Fight low calcium and vitamin D levels with the Oyst-Cal-D dietary supplement. Whether you’re not getting enough calcium because of certain prescription medications, an insufficient diet or are pregnant and want to make sure you have healthy amounts of calcium in your body, Oyst-Cal-D capsules can help. They’re formulated with calcium, vitamin D and phosphorus to help your bones stay healthy and guard against diseases related to calcium deficiency, like osteoporosis.