Fat-Soluble Vitamins Flashcards
What do fat soluble vitamins require for absorption?
- requirement for dietary fat and bile acids for absorption in the intestine
- malabsorption issues such as pancreatic disease (cystic fibrosis) can impact this
What is the transport system for fat-soluble vitamins?
- Chylomicrons
- Travel with triglycerides in the lymph to enter blood stream
High levels of fat-soluble vitamins in the body causes?
- Can be stored in the body
- Can build up to toxic levels
Animal vs plant sources of Vitamin A?
- Animal sources are preformed, plants contain provitamin form (carotenoids)
Are plant sources or animal sources easier to absorb vitamin A?
- Animal sources, because it is similar to our biology
Beta-carotene?
- Plant source
- Absorbed as we need it, greater intake results in less absorption
Greater intake of beta-carotene results in…?
- Less absorbed
Both plant and animal sources of Vitamin A must….?
- Detach from its protein by pepsin in stomach for absorption
Best sources of Vitamin A in our diet?
- Egg yolks
- Squash
- Yellow and orange vegetables and fruit
- Beef liver extremely high
- Dairy
Where in Canada is Vitamin A deficiency most prevalent?
- Newfoundland
What is the main cause of Vitamin A deficiency?
- Poor dietary choices
- Common in children
What can Vitamin A deficiency cause?
- Blindness
- Decrease in immune function
- mostly in developing countries
Role of Vitamin A in cell differentiation?
- maintains epithelial tissues such as skin and internal cavities, teeth, skeletal and soft tissue
- also known as retinol, important for vision
What is retinol?
- Form of Vitamin A, converted to retinal for vision
Retinal and cis bonds?
- Has a cis bond
- This kinks the molecule
What is vitamin A’s role in the visual cycle?
- retinal combines with opsin to form light-sensing rhodopsin
- must be replenished form diet, as lost in cycle
- when light hits, retinal changes it’s conformation from curved to straight, sending signal to the brain that there is light
First symptom of Vitamin A deficiency?
- Night blindness
What happens to eyes without vitamin A?
- Mucus secreting cells are replaced by keratin producing cells, resulting in a hard dry layer lacking protective properties of mucus membranes - leads to blindness
- Without vitamin A, cells will not differentiate into mucous membrane
What do fat soluble vitamins need in the blood?
- Carrier protein (thus also important to have adequate protein intake)
What can vitamin A penetrate?
- lipid bilayer
What can vitamin A change?
- The amount of mRNA produced by binding to receptor protein in nucleus, and binding to DNA
- impacts gene expression and cell differentiation
What can cells differentiate into, inside bone marrow?
- Red blood cells
- Different WBCs
Lack of Vitamin A impairs….?
- Immune function
- Growth and reproduction
- Due to its role in deciding cell fate
What is keratin not compatible with?
- Eye tissue
- Results in blindness
Hypercarotenemia vs too much preformed Vitamin A?
- Much safer
- Too much Vitamin A can be toxic because it is all absorbed
What can result due to hypercarotenemia?
- Less absorbed and less converted to vitamin A
- Shows up as orange colour in skin
What can hypercarotenemia cause in smokers?
- Increase smokers’ risk for developing lung cancer
Are all micronutrients transcription factors and are they all involved in gene expression?
- No
- Some are coenzymes that allow other enzymes to function
What does vitamin D allow?
- Calcium absorption in the intestine
Vitamin D function?
- Maintain calcium and phosphorus levels in blood that favour bone mineralization
Where in our body is Vitamin D made?
- In our skin
Where is vitamin D3 further processed into Vitamin D?
- Liver and kidneys
- Adds a hydroxyl group in both organs
What stimulates the conversion of D3 into active vitamin D? What does this result in?
- Parathyroid gland releasing PTH
- Low levels of active vitamin D causes expression of calcium transporter in intestines
- Higher levels cause differentiation of osteoclasts along w PTH
- Also causes the kidneys to retain calcium
Vitamin A deficiency in children?
- Rickets
- Bones form poorly
- Bowing in legs
Vitamin A deficiency in adults?
- Osteomalacia
- Greater risk of bone fracture, muscle and bone pain
- Can lead to osteoporosis
- Those 50+ should take supplement because skin has reduced ability to make vitamin D
Vitamin D sources in diet?
- Salmon, eggs, dairy
Vitamin D deficiency by latitude?
- 40 degrees north and below 40 degrees south
How many people in the world are vitamin D deficient?
- 1 billion
Vitamin D deficiency is linked to what chronic diseases?
- Osteoporosis
- MS
- Heart Disease
- Cancer
- Infectious diseases
Milk consumption and Vitamin D deficiency?
- Low milk consumption = more vitamin D deficiency cases
Vitamin E function?
- Protects proteins and DNA
- Scavenges free radicals before damage to unsaturated fatty acids in lipid membrane
Transfer proteins in liver and Vitamin E
- Incorporate vitamin E into VLDL particles for delivery
What does Vitamin C cause?
- Regeneration of Vitamin E
Vitamin E deficiency? Symptoms?
- Rare
- Poor muscle coordination and impaired vision
- Weakness
High dose vitamin E supplementation?
- Increase mortality rate rather than decreasing CV risk
- Indication how it is better to get source from foods
Vitamin E sources in the diet?
- Nuts
- Eggs
- Salmon
- Plant oils
- Sunflower seeds
Vitamin K function?
- Helps with blood clot formation
- Factor in bone mineralization
What do factors II, VII and X, proteins C and S require for post-translational modifications?
- Carboxylase and Vitamin K (co-factor)
What occurs if Vitamin K is deficient?
- blood clotting factors will lack a carboxyl group, can’ t bind to calcium in order to form clotting complexes on platelet phospholipid membranes
Warfarin and Vitamin K?
- Similar structure to Vitamin K
- Competes and prevent y-carboxylation of the blood clotting factors
- Large levels of vitamin K can offset warfarin and inactivates it
What is warfarin prescribed for?
- Prevents thrombi formation and emboli formation
Vitamin K deficiency?
- uncommon because our gut bacteria makes Vitamin K
- deficiency can occur due to fat malabsorption or antibiotics
- most common in newborns as they are not colonized w microbiota, thus they are given a shot at birth
Vitamin K sources in the diet?
- Fruits, Vegetables, Kale, Spinach, Kiwi
- Monitor in patients with CV diseases/those prescribed with warfarin
Vitamin D toxicity can cause?
- Calcium deposition in the blood and kidneys leading to CV DAMAGE
- Toxicity manifesting as weight loss, muscle and joint pain, liver damage and birth defects in women who are pregnant
High doses of Vitamin K cause?
- Interference w anticoagulant drugs
