vitaminsmineralsforw eb

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Information about vitaminsmineralsforw eb

Published on March 6, 2008

Author: bruce


Slide1:  Vitamins & minerals HE 3511 2008 Dr Lindsey Masson Department of Public Health Slide2:  Vitamins Organic compounds required in very small amounts. Deprivation  development of a more or less specific clinical deficiency disease & abnormal metabolic signs Restoration  prevents/cures deficiency disease & normalises metabolic abnormalities Vitamins A, B1, B2, B6, B12, C, E, K, folate, biotin & pantothenic acid must be supplied by the diet. Niacin & vit D can be made in the body if there is sufficient tryptophan & sunlight respectively. Slide3:  Fat soluble vitamins A (retinol) (-carotene – precursor to vitamin A) D (cholecalciferol) E (tocopherol) K (phylloquinone) Slide4:  Water soluble vitamins B1 (thiamin) B2 (riboflavin) Niacin B6 (pyridoxine) B12 (cobalamin) Folate Pantothenic acid Biotin C (ascorbic acid) Slide5:  Vitamin A The vitamin A family includes all naturally occurring compounds with the biological activity of retinol and pro-vitamin A carotenoids. 2 forms: Pre-formed vitamin A - retinol (in animal foods) Pro-vitamin A - carotenoids (in plant foods) -carotene -carotene -carotene -cryptoxanthin Vitamin A in foods:  REQ = ∑preformed vit A + β-carotene + other pro-vit A carotenoids 6 12 1 μg REQ = 1 μg preformed retinol 6 μg β-carotene 12 μg other carotenes with vit A activity Vitamin A in foods Total vitamin A in foods is expressed as μg retinol equivalents (REQ) International units (IU) Vit A content of foods used to be expressed in standardised international units: 1 IU = 0.3 μg retinol Slide7:  Dietary sources of vitamin A Retinol Foods of animal origin and a small number of bacteria, mainly in the form of retinyl palmitate Liver Fatty fish Egg yolk Milk Butter Enriched margarine β-carotene Carrots, peppers, tomatoes Brocolli, kale, spinach, brussels sprouts Apricots, mangoes, pink grqpefruit, watermelon Slide8:  Functions of vitamin A Vision Forms light sensitive complex rhodopsin in retina – night vision Cell differentiation & turnover Epithelial cell function – prevents dryness & thickening of eye, skin, lung & intestine -carotene is an antioxidant High intakes associated with low incidence of CVD & some cancers, but not as supplements! Slide9:  Eastern Mediterranean 13m at risk, 1m deficient south-east Asia 138m at risk, 10m deficient Africa 18m at risk 1.3m deficient Americas 2m at risk 0.1m deficient western Pacific 19m at risk 1.4m deficient WHO 1995; Bender DA, 2002 In total 190 million people at risk 14 million children deficient Vitamin A - deficiency 1 Slide10:  Vitamin A deficiency Earliest signs of deficiency Impaired colour vision: loss of sensitivity to green light Impairment of the ability to adapt to dim light Inability to see in dim light: night blindness Prolonged or severe deficiency: Xerophthalmia – causes keratinisation of the cornea followed by ulceration & eventual blindness Mild deficiency: Increased susceptibility to infectious diseases Clinical signs of deficiency Bitot’s spots Keratomalacia Slide11:  Vitamin A deficiency cont. In protein-energy malnutrition: Impaired synthesis of retinol binding protein which delivers the vitamin to target tissues. Therefore, functional vit A deficiency can occur secondary to protein-energy malnutrition. Slide12:  Vitamin A deficiency Vit A deficiency is a major public health problem in many areas of the less-industrialised world WHO estimate 256 million children <5y show subclinical deficiency & 2.7 million have xerophthalmia Treatment for xerophthalmia in 1-6y olds = oral doses of retinyl palmitate in oil. Those at risk include Those with diets low in animal fats & vegetables Low protein diets Fat malabsorption Slide13:  Vitamin A toxicity Excess is stored in the liver and is toxic in large amounts Liver is a rich source Not advised in pregnancy – teratogenic - Abortion - Birth defects - Permanent learning disabilities Polar bear livers definitely not advised! Slide14:  Vitamin D Vit D is the generic term for 2 molecules: Ergocalciferol (vitamin D2) Cholecalciferol (vitamin D3) – major form of vit D in nature Cholecalciferol is made from cholesterol by