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Micronutrients. Extension. Learning objectives. To understand the importance of micronutrients. To recognise the difference between water soluble and fat soluble vitamins, major minerals and trace minerals. To know the sources and functions of the micronutrients.
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Micronutrients Extension
Learning objectives • To understand the importance of micronutrients. • To recognise the difference between water soluble and fat soluble vitamins, major minerals and trace minerals. • To know the sources and functions of the micronutrients. • To know the problems caused by malnutrition. • To understand some interactions between nutrients.
Micronutrients Micronutrients are needed in much smaller amounts than the macronutrients. In general vitamins are needed to regulate the maintenance and growth of the body, and to control metabolic reactions in cells. Most vitamins are provided to the body by the diet, however, the body can make vitamin D, vitamin K and niacin.
Vitamin A (retinol, carotene) Vitamin A is needed for vision in dim light, healthy skin and eyes and for growth. This fat soluble vitamin and protects against cancer. Found in two forms, retinol in foods from animal sources and carotenoids from plant sources. Vitamin A – retinol is found in liver, whole milk, Vitamin A – carotenoids are found in dark green leafy vegetables, carrots and orange coloured fruits.
Too much or too little? Deficiency leads to poor vision in dim light or night blindness. In severe deficiency it can lead to total blindness. Vitamin A is stored in the liver and too much vitamin A can be toxic. Consuming too much vitamin A whilst being pregnant has been linked with birth defects.
Vitamin D (Cholecalciferol) Vitamin D is needed for the growth and maintenance of healthy bones and teeth and to help calcium and phosphorous absorption. Vitamin D is found in the diet as well as being made by the action of ultra violet rays on the skin. Vitamin D occurs naturally in some animal products, including fish liver oils, oily fish, egg yolk, butter and meat. Margarine and low fat spreads are also fortified with vitamin D.
Vitamin D deficiency Deficiency in vitamin D leads to rickets and the formation of soft bones. Bones in the legs may bend due to body weight. Osteomalacia may also occur in the elderly, as pain and muscular weakness. Vitamin D can be stored by the body and so too much will result in the body absorbing too much calcium. Young children, the housebound elderly, and people in religions who cover themselves, may be at risk of deficiency.
Vitamin E (Tocopherol) Vitamin E is a group of similar molecules with common properties and functions. The exact functions are not clear, but it is suggested that they protects against heart disease and also help cell membrane maintenance. Vitamin E is mainly found in vegetable oils, wheat germ, eggs, liver, meat, oatmeal and margarine and low fat spreads.
Deficiency and excess of vitamin E A deficiency in this vitamin is rare because it is so widely available in the diet. In very rare cases neurological disabilities such as lost reflexes have developed. There are no recorded adverse reactions to large doses of vitamin E.
Vitamin K Vitamin K helps blood to clot and build strong bones. Infants are given vitamin K at birth. Vitamin K is also produced by the bacteria in the gut. Vitamin K is found in fresh green vegetables e.g. broccoli, lettuce, cabbage, spinach and beef liver.
Too much or too little? Deficiency of vitamin K is rare in adults, but is sometimes seen in new born babies.
Thiamin (B1) Thiamin is needed for the release of energy from carbohydrates. Thiamin cannot be stored in the body, so it is necessary to obtain this from the diet. Thiamin is mainly found in whole wheat, bran, pork, milk, and fortified breakfast cereals.
Thiamin deficiency Thiamin deficiency can lead to the development of the condition called Beri-beri. This leads to symptoms such as fatigue, weakness of the legs and anorexia. Alcohol can prevent absorption of this vitamin causing Wernick-Korsakoff syndrome (a neurological disorder characterised by numb limbs, confusion, vision changes and lack of coordination).
Riboflavin (B2) Riboflavin is needed for normal growth and the release of energy from protein, carbohydrates and fat. Riboflavin is found in liver, milk, cheese, eggs, some green vegetables, and yeast.
Too much or too little? The body is not dependent on diet for this nutrient as it can produce it. It also can be stored in the body in the liver, spleen and kidneys. The tongue, lips and skin become affected when the body is low in riboflavin. Over nutrition of this vitamin is rare.
Niacin (B3) Niacin is important for releasing energy from carbohydrate. Niacin also maintains the health of the nervous and digestive system. Niacin can be found in cereals, yeast, meat, fish, eggs, and milk.
Too much or too little? A deficiency in niacin can lead to pellagra including the development of: Dermatitis; Dementia; Diarrhoea. Over nutrition is rare.
Folate Folate describes a group of molecules with common properties and functions. Folic acid is the most stable form of folate. It is important for the formation of healthy red blood cells and can reduce the risk of neural tube defects in a fetus, e.g. spina bifida. Good sources of folate include, liver, yeast extract, and green leafy vegetables.
Deficiency of folate Deficiency of folate can lead to megaloblastic anaemia – where the red blood cells become enlarged. Women planning on becoming pregnant are recommended to increase their intake of folate to prevent neural tube defects in the fetus. It is recommended that these women take a supplement because it is difficult to achieve such high levels of folate through diet alone.
Vitamin B12 Vitamin B12 is needed for the formation of red blood cells and synthesising fatty acids in the myelin of nerve tissue. Vitamin B12 is found in animal sources only. Good food sources are eggs, milk and meat.
Deficiency of vitamin B12 Deficiency of vitamin B12 can lead to megaloblastic anaemia. It can also lead to some neurological problems. Vegetarians and vegans are often at risk of malnutrition.
Vitamin C (Ascorbic acid) Ascorbic acid is needed for the production of a protein called collagen which helps bones to grow and wounds to heal. It also acts as an antioxidant that protects the body from free radicals. Sources of ascorbic acid include strawberries, citrus fruits, tomatoes and vegetables including cabbage, cauliflower, and broccoli.
Too much or too little? Scurvy can result from lack of vitamin C. It tends to occur in infants and the elderly. Scurvy leads to spots on the skin, bleeding gums and loose or loss of teeth. Over nutrition of ascorbic acid is rare.
Minerals Minerals are inorganic substances needed by the body for many different functions. These are needed in different amounts in large (major minerals) and small (trace minerals) amounts.
Calcium (Ca) Calcium is for building strong bones and teeth, blood clotting and muscle contraction. Sources of calcium can be found in milk, cheese and other dairy products, green leafy vegetables, soft edible bones in fish, calcium enriched soya bean products.
Too much or too little? Rickets (develops in children) and Osteomalcacia (develops in adults) may both develop, but this will not be due to calcium deficiency alone. Tetany may also develop, where muscles contract rigidly. Too much calcium can lead to deposits in the body, eventually causing to death.
Sodium (Na) Sodium helps to regulate body water content and electrolyte balance, and is involved in energy utilisation and nerve function. Sodium is present in very small amounts in raw foods. It is often added as salt during processing, preparation, preservation and serving. High salt processed foods are bacon, cheese, yeast extract and smoked fish.
Too much or too little? Consuming too much sodium can lead to hardening of the artery walls and high blood pressure or hypertension. Consuming too little sodium can be caused by excessive vomiting, diarrhoea and is accompanied by a loss of water from the body.
Iron (Fe) Iron is needed for needed for the formation of haemoglobin in red blood cells which transport oxygen around the body. It is also required for normal metabolism and for removing substances from the body. The immune system also requires iron. Haem iron is present in animal sources (including eggs) in the form of haemoglobin. Non haem iron is present in plant sources such as beans, nuts, dried fruits, wholegrains, soya bean flour and dark green leafy vegetables.
Too much or too little? A lack of iron will lead to anaemia. The symptoms of this are: • Feeling tiredness; • Lacking in energy; • General weakness; • poor concentration. Too much iron in the diet will lead to constipation, nausea and vomiting.
Potassium (K) Potassium is found in body fluids and is essential for water and electrolyte balance and proper functioning of cells, including nerves. It is needed for clotting of the blood, after injury. Potassium is present in all foods, but found richly in fruit (dried fruits, bananas, berry fruits), leafy green vegetables (e.g. broccoli and spinach) and milk.
Phosphorus (P) Phosphorus is essential for the structure bones and teeth, for the structure of cell membranes and for energy metabolism. Phosphorus is found in all foods.
Fluoride (F) Fluoride hardens tooth enamel and ensures bones have correct amounts of minerals deposited in them. This is a trace element, therefore only a small amount of this mineral is required for good health. Fluoride can be found in drinking water, small amounts in tea and saltwater fish. Some areas choose to have fluoride added to the drinking water.
Too much or too little? Excess fluoride in the diet can lead to mottling or discolouration of teeth.
Nutrient interactions Some nutrients work together in the body completing different functions. For example: • The vitamins A,C and E; • Calcium phosphorus and fluoride; • Iron and vitamin C; • Carbohydrates and B vitamins.
Anti-oxidants Vitamins A, C and E all create anti-oxidant activities in the body. These work on protecting the body from free radicals. Free radicals are atoms or groups of atoms with an unpaired or spare electron. Cells within the body may function poorly or cease to function as a result of free radicals acting on the DNA structure of cells.
Calcium, phosphorus and fluoride Together, these nutrients help teeth and bones harden. Vitamin D controls the amount of calcium available. Less vitamin D means less available calcium.
Iron and Vitamin C Vitamin C will increase the body’s absorption of non haem iron (non meat sources of iron). This is particularly important for vegetarians and vegans.
Carbohydrates and Vitamins B For the body to use the energy contained in carbohydrates there are two B vitamins that help in the production of energy. These are: Riboflavin; Thiamin.
Review of the learning objectives • To understand the importance of micronutrients. • To recognise the difference between water soluble and fat soluble vitamins, major minerals and trace minerals. • To know the sources and functions of the micronutrients. • To know the problems caused by malnutrition. • To understand some interactions between nutrients.
