Food and Diet Nutrients
Nutrients Carbohydrates Water Fats Minerals Proteins Vitamins
Composition of Carbohydrates • Come from plant foods • Cheapest and most plentiful of all nutrients • Foods which contain carbohydrates, are called energy foods • All of the energy obtained from food starts with a single sugar unit - glucose. Some plants store energy for later use by combining sugars to make starch.
Classification of Carbohydrates • Sugar • Starch • Cellulose • Pectin
Carbohydrates - Sugar • Sugars arefound in honey, fruit (both fresh and dried) soft drinks, milk and sugar.
Carbohydrates - Starch • Starches arefound in cereals, pasta, flour, bread, potatoes, root and pulse vegetables.
Carbohydrates – Cellulose / Fibre • Cellulose or Dietary Fibre isfound in • whole cereals • wholemeal bread • outer skins of fruit and vegetables • brown rice • Oatmeal • In refined foods the dietary fibre is removed during processing e.g. wholemeal flour contains fibre but white flour does not.
Carbohydrates - Pectin • Pectin is found in ripe fruit
Functions of Carbohydrates • Carbohydrates provides the body with heat and energy • Fibre helps the movement of food through the intestine. • Fibre rich and starchy foods provide a "full feeling“ • Pectin helps jam to set
RDA • Nutritionists believe that the amount of sugar eaten in the western countries needs to be decreased and the amount of fibre needs to be increased. • The Recommended Dietary Allowance (RDA) of fibre is now 30g per day. We in the western world eat about half the recommended amount-15g per day.
Fats • Fat is an important nutrient because it gives us energy • The body stores energy as a layer of fat under the skin. This is called adipose tissue
Composition of Fats • Fats are made from glycerol and fatty acids • Each glycerol is attached to three fatty acids • Glycerol and fatty acids contain the elements carbon, hydrogen, and oxygen • Fats contain a lot of carbon. This is why they give us so much energy. • 1 gram of fat gives us 9 kilocalories
Classification of Fats Fats are classified into two groups: • Saturated Fats come mainly from an animal source such as meat, eggs, milk and dairy produce e.g. cream and butter. There is a lot of saturated fat in butter and lard • Unsaturated Fats come mainly from plant and fish sources such as peas, beans and lentils, whole cereals, nuts, cooking oil, polyunsaturated margarine and oily fish
Functions of Fats • Fat insulates the body. A layer of fat under the skin prevents heat loss from the body. • Fat protects the delicate organs such as the kidneys and nerves. A layer of fat surrounds them. • Fats provide the body with heat and energy. This helps to keep the body at the correct temperature (37o C). • Fat is a source of the fat-soluble vitamins
RDA of Fats • It is recommended that we eat 50% saturated fat and 50% unsaturated fat in our diet • People in the western world eat too much saturated fat and it is recommended that we cut down on our intake • We should also increase our intake of unsaturated fats
To cut down on Saturated Fats • Grill rather than fry. • Use vegetable oil instead of hard fats for frying. • Remove visible fat from meat. • Look for hidden fats in the diet e.g. pastries and crisps. • Use low fat milk, cheese, yoghurt and mayonnaise
Protein • Our bodies are made up of billions of cells, which contain protein • Throughout our lives cells wear out and are replaced • All the material for new cells comes from food • The main nutrient involved in the building of new cells and replacing of worn cells is protein
Composition of Proteins • Proteins are made up of small units called amino acids • The amino acids, which the body cannot make, are known as essential amino acids • Adults need 8 and children need 10 essential amino acids.
Composition of Proteins • Proteins are broken down into amino acids in the digestive system • Amino acids are smallest units of Protein. They can then be used to build up different proteins for the formation of new cells in the body • Amino acids are made up of the elements carbon, hydrogen, oxygen and nitrogen
Classification of Proteins Classified into two groups: HBV and LBV • High Biological Value Proteins come mainly from animal foods such as meat, fish, eggs, cheese and milk • Low Biological Value Proