Vitamin D Council Glossary

C-Reactive Protein (CRP)

An acute phase response protein that is only present in blood during or after trauma, infection, or serious illness.

Calbindin-D (CaBP,Vitamin D dependent calcium-binding protein)

Protein that plays a fundamental role in vitamin D-mediated calcium transport.

Calbindin-D28K (28-kilodalton calbindin-D)

Calcium-binding protein which protects neurons against apoptotic cell death.

Calbindin-D9k (CaBP-9k)

Vitamin D-induced calcium-binding protein that has a high affinity for calcium. Production of Calbindin-D9k is stimulated by dietary vitamin D or calcium restriction.

Calcidiol (25-hydroxyvitamin D,25(OH)D,25(OH)D3,25-hydroxycholecalciferol)

A prehormone in the blood that is produced in the liver from the metabolism of vitamin D3 cholecalciferol and the body's main storage form of vitamin D.

Calcitriol ("1,25-dihydroxyvitamin D3","1,25(OH)2D3",Activated vitamin D)

Referred to as activated vitamin D, calcitriol is the most potent steroid hormone in the human body and has powerful anti-cancer properties. Calcitriol is made from calcidiol in the kidneys and other tissues and is also produced synthetically as an analog. Calcitriol levels should never be used to determine if you are deficient in vitamin D.

Calcitroic acid (1 alpha-hydroxy-23 carboxy-24,25,26,27-tetranorvitamin D(3))

Metabolite of calcitriol whose formation is catalyzed by the enzyme CYP24A1. Calcitroic acid is soluble in water and excreted in urine.

Calcium

Metallic, bivalent element that is essential to living organisms and plays a key role in metabolism. Calcium keeps bones and teeth strong and ensures proper functioning of muscles and nerves.

Calmodulin (CaM)

Calcium-binding protein that binds to and regulates many different protein targets, thereby affecting many different cellular functions. Mediates processes such as metabolism, inflammation, apoptosis, muscle contraction, intracellular movement, nerve growth, short-term memory, long-term memory, and the immune response.

Calretinin (CR,29 kDa calbindin)

Calretinin is a calcium-binding protein that belongs to the calbindin family and is abundant in auditory neurons.

Carotenoid (Carotenoids)

One of a family of about 600 different plant, fruit, and vegetable pigments (yellow, orange, and many of the red) that function as antioxidants, with some functioning as precursors to vitamin A.

Catabolism (Catabolic)

Degradative metabolism involving the release of energy and resulting in the breakdown of complex materials (as proteins or lipids) within the organism.

Cathelicidin

Family of antimicrobial polypeptides that serve a critical role in mammalian innate immune system defense against invasive bacterial infection.

Cathelicidin Antimicrobial Peptide gene (cAMP)

Direct target of the vitamin D receptor and an effector of innate immune response in mammals. Humans and mice have only one cathelicidin gene, as compared to domesticated mammals who have multiple.

CD4+ cell

Helper T-cells within the immune system that express the surface protein CD4. CD4+ cells are the cells that are infected by the human immunodeficiency virus (HIV), decreasing their count and leading to the symptomatic stage of infection known as acquired immunodeficiency syndrome (AIDS).

Centers for Disease Control and Prevention (CDC)

One of the 13 major operating components of the United States Government's Department of Health and Human Services (HHS) whose mission is "to prevent and control infectious and chronic diseases, injuries, workplace hazards, disabilities, and environmental health threats."

Central Nervous System (CNS)

Largest part of the nervous system. Composed of the brain and spinal cord.

Chemotaxis

Chemotaxis is the way in which bodily cells, bacteria, and other organisms direct their movements as a result of certain chemicals in their environment.

Chlorophyll

Green pigment found in most plants, algae, and cyanobacteria that is said to provide many different health benefits to humans. Chlorophyll is a great source of magnesium.

Cholecalciferol (Vitamin D3)

Prohormone that is synthesized in the skin by ultraviolet-B irradiation of 7-dehydrocholesterol.

Cholestasis

Any condition in which the flow of bile from the liver is blocked.

Cholesterol

The principal sterol synthesized by animals that is essential for life. Cholesterol is the major precursor of steroid hormones, such as vitamin D. It aids in the manufacture of bile, helps digest fat, and is important for the metabolism of fat-soluble vitamins. Cholesterol has also been implicated in cell signaling processes and may act as an antioxidant.

Circadian rhythm

Internal "body clock" that regulates the (approximately) 24-hour cycle of biological processes in animals and plants.

Cohort effect

Variation in health status arising from different causal factors to which each birth cohort in a population is exposed as environment and society change.

Collagen

Main protein of connective tissue in animals and most abundant protein in mammals.

Comorbidity

The presence of coexisting or additional diseases with reference to an initial diagnosis.

Congestive Heart Failure (CHF)

A condition in which the heart is unable to adequately pump blood throughout the body and/or unable to prevent blood from "backing up" into the lungs.

Coronary atherosclerosis

The build up of plaque from substances such as cellular waste products, calcium, and fibrin in the inner lining of an artery, causing coronary heart disease.

Cortex

Structure within the brain that plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness.

Council for Responsible Nutrition (CRN)

Washington-based trade association representing ingredient suppliers and manufacturers in the dietary supplement industry.

Cross-sectional study

Study design in which disease and exposure status are measured simultaneously in a given population, providing a "snapshot" of the frequency and characteristics of the disease in that population at a particular point in time.

CTA018

Vitamin D analog designed to activate the vitamin D signaling pathway as well as inhibit CYP24.

CYP24A1 ("1,25-dihydroxyvitamin D3 24-hydroxylase",Vitamin D 24-Hydroxylase,24-OHase,CP24,CYP24,Cytochrome P450 24A1)

CYP24A1 is an enzyme that regulates vitamin D3 by initiating the degradation of calcitriol, and thus plays a role in calcium homeostasis and the vitamin D endocrine system.

CYP27A1

Gene commonly known as sterol 27-hydroxylase, an enzyme involved in the degradation of cholesterol to bile acids and also involved in the metabolism of vitamin D3.

CYP27B1 (25-hydroxyvitamin D 1alpha-hydroxylase,1α-hydroxylase)

Renal enzyme that converts calcidiol to calcitriol in the kidneys and is important in calcium homeostasis. Mutations in this gene can result in vitamin D-dependent rickets type I.

Cytochrome P450

Group of enzymes whose primary role is one of metabolism and detoxification of endogenous compounds as well as the metabolism of vitamin D. The gene for cytochrome P450 has existed for more than 3.5 billion years.

Cytokine

A protein or peptide used as a signaling compound in organisms.

Cytotoxic

Any agent or process that is toxic to cells.