Vitamins Flashcards
Lipid soluble vitamins
- A, D, K, E
- Deficiencies don’t arise as quickly and toxicity may be a problem
Water soluble vitamins
- B vitamins and vitamin C
- Deficiencies arise more quickly and less likely to be toxic
Vitamin A Functions
-Visual cycle (rhodopsins and cone opsins), glycoprotein and mucopolysaccharide synthesis, retinoic acid, antioxidant
Vitamin A Deficiency signs
- Night blindness
- Xerophthamia
- Follicular hyperkeratosis
- Anemia
- Poor growth
- Increased susceptibility to infection and cancer
Vitamin A toxicity
- Accumulates in the liver
- Nausea, diarrhea, bone pain, scaly skin, orange tint of skin
Vitamin A family
- All trans retinol
- Includes carotenoids that are pro-vitamins
Vitamin D Functions
- Maintain bone
- Calcium homeostasis
- Acts as a hormone
Vitamin D Deficiency
- Rickets in children
- Osteomalacia in adults
- Increased susceptibility to some cancers
Synthesis of Vitamin D
- Requires skin, liver, and kidney
- 7-dehydrocholesterol–>Cholecalciferol–>25-hydroxycholecalciferol–>1,25-hydroxycholecalciferol
- Active D3=Calcitrol
Vitamin D toxicity
- Rare
- Leads to high serum levels of calcium and bone loss
Vitamin D and Cancer
-Low serum vitamin D levels correlated with increased risk of breast cancer
Vitamin K Function
- Localization of enzymes required for blood clotting
- Catalyzes addition of gamma-carboxyglutamate to clotting enzymes
Vitamin K deficiency
-Easy bruising, bleeding, hemorrhage
Vitamin K synthesis
- Involves bacteria in gut
- This is why newborns may be vitamin K deficient
Vitamin E function
- Antioxidant: scavenges free radicals
- Protects membranes from damage
- Prevents oxidation of LDL
Vitamin E deficiency
- Cardiovascular disease
- Neurological symptoms
Vitamin E family
-Closely related to tocopherols and tocotrienols
Vitamin C function
- Ascorbic acid
- Cofactor for oxidases involved in collagen formation (hydroxylation of proline and lysine)
- Required for synthesis of steroids in stress response
- Aids iron absorption
- Has antioxidant activity
Vitamin C deficiency
- Bruising
- Immunocompromised
- Scuvy (decreased wound healing, osteoporosis, hemorrhage, anemia, fatigue)
Characteristics of scurvy
- Corkscrew hairs
- Pinpoint hemorrhages
- Periodontal disease
Vitamin C toxicity
- Rare
- GI upset
- Kidney stones
Energy releasing B vitamins
- B1: Thiamine
- B2: Riboflavin
- B3: Niacin
- B5: Pantothenic acid
- B6: Pyroxidine
- B7: Biotin
Hematopoietic B vitamins
- B9: Folate
- B12: Cobalamin
Common effects of deficiencies in energy releasing B vitamins
- Dermatitis
- Swollen red tongue: glossitis
- Diarrhea
- Peripheral neuropathy
- Depression, confusion
- Lack of coordination
- Malaise
B1 Functions
- Thiamine
- Precursor of TPP
- Required cofactor for several enzymes in cellular energy metabolism
- Critical in nervous system
B1 Deficiency
- GI, depression, fatigue
- Wernicke-Korsakoff syndrome
- Beriberi
Three enzymes that use TPP in metabolism
- Transketolase/transaldolase
- Pyruvate dehydrogenase
- alpha-ketoglutarate dehydrogenase
Wernicke-Korsakoff Syndrome
- Thiamine deficiency seen in chronic alcoholics
- Mental disturbance, unsteady gate, uncoordinated eye movements
- Occasionally congestive heart failure
Beriberi
- Very severe thiamine deficiency
- Extreme muscle weakness
- Poly-neuropathy
- Heart failure
- Sometimes edema (wet and dry beriberi exist)
B2 Function
- Riboflavin
- Precursor of FAD and FMN
- Key coenzyme for redox reactions in metabolism
B2 Deficiency
- Ariboflavinosis–rash around nose, inflammation of mouth and tongue, burning and itchy eyes, light sensitivity
- Alcoholics get it sometimes but it’s pretty rare
B3 Function
- Niacin
- Precursor of NAD and NADP coenzymes important in redox reactions of energy metabolism
- Given to patients with hypercholesterolemia or hypertriglyceridemia
B3 Deficiency
- Pellagra: dermatitis, diarrhea, dementia, death
- People with corn or millet based diets are susceptible
- Treat with tryptophan or niacin supplementation
B7 Function
- Biotin
- Coenzyme for some carboxylases
B7 Deficiency
- Rare
- Can be caused by eating a lot of rare eggs (contain avidin–binds biotin tightly)
B5 function
- Pantothenic acid
- Required for synthesis of CoA
- Required for TCA cycle and metabolism of all fats and proteins
B5 Deficiency
- Very rare
- Typical B vitamin deficiency symptoms
B6 Function
- Pyridoxine
- Precursor of pyridoxyl phosphate (PLP) enzyme cofactor
- Required for glycogen breakdown and synthesis of GABA and heme
B6 Deficiency
- Mild irritability, nervousness, depression
- Peripheral neuropathy, convulsions, decreased glucose tolerance, hyperhomocystenemia, anemia
- People treated with isoniazid are susceptible
