Iodine RDA 15ug for men and women Sources o Plants Animals varies greatly soil and water content o Fortified Iodized salt Digesion o Eaten Bound to amino acids Free as Iodine 3 or Iodide 1 o Absorption o Iodine found in Through GI including stomach Thyroid Gland 18 Kidneys for excretions Small amounts in the ovaries placenta skins gastric saliva Function o Synthesis of thyroid hormones Thyroxine T4 Triiodothyronine T3 o Thyroid gland Growth Development Regualtion of BMR Hyperthyroidism increased BMR o Leaking proteins burning glucose and no ATP yield Hypothyroidism decreased BMR o Burning fever glucose o Work harder to maintain weight Thyroid o Formation of Thyroid Hormones Thyroid cells collect Iodide via Na K ATPase Pump 60mg day Iodine Iodide Iodide binds to tyrosine residue MIT mono MIT iodinates to DIT dio DIT MIT Triiodothyronine T3 DIT DIT Thyroxine T4 Higher concentrations than T3 T4 T3 if needed Se dependent o Regulation of Thyroid Gland Hypothalamus Small part of the brain above Pituitary gland Produces thyrotropin releasing hormone TRH which stimulates the release of TSH o Explained in pituitary gland Pituitary Gland Located at the base of the brain Produces TSH o Decreased levels of thyroid hormone in blood stimulates this release TSH Stimulates thyroid hormone production Causes growth of thyroid cells Lets Break it down o Hypothalamus releases TRH Pituitary Gland for TSH Thyroid T3 and T4 First 2 steps are Grn dependent Last step is Iodine Dependent Deficiency o Causes decreased synthesis of T3 T4 Stimulates TRH TSH Increased Growth of thyroid cells Persistent low levels of iodine causes and increased size of thyroid gland o Goiter enlargement of thyroid gland Diseases pregnancy and puberty Interactions o Goitrogens substances that inhibit iodine metabolism and thyroid hormone synthesis Lithium used to treat bipolar disorders Thiocynated foods prevent the uptake of iodine at the thyroid gland Cabbage kale cauliflower no evidence to cause goiter Cassava consumed in large enough amounts in 3rd world countries to be directly related to goiter formation Toxicity none Vitamin A Tony Berardi typed this part 1 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 retinoic acid and retinyl esters The cartoenoids are the provitamins These get cleaved in the body to retinal which is later reduced to retinol Such as beta carotene beta cryptoxanthin lycopene lutein and zeaxanthin so any weird named molecule and milk 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 The form in supplements is Retinyl palmitate acetate 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 IU or 900 REA 1 RAE is equal to 1ug retinol or 12ug beta carotene or 24 ug other some other carotenoid 3 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 is the 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 Depending on its target tissue it will have a different binding protein called the cellular retinol binding protein or CRBP CRBP 1 for the liver and kidney CRBP 2 for the intestine CRBP 3 for the muscle and heart CRBP 4 for the colon 4 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 retinal As this process always happens when we see light we have to replace the 11 cis retinal in our diet that is the retinol that is in animal products For the other functions involve the other forms Retinal is oxidized to retinoic acid Cell differentiation involves retinoic acid Growth is both retinoic acid and retinol By remodeling the epiphsyseal cartilage Fertility is retinol Immunity is retinoids and carotenoids Skin integrity is retinoic acid Gene expression via retinoic acid binding to RAR receptors to induce Then the last function is as an antioxidant The carotenoids are the best The carotenoids function to prevent macular degeneration and inhibit LDL transcription antioxidants oxidation 5 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 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 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
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