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
A1c
Glycosylated hemoglobin that is usually elevated (6.5%–7.0% or higher) in people with diabetes mellitus. Normal range is 4%–5.9%.
Actin
The most abundant protein in eukaryotic cells. Actin is released into circulation by dying cells.
Activated vitamin D
see calcitriol.
Adenoma
Benign tumor of a glandular origin which typically originates from epithelial cells.
Adequate Intake (AI)
Amount of a nutrient that appears to support good health. Used when the RDA cannot be set due to lack of information about that particular nutrient.
Adjuvant
Pharmacological or immunological agent that modifies the effect of other agents (e.g., drugs, vaccines) while having few, if any, direct effects when given by itself.
Agonist
A drug that binds to a specific receptor on a cell and triggers a response in the cell by imitating the action of the natural hormone or neurotransmitter that binds to that same receptor.
Albumin
Albumin is a protein that is made by the liver and is essential for maintaining the proper distribution of body fluids between intravascular compartments and body tissues.
Alfacalcidol
1α-hydroxyvitamin D3. Synthetic analogue of calcitriol. Used in the treatment of hypocalcemia, hypophosphatemia, rickets, and osteodystrophy associated with various medical conditions.
Alkaline phosphatase
Enzyme found primarily the liver (isoenzyme ALP-1) and bone (isoenzyme ALP-2).
Allele
An alternative form of a gene that can occupy a particular place on a chromosome.
American Medical Association (AMA)
Largest association of medical doctors and medical students in the United States and publisher of the Journal of the American Medical Association (JAMA).
Amino acids
The building blocks of proteins, amino acids are critical to life and play an important role in nutrition.
Anabolic process
The metabolic process that builds larger molecules from smaller ones and thus uses up energy (endergonic).
Analog
see Vitamin D Analogue.
Angiogenesis
Physiological process involving the growth of new blood vessels from pre-existing vessels that is normal in growth and development and in wound healing, yet also involved in the transition of tumors from dormancy to malignancy.
Anterior pituitary
The anterior lobe of the pituitary gland and part of the endocrine system. Regulates several physiological processes including stress, growth, and reproduction through the production and secretion of peptide hormones.
Anthracosis
Noncollagenous and less-inflammatory pneumoconiosis caused from inhaling carbon or coal dust.
Antiangiogenic
Anything which blocks, or helps to reduce, the formation of new blood vessels. Relatively new in cancer treatment strategy, antiangiogenetic drugs bear fewer side effects and are less-risky than treatments such as chemotherapy.
Antibody
A protein on the surface of B cells that is secreted into the blood (or lymph) in response to an antigenic stimulus and that neutralizes the antigen by binding to it.
Antigen
An antigen is any substance (such as a chemical, bacterium, virus, or pollen) that causes your immune system to produce antibodies against it. An antigen may also be formed within the body, as with bacterial toxins or tissue cells.
Antimicrobial
Substance that kills or inhibits the growth of microbes such as bacteria, fungi, or viruses.
Antimicrobial Peptide (AMP)
Small protein with broad-spectrum antimicrobial activity against bacteria, viruses, and fungi. AMPs alter the host immune response through receptor-dependent interactions and have been shown to be important in such diverse functions as angiogenesis, wound healing, and chemotaxis. Vitamin D up-regulates ability to fight infections by helping produce over 200 antimicrobial peptides, the most important of which is cathelicidin.
Antioxidant
Compound synthesized in the body (or obtained from diet) which helps prevent the formation of, and removes, reactive oxygen species.
Apoptosis
One of the main types of programmed (normal) cell death.
Astrocyte
Star-shaped glial cells in the brain and spinal cord that perform many functions, including biochemical support of endothelial cells, provision of nutrients to nervous tissue, and a principal role in the repair and scarring process of the brain and spinal cord following traumatic injuries.
Astrocytoma
Cancer of the brain that originates in brain cells called astrocytes.
Asymptomatic
Neither causing, nor exhibiting, symptoms of disease.
Atherosclerosis
Commonly referred to as "hardening of the arteries." A chronic inflammation of the arterial blood vessel walls due to the formation of plaques.
Athymic mice
Laboratory mice lacking a thymus gland. Athymic mice have no T cells and therefore are useful in research because they do not reject tumor, or other, cells transplanted from mice, humans, or other species.
Autocrine
A cell signaling itself through a chemical that it first synthesizes and then responds to. Autocrine signaling occurs either within the cell's cytoplasm or by the cell's secretion of the chemical, which then interacts with receptors on the cell's surface.
Autonomic Nervous System (ANS)
The part of the Peripheral Nervous System consisting of motor neurons that control internal organs such as muscles in the heart and smooth muscle in the intestine, bladder, and uterus. The Autonomic Nervous System has two subsystems, both of which innervate the same organs yet operate in the reverse of the other (antagonism) to maintain homeostasis: the Sympathetic Nervous System (involved in "fight or flight" response) and Parasympathetic Nervous System (involved in relaxation).
Axon
An extension of a neuron cell body that transports information away from the cell body, usually by an electrical impulse.

*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.