Socioeconomic Factors MeSH
• Vitamin D * administration & dosage   MeSH
• Health Knowledge, Attitudes, Practice * MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Vitamin D * MeSH