MCP Lecture 5 Flashcards
What type of nutrient are vitamins and minerals referred to as? What does a deficiency in a vitamin cause?
- micronutrients
- loss of enzyme activity (bc they act as coenzymes)
What is DRI? RDA?
DRI: dietary reference intakes
RDA: recommended daily allowance (which varies for different populations)
How do vitamin deficiencies arise?
- poor nutrition
- increased demand
- problem with absorption
- interactions with medications
What are the classifications of vitamins, and which vitamins fall in the classifications?
lipid soluble: A, D, K, E
water soluble: B, C
Which vitamins are less likely to be toxic and why?
B and C because they are water soluble are excreted efficiently (lipid soluble can be stored efficiently so deficiencies don’t arise as easily)
Vitamin A: function, deficiency, susceptible groups
Function: visual cycle (rhodopsin and cone cofactor), synthesis of certain glycoprotein and mucopolysaccharides, retinoic acid (hormone), antioxidant
Deficiency: night blindness, xerophthaliam, follicular hyperkeratosis, anemia, poor growth (children)
Susceptible groups: poor, malnourished, premies
Sources of Vitamin A
retinol (vit A): egg yolks, liver, butter, whole milk (animal sources)
carotenoids (precursor vit A): plant sources (pro vitamins)
When is Vitamin A toxic? What are the symptoms?
When it accumulates in the liver - nausea, diarrhea, bone pain, scaly skin, orange cast to skin
What is follicular hyperkeratosis?
vitamin A deficiency - skin in permanent goosebumps
What is xerophthalmia?
vitamin A deficiency - overgrowth of cornea (extreme dryness and thickening of the conjunctiva)
Vitamin D: function, deficiency, susceptible groups
function: maintaining bone, calcium homeostasis, acts as hormone
deficiency: rickets, osteomalacia, increased susceptibility to breast and other cancers
susceptible: poor, elderly, alcoholics
How is active Vitamin D synthesized?
skin (sunlight) - dietary sources = saltwater fish
liver (hydroxylation)
kidney (hydroxylation)
converted to D3 = calcitriol
Vitamin K: function, deficiency, susceptible groups
function: localization of enzymes required for blood Klotting (helps catalyze addition of gama-carboxyglutamate to clotting enzymes)
deficiency: easy bruising, bleeding, hemorrhage
susceptible: newborn infants and long term antibiotics
What causes deficiency in Vitamin K?
lack of intestinal bacteria that makes it (why its newborns and long term antibiotics) - shot now given at birth
Vitamin E: function, deficiency, susceptible groups
function: ANTIOXIDANT (protect membranes, prevent oxidation of LDL)
deficiency: cardiovascular disease and neurological symptoms
susceptible: prolonged defects in absorption, genetic defects
What are dietary sources of vitamin E?
OILS
Vitamin C: function, deficiency, susceptible groups
function: cofactor for oxidases involved in COLLAGEN formation, synthesis of steroids, absorption of iron, antioxidant
deficiency: mild bruising and immunocompromise
severe: SCURVY (decreased wound healing, osteoporosis, hemorrhage and anemia, fatigue)
susceptible groups: pirates, people with poor diet, smokers
What is the major function of vitamin C?
hydroxylation of proline and lysine - important in collagen synthesis
What are the early and later signs of scurvy?
early: corkscrew hairs and pinpoint hemorrhages
later: severe periodontal disease
What are the two subcategories of B Complex vitamins? What are the vitamins in the groups?
Energy releasing: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin)
Hematopoietic: B9 (folate), B12 (cobalamin)
What are common effects of deficiencies in energy-releasing B vitamins?
first show up in rapidly growing tissues: dermatitis, swollen red tongue (glossitis), GI (diarrhea)
also seen in nervous system bc energy demand: peripheral neuropathy (tingling of extremities), depression, confusion, lack of coordination, malaise)
Thiamine: number, function, deficiency, susceptible groups
number: B1
function: cofactor for several enzymes in cellular energy metabolism, critical in nervous system
deficiency: mild - GI symptoms, depression, fatigue
moderate - wernicke korsakoff syndrome
severe - beriberi
What is thiamine a precursor of?
TPP - coenzyme for critical metabolic enzymes
thiamine not stored in body - deficiency can be quick
What is Wernicke- Korsakoff syndrome?
moderate/severe thiamine deficiency - seen in chronic alcoholics
-mental disturbance (like they’re drunk) - unsteady gait, uncoordinated eye movements
What is Beriberi?
very severe thiamine deficiency
common in polished rice
-extreme muscle weakness, poly-neuropathy, heart failure
Riboflavin: number, function, deficiency, susceptible groups
B2
function: precursor of FAD and FMN - coenzymes for redox reactions in energy metabolism
deficiency: ariboflavinosis - rash around nose, inflammation of mouth and tongue, buring and itchy eyes, light sensitivit
susceptible: alcoholics
Niacin: number, function, deficiency, susceptible groups
B3
function: precursor NAD and NADP - redox reactions of energy metabolism
deficiency: pellagra
susceptible groups: people with corn or millet based diets
What are good sources of niacin?
meat and other high protein foods (contain TRYPTOPHAN)
What are niacin and riboflavin particularly important?
essential coenzymes for catabolism of other nutrients
niacin - NAD
riboflavin - FAD
Biotin: number, function, deficiency, susceptible groups
B7
function: coenzyme for several carboxylases
deficiency: rare becasue it can be found in many foods and be synthesized by intestinal bacteria - can get by eating raw eggs
Pantothenic acid: number, function, deficiency, susceptible groups
B5
function: synthesis of CoA (required for TCA cycle and metabolism of all fats and proteins)
deficiency: very rare
Pyridoxine: number, function, deficiency, susceptible groups
B6
function: precursor of pyridoxyl phosphate (PLP) - required for glycogen breakdown, synthesis of GABA and heme
deficiency: irritability, nervousness, depression (GABA)
- severe: peripheral neuropathy, convulsions, decreased glucose intolerance, hyper-homocysteinemia, anemia
susceptible: patients treated with certain drugs
