VITAMIN & MINERAL DEFICIENCIES

Dr Shahin Hameed

AIMS

Thirteen vitamins are necessary for health

Vitamins A, D, E, and K are fat-soluble, and all others are water-soluble

The distinction between fat- and water-soluble vitamins is important.

Fat-soluble vitamins are more readily stored in the body, but they may be poorly absorbed in fat malabsorption disorders

A deficiency of vitamins may be primary (dietary in origin) or secondary because of disturbances in

intestinal absorption, transport in the blood, tissue storage, or metabolic conversion

Vitamin A

Vitamin A is the name given to a group of related compounds retinol (vitamin A alcohol), retinal (vitamin A aldehyde), retinoic acid (vitamin A acid)

The generic term retinoids encompasses vitamin A in its various forms and both natural and synthetic chemicals that are structurally related to vitamin A

Functions of vitamin A

Maintenance of normal vision

Cell growth and differentiation

Metabolic effects of retinoids

Host resistance to infections

Vitamin A Deficiency

Earliest manifestations of vitamin A deficiency is impaired vision, particularly in reduced light (night blindness).

Persistent deficiency gives rise to a series of changes involving epithelial metaplasia and keratinization.

The most devastating changes occur in the eyes and are referred to as xerophthalmia (dry eye). First, xerosis conjunctivae Buildup of keratin debris in small

opaque plaques (Bitot spots) and, eventually,

Erosion of the roughened corneal surface with softening and destruction of the cornea (keratomalacia) and total blindness.

Epithelium lining the upper respiratory passage and urinary tract is replaced by keratinizing squamous cells (squamous metaplasia)

Another very serious consequence is immune deficiency

Vitamin A Toxicity Acute Chronic

Well-established teratogenic effects of retinoids – contraindicated in pregnancy

Vitamin D

Major function of the fat-soluble vitamin D is the maintenance of adequate plasma levels of calcium and phosphorus Metabolic functions, Bone mineralization, and Neuromuscular transmission

Rickets (in children whose epiphyses have not already closed)

Osteomalacia (in adults), and

Hypocalcemic tetany [Extracellular concentration of ionized calcium, which is required for normal neural excitation and the relaxation of muscles]

Normal reference range for circulating 25-(OH)-D is 20 to 100 ng/mL; concentrations of less than 20 ng/mL

constitute vitamin D deficiency

Causes Diet deficiency Limited exposure to sunlight Renal disorder

Morphology.

Basic derangement in both rickets and osteomalacia is an excess of unmineralized matrix

Rickets

Most common during the first year of life.

The gross skeletal changes depend on the severity and duration of the process the stresses to which individual bones

are subjected.

During the nonambulatory stage of infancy, the head and chest sustain the greatest stresses.

Craniotabes Frontal bossing and a squared

appearance to the head Rachitic rosary Pigeon breast deformity

Ambulating child deformities are likely to affect the spine, pelvis, and tibia lumbar lordosis and bowing of the legs

In adults, the lack of vitamin D deranges the normal bone remodeling that occurs throughout life.

Production the excess of persistent osteoid that is characteristic of osteomalacia.

Bone is weak and vulnerable to gross fractures or microfractures, which are most likely to affect vertebral bodies and femoral necks.

Non-Skeletal Effects of Vitamin D Effective against infection by

Mycobacterium tuberculosis (stimulates the synthesis of cathelicidin, an antimicrobial peptide from the defensin family)

Innate and adaptive immunity Gene expression (>200 genes)

Ca colon, prostrate, breast

Vitamin C (Ascorbic Acid)

Scurvy, characterized principally by bone disease in growing children and by hemorrhages and healing defects in

both children and adults

Vitamin C is present in milk and some animal products (liver, fish) and is abundant in a variety of fruits and vegetables

Function

Best-established function of vitamin C is the activation of prolyl and lysyl hydroxylases from inactive precursors, providing for hydroxylation of procollagen

Collagen, which normally has the highest content, of hydroxyproline, particularly in blood vessels, accounts for the predisposition to hemorrhages in scurvy

Antioxidant properties scavenge free radicals directly and Act indirectly by regenerating the

antioxidant form of vitamin E

MINERAL DEFICIENCIES