Calcichew D3 Preference Study in Participants Eligible for Calcium and Vitamin D Supplementation.

Inclusion Criteria: 1. In the opinion of the investigator, the participant is capable of understanding and complying with protocol requirements. 2. Signs and dates a written, informed consent form and any required privacy authorization prior to the initiation of any study procedures. 3. Is eligible for or currently receiving treatment with calcium and vitamin D supplement as determined by the treating clinician in accordance with local treatment guidelines. 4. Eligible participants will either be: 1. Aged 65 years or older requiring calcium and vitamin D supplementation for the prevention or treatment of deficiencies, or 2. Aged 18 years or older that require calcium and vitamin D as an adjunct to specific osteoporosis treatment in participants at risk of calcium and vitamin D deficiencies. 5. Is male or female. 6. A female participant of childbearing potential who is sexually active with a nonsterilized male partner agrees to use routinely adequate contraception from signing of informed consent throughout the duration of the study, and for 12 weeks after last dose of study medication. Exclusion Criteria: 1. Has received Calcichew D3, Adcal-D3 (if the participant is in Test Group 1) or Kalcipos-D (if the participant is in Test Group 2) within the 6 months prior to the first dose of study medication. 2. Has received any investigational compound within 30 days prior to Screening. 3. Has a disease and/or condition resulting in hypercalcaemia and/or hypercalciuria and for which the study drugs are contraindicated e.g. Zollinger-Ellison syndrome, nephrolithiasis. 4. Has any of the contraindications listed in the corresponding Summary of Product Characteristics (SPC) of the study drug that the participant may receive depending on the Test Group: Calcichew D3 or Adcal-D3 (if the participant is in Test Group 1); Calcichew D3 or Kalcipos-D (if the participant is in Test Group 2). 5. Is an immediate family member, study site employee, or is in a dependant relationship with a study site employee who is involved in conduct of this study (eg, spouse, parent, child, sibling) or may consent under duress. 6. Has a history of hypersensitivity or allergies to the active substances or to any of the excipients in the investigational products. 7. Has a history of known fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency. 8. If female, the participant is pregnant or lactating or intending to become pregnant before, during, or within 12 weeks after participating in this study; or intending to donate ova during such time period.