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
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-induced calcium-binding protein.
also, 28-kilodalton calbindin-D. Calcium-binding protein which protects neurons against apoptotic cell death.
25(OH)D (25-hydroxyvitamin D). A prehormone in your blood that is produced in the liver from the metabolism of vitamin D3 cholecalciferol. When testing for vitamin D deficiency, this is the only form that should be tested for.
see Ergocalciferol.
Vitamin D analogue. Also referred to as Calcipotriene.
1,25(OH)2D3 (1,25-dihydroxyvitamin 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 analogue. Calcitriol levels should never be used to determine if you are deficient in vitamin D.
Calcitroic acid
Metabolite of calcitriol whose formation is catalyzed by the enzyme CYP24A1. Calcitroic acid is soluble in water and excreted in urine.
A metallic, bivalent element that is essential to living organisms and plays a key role in metabolism. Calcium is responsible for the growth, maintenance, and radiopacity of bone and is a factor in the production of lymphatic fluids. Vitamin D is crucial for calcium absorption.
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)
Also known as 29 kDa calbindin. Calretinin is a calcium-binding protein that belongs to the calbindin family and is abundant in auditory neurons.
Cathelicidin Antimicrobial Peptide gene. 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.
Family of about 600 different plant pigments that function as antioxidants, with some functioning as precursors to vitamin A. The yellow, orange, and many of the red pigments in fruits, vegetables, and plant materials are carotenoids.
Degradative metabolism involving the release of energy and resulting in the breakdown of complex materials (as proteins or lipids) within the organism.
Family of antimicrobial polypeptides that serve a critical role in mammalian innate immune system defense against invasive bacterial infection.
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 is the way in which bodily cells, bacteria, and other organisms direct their movements as a result of certain chemicals in their environment.
Green pigment found in most plants, algae, and cyanobacteria. Chlorophyll is vital for photosynthesis, which allows plants to obtain energy from light.
Vitamin D3. Cholecalciferol is the naturally occurring form of vitamin D. It is a prehormone that is synthesized naturally in the skin by ultraviolet B irradiation of 7-dehydrocholesterol. Cholecalciferol is real vitamin D. All other compounds are either metabolic products or chemical modifications.
Any condition in which the flow of bile from the liver is blocked.
The principal sterol synthesized by animals. Cholesterol is an essential component of mammalian cell membranes to establish proper membrane permeability and fluidity. It aids in the manufacture of bile and helps digest fat, is important for the metabolism of the fat soluble vitamins A, D, E, and K, and is the major precursor of steroid hormones. It also covers nerves in the form of myelin, to conduct nerve impulses. Recently, cholesterol has also been implicated in cell signaling processes and may act as an antioxidant. Minimum levels of cholesterol are essential for life but not necessary in the diet as the liver makes about 1gm a day.
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.
Main protein of connective tissue in animals and most abundant protein in mammals.
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.
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
A cross-sectional study is a study in which disease and exposure status are measured simultaneously in a given population and thus provides a "snapshot" of the frequency and characteristics of the disease in that population at a particular point in time.
Vitamin D analogue designed to activate the vitamin D signaling pathway as well as inhibit CYP24.
25-hydroxyvitamin D3-24-hydroxylase. Gene that encodes the mitochondrial protein which initiates the degradation of calcitriol, thereby regulating calcitriol levels and playing a role in calcium homeostasis and the vitamin D endocrine system.
Vitamin D 24-Hydroxylase. 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.
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.
Gene that encodes the enzyme which regulates the level of calcitriol in the body and is important in calcium homeostasis. Mutations in this gene can result in vitamin D-dependent rickets type I.
Cytochrome P-450 enzymes
Group of enzymes that are of particular importance when studying drug biotransformation and drug metabolism and whose primary role is one of metabolism and detoxification of endogenous compounds, as well as the metabolism of vitamin D. The gene for cytochrome P-450 has existed for more than 3.5 billion years.
A protein or peptide used as a signaling compound in organisms.
Toxic to cells. Any agent or process that kills cells.

*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.