Transcript Minerals
© PDST Home Economics Major mineral Calcium (Ca) Trace mineral Iron (Fe) Phosphorus (P) Chlorine (Cl) Sodium (Na) Potassium (K) Zinc (Zn) Copper (Cu) Manganese (Mn) Fluorine (F) Magnesium (Mg) Iodine (I) Chromium (Cr) Cobalt (Co) Selenium (Se) Iron is an important mineral Deficiency in iron is the most common mineral deficiency in humans Iron is present in haemoglobin in the blood, myoglobin in the muscles, enzyme systems in the body cells, and is also stored in the liver, spleen and bone marrow Functions Effects of deficiency Sources RDA (mg/day) •Iron is necessary for the formation of haemoglobin, which carries oxygen around the body •Iron deficiency causes haemoglobin levels to fall, which means that there is not enough oxygen going to the body tissues • Children 10 •Adolescents 13-14 •Adults: Males 10, f females 14 •Pregnant or lactating women 15 •Its forms part of myoglobin which carries oxygen to the muscles •It 1. 2. 3. 4. •Meat •Meat products •Chicken •Cereals •Eggs •Pulses •Green Vegetables •Fish •It is an important part of enzyme systems that use oxygen to release energy from food • can lead to: Tiredness Paleness Breathlessness Anaemia Anaemia is a common condition in Ireland especially women Definition & Cause: Anaemia is a disease caused by a shortage of haemoglobin, as a result of insufficient iron in the diet, or an inability to absorb iron It is more common in females due to menstruation Symptoms: Tiredness, dizziness, headaches, paleness, shortness of breath & loss of appetite Haem iron • This is ferrous iron • Its chemical symbol is Fe²+ • It is soluble & easily absorbed •Sources of haem iron include meat, meat products, chicken Non-haem iron • This is a ferric iron •Its chemical symbol is Fe²+ •It cannot be absorbed in the body & must be changed into ferrous iron to be absorbed •Sources of non-haem iron include cereals, eggs, pulses, green vegetables, fish Factors aiding iron absorption Eating haem iron (because it is more easily absorbed than non-haem iron) Eating non-haem and haem iron together increases non-haem iron absorption Vitamin C is a reducing agent, as it changes ferric iron (Fe³+) to the more easily absorbable ferrous iron (Fe²+) Hydrochloric acid in the stomach aids absorption by changing non-haem iron to haem iron Factors hindering iron absorption Phytic acid, in cereals and legumes, binds to iron, decreasing its absorption A dietary fibre intake above 35g per day has a tendency to bind iron, decreasing its absorption Oxalic acid, which is found in some fruit and vegetables (rhubarb & spinach), combines with iron, inhibiting its absorption Tannins in tea, coffee & cocoa decrease iron absorption. 99% of calcium in the human body is present in human bones Functions Effects of Deficiency Sources RDA mg/day •Calcium plays a major •Rickets •Dairy products, •Children It is also found in the blood, muscles and nerves role in the formation & •Osteomalacia in e.g. Milk, 800 development of bones & adults cheese, eggs •Adolescents teeth •Osteoporosis in the •Dark green 1200 •Calcium is important in elderly vegetables e.g. •Adults 800 blood clotting Spinach, •Pregnant/ •Calcium is necessary for •Tooth decay •Poor blood clotting cabbage lactating muscle contractions, •Failure of the •Canned fish, women 1200 normal functioning of nerves & membrane muscles to relax e.g. Salmon permeability (muscular spasms) •Fortified Flour •Calcium is required to •Hard water regulate metabolism in the cells 10 Factors aiding calcium absorption Vitamin D which stimulates calcium binding protein & increases absorption Parathormone is a hormone that controls the level of calcium in the blood (It is produced by the parathyroid gland) Amino acids combine with the calcium salts, which are absorbed easily Phosphorus combines with calcium to form calcium phosphate An acid environment helps calcium absorption (eating vitamin C with calcium rich foods) Approx. 20% of Calcium intake is absorbed in the small intestine where it is bound to a specific carrier protein Factors hindering calcium absorption Phytic acid, present in cereals and grains binds to calcium, preventing its absorption Oxalic acid, present in rhubarb & spinach, binds to the calcium, preventing its absorption Fibre binds to calcium, preventing its absorption Excess saturated fat forms insoluble soaps with calcium, preventing its absorption Overconsumption of soft drinks An incorrect calcium/phosphorus ratio Levels of oestrogen in postmenopausal women play a major role in the absorption of calcium Tannins in tea Zinc Function •Reinforces the immune system •Protects against infection •Needed for: The metabolism of carbohydrate and protein The production of male sperm and female ova The formation of bone tissue and healing wounds Sources •Zinc from animal foods, such as meat, liver, eggs, poultry and milk, is more readily absorbed than zinc from plant foods •Seafood, wheat germs, nuts, pulses, bread Zinc Effects of deficiency •Deficiency is found in those whose diet is high in refined cereals, and whose intake of animal protein is low. Deficiency can cause: Skin problems General tiredness Hair loss Prolonged healing of wounds RDA •Zinc is not stored in the body so a daily intake is required 4 – 7 mg for children 7 – 9 mg for adolescents 7 – 10 mg for adults Iodine Function •Very important as it is a part of the thyroid hormone thyroxine, which is essential for normal growth and physical and mental development •Also involved in maintaining metabolic rate Sources •Fish, meat, milk, table salt Effects of deficiency •Deficiency is rare in the Western world but it may cause: Goitre Cretinism Increased incidence of miscarriage and still births RDA •150 g for adults, 90 g for children Potassium Function •Vital for the correct functioning of the heart muscles and nerves •Helps protein metabolism Sources •Found in nearly all foods including green veg, wholemeal products, pork, fruit (especially bananas), fruit juices, dairy products and grains Effects of deficiency •Deficiency is rare but it may cause: Diarrhoea, excessive sweating, fatique, bloating, insomnia RDA •As potassium is stored in the fluids of the body cells, it is excreted, therefore a daily intake is essential 3 g for children, 3.5 g for adults Sodium Function •Needed to regulate body fluids •Needed for energy release •Needed for proper functioning of nerves and muscle contraction Sources •Smoked fish, soy sauce, ham, bacon, olives, processed foods and table salt Effects of deficiency •As sodium is found in small amounts in many foods and is particularly high in processed foods, most people have a higher sodium intake than they need. High sodium intake has been linked to high blood pressure and strokes RDA •RDA met by a high intake of processed foods Vitamin Relationship with Minerals 1. Vitamin D •Works in the absorption of calcium & phosphorus 2. Vitamin K •Works with calcium in clotting blood 3. Vitamin C •Works in the absorption of iron & calcium 4. Vitamin B6, B12, Folic Acid •Works with iron in the formation of red blood cells Water (H2O) •Water is essential for life •Two-thirds of our body is made up of water •Water is the main component of blood, lymph and digestive secretions, as well as all other liquid parts of the body •It is made up of hydrogen and oxygen molecules in the ratio 2:1 Water Properties •Colourless, odourless and tasteless liquid •Boils at 100°C and freezes at 0°C •Neutral PH of 7 •Excellent solvent capable of dissolving a number of substances •Exists in three states: solid (ice), liquid (water), and gas (steam) •Able to absorb heat and maintain it Sources •Tap/ bottled water •Beverages such as tea and coffee •Fruit and vegetables •All foods contain a certain amount of water Water Functions •Transporting nutrients, oxygen, enzymes and hormones around the body •Removal of waste products from the body, e.g. from the kidneys •Quenches thirst •Contains the minerals calcium and fluorine •Controls body temperature through perspiration •Significant in the hydrolysis of nutrients during digestion •Essential element of all body fluids and tissues RDA •Between 2 and 3 litres per day