Vitamins
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Vitamin Deficiencies
result from inadequate supply
Vitamin Insufficiencies or vitamin Dependencies result from
result from abnormal metabolism with an adequate supply
Vitamin toxicity ( Fat soluble) can result if
can result if over-ingested
Vitamins physiological functions
• Serve primarily as cofactors of enzymatic reactions in body • Some function as hormones (Vit A & D) • Some function as transcription regulators (Vit A) ** Must be obtained from external sources
Vitamins that serve as transcription factors
Vitamin A
Vitamins that serve as hormones
Vit A and D
Vitamins metabolism
1.Reduced serum levels may not indicate a deficiency that interrupts cellular function 2.Normal values may not reflect adequate function 2A) Clinical expression of Vit abnormalities 2B) Clinical symptoms of Vit deficiencies: nonspecific in early as well as in mild chronic stages ➡ Deficiencies difficult to diagnose initially
Fat soluble vitamins
A, E, D, K
Water soluble vitamins
B vitamins: thiamine, riboflavin, niacin, B6, B12, folate, pyridoxine, pantothenic acid & others ➢Biotin ➢Vitamin C ➢Carnitine
Laboratory measurements of vitamins
➢ vitamin precursors ➢ vitamin ➢ vitamin metabolites ➢ some biochemical function with and without vitamin (Schilling, etc.) Blood (serum/plasma) or urine * Immunoassay, HPLC, CPB • RIA, MEIA, and FPIA
Immunoassays of vitamins
HPLC, CPB RIA, MEIA, FPIA
FAT soluble vitamins types Absorbed as part of what must be present for Absorption what conditions are they deficient
-A,D,E,K -Absorbed as part of the chylomicron * Fat must be present for absorption * Chronic malabsorptive states
Fat soluble Vitamins come from what sources and where are they stored
Dietary sources animal & plant products—varies with vitamin Stored in liver and fat tissue
Deficiencies of fat soluble vitamins Vitamin A, E, and D+K storage May be difficult to
Deficiencies: develop slowly - Vit A storage: 1 year - Vit E storage: several months - Vit D & K: storage days or weeks may be difficult to diagnose; vague symptoms
Fat soluble vitamins disorders
Bile and pancreatic function, bowel mucosa mpaired bile flow, * Pancreatic disease * Chronic bowel inflammatory conditions * Fistula * Small bowel obstruction * Alcohol liver disease * Cryptosporidium infection
New acquired form of lipid soluble vit deficiency • A,D,E,K
✴ Lipase inhibitor: Xenical ✴ Ingestion of non-bioavailable fat substitutes: Olester ✴ Patient after bilopancreatic diversion for obesity
Water soluble vitamins At least how many water soluble vitamins Moderate excess intake is Most are stored for Deficiencies develop more rapid then
• At least 9 water soluble vitamins • Moderate excess intake is almost immediately excreted in the urine • Most are stored for <2 months ➢Deficiencies develop more rapidly than fat soluble vitamin deficiencies
Exceptions is vitamin
-B-12 -can be stored in the liver for up to 12 months.
Vitamin A has how many active forms and what are there names * Derived from dietary carotenoids (β-carotene)
Three biologically active forms ➢Retinol, Retinal, Retinoic acid
Vitamin A dietary source
➢animal and plant ➢butter, al-livcream, whole milk, whole milk cheeses, egg yolk ➢dark green leafy vegetables, yellow vegetables, yellow fruit & fortified margarine
Retinol is carried by
Chylomicrons in the lymphatics to the liver where retinol binds to RBP and pre-Albumin Retinol + RBP/ Pre-albumin attaches to RBP-receptor and allows Retinol + cRBP into the cell.
Functions of vitamin A
➢Vision (most clearly defined role) ➢Growth ➢Reproduction ➢Mucus secretion ➢Immune system functions ➢Epithelial cell development, differentiation, regulation.
Vitamin E: Tocopherol has several isomers but
a form is most studied
Vitamin E: Tocopherol dietary sources
➢Vegetables oils ➢Wheat germ, rice germ, ➢Leafy green vegetables, ➢Legumes & nuts * Transported: w/ chylomicrons & VLDL (aTTP) * Stored primarily in adipose tissue