10. Vitamins and minerals.pptx biochemistry

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1. Vitamins and minerals Lecture 20, 21 Noor Ullah B.Sc MLT, M.Sc Biochemistry, M.Phil Biochemistry/ Mol. Biology PhD Scholar Biochemistry Lecturer MLT, KMU IPMS [email protected]

2. Vitamins Vitamins are organic compounds required in the diet in small amounts to perform specific biological functions for normal maintenance of optimum growth and health of the organism The bacterium E.coli does not require any vitamin, as it can synthesize all of them It is believed that during the course of evolution, the ability to synthesize vitamins was lost Hence, the higher organisms have to obtain them from diet Khyber Medical University Institute of Paramedical Sciences 2

3. History Hopkins coined the term accessory factors to the unknown and essential nutrients present in the natural foods Funk (1913) isolated an active principle amine from rice polishings and , later in yeast, which could cure Beri Beri in pigeons He coined the term vitamine (Greek: vita-life ) to the accessory factors with a belief that all of them were amines It was later realized that only few of them are amines The term vitamin, however, is continued without the final letter ‘e’ Khyber Medical University Institute of Paramedical Sciences 3

4. Nomenclature McCollum and Davis used A, B and C to represent vitamins in 1915 They first felt there were only two vitamins— fat soluble A and water soluble B (anti-beriberi factor) Soon another water soluble anti-scurvy factor named vitamin C was described Vitamin A was later found to possess two components- one that prevents night blindness (vitamin A) and another anti-ricket factor named as vitamin D Khyber Medical University Institute of Paramedical Sciences 4

5. Nomenclature A fat soluble factor called vitamin E, in the absence of which rats failed to reproduce properly, was discovered Yet another fat soluble vitamin concerned with coagulation was discovered in mid 1930s It was named as vitamin K- In the sequence of alphabets it should have been F, but K was preferred to reflect its function ( koagulation ) Khyber Medical University Institute of Paramedical Sciences 5

6. Nomenclature As regards the water soluble factors, vitamin C was identified as a pure substance and named as ascorbic acid Vitamin B was found to be a complex mixture and nomenclature also became complex B1 was clearly identified as anti- beri - beri factor Many investigators went on naming them as the water soluble vitamins B2, B3, B4, B5, B6, B7, B8, B9, B10, B11 and B12 Some of them were found to be mixtures of already known vitamins and for this reason, a few members of the B-complex series disappeared from the scene Except for B1, B2, B6 and B12, names are more commonly used for other B-complex vitamins Khyber Medical University Institute of Paramedical Sciences 6

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8. Synthesis of vitamins by intestinal bacteria Gut bacteria can produce some of the vitamins, required by man and animals The bacteria mainly live and synthesize vitamins in the colon region, where the absorption is relatively poor Some of the animals (e.g. rat, deer etc.) eat their own feces, a phenomenon known as coprophagy As far as humans are concerned, it is believed that the normal intestinal bacterial synthesis, and absorption of vitamin K and biotin may be sufficient to meet the body requirements For other B-complex vitamins, the synthesis and absorption are relatively less Administration of antibiotics often kills the vitamin synthesizing bacteria present in the gut, hence additional consumption of vitamins is recommended Khyber Medical University Institute of Paramedical Sciences 8

9. Vitamins Dose- Daily reference intake Recommended Dietary Allowances (RDA): Adequate Intakes (AI): The amount of a nutrient thought to be adequate for most people; used when EAR & RDA can not be determined. Estimated Average Requirements (EAR): The amount of a nutrient that meets the requirement of 50% of the people of a particular age & gender Tolerable Upper Intake Levels (UL): The maximum amount of a nutrient that is unlikely to pose risk or harm in healthy people when consumed daily; intake above the UL can be harmful. 9 Khyber Medical University Institute of Paramedical Sciences

10. Fat soluble vitamins—general Vitamin A, D, E, and K- fat soluble Their availability in the diet, absorption and transport are associated with fat They are soluble in fats and oils and also the fat solvents (alcohol, acetone etc.) Fat soluble vitamins can be stored in liver and adipose tissue They are not readily excreted in urine Excess consumption of these vitamins (particularly A and D) leads to their toxicity All the fat soluble vitamins are isoprenoid compounds, since they are made up of one or more of five carbon units namely isoprene units (CH=C.CH3-CH=CH- ) Khyber Medical University Institute of Paramedical Sciences 10

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12. Water soluble vitamins—general The water soluble vitamins are a heterogenous group of compounds since they differ chemically from each other The only common character shared by them is their solubility in water Most of these vitamins are readily excreted in urine and they are not toxic to the body Water soluble vitamins are not stored in the body in large quantities (except B12) For this reason, they must be continuously supplied in the diet Khyber Medical University Institute of Paramedical Sciences 12

13. Water soluble vitamins—general Water soluble vitamins form coenzymes (Refer Table 6.3) that participate in a variety of biochemical reactions, related to either energy generation or hematopoiesis It may be due to this reason that the deficiency of vitamins results in a number of overlapping symptoms The common symptoms of the deficiency of one or more vitamins involved in energy metabolism include dermatitis, glossitis (red and swollen tongue), cheilitis (rupture at the corners of lips), diarrhea, mental confusion, depression and malaise Deficiency of vitamins B1, B6 and B12 is more closely associated with neurological manifestations Khyber Medical University Institute of Paramedical Sciences 13

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16. Vitamers The term vitamers represents the chemically similar substances that possess qualitatively similar vitamin activity Some good examples of vitamers are Retinol, retinal and retinoic acid are vitamers of vitamin A Pyridoxine, pyridoxal and pyridoxamine are vitamers of vitamin B6 Khyber Medical University Institute of Paramedical Sciences 16

17. Cases of Vitamin Deficiency and Toxicity Avitaminosis: It is any disease caused by chronic or long-term vitamin deficiency or caused by a defect in metabolic conversion, such as tryptophan to niacin. It leads to well defined symptoms e.g. Xerophthalmia due to Vitamin A deficiency Rickets due to Vitamin D deficiency Pellagra due to Vitamin B3 deficiency Beriberi due to Vitamin B1 deficiency Scurvy due to Vitamin C deficiency 17 Khyber Medical University Institute of Paramedical Sciences

18. Cases of Vitamin Deficiency and Toxicity Hypovitaminosis: Result from inadequate supply of one or more vitamins. It appears in the form of well defined symptoms as skin changes, reduced vitality and low resistance to infections. Latent Hypovitaminosis: A case of unrecognizable deficiency symptoms but immediately appeared under sudden stress or exposure to different environment. 18 Khyber Medical University Institute of Paramedical Sciences

19. Cases of Vitamin Deficiency and Toxicity Hypovitaminosis due to Anti- vitamins: Thiaminase in raw fish destroy Vitamin B1. Avidin in raw egg forming complex with biotin (vitamin) (biotin-avidin) prevents absorption of biotin. Liatin in linseed oil is antagonist to Vitamin. B6. Hypervitaminosis: A case which develops only upon prolonged use of excessive amount of vitamins. 19 Khyber Medical University Institute of Paramedical Sciences

20. Minerals Minerals are small, naturally occurring, inorganic, chemical elements- Occur naturally in rocks and soil Serve as structural components & in many vital processes in the body Inorganic- being composed of matter other than plant or animal More than 25 have been isolated 21 elements have been shown to be essential Minerals make up about 4 to 5% of body weight Categorized as major, trace, or ultra-trace 20 Khyber Medical University Institute of Paramedical Sciences

21. Minerals Major: required at least 100 mg per day Trace: required less than 100 mg per day Ultra-trace: required less than 1 mg per day Sodium Potassium Phosphorus Chloride Calcium Magnesium Sulfur Flouride Iron Manganese Zinc Chromium Copper Iodine Molybdenum Selenium 21 Khyber Medical University Institute of Paramedical Sciences

22. General functions of Minerals Minerals provide a suitable medium for cellular activity Permeability of membranes Irritability of muscles and nerve cells Play a primary role in osmotic phenomenon Involved in acid base-balance Confer rigidity and hardness to certain tissues (bones and teeth) Become part of specialized compounds 22 Khyber Medical University Institute of Paramedical Sciences

23. Minerals Vs Vitamins Similarities Do not contribute energy (calories) to the diet Have diverse functions within the body Work with enzymes to facilitate chemical reactions Required in the diet in very small amounts Dissimilarities Whereas vitamins are organic compounds, minerals are inorganic compounds Unlike vitamins, some minerals contribute to the building of body structures Khyber Medical University Institute of Paramedical Sciences 23

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