the action of UV light on the skin - between May & Sept in Scotland The active form of vit D is made by reactions in liver & kidney Vit D could be termed a hormone rather than a vitamin Slide15:  Dietary sources of vitamin D Fish oils Egg yolk Cheese Butter Margarine (fortified) The major food source is supplemented margarines & spreads Sunlight is the best source of vitamin D Slide16:  Functions of vitamin D Regulates calcium levels by Stimulating Ca absorption by the small intestine Stimulating bone resorption & formation Contributes to the regulation of the formation of immune cells in the blood Slide17:  Vitamin D deficiency Rickets in children Bones are undermineralised Osteomalacia in adults Demineralisation of bone May occur with low sunlight exposure, very high fibre diets, liver & kidney disease Those at high risk include Elderly housebound Asian immigrants Slide18:  Vitamin D toxicity Excessive exposure to sunlight does NOT lead to excessive formation of vitamin D Excessive intake of vit D results in disturbance of Ca metabolism, resulting in hypercalcaemia ( blood ca concs   BP, possibility of brain damage, kidney damage) Slide19:  Vitamin E Two main groups of compounds have vitamin E activity: -, -, -, - tocopherol -, -, -, - tocotrienols Dietary sources Vegetable oils Margarine, butter Fruit, vegetables, nuts, seeds Meat, fish, eggs Slide20:  Functions of vitamin E Acts as an antioxidant: donates H to free radicals which become unreactive Other functions Maintenance of cell membrane integrity Anti-inflammatory effects In DNA synthesis In stimulating the immune response Cell signalling May be important in prevention of CHD & cancer Slide21:  EJCN 1994;48:822-31 Slide22:  Vitamin E deficiency Deficiency is rare but may occur in premature babies and in those with fat malabsorption Intake dependent on PUFA intake ( PUFA in diets low in vit E   plasma tocopherol levels Vitamin E toxicity Few adverse effects have been reported with doses up to 3200 mg/d; none were observed consistently Slide23:  Vitamin K Phyloquinone (vitamin K1) All green leafy vegetables Soyabean, rapeseed, olive oil Menaquinones (vitamin K2) Cheese Synthesised by intestinal bacteria Menadione & menadiol diacetate Synthetic compounds Can be metabolised to phylloquinone Slide24:  Functions of vitamin K Vit K is a co-factor for the carboxylase enzyme that facilitates the synthesis of -carboxyglutamic acid (Gla) Gla is an essential component of 4 of the coagulation factors Prothrombin Factor VII Factor IX Factor X Gla is also present in bone matrix proteins Slide25:  Vitamin K & bone health Increases bone mineral density in osteoporosis (degeneration of the bones with increasing age due to loss of bone mineral & protein) Reduces fracture rates Vit K & vit D work synergistically on bone density Positively influences Ca balance, a key mineral in bone metabolism Slide26:  Vitamin K deficiency Bleeding disorder characterised by low plasma prothrombin activity Newborns at risk because of poor placental transfer & sterile gut. Babies therefore given an injection at birth to prevent haemorrhagic disease of the newborn Others at risk Those with malabsorption Those with prolonged use of broad spectrum antibiotics Those on anti-coagulant drugs e.g. warfarin & dicoumarol which are vit K antagonists Slide27:  Vitamin B1 (thiamin) Dietary sources Thiamin is widely distributed in foods. Good sources include yeast, bran, pork, soya, wheat, pulses Functions Required for carbohydrate metabolism Easily destroyed by heat (>100oC) & alkaline conditions Absorption reduced by tannins in tea Slide28:  Vitamin B1 (thiamin) deficiency Beri-beri (now rare, occasionally seen in alcoholics) Acute (wet) Beri-Beri (heart disease) Chronic (dry) Beri-Beri (neurological symptoms) Infantile Beri-Beri (breast fed) Wernike-Korsakoff Syndrome (alcoholics) Loss of short term memory, confabulation, apathy & brain degeneration Toxicity low Wet beriberi:  Wet beriberi Cardiovascular manifestations include  heart rate warm extremities enlargement of the heart oedema congestive heart failure Dry beriberi:  Dry beriberi Neurological symptoms include peripheral neuropathy, abnormal reflexes, diminished sensation & weakness in limbs Weakness, stiffness & cramps in legs; unable