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Vitamin

Compound needed in small amounts in the diet to help regulate and support chemical reactions and processes in the body.

Fat-soluble vitamins

Vitamins that dissolve in fat and such substances as ether and benzene but not readily in water. These vitamins are A,D,E, and K.

Water-soluble vitamins

Vitamins that dissolve in water. These vitamins are the B vitamins and vitamin C.

Coenzyme

A compound that combines with an inactive enzyme to form a catalytically active form. In this manner, coenzymes aid in enzyme function.

Megadose

Intake of a nutrient beyond estimates of needs to prevent a deficiency or what would be found in a balanced diet; 2 to 10 times human needs is a starting point for such a dosage.

retinoids

Chemical forms of preformed vitamin A; one source is animal foods.

carotenoids

Pigment materials in fruits and vegetables that range in color form yellow to orange to red; three of the various carotenoids yield vitamin A.

provitamin

A substance that can be made into a vitamin

night blindness

A vitamin A deficiency condition in which the retina (in the eye) cannot adjust to low amounts of light.

mucus

A think fluid secreted by many cells throughout the body. It contains a compound that has both carbohydrate and protein parts. It acts as a lubricant and means of protection for cells.

xerophthalmia

Literally "dry eye". This is a cause of blindness that results from a vitamin A deficiency. A lack of mucus production by the eye, which leaves it at a greater risk of damage from surface dirt and bacteria.

macular degeneration

A painless condition leading to disruption of the central part of the retina (in the eye) and, in turn, blurred vision.

epithelial cells

The cells that line the outside of the body and the inside of all external passages within it, such as the GI tract.

gene expression

Use of DNA information on a gene to produce a protein. This is a major determinant of cell development.

prostate gland

A solid, chestnut-shaped organ surrounding the first part of the urinary tract in the male. The prostate gland secretes substances into the semen.

analog

A chemical compound that differs slightly from another, usually natural, compound. Analogs generally contain extra or altered chemical groups and may have similar or opposite metabolic effects compared with the native compound.

International Unit

A crude measure of vitamin activity, often based on the growth rate of animals in response to the vitamin. Today IUs have largely been replaced by more precise milligrams or microgram measures.

Fetus

The developing human life form from 8 weeks after conception until birth.

Parathyroid hormone (PTH)

A hormone made by the parathyroid glands increases synthesis of the vitamin D hormone and aids calcium release from bone and calcium conversation by the kidneys, among other functions.

Rickets

A disease characterized by poor mineralization of newly synthesized bones because of low calcium content. The deficiency disease arises in infants and children from insufficient amounts of the vitamin D hormone in the body.

osteomalacia

Adults form of rickets. The weakening of the bones seen this disease is caused by low calcium content. A reduction in the amount of the vitamin D hormone in the body is one cause.

hemolysis

Destruction of red blood cells. The red blood cell membrane breaks down, allowing cell contents to leak into the fluid portion of the blood.

tocopherols

The chemical name for some forms of vitamin E. The alpha form is the most potent.

Isomers

Different chemical structures for compounds that share the chemical formula.

hemorrhage

An escape of blood from blood vessels.

Coagulation

Blood clotting; essentially a essentially a transition of blood from a liquid cell suspension into a solid, gel-like form.

Bioavailability

The degree to which an ingested nutrient is absorbed and thus is available to the body.

Beriberi

The thiamin deficiency disorder characterized by muscle weakness, loss of appetite, nerve degeneration, and sometimes edema.

dementia

A general loss or decrease in mental function.

premenstrual syndrome (PMS)

A disorder found in some women a few days before a menstrual period begins. It is characterized by depression, anxiety, headache, bloating, and mood swings. Severe cases are currently termed premenstrual dysphoric disorder (PDD).

megaloblast

A large, immature red blood cell that results from the particular cell's ability to divide normally.

erthrocytes

Mature red blood cells. These have no nucleus and a life span of about 120 days; they contain hemoglobin, which transports oxygen and carbon dioxide.

megaloblastic anemia

Anemia characterized by the presence of abnormally large red blood cells.

neural tube defect

A defect in the formation of the neural tube occurring during early fetal development. This type of defect results in various nervous system disorders, such as spina bifida. Folate deficiency in the pregnant woman increases the risk that the fetus will develop this disorder.

intrinsic factor

A protein-like compound produced by the stomach that enhances vitamin B-12 absorption.

pernicious anemia

The anemia that results from a lack of vitamin B-12 absorption; it is pernicious because of associated nerve degeneration that can result in eventual paralysis and death.

lecithin

A group of phospholipid compounds that are major components of cell membranes.

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