Vitamin D Flashcards
What is the Animal form of Vitamin D? What is the Plant form?
Animal Form - Cholecalciferol (Vit D3)
* Made from Cholesterol
Plant Form - Ergocalciferol (Vit D2)
What is the digestion process of vitamin D we get from our food?
1) We take in food with Vitamin D
2) as it enters small intestine bile is released from gall bladder
3) 50% of vitamin D present is absorbed via Passive diffusion in SI (Ileum)
4) 60% of that absorbed Vit D is packed into chylomicrons and sent out in the lymph
5) 40% of that absorbed vitamin D is bound to Vitamin D Binding Protein (DBP) and sent to liver
By what process is Vitamin D Absorbed?
Passive Diffusion
What is the process of synthesizing Vitamin D from its inactive storage from in the liver to its active form we can use in the body
1) Vit D3 (Inactive form stored in liver) is converted to 25-hydroxy vitamin D3 by the enzyme 25 hydroxylase (Inactive still) = Calcidiol
2) 25-hydroxy vitamin D3 is turned into 1, 25-hydroxy vitamin D3 by 1alpha- hydroxylase (active form) = calcitriol
What types of enzymes are used to convert Vitamin D from its inactive form to its active form?
Cytochrome P450 enzymes
How long can Vitamin D survive in its inactive form? in its inactive form?
Inactive form (Calcidiol) = 60 days Active form (Calcitriol) 4 -6 hours
How do we absorb vitamin D3 we get from our skin?
as it enters in its inactive form it is bound to Vitamin D Binding protein and sent to the liver
how is Vitamin D transported in the body
by Vitamin D binding protein (DBP)
what enzyme regulates Vitamin D? Where is this enzyme found? how how it control vitamin D?
24-hydroxylase
- found in all cells but mostly in kidneys
- limits the amount of the active form of Vitamin D Calcitriol
how will a deficiency in 24 hydroxylase effect the body?
will cause Hypercalcemia
(it regulated the active form of Vit D Calcitriol - so if we don;t have this enzyme calcitriol will build up in the body)
What is the body’s response to low blood calcium?
1) Parathyroid Hormone is released from Parathyroid Gland
2) PTH stimulates hydroxylase enzyme to convert Vit D from inactive form (Calcidiol) in the liver to turn into active form (Calcitriol)
3) Calcitriol stimulates synthesis of Calcium Binding Proteins
4) Calcium Binding Proteins increase Calcium Absorption and decrease calcium excretion in kidneys
What is Vitamin D’s Function in Muscles?
required for muscle contraction
- calcitriol if required to mobilize calcium from sarcoplasmic reticulum to be used in contraction
- deficiency in vitamin D can lease to Type 2 muscle fiber degradation
How does Vitamin D effect Insulin levels?
Muscle accounts for 80% of insulin mediated glucose uptake (GLUT4 in membrane)
- Calcium needed to get GLUT4 into membrane
How does Vitamin D effect Inflammation
has anti inflammatory effects
What are the Vitamin D recommendations?
less than 1 = 400 IU
1-70 -= 6-00IU
70+ = 800IU
what are some good sources of Vitamin D
fish oil, salmon, mackerel, tuna
what is the minimum vitamin D requirement to prevent rickets?
30ng/mL
What levels of serum Calcidiol indicate
Deficiency? Insufficiency? Normal? Excessive?
Deficient = less than 20 ng/mL Insufficient = 20-29ng/mL Normal = 30-80 ng/mL Excessive = more than 150 ng/mL
How many IU will it take to increase serum Calcidiol by 1 ng/mL
100IU
how many grams of fat are required to consume with vitamin D in order to absorb it
5-10g
What are symptoms of Hypovitaminosis D (deficiency)
Soft Spongy Bones
- Rickets In Children (bow legged)
- Osteomalacia in Adults (muscle weakness and pain)
Osteoporosis
RA, MS, Diabetes, Solid Cancers, Mental Issues,
Etc..
How many IU/day is required to prevent nonvertebral and hip fractures
800IU
what are some causes of Hypovitaminosis D
Sunscreen Use Skin Pigment Aging Season, Latitude, Time of Day Malabsorbption Obesity
what are some strategies to prevent Vitamin D deficiency?
- supplement 600IU/day
- get adequate sun exposure
