Fat soluble vitamins Flashcards
Retinol, retinal and retinoic acid (collectively known as retinoids) are all forms of what vitamin?
What kind of foods are they commonly derived from?
A
Animal products
What is the form of vitamin A is found in foods derived from plants (precursor to vitamin A)?
Carotenoids
(phytochemical)
Major roles of vitamin A
- vision and eye health
(maintain crystal-clear cornea + participates in conversion of light into nerve impulses at retina) - protein synthesis and cell differentiation
(majority of vit A is in cells lining the body’s surfaces where it provides antioxidant and immune functions, and helps maintain integrity of mucous membranes e.g. protect against skin damage from sunlight) - reproduction and growth
(sperm development and foetal growth)
Some good dietary sources of vitamin A
- liver
- carrot
- sweet potato
- nori
- mango
- spinach
Signs of vitamin A deficiency?
- night blindness / total blindness
- dry and scaly skin (goose bump-like appearance | keratinisation)
- bone defects
Where is vitamin A primarily stored?
Liver
Some good dietary sources of vitamin E?
- tahini
- almond
- olive oil
- sunflower seed
Vitamin E consists of a family of molecules. How many molecules are there and which form is maintained in the body to meet vitamin E needs?
8
(subgroups: tocopherols and tocotrienols)
Alpha-tocopherol
Main functions of vitamin E?
- antioxidant
- anti-inflammatory
- immune function
- regulates gene activity
Signs and symptoms of vitamin E deficiency?
- fragile red blood cells (break and spill content)
- nerve damage
Is vitamin D essential or non-essential? Why?
Non-essential because the body can make it with help from sunlight from a precursor
Vitamin D needs to be activated in which part of the body?
Kidney
(activated by parathyroid hormone (PTH))
What is the active form of vitamin D called?
Calcitriol
Vitamin D from foods is absorbed (no digestion required) by passive diffusion into the enterocyte. Approximately how much dietary vitamin D is absorbed?
50%
How is vitamin D synthesised and activated in the body?
- exposure to UV light converts precursor (7-dehydrocholesterol) in the skin into pre-vitamin D
- pre-vitamin D is converted to cholecalciferol in the skin over the next 2-3 days (using heat from the body)
- Cholecalciferol binds to protein in the blood and travels to the liver
- Hydroxylated in the liver and then kidneys to the active form (parathyroid hormone stimulates hydroxylation in kidneys)
