Ch. 11 Fat-Soluble Vitamins Flashcards
Vitamin A
Fxns:
- Vision
- Maintenance of skin, epithelial, and mucosal cells
- Bone and tooth remodeling
- Reproduction
- Immune response
- Antioxidant
Deficiency: keratinization of epithelial cells, Hypovitaminosis A
Recommendations:
• Men: 900 micrograms RAE/day
• Women: 700 micrograms RAE/day
Toxicity: yellowish-skin, Hypervitaminosis A
Food Sources:
- Retinol: fortified dairy, eggs, liver
- Beta-carotene: dark leafy greens, broccoli, orange fruits/vegetables
Vitamin D
aka the sunshine vitamin
- UV light→ Previtamin D3 (active form)
- foods→ Vitamin D3 (inactive form)
- ->Animal version: D3, Plant version: D2
Fxn: calcium absorption, bone formation, much more
Recommendations:
- 1-70 y/o: 600 IU/day
- over 70 y/o: 800 IU/day
- TUL for adults: 4000 IU/day
Deficiency:
- -Rickets: children (bowed legs)
- -Osteomalacia (soft bones): adults
- -Osteoporosis (weak bones): adults
Toxicity:
- Hypercalcemia- increased calcium intake
- Calcification of soft tissues (kidneys, heart valves, tissues around joints) –> kidney stones
Food Sources: dairy, fatty fish, irradiated mushrooms
Vitamin E
Fxn: antioxidant (protect cell membrane against oxidation)
Recommendation:
-adults: 15 mg/day
Deficiency: rare, requires significant malnourishment
- Red blood cell breakage
- Nerve damage
Toxicity: rare
Food Sources: polyunsaturated plant oils (margarine, salad dressings, shortenings), seeds, nuts, other
Vitamin K
Fxn: blood clotting
–Coumadin (blood thinner): don’t overdo vitamin K in diet
Deficiency: rare, produced sufficiently in gut metabolism
- -secondary issues: fat malabsorption, antibiotics (kill bacteria in gut that produce K)
- hemorrhaging
Toxicity: rare
- *Newborn infants (especially preemies) are also at risk
- Placenta is insufficient in the transfer of Vitamin K
- Concentration of circulating Vitamin K drops immediately after birth
- Gut of the newborn is sterile (no capacity to produce K)
- -> Thus, newborns are given injection of Vitamin K immediately after birth
Food Sources: bacterial synthesis of GI tract, leafy green vegetables, cabbage-type vegetables, vegetable oils, liver, milk
Identify the 3 active forms of vitamin A in the body. How does beta-carotene fit into this picture?
3 forms:
- -Retinol
- -Retinal
- -Retinoic Acid
Foods derived from plants provide carotenoids, some of which can be converted to vitamin A.
–> beta-carotene: can be split to form retinol in the intestine and liver
Describe vitamin D synthesis and activation.
- Skin:
- -precursor made in liver from cholesterol
- -sun hits skin; precursor made into previtamin D3
- -made into inactive form of vitamin D3 - Liver:
- -converts inactive vitamin D3 - Kidneys:
- -active form of vitamin D3
What is Coumadin and what’s the relevance to vitamin K?
Coumadin is a blood thinner.
Vitamin K clots blood. Coumadin and lots of vitamin K do not mix well.
Don’t overdo vitamin K in diet of a person on Coumadin.
Explain the rationale for a single dose of vitamin K given at birth.
Newborn infants present a unique case of vitamin K nutrition because they are born with a sterile intestinal tract, and the vitamin K-producing bacteria take weeks to establish themselves.
To prevent hemorrhagic disease in the newborn, a single dose of vitamin K is given at birth by intramuscular injection.
What is Hypovitaminosis A?
-Most prevalent vitamin deficiency worldwide
Symptoms:
• Night blindness
• Corneal drying (xerosis) → damage to cornea → blindness
• Impaired immunity (infections)
• Hyperkeratosis (build up of keratin → dry flaky skin)
What is Hypervitaminosis A?
Acute:
• Blurred vision
• Nausea, vertigo
• Headaches
Chronic Toxicity: • Reduced bone density • Liver abnormalities • Birth defects • “Oranging” of skin with large doses
What is the precursor of Vit A? Sources?
carotenoids such as beta-carotene
–> all carotenoids can be changes into each other
Sources:
- Retinyl esters (in animal foods)
- Beta-carotene (in plant foods)
