Vitamin A Flashcards
Name the energy releasing vitamins.
Niacin, riboflavin, thiamin, biotin, pantothenic acid.
Name the hematopoietic vitamins.
Folate, B6 and B12
True or False. The liver is the primary storage site for Vit A.
True. The liver is the primary storage site. However, other organs like the kidney, bone marrow, lung, adipose and eyes stores significant amounts of Vit A.
What two proteins are needed for the transport of retinol to target tissues?
Retinol binding protein (RBP), synthesized by the liver, and transthyretin (TTR) formed a protein complex to transport retinol.
Why Retinol binding protein (RBP) and transthyretin (TTR) are good measures to asses Vit A status?
RBP synthesis is tightly regulated by the availability of retinol.
Biochemical function of Vit A is dependent on its particular form. So, what are the functions for retinol, retinaldehyde and retinoic acid?
Retinol is required for repoduction.
Retinaldehyde is required for vision.
Retinoic acid is required for normal structure and function of epithelial cells.
What are some sources of Vit A?
Eggs, fortified milk, liver, dark green and yellow-orange vegetables
What are the most common signs of Vit A def?
All ocular (related to eye): night blindness, bitot’s spots and conjunctival xerosis.
What is the main cause for elevated plasma Vit A levels or toxities?
Renal disease/ both acute and chronic renal failure since the kidneys are the primary route for Vit A excretion.
Why would protein calorie malnutrition and/or zinc def compromise circulating serum Vit A levels?
Because the proteins RBP and TTR is needed for retinol (Vit A) transport.
Why is Vit A supplementation common for wound healing?
It is used to counteract the inhibitory effects steroids have on collagen synthesis and connective tissue repair. A dose of 10,000 to 50,000 IU/d (3-5mg/d) for 7 days is recommended.
What are the DRI for Vit A?
For all groups: 900/700 mcg RE/d for men/women
