Fat Soluble Vit-- Review with handout Flashcards
Fat soluble vitamin
Vit ADEK
Water soluble vs fat soluble
water soluble: Not stored (except B12) Highly absorbed from diet Excreted in urine Low toxicity
Fat Soluble Accumulate in “stores” Require dietary fat absorption \+/- blood transport system Potential toxicity with excess intake
Micronutrient Deficiency Risk
Inadequate or monotonous diet
Increased nutrient requirements
Increased metabolic demands
Malabsorption
Interactions w/ pharmaceuticals
Vit A Function
Photochemical for vision
retinal signaling
Maintenance of conjunctiva and cornea
Vit A Sources
- Preformed retinyl palmitate from animal sources
Liver, dairy, egg yolk, fish oil - Precursor Beta-carotene
Deep yellow and green vegetables
Spinach, carrots, broccoli, pumpkin
Vit A Deficiency
EYES: xerophthalmia (corneal dryness) Bitot’s Spots, night blindness leading to total blindness
EPITHELIUM:
linings flat, dry, and keratinized
Immune Impairment:
Dysregulation
Effect depends on infectious agent
Treatment of Deficiency decreases all cause child mortality 23-34% in developing world
Vit A treatment with measles reduces morbidity and mortality
including in US when retinol level is low
Risk of Vit A Deficiency
Low Vit A intake:
- Diet poor in colored vegs, meat/dairy
e. g. autistic child with severely restricted diet - Protein Energy Malnutrition
- Very Low fat intake (
Vit A Toxicity
NOT from precursor beta carotene
-ONLY with preformed Vit A (retinyl palmitate) eg cod liver oil
Sx:
Vomiting, increased ICP, headache
bone pain, osteopenia/porosis
liver damage hepatitis–>fibrosis–> failure
-death
-birth defects e.g. isotretinoin (Accutane, an acne medication)
Vit A Lab Testing
Serum Retinol level
-Remains normal until liver stores exhausted
-Decreased with inflammation:
Negative Acute Phase Reactant
Vit D Function
Hormone
-Plasma membrane and nuclear receptors in a range of tissues
Maintains intra/extracellular Ca++ levels
-Mediates intestinal absorption Ca and Phos, renal reabsorption, and mobilization from bone
Immune function –
- Innate: helps with antimicrobial peptide generation (cathelicidin and defensins) in macrophages
- Adaptive: modulation of cytokines
Regulates cell growth and differentiation
Vit D Sources
Conversion in skin
UVB light–> Dehydrocholesterol–> Cholecalciferol D3 in skin
Dietary:
Fish liver oils, fatty fish, egg yolks
Fortified milk and formula
Sources
Plant algae, yeast+UV–> D2 ergocalciferol
Animal D3 cholecalciferol –> more potent? larger AUC than D2, similar peak plasma 25OH
(D2 or D3 can be effectively used as a supplement)
Vit D Metabolism
Absorption – chylomicrons
Requires fat absorption
Hydroxylation
D2 or D3 +OH in liver
25 OH Vit D –level reflects body stores
25 OH Vit D hydroxylated in kidney to active form 1,25 OH Vit D (Calcitriol)
Lab test looks at 25 OH Vit D
Vit D Deficiency
Definition IOM Standard:
Deficiency 25OH Vit D less than 20 ng/mL
Insufficient 20-30
Sufficient: >30
Classical Syndrome
Childhood rickets -
Emerging Associations w/ Vit D Def
-mostly epidemiologic/in vitro
-few RCTs
Autoimmune Disorders (e.g. MS)
Neuromuscular function
Cardiovascular Disease
Cancer incidence
Overall Mortality
-Adequate evidence not yet found
Risk for Vit D deficiency
Low Sun exposure (NE winter) Dark Pigmentation Low dietary intake Fat Malabsorption Breastfed Infant --> supplement Obesity: Fat sequestration, sedentary Liver or Renal Disease (X-OH, can't perform hydroxylation steps): Need Calcitriol Rx supplementation
Vit D Supplementation
Breastfed Infants
400IU D3 per day by 2 months
Until 500ml/d (>16oz) formula or milk
Or formula fed taking 70 years
Some experts have recommended higher dosing 800-1000IU per day
To Maintain 25OH D >30ng/mL, but evidence lacking
Vit D Toxicity
Findings
Hypercalcemia
Vomiting, seizures, nephrocalcinosis, vascular and soft tissue calcinosis
Risk
Sarcoidosis (granulomas throughout body activate D)
>10,000 IU/d for wks in child or during pregnancy
50-100,000 IU daily in adult >3wks
Vit E Function and Sources
Function: antioxidant, scavenges free radicals, stabilizes cell membranes
Sources: Polyunsaturated fat rich vegetable oils (e.g. sunflower), corn, nuts, wheat germ
Vit E Deficiency
Neurologic Degeneration IRREVERSIBLE Loss of reflexes (DTRs) Loss of coordination Loss of vibration and position sense Spinocerebellar ataxia Neuropathy Ophthalmoplegia
Hemolytic Anemia
Risk: malnourishment, prematurity, fat malbsorption /short gut
Vit E Toxicity
Relatively Low
Coagulopathy
-Very large doses inhibit Vit K dependent clotting factors
Literature does not support megadoses for CVD/cancer protection
Vit K Function and Sources
Function – carboxylation of clotting factor proteins (II prothrombin, VII, IX, X)
Sources – leafy greens, brocolli, fruits, seeds, beef liver
Synthesis by Intestinal Bacteria
Vit K Deficiency
Findings:
-prolonged coagulation time
-Hemorrhagic disease of the newborn:
Purpura, GI bleeds, CNS bleeds
Risk: Newborns – poor placental transport (large molecule) 2-12 wks breastfed untreated Fat Malabsorption Chronic Antibiotics
Prevention:
- all Newborns 0.5-1.0mg IM once
- Adequate oral dosing has not been defined
Summary of Deficiency findings
A:
finding:Eyes, epithelium, infections
Risk: Poor or extreme low fat diet
D:
Finding:Rickets, Osteopenia/malacia, possibly more?
Risk: Low sun, dark pigment, obesity, breastfeeding, liver/kidney dz
E:
finding: Neurologic, anemia
risk: prematurity
K:
finding: impaired clotting
Risk: newborn, abx, poor diet
