The main ingredient in vitamin D3 supplements is cholecalciferol, as noted by Vitashine. Other ingredients vary depending on the supplement. Vitamin D3 is a form of vitamin D and can be taken as a supplement.
Vitamin D3 serves as an effective supplement for individuals who lack sufficient vitamin D in their everyday lives and diets, according to the National Institutes of Health. The manufacture of vitamin D3 involves the chemical conversion of cholesterol and the irradiation of lanolin. Other ingredients differ from supplement to supplement. Vitashine lists various caking agents and antioxidants as ingredients in its vegan vitamin D3 supplement tablets and natural vitamin E and fatty acids in its D3 supplement spray.
Vitamin D helps the body absorb calcium, which is important for bone strength and immune, muscle and nerve systems, according to MedlinePlus. People who may benefit from vitamin D3 supplements are breastfeeding mothers, seniors, and those suffering from certain conditions, such as obesity, liver diseases or cystic fibrosis.
It is also possible to overdose on vitamin D3. Possible symptoms as listed the National Institutes of Health are anorexia, heart arrhythmia and weight loss. Vitamin D toxicity usually occurs from the overuse of supplements and can result in the calcification of blood vessels and kidney stones.