Exam #1: Vitamins II Flashcards
What are the two types of reactive species? What are reactive species?
Oxygen
Nitrogen
*****Highly reactive free radicals that are formed in the process of radiation, exposure to chemicals, & normal physiologic processes
What are antioxidants?
Electron donors able to stabilize the free radical by “adding” an electron
What are the three major antioxidant enzymes?
1) Superoxide dismutase
2) Glutathione peroxidase
3) Catalases
What are the water soluble antioxidants?
- Vitamin C
- Urate
- Glutathione
- Bilirubin
What are the lipid soluble antioxidants?
- Vitamin E
- B-Carotene
- A-Carotene
- Lycopene
- Lutein
Can vitamins prevent atherosclerosis?
Yes, Vitamin E & C have been shown to slow the development of atherosclerosis
Generally, which foods have higher antioxidant properties?
Red fruits and vegetables
How do the antioxidant properties of foods compare to supplements?
Higher antioxidant defense in food (or other properties in food) vs. antioxidant supplement
What is the relationship between AMD & antioxidants? What are the treatment implications?
AMD= Age Related Macular Degeneration
- Caused by oxidative stress
- Treatment with antioxidant supplementation slows progression
Describe how fat soluble vitamins enter and are stored in the body.
1) Require bile salts/ emulsification for absorption
2) Carrier protein for transport
3) Stored in body fat (to some extent)
What is the name for Vitamin A?
Retinol
What is the name for Vitamin D?
Cholecalciferol
What is the name for Vitamin E?
a-Tocopherol
What is the function of Vitamin E?
Generally, Vitamin E is an antioxidant. Specifically it functions to:
- Maintain cell membrane integrity by preventing oxidation of unsaturated FAs
- Works closely with glutathione peroxidase
What organs is Vitamin E especially important for?
- Lungs
- Brain
- Erythrocytes
What are the negative interactions of Vitamin E with other fat soluble vitamins?
Vitamin K= antagonist (clotting factors)
Vitamin D= interfere with bone mineralization
Vitamin A= competition that may lead to deficiency
What is the relationship between PUFAs and Vitamin E?
- Vitamin E stabilizes PUFAs
- Increased PUFA intake requires increased Vitamin E
What are the causes of Vitamin E deficiency? What is Abetalipoproteinemia?
Abetalipoproteinemia= Rare genetic disease resulting in Vitamin E deficiency
Malabsoprtion syndromes e.g. celiac sprue and CF
What are the manifestations of Vitamin E deficiency?
1) Hemolytic anemia
2) Retinal degeneration
3) Ceroid pigment accumulation
4) Neurologic deficits including damage to:
- Posterior columns
- Lateral corticospinal tracts
- Spinocerebellar tracts
What are the signs of Vitamin E toxicity?
- Fatigue
- Diplopia
- GI distress
- Interference with other fat-soluble vitamins
What are the major functions of Vitamin D?
1) Maintenance of adequate blood Ca++ and phosphorus
2) Cell differentiation
3) Immunity
How is Vitamin D synthesized?
1) UV + 7-dehydrocholesterol forms D3
2) D3 from UV and dietary D3/D2 are transported to the liver
3) In the liver, Vitamin D is converted to 25-OH-D3, calcidiol*
4) This is transported to the kidneys, where it is further hydroxylated to 1, 25-OH D3 i.e. activated Calcitriol
*Measured in serum
What is the active form of Vitamin D? What is the inactive form of Vitamin D? What is unique about the inactive form?
Active= Calcitriol Inactive= Calcitroic acid
*****Inactive= water soluble for excretion from the body
What is the role of macrophages in Vitmain D synthesis? What is the role of Vitamin D in immunity?
Macrophages release Vitamin D, which then turns T/B cells on or off
What are the major factors that influence Vitamin D synthesis?
- Time of day
- Season
- Latitude
- Exposure to sunlight
- Age
- Skin pigmentation
Above what latitude do individuals require Vitamin D supplementation in the winter months?
37 degrees i.e. us in Iowa
What is the effect of low blood Ca++ on PTH and Vitamin D?
- PTH and Vitamin D3 are produced when blood Ca++ is low
- PTH
1) stimulates Ca++ resorption from bone
2) enhances renal tubular reabsorption to INCREASE blood Ca++
3) stimulates renal production of Vitamin D3
*****PTH induced increased in D3 leads to increased intestinal absorption of Ca++ and phosphorus
What is the effect of Vitamin D supplementation on hip and nonvertebral fracture?
Supplementation prevented fracture
What is the connection between autoimmune disease and Vitamin D?
Patients with autoimmune disease have low Vitamin D levels or receptor polymmorphisms
What happens with Vitamin D toxicity?
1) Kidney stones
2) Metaststaic calcifications of the kidney/ hypercalcemia
3) Anorexia
4) Abdominal pain
What do you need to keep in mind with Vitamin D supplementation?
D2 vs. D3
What are the major functions of Vitamin A?
1) Constituent of visual pigments
2) Cell differentiation i.e. epithelial cell to specialized cell (transcription factor)
3) Antioxidant
4) Skin health
What are the major symptoms of Vitamin A deficiency?
1) Night blindness
2) Dry skin
Exacerbation of measles infection
What is Vitamin A used as a therapy for? What form?
- Acne
- Psoriasis
- Leukemia
Note that toxicity can happen with isotretinoin for acne
What are the major manifestations of Vitamin A toxicity?
1) Alopecia
2) Visual changes
3) Headache
4) Skin changes
5) Hyperlipidemia
6) Hepatotoxicity
7) Arthralgia
8) Teratogen
- Cleft palate
- Cardiac abnormalities
What are the three types of Vitamin K? Where do they come from?
1) Phylloquinone- Plants
2) Menaquinone- Animals & Bacteria
3) Menadione- Synthetic
What are the functions of Vitamin K?
1) Carboxylation of glutamate, essential for production of blood clotting proteins
- II, VII, IX, X and proteins S and C
2) Post-translational modification of proteins
3) Synthesis of bone, skeletal tissue and kidney Gla proteins
What is unique about the synthesis of Vitamin K? Why is this important?
Vitamin K is synthesized to an active form by the gut flora
1) Antibiotics can deplete the normal gut flora leading to Vitamin K deficiency
2) Newborns are born with a lack of gut flora and are deficient in Vitamin K
- Neonatal hemorrhage with increased PT and aPTT
What are the symptoms of Vitamin K deficiency?
**Hemorrhage*
- Recall, neonatal hemorrhage with increased PT and aPTT
What form of Vitamin K can be toxic?
- Synthetic, not natural
*****Note that it combines with sulfhydryl groups cause oxidation of phospholipids
What are the manifestations of Vitamin K toxicity?
1) Hemolytic anemia
2) Hyperbilirubinemia
What are the symptoms of Vitamin D deficiency?
1) Rickets in children
- Bending bones
- Rachitic bones
2) Osteomalacia
3) Tetany from hypocalcemia
**High risk in kids that are specifically breastfed*
