Nutrition 12 ch 9
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What are the fat soluble vitamins?
Vitamins A, D, E, and K.
What is a provitamin?
A susbtance that can be converted in the body to a vitamin.
What two forms can Vit A be found in?
Vitamin A can be found in food as preformed ( it's already Vit A ), or, as a provitamin ( precursor to Vit A, almost Vit A but not quite. The body can convert this to regular Vit A ).
In what kinds of foods is preformed Vit A found?
In what kinds of food is provitamin A found?
What is cell differentiation?
The ability of a stem cell to become a specific kind of cell.
What are retinoids?
Retinoids are provitamin forms of Vit A.
Retinol, retinal, and retinoic acid are all retinoids, provitamin forms of Vit A.
What are retinyl esters?
Retinyl esters are a storage form of Vit A.
Retinyl ester gets converted to retinol.
What is retinol, what's it good for?
Retinol is a provitamin A / Vit A precursor.
Retinol is good for reproduction? ( according to lecture notes. )
"Retinol" is also another name for Vit A.
Retinol can become: retinal and retinoic acid.
Retinol is the form of Vit A that circulates in the blood.
What is retinal, what is it good for?
Retinal is a Vit A precursor / provitamin A.
Retinal is good for vision.
Retinal can become retinoic acid.
What is retinoic acid, what is it good for?
Retinoic acid is a Vit A precursor / provitamin A.
Retinoic acid regulates growth. Important for cell differentiation.
Retinoic acid... cannot really become anything. It's stuck as retinoic acid.
What are carotenoids?
Pigments found in plants that give plants an orange, orange / red color. Some carotenoids can be converted to Vit A precursors / retinoids.
Carotenes not converted to Vit A can act as antioxidants.
What is beta-carotene?
A special kind of carotenoid that has more provitamin A activity than other carotenoids. Beta-carotene is found in fruits and vegetables with dark orange colors.
Beta carotene can become retinal.
Absorption of Vit A...
Vit A needs to have some fat in the diet to be absorbed. If diet is very low in fat, Vit A cannot be absorbed very well. If someone is taking medication that prevents the absorption of fats then Vit A will not be absorbed very well.
What are chylomicrons?
Chylomicrons are lipoproteins that move preformed Vit A and carotenoids to different parts of the body, including the liver.
Carotenoids and retinol in the liver...
Carotenoids can be converted to retinol in the liver.
To move from the liver to other parts of the body retinol must be bound to retinol-binding proteins.
What is night blindness?
Difficulty or inability to see in dark, especially after seeing a bright light.
How does Retinal form of Vit A help with vision?
The retinal vitamin is shaped like a straight line that has been bent
It binds with a protein called opsin and together they are called rhodopsin.
When light enters the eye it straightens out the bent cis form of retinal to a straight trans form.
This sends a nerve impulse to the brain which is interpreted as an image.
If there is not enough Vit A in the diet then this process takes a lot longer and can make it very hard to see in dark areas.
Vit A, cell differentiation, and eyeballs...
Vit A is important for cell differentiation - allowing certain cells to become other cells.
If there is not enough Vit A in the diet the cells that would become mucous producing cells can become keratin producing cells instead.
Mucous is good for your eyes, makes then nice and moist and keeps them clean and kills some bacteria. Keratin just makes things kind of hard, it's the same stuff fingernails and hair is made of.
So, without enough Vit A the cells in your eyes can end up making keratin instead of mucous and eyes can become dry and infected.
Accutane is a drug used to treat acne that is made from a special form of Vit A. It can also cause birth defects. If a woman stops taking accutane, there is still a risk of birth defects for another couple months, why is this?
Since Accutane is derived from Vit A, and since Vit A is fat soluble and stored in fat, there can still be amounts of Accutane in the woman's system, stored in fat for two months or more after stopping usage.
Vit A is important for...
Vision, healthy skin, fetal development, sperm production.
Beta-cerotene acts as an antioxidant.
What are some signs of Vit A deficiency?
Night blindness, corneal degeneration, infections ( impaired immunity - not enough b-carotene ), hyperkeratosis - too much keratin = hardening of the skin.
What are some signs of chronic Vit A toxicity ( too much Vit A over time )?
Reduced bone density - Vit A stimulates osteoclasts - osteoclasts break down bones.
Liver abnormalities and birth defects can also occur.
What are some signs of acute ( too much all of a sudden ) Vit A toxicity?
Blurred vision, nausea, vomiting, headache, increase of pressure inside skull, skin problems.
What is hypercarotenemia?
Too much carotenoids in the body.
Carotenoids are pigments in red, orange plants and fruits and consuming too much of them can cause them to be stored in fat just below the surface of the skin, causing the skin to appear orange.
What are Retinol Activity Equivalents RAEs?
A measurement of how much retinol is in something like beta carotene. There isn't really a daily requirement for beta carotene but more for the equivalent of retinol in a certain amount of beta carotene. So something with beta carotene ( which contains retinol ) will be rated with a Retinol Activity Equivalent.
What is the RDA for beta carotene?
700 - 900 ug ( micrograms ) RAE ( retinol activity equivalents ).
What are some functions of Vit. D?
- Helps with mineralization of bone.
- Increases absorption of calcium in SI.
- Decreases excretion of calcium by the kidneys.
- Helps osteoclasts release Ca from bone.
Kidneys can excrete calcium, Vit D helps the kidneys retain calcium and return it to the bloodstream when it is needed.
Calcium is stored in bones. Osteoclasts are cells in bone that break down bone and release calcium into the bloodstream. Vit D helps immature cells differentiate into osteoclasts which release calcium into the bloodstream.
Vit D and sunlight - synthesizing your own Vit D.
A cholesterol in the skin, 7-dehydrocholesterol, is converted to cholecalciferol, or, Vit D3, an inactive form of Vit D, when sunshine comes into contact with the skin.
Vit D3 in the body...
Vit D3 has a lot of carbon atoms in it and once Vit D3 enters the liver, the liver adds a hydroxyl group ( OH - oxygen atom bound to hydrogen atom ) to carbon number 25. This makes:
25-hydroxyl vit D3
Once25-hydroxyl vit D3 makes its way to the kidney, the kidneys add another hydroxyl group to carbon number 1, this makes:
1, 25-hydroxyl vit D3
This is the active form of Vit D that can be used by the body.
Vit D blood tests...
The liver converts cholicalciferol to 25-hydroxyl D3. The kidneys convert 25-hydroxyl D3 into 1, 25-hydroxyl D3 ( active Vit D ).
If blood tests show low levels of 25-hydroxyl D3 then it could mean the liver is not working well and / or calcium levels could also be low. Not enough active Vit D - decreased calcium absorption in SI.
If blood tests show too much 1, 25-hydroxyl D3 it could mean the kidneys are not working right and / or calcium levels could be too high. Too much Vit D - too much calcium retained in body - calcium gets deposited in soft tissue and blood vessels.
Vit D deficiency...
Not enough Vit D for very young children can lead to rickets - a bowing of the legs. If there is not enough Vit D in their diet then calcium absorption is poor and their bones do not get enough of it. When they begin to stand on their legs the weight of their upper body on their weak leg bones causes the legs to bow out. It can also cause ribs to become deformed. It can also mean the children do not grow to their full height.
Osteomalacia is a similar disease that affects adults. Since bones are already fully formed in adults it does not cause bones to be deformed but does make them weak and prone to fracture.
Vit D toxicity...
Too much Vit D doesn't usualy come from diet but from Vit D supplements. It can cause too much calcium to be absorbed and retained by the body. This extra calcium stays in the blood stream and can then be deposited in soft tissues like blood vessesls and kidneys.
Daily Vit D intake..
- 19 - 50yo: 5 ug / day
- 51 - 70yo: 10 ug / day
- 70 +: 15 ug / day
Peoples ability to synthesize Vit D decreases with age.
UL - 50 ug / day
It's Vit E!
Good sources of Vit E are wheat germ, whole grains, liver, egg yolks, nuts, plant oils, corn, sunflower oil, some leafy greens.
What are some functions of Vit E?
- Stabalization of cell membranes
- Protection of polyunsaturated fatty acids
Vit E is important in protecting different cells ( red blood cells, nervous tissue cells, lung cells, etc ) from free radicals.
Vit E can be destroyed by heat and oxygen.
Vit E deficiency...
Not enough Vit E can lead to nerve damage and red blood cell damage since it is needed to protect both of these kinds of cells. Fetuses don't get much Vit E until the final weeks of pregnancy so premature babies are especially at risk.
Myelin, is a substance which coats nerves and acts as a kind of insulator, protecting the nerve. Vit E is needed for myelin.
Not enough Vit E can lead to poor muscle coordination, weakness, poor vision.
Vit E toxicity...
There aren't many risks of taking too much Vit E but it can interfere with the action of Vit K, which helps blood clot. For people taking blood thinning medication, too much Vit E and blood thinner could make blood clotting difficult.
What are some functions of Vit K?
Vit K helps blood coagulate.
It acts as a coenzyme for a protein called prothrombin. Prothrombin needs Vit K for it to work.
What is coagulation?
The process of blood clotting. So when you get a cut or scrape the blood coagulates at the surface of the skin, kind of clumps up into a kind of solid and blocks the flow of blood rather than staying liquid and flowing out of the cut.
What is phyloquinone?
The form of Vit K found in plants.
What is menaquinone?
The form of Vit K found in fish oils and meats. It can be synthesized in the digestive tract.
What are good sources of Vit K?
Leafy greens - kale, brussel sprouts, mustard greens, broccoli, spinach.
Vit K deficiency...
Not enough Vit K means your blood will not clot very well. Not only will cuts keep bleeding but tiny breaks in blood vessels and capillaries will keep leaking blood outside of these vessels in your body.
Vit K toxicity...
There really isn't any toxicity. But, if a person needs to take blood thinners to say, reduce risk of heart disease, lots of Vit K can interfere with the ability of blood thinners to do their job.
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