Vitamins are essential for good health, but taking them in high doses is usually unnecessary and can be harmful. No supplement can replace a balanced diet. For preventing osteoporosis, calcium and vitamin D are important. Calcium is needed for bone health, and vitamin D helps the body absorb calcium. It is recommended to get these nutrients from food sources like dairy products, leafy greens, and fortified foods. Supplements can be used if dietary intake is insufficient, especially for older adults. Always consult with a doctor before starting any supplement regimen.