Nutrition- exam 2- Fat Soluble Vitamins Flashcards
What does your body make when it needs vitamin A?
Retinol binding protein. It carries retinol from the liver (where vitamin A is stored) to body cells
Vitamin A - structure
3 forms :
Retinol (alcohol form)
Retinal (aldehyde form)
Retinoic acid (acid form)
Where is most of vitamin A stored?
The liver
What form of vitamin A affects a person’s vision?
Retinal (aldehyde form)
Vitamin A : vision chemistry
Rhodopsin is a visual molecule found in the retina. It is composed of retinal and opsin(a protein).
Light breaks away retinal.
Enzymatic reaction.
Slow process
Night blindness
Slow recovery of vision in the dark after bright flash due to vitamin A deficiency.
Vitamin A deficiency
Uncommon in US
Takes 1-2 years for symptoms to show because 90% of body’s amount is stored in the liver.
S/S
⋅ xerophtalmia- blindness caused by damage to cornea (progressive /gradual)
⋅keratinization - secretion of keratin (rough, dry, scaly skin)
⋅decrease in mucus secretion
What other roles does vitamin A have?
Development of epithelial and goblet cells
BONE REMODELING- vitamin A helps in dismantling bones so they can grow bigger.
Production of steroids and thyroid hormones
Beta carotene
Found in carrots
A precursor of vitamin A
Inefficient for providing vitamin A so body usually uses it as an antioxidant instead of converting it into vitamin A
Accutane/Retin-A
Accutane - orally. Made from vitamin A but chemically different. Effective but highly toxic (severe birth defects)
Retin-A - topical. Fights acne, wrinkles, other skin disorders. Thins out skin.
**More prone to skin cancer. **
Vitamin A toxicity
Free vitamin A damages cells (sorta like free radicals)
S/S
⋅ slow clotting time, birth defects
⋅bone defects- too much vitamin A means too much bone dismantling activity, interferes with vitamin D to maintain normal blood calcium
Vitamin A supplements are a BAD idea
Why is vitamin D non essential?
Can be made in the skin with cholesterol and sunlight
Vitamin A sources
Liver(with caution)
Dark green vegetables
Deep orange vegetables and fruits (squash, cantaloupe, carrots, sweet potatoes)
How does vitamin D increase Calcium absorption?
Calbindin synthesis
Calbindin is a protein needed to absorb calcium. Synthesis of Calbindin requires vitamin D
Roles of vitamin D
Elongates intestinal Vili
Increases Calcium absorption
Promotes bone mineralization
Increases TB resistance
Vitamin D deficiency
Rickets- bones fail to calcify normally, affects children (bow legged)
Osteomalacia - poor mineralization of bones, affects adults (soft, flexible, brittle and deformed bones)
Osteoporosis - Loss of calcium from bones (results in fractures), elderly
What are 3 conditions that are prone to seeing vitamin D deficiency?
Dark skin, breastfeeding, lack of sunlight
Vitamin D toxicity
Raises blood calcium concentrations
Forms stones in soft tissues and kidneys
May harden blood vessels
Free radicals
Molecules with unpaired Electron
Very reactive - tries to find things to bond with but destroys cells in the process. Antioxidants make compounds with free radicals to prevent damage to cells.
Sources of vitamin D
Dairy products (fortified milk) Sunlight
Vitamin D structure
Vitamin D2 - ergo calcification, plant version
Vitamin D3 - cholecalciferol, animal version
Vitamin E structure
Tocopherol : 4 forms
Alpha, beta, gamma, delta
Vitamin E roles
Fat-soluble antioxidant
Free radicals and fats do not get along!!!
You will find tocopherol in mayonnaise to keep the fat from oxidizing. It helps shelf life.
(Vitamin E : Fat-soluble) = (_______: water-soluble)
Vitamin C
Both act as antioxidants
