Vitamin D Council Glossary

# A B C D E F G H I J–K L M N O P R S T U V
Observational study
An observational study draws inferences about the possible effect of a treatment on subjects.
Occupational Safety and Health Administration (OSHA)
A branch of the U.S. Government's Department of Labor which sets and enforces standards of workplace safety.
OFELY
A prospective study of the bone loss determinants in women aged 30–95 yrs.
Osseous
Having to do with the bone, consisting of bone, or resembling bone.
Osteoarthritis
Also called degenerative joint disease or osteoarthrosis. The most common type of arthritis, usually among older people, that affects only joint function and does not affect skin tissue, the lungs, eyes, or blood vessels.
Osteoblast
Bone-forming cell of the skeleton. Active vitamin D (calcitriol) regulates osteoblastic cell proliferation, differentiation, and mineralization of its extracellular matrix.
Osteocalcin
Noncollagenous protein found in bone and dentin that is manufactured by osteoblasts and is often used as a biomarker for the bone formation process — higher serum osteocalcin levels are correlated with increases in bone mineral density.
Osteoclast
A specialized bone cell that absorbs bone, allowing for the deposition of new bone and maintenance of bone strength.
Osteoclastic resorption (bone resorption)
The opposite of bone formation. Involves hydrolysis of collagen and the dissolution of bone mineral by large multinucleated cells called osteoclasts.
Osteomalacia
Pain, weakness, and fragility of the bones due to defective bone mineralisation, usually as a result of vitamin D deficiency. The name rickets is used when the condition occurs in children.
Osteopenia
A condition of decreased calcification or density of bone that has several risk factors, including low dietary intake of calcium and vitamin D and declining levels of estrogen after menopause. Having osteopenia increases one's risk for developing osteoporosis.
Osteoporosis
A disease in which bones become fragile and more likely to break. If not prevented or left untreated, osteoporosis can progress painlessly until a bone breaks—usually in the hip, spine, or wrist. Women are four times as likely than men to develop osteoporosis.

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.