Vitamin D3 (Cholecalciferol)

General Info


Vitamin D is absorbed with the use of bile from both the middle portion and lowest division of the small intestine.

Dietary Origins

Vitamin D does not occur in large amounts in many foods. It occurs in small and highly variable amounts in supplemented butter, cream, and milk. Milk fortified with vitamin D is the major source of this vitamin within the United States. Vitamin D is actually a hormone and we get its benefits form sun exposure.


The term "Vitamin D" refers to a group of fat-soluble vitamins whose primary purpose is to maintain appropriate blood levels of calcium and phosphorus. Of the different form of vitamin D – vitamin D3/Cholecalciferol is the most potent form. Not available in many foods, vitamin D can be manufactured by the body through the skin by virtue of a reaction with sunlight. Hence vitamin D is known as the sunshine vitamin.

Toxicities & Precautions


Vitamin D can be toxic in excessive amounts, resulting in hypercalcemia (hī-pər-ˌkal-ˈsē-mē-ə) that causes calcium deposits in soft tissues such as arteries, heart, ears, kidneys and lungs. Signs of vitamin D toxicity include constipation, headache, nausea, vomiting, and weakness.

Functions in the Body


Involved in both the mineralization of bone, as well as in the de-mineralization of bone.

Immune System

Vitamin D enhances the immune system by stimulating the activity of large white blood cells.


Vitamin D may play a role in neuromuscular function in older adults.

Symptoms & Causes of Deficiency

Rickets is a childhood vitamin D deficiency disease. Insufficient deposition of calcium phosphate into the bone matrix creates bones that are not strong enough to withstand the ordinary stresses and strains of weight. In adults, vitamin D deficiency can result in osteoporosis and osteomalacia. Vitamin D deficiency can result from inadequate diet, insufficient exposure to sunlight, and kidney or liver malfunctions, which prevent the conversion of vitamin D within the body. Osteoporosis increases the risk of skeletal fractures. Osteomalacia is the adult equivalent of rickets where vitamin D deficiency causes softening of the bones that can lead to deformities. This condition occurs more frequently in the elderly. It can cause muscle weakness, rheumatic pain, and increases the likelihood of hip and pelvis fractures. Vitamin D deficiencies can also cause hearing loss, muscle weakness, phosphorus retention in the kidneys, and severe tooth decay.