to walk more than a short distance Ankle jerk reflex lost, muscular weakness spreads upwards. Loss of sensation in feet. Pronounced toe & foot drop Deep muscle pain, slight pressure causes pain More resistant to treatment Vitamin B2 (riboflavin):  Vitamin B2 (riboflavin) Water soluble B vitamin Functions Required to produce energy from food Synthesis & oxidation of fatty acids As co-enzymes for many oxidation reactions in the body - Flavin mononucleotide (FMN) - Flavin adenine dinucleotide (FAD) Dietary sources:  Dietary sources Main dietary sources are dairy products and fortified breakfast cereals. Poultry, meat, fish, broccoli and asparagus provide much smaller amounts. Most dietary riboflavin occurs in the form of the coenzymes FAD and in smaller amounts as FMN, bound to their respective proteins. Deficiency - 1:  Deficiency - 1 Ariboflavinosis Symptoms include - angular stomatitis (lesions of the corner of the mouth) - cheilosis (cracking of edges of lips), - magenta tongue (sore, red, dry & atrophic) - seborrheic dermatitis & anaemia. Widespread in much of the developing world Rarely fatal because there is efficient reutilization of riboflavin released in catabolism of enzymes Anorexia, intestinal malabsorption & chronic alcoholism may precipitate deficiency. Niacin:  Niacin Sources Liver and kidney (richest sources) Other meat and poultry, fish Yeast extracts, Peanuts Bran, Pulses, Whole wheat, Coffee Can also be made from tryptophan 60 mg tryptophan = 1 mg niacin Milk & eggs good sources of tryptophan Niacin is sometimes bound in cereals and in a form which can’t be absorbed. The treatment of maize with lime water liberates the niacin and explains the absence of pellagra in ancient Mayans and present-day Mexicans Slide35:  Niacin Functions Component of co-enzymes (NAD & NADP) needed to produce energy from food Nicotinamide adenine dinucleotide (NAD) & NAD phosphate (NADP) act as H acceptors in oxidative reactions and can in turn act as H donors. Deficiency: Pellagra Dermatitis - inflammation of skin where it’s exposed to sunlight Diarrhoea - as well as diarrhoea, inflamed tongue Dementia - not seen until later stages of deficiency Slide36:  High intakes of niacin 1-6g/d of nicotinic acid has been used to lower blood TG and cholesterol in patients with hyperlipidaemia. Dilation of blood vessels & flushing Skin irritation Itching Burning sensation >500mg/d of nicotinic acid & nicotinamide can cause liver damage. Prolonged use can result in liver failure. Slide37:  Folate Required for cell division (fundamental to growth & repair) Prevention of neural tube defects High intakes may reduce plasma homocysteine levels, and therefore reduce risk of CHD & stroke Dietary sources of folate Cereals Potatoes Meats esp. liver Leafy greens Tea, beer Slide38:  Folate deficiency Anaemia (similar to the anaemia associated with B12 deficiency) Diarrhoea Growth failure Causes of low folate status Low intake from diet Impaired intestinal absorption Pregancy Drugs Chronic alcohol abuse Slide39:  Vitamin B12 (cobalamin) Needed for cell division Deficiency symptoms include anaemia which may be masked by folate supplementation Main cause of deficiency is lack of ‘intrinsic factor’ which is needed for B12 absorption (pernicious anaemia) Dietary sources Found in animal foods but also enters the diet via bacteria, fungi & seaweed Meat (liver & kidney again!) Eggs, cheese Slide40:  Sources of vitamin C (ascorbic acid) Berries Citrus fruits Salad vegetables Green vegetables (potatoes) (liver, milk) Rapidly destroyed by heat, light, air, acid etc. Humans, primates, fruit flies & guinea-pigs require vit C from the diet Extra vit C needed for smokers, during stress & for wound healing Slide41:  Vitamin C Functions antioxidant connective tissue formation some reactions in the liver microsomes involved in detoxifying certain drugs immune function Deficiency: scurvy fatigue skin haemorrhages swollen gums joint swelling sudden heart failure Slide42:  Vitamin C toxicity Excess may lead to kidney stones diarrhoea systemic conditioning - Suddenly stopping consuming high doses may precipitate scurvy as body gets used to high amounts Slide43:  Requirements for vitamins & minerals See: Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Department of Health, 1991 London, HMSO Slide44:  Vitamin supplementation Many claims for health benefits E.g. vitamin C & common cold Antioxidant role of certain vitamins in the prevention of some diseases – supplementation to date not proven and may even be detrimental Foods also contain other bioactive compounds Slide45:  Minerals & trace elements Inorganic elements needed from the diet (or drinking water) for optimum growth & health. Trace elements are present in trace amounts in the body but nevertheless are needed in metabolism. Minerals Trace elements Calcium Iodine Iron Selenium Sodium Fluorine Potassium Copper Phosphorus Cobalt Magnesium Chromium Sulpher Zinc Slide46:  Calcium Major bone mineral Average adult contains ~1200g of calcium 99% found in mineralised tissues (bones, teeth) 1% found in blood, extracellular fluid, muscle & other tissues Ca balance controlled by interaction of the calcitropic hormones (parathyroid hormone, vit D, calcitonin) with specific target tissues (kidney, bone, intestine) Slide47:  Functions of calcium Required for normal growth & development of the skeleton Adequate Ca intake critical to achieving peak bone mass & modifies the rate of bone loss associated with ageing Peak bone mass occurs ~ 30y and is dependent on many factors, e.g. genetics, nutrition, exercise etc. From ~ 50y in men and the menopause in women, bone balance becomes negative and bone is lost from all skeletal sites. This bone loss is associated with an increase in fracture rates Slide48:  Dietary sources of calcium Milk & milk products Canned fish (bones) Some green leafy vegetables Some ca enriched soya products In the UK, white flour is fortified with Ca therefore white bread is an important source Slide49:  Calcium deficiency Inadequate intake / poor absorption triggers in PTH synthesis & release. PTH acts on 3 target organs (kidney, bone, intestine) to restore circulating Ca conc. to normal Chronic inadequate intake / poor intestinal absorption Circulating Ca conc. maintained at expense of the skeleton   bone mass & osteoporosis. In younger people this may prevent the attainment of genetically determined maximal peak bone mass &  risk of osteoporosis in later life. May also play role in etiology of hypertension, including pre-eclampsia, & colon cancer Slide50:  Calcium toxicity Available data on adverse effects of high Ca intakes in humans are mainly from Ca intake from supplements Kidney stone formation Hypercalcaemia & renal insufficiency Effects on absorption of other minerals e.g. Fe, Zn, Mg, P Slide51:  Iron Present in - haemoglobin (60%) - myoglobin (5%) - various haem & non-haem enzymes - ferritin (20%) - haemosiderin (10%) Two forms in the diet – haem & non-haem Many components of the diet influences iron absorption vit C, meat, fish, seafood phytates, Ca Slide52:  Iron deficiency Iron deficiency is a major nutritional problem worldwide. Prevalence of Fe deficiency anaemia in infants and young children can range from 35-70% in some developing countries Motor & language function (children) Reduced physical performance Mood changes and poor concentration Brain function Impairment of immune response Anaemia & fatigue Slide53:  Iodine Iodine is a constituent of the thyroid hormones Thyroxine (T4) Triiodothyronine (T3) which have key roles in development & growth Dietary sources I content in most foods reflects the I content in the soil, water & fertilizers used in plant & animal production Sea foods & seaweed Vegetables grown in soil containing iodide Slide54:  Iodine deficiency disorders Fetus Abortions, stillbirths, congenital anomalies… Neonate Neonatal goitre, hypothyroidism… Children & adolescents Goitre, juvenile hypothyroidism, impaired mental function, retarded physical development… Adults Goitre, hypothyroidism, impaired mental function… Slide55:  Iodine deficiency disorders Goitre Mildest form of IDD Enlargement of the thyroid gland Range from those only detectable by touch to large goitres that can cause breathing difficulties Arises from stimulation of thyroid cells by TSH Cretinism Severest form of IDD Congenital, severe, irreversible mental & growth retardation Arises if the fetus suffers from I deficiency

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