1 Metabolism 2 Study Guide 3 1. What are vitamins and difference between fat and water soluble? - Vitamins are micronutrients that must be supplied from the diet. They are needed for normal function and their absence cause certain symptoms with each one. The body can make some, but not in appreciable amounts. Fat soluble is obviously soluble in fat, stored in the body in large amounts so it’s not required every day. Since these are stored, deficiency takes a long time to occur. Most have precursors, and only higher organisms need them. Can be toxic at low amounts (but still way higher than the UL). Water soluble are stored minimally, excreted in the urine, so deficiency can happen much faster.They are absorbed directly via the blood stream and both simple and complex organisms need. Since they aren’t really stored, they are only toxic at mega doses (100x DRI). The B vitamins are mostly coenzymes for all metabolic pathways.Vitamin A1. Explain the retinoids and cartoenoids.- You have two main types of Vitamin A, the retinoids and the carotenoinds. The retinoids are the active form, these are the retinal, retinol ect. The cartoenoids are the provitamins. These get cleaved in the body to retinal, which is later reduced to retinol. 2. What are the sources for both types?- The carotenoids are the form that is in the veggies, like carrots. Most colorful veggies are full of them; there are over 600. The retinoids are in animal products. The best sources are egg yolks, butter, and milk. The form in supplements is Retinyl palmitate or some have carotene. Since vitamin A is not found in low fat dairy and some breakfast items, it is supplemented at around 500 IU. Supplement pills contain 3000-25000 IU. The RDA is around 5000 IUTony Berardi23. How is it digested, absorbed, and transported?- In food, it is in the form as either carentoids or retinyl esters attached to a protein, so just like all the other nutrients we learned, it has to be cleaved out of the protein. First pepsin (or HCl) cleaves out the free retinols or carotenoids, and these free carentoids and the retinols then form micelles just like lipids do when they get absorbed (meaning it enters via lymph, not the blood stream, as it is a fat soluble vitamin. Retinol is 70-90% absorbed and carotenoids are 20-50%. They then go to their target, so either the retina, bone, kidney, intestine, or gonad. In order to circulate in the plasma, they need a protein called Retinol Binding Protein, or RBP. Each mole of retinol combines with one mole of RBP to form a holo-RBP. So it is a one to one ratio. Once you have your holo-RBP, this will react with another protein called transthyretin. This complex (now a RBP-TTR) will then go to the tissues.- So you have a free retinol, it will combine with a RBP, and this will then combine with a TRR. This isthe circulating form. When the retinol is deposited in whatever tissue it goes to, the RBP and the TTR will be released to bind to another free retinol.4. What is the DRI?- This is tricky. The RDA is 900 RE, and 700 RE for men and women. Or 5000 IU. Now 1 RE is considered either 1ug retinol, or 6ug beta carotene, or 12 ug of some other carotenoids. The new guidelines also call them RAE sometimes. And RAE is equal to 1ug retinol, or 12ug beta carotene, or 24 ug other soe other carotenoid. o So if you notice, and RAE is double an RE if we are talking about a carotenoid. And RE can be 6ug of beta carotenoid or 12ug of another carotenoid; an RAE is 12ug beta carotenoid or 24ugof another. NOW for retinol, and RAE is equal to an RE; so no math is involved. You will have to calculate a question of this.- Now for the IU unit. Depending on the food, it will be different. Animal products give 3.3, cheese gives 3.5, yogurt gives 4.1, and plants give 10 IU. Now these also.Tony Berardi35. What are the functions?- Everyone knows the main function of vitamin A is for eyesight, but also for other systemic actions, such as cell differentiation/growth/reproduction/bone and immune development. How it works for vision is this: Retinal (11-cis retinal) is the form that the eyes use. The 11-cis retinal will bind with opsin (protein in the retina) to form rhodopsin. This rhodopsin helps communicate the light signal to the brain, and will break down to all-trans retinol. As this process always happens when we see light, we have to replace the 11-cis retinol in our diet (that is the retinol that is in animal products)- For the other functions, we will have to know the precursors involved in them. Retinal is oxidized to retinoic acid. Cell differentiation involves retinoic acid Growth is both retinoic acid and retinol Fertility is retinol Immunity is retinoids and carotenoids Skin integrity is retinoic acid. Then the last function is as an antioxidant. The carotenoids are the best antioxidants. 6. What is the deficiency and toxicity?- Vitamin A deficiency will lead to night blindness (as it is needed for vision is the dark), retarded growth, anorexia, lowered immunity, and keratinization of the skin. So basically if you follow the functions of it, then the deficiencies will be easy to predict. The populations that are more likely to become deficient are those with pancreatic, gallbladder,or liver disease, and those with steatorrhea.- On the other end, toxicity is very dangerous with vitamin A. This will lead to a whole list of problems, along with liver disease. This is with retinol toxicity; beta carotene toxicity just makes your skin yellow (kind of weird).7. How do you assess?- There are many tests for vitamin A assessment. One is the serum retinol test, but this a nonspecific test. The serum carotenoid test, but this is reflective of what you just consumed. Tony Berardi4 The best is the relative dose response, or RDR. This test measures the storage amount in the liver. First you measure their plasma retinol, then you give them an oral dose. Measure 5 hrs later and plug the values into this formula: 5hr amount-initial/5hr multiplied answer by 100. The thing you want to know is the ranges based on this final number. This is the only thing I will copy and paste, as you just have to remember these.Vitamin E1. What is this vitamin?- This is another fat soluble vitamin, which if you remember from learning about vitamin A, means itis stored in the body. Since it is
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