Supports bone strength. Ostelin Vitamin D3 1000IU provides a daily dose of vitamin D3, the form found naturally in the body, in a small, easy to swallow capsule. Vitamin D is a key nutrient which supports: Bone strength and muscle function Dietary calcium absorption Bone mineralisation Healthy immune system function Vitamin D is made in the skin when exposed to ultraviolet light from the sun. Vitamin D is difficult to obtain from diet alone as not many foods are rich in vitamin D. People who have an indoor lifestyle or who always wear sun protection have been found to be low in vitamin D. Ostelin Vitamin D3 1000IU maintains vitamin D levels in the body.