Vitamins and minerals

vitamins and minerals, for mbbs undergraduate students

1. Vitamins and minerals

2. Vita + Amines Micronutrients Do not yield energy Not synthesized by the body

3. Vitamin A - sources Retinol in animal foods Beta carotene in plant foods Animal foods – liver, eggs, cheese, butter, whole milk, fish and meat. fish liver oils are the richest source. Plant foods – green leafy vegetables e.g. spinach, papaya, mango, pumpkin, carrot Fortified foods – vanaspati, milk, margarine. Carotenes are converted to retinol in small intestine .

4. Functions Production of retinal pigments. Supports skeletal growth Maintains the integrity and normal functioning of glandular and epithelial tissue lining the respiratory, intestinal tract as well as skin and eyes. Anti-infective property

5. Vitamin A deficiency Ocular - xerophthalmia Night blindness – impairment in dark adaptation. Conjunctival xerosis – first clinical sign. Dry and non-wettable conjunctiva. Muddy and wrinkled. Bitot’s spot – triangular, pearly white or yellowish foamy spots on the bulbar conjunctiva on either side of the cornea. Corneal xerosis – cornea appears dull, dry non-wettable and opaque. There may be ulceration – scarring. Keratomalacia – liquefaction of the cornea. Cornea may become soft and burst open. Vision may be lost.

6. Extra ocular manifestations – Anorexia Growth retardation Follicular hyperkeratosis Increased respiratory and intestinal infections.

7. Treatment - Administration of 200000 IU of retinol palmitate on two successive days. All children with corneal ulcers should receive vitamin A.

8. Prevention Administration of single dose of 200000 IU vitamin A oil orally every 6 months (1 to 6 years) 100000 IU between 6 months to 1 year.

9. Vitamin D Calciferol ( vit –D2) – derived from plant Cholecalciferol ( vit D3) – animal fats and fish liver oils UV rays also convert skin cholsesterol to vitamin . Endogenous transformation into 25 HCC and 1;25 DHCC in liver and kidney. Can be considered a kidney Hormone.

10. Sources Sunlight – synthesized in the body bu action of UV rays on 7 dehydrocholesterol. Foods – only in foods of animal origin. liver, egg yolk, butter, cheese, Fish liver oils are the richest source Fortified foods such as milk, vanaspati etc

11. Functions Intestine – promotes absorption of calcium and phospohorus Bone – stimulates normal mineralisation, enhances bone resorption Kidney – increases tubular reabsorption of phosphates, variable effect on calcium

12. Deficiency Rickets – Young children 6 months to 2 years Reduced calcification of growing bone Growth failure, bone deformity, muscular hypotonia, tetany and convulsions Elevated alkaline phosphatase Curved legs, deformed pelvis, pigeon chest, Hrrison’s sulcus, rickety rosary, kyphoscoliosis Delayed developmental milestones such as walking and teething.

13. Osteomalacia – in adults, mainly women. Prevention – Exposing children regularly to sunshine Periodic dosing of children with vitamin D Food fortification with vitamin D

14. Vitamin E Tocopherols – alpha tocopherols most potent Source – vegetable oils, cotton seeds, sunflower seed, egg yolk and butter. No clear symptoms of vitamin E deficieny Requirement - 8 -10 mg per day

15. Vitamin K Vitamin K1 – fresh green vegetables, fruits. Cow milk > human milk. Vitamin K2 – synthesized in intestinal bacteria. Stored in liver. Stimulates the production and release of coagulation factors. In Vit K deficiency, prothrombin decreases and coagulation time increases. New-borns are deficient in vitamin K.

16. Vitamin B1 – Thiamine Essential for carbohydrate metabolism. thiamine pyrophosphate activates transketolase enzyme involved in direct oxidative pathway of glucose metabolism In thiamine deficiency – accumulation of pyruvic and lactic acids. Sources – whole grain cereals, wheat, gram, yeast, pulses, oilseeds, nuts Milk important source for infants.

17. Deficiency Beriberi – Dry form – characterized by nerve involvement, (peripheral neuritis) Wet form – heart involvement Infantile – seen in infants between 2 to 4 months. Wernicke’s encephalopathy – ophthalmoplegia, polyneuritis, mental deterioration. Seen in alcoholics and people who fast.

18. Riboflavin B2 Role in cellular oxidation Maintain the integrity of mucocutaneous structure Co-factor for glutathione reductase – helps in metabolism of other vitamins like B6, niacin and Vitamin K Sources Milk, eggs, liver, kidney and green leafy vegetables. Cereals and pulses are relatively poor source. Deficiency – Angular stomatitis, Cheilosis, Glossitis

19. Niacin B3 Essential for metabolism of carb, fats and proteins Essential for normal functioning of skin, intestine and nervous system. Tryptophan is the precursor. Sources – liver, kidney, meat, poultry, fish, legumes, ground nut. Milk poor source for niacin, but rich in tryptophan.

20. Deficiency – Pellagra – D iarrheal, D ermatitis, D ementia. Glossitis and stomatitis Dermatitis – bilaterally symmetrical, occurs in skin exposed to sun Mental changes as depression, delirium and irritability can also occur. Prevention – Good mixed diet containing milk and/or meat Avoidance of diet dependent of maize or sorghum

21. Pyridoxine B6 3 forms – pyridoxine, pyridoxal, pyridoxamine Metabolism of amino acids, fats and carbohydrates Source – milk, liver, meats, egg yolk, fish, whole grain cereals, legumes and vegetables. Deficiency – peripheral neuritis.

22. Vitamin B12 Cooperates with folates in synthesis of DNA. Synthesis of fatty acids in myelin. Sources – liver, kidney, meat, fish, egg, milks and cheese. Synthesised by bacteria in colon. Stored in liver. Deficiency – Megaloblastic anaemia, demyelinating lesion in spinal cord

23. Vitamin C Potent antioxidant Formation of collagen – supportive matrix for blood vessels, connective tissues, bone and cartilages. Sources – fresh fruits and green leafy vegetables, germinating pulses, amla, guavas. Deficiency – Scurvy – swollen and bleeding gums, subcutaneous bruising, bleeding into the skin and joint, delayed wound healing, anaemia and weakness.

24. Minerals Major minerals – calcium, phosphorus, sodium, potassium, magnesium Trace elements – irone, iodine, fluorine, zinc, copper, cobalt, chromium, manganese, molybdenum, selenium, tin, nickel, silicon, vanadium Trace contaminants with no known functions – lead, mercury, barium, boron and aluminium.

25. Calcium 1.5 – 2% of body weight. Equilibrium between blood calcium and skeleton Functions – Formation of bones and teeth Coagulation Muscle contraction Cardiac action Milk production Transformation of light to electrical impulse in retina

26. Sources – Milk and milk products, eggs and fish. Cheapest source - green leafy vegetables, cereals and millets. Calcium oxalate limits absorption. Calcium phytate in cereals. Sitaphal good source of calcium Absorption – enhanced by vitamin D, decreased by phytates, oxalates and fatty acids

27. Iron Source – Two forms – haem iron and non haem iron Haem iron – liver, meat, poultry, fish. Non haem iron – cereals, green leafy vegetables, legumes, nuts, oilseeds, jaggery, dried fruits Poor bioavailability due to phytates, oxalates carbonates, phosphates and dietary fibres. Milk, egg, tea inhibits iron absorption.

28. Absorption Mostly absorbed from duodenum and upper intestine in ferrous stae . Rate of absorption depends on – Iron storage Presence of inhibitors such as phosphates Promoters such as ascorbic acid and ascorbic acid rich food Disorders of jejunum and ileum Iron losses – Through haemorrhage Basal loss

29. Iron deficiency 3 stage – Decreased storage – no detectable abnormality Latent iron deficiency – storage exhausted, no anaemia, low serum ferritin, low transferrin saturation Overt – decrease in haemoglobin concentration

30. Evaluation of iron status Hb concentration – Serum iron concentration – normal 0.8 – 1.8 mg/dl. Serum ferritin – measures the iron storage in body. < 10mcg/dl indicates low storage Serum transferrin saturation – normal value 30%. Should be above 16%

31. National Iron Plus Initiative

32. Iodine Required for synthesis of thyroid hormone. Daily requirement – 150 mcg. Sources – Sea foods (sea salt, sea fish) and cod liver oil. 90% of iodine comes from food, rest from drinking water. Iodine content of the ground determines the iron content of water and food grown. Goitrogens – Interfere with iodine utilisation of thyroid gland. Cauliflower, cabbage Most important are cyanoglycosides and thiocyanates.

33. Spectrum of Iodine Deficiency Disorder

34. Control Iodized salt – iodine concentration 30 ppm at production level and 15 ppm at consumer level. Iodized oil – injectable method, 1 ml provides protection for 4 years Iodized oil, oral. Iodine monitoring – Iodine excretion determination, level of iodine in salt, water and food Determination of iodine in salt Neonatal hypothyroidism indicator for environmental iodine deficiemcy .

35. Fluorine Essential for normal mineralisation of bones and dental enamel formation. Sources- Drinking water – 0.5 mg/L, in fluorosis endemic area 3 -12 mg/L Foods – sea fish, cheese and tea. Deficiency/excess – prolonged ingestion in excess through drinking water dental and skeletal fluorosis Inadequate intake – dental caries

36. Dental fluorosis – excess fluoride ingestion (>1.5 mg/L) during first 7 years of life . Mottling of dental enamel. (upper incisor) Chalk white patches – becomes yellow then brown or black. In severe cases complete loss of dental enamel. Skeletal fluorosis – Daily intake > 3.0 – 6.0 mg/L. heavy fluoride deposition. >10mg/L crippling fluorosis