Vitamin C Flashcards
Where is Vit C mainly absorbed?
Vit C absorption occurs mainly in the ileum, with some occurring in the jejunum via a Na, energy dependent active transport system.
What does it means that Vit C transport systems are both saturable and dose dependent?
Regarding dose dependent, Vit C absorption decreases as intake increases. At normal intakes (20 - 120mg/d), absorption is 80% - 90%. When Vit C serum levels reaches saturation point (80 - 90 umol/L), renal clearance sharply increases.
List some functional roles of ascorbic acid (Vit C).
- Synthesis of collagen, carnitine, and neurotransmitters.
- The enhancement of intestinal absorption of nonheme iron.
- Cholesterol hydroxylation into bile acids.
- Reduction of toxic transition metals.
- Reductive protection of folic acid and Vit E.
- The immune-mediated and antibacterial functions of WBC.
What are good sources of Vit C?
Citrus fruits and other fruits and vegetables
What is the RDA for Vit C?
75/65mg/d age 14-16 (boys/girls) and 90/75mg/d all other groups (men/women).
What are the characteristic of severe Vit C deficiency?
Scurvy, which is characterized by anemia, bleeding gums, petechiae, perifollicular hemorrhage, impaired wound healing, joint effusions, fatigue, depression, and/or weakening of collagen of teeth, bone, and connective tissues.
What is the association between hyperglycemia and vit C?
Hyperglycemia, which is common during acute stress states prevents Vit C transport, which is needed for leukocytes function.
What conditions warrants large Vit C supplementation?
Individuals with renal failure, kidney stones, iron overload disease and/or individuals receiving heparin or warfarin therapy.
What method is used to evaluate Vit C status?
Plasma ascorbic acid analysis. According to NHANES-II, plasma levels >11umol/L indicates deficiency. 11 to 23umol/L = low status and <23umol/L = acceptable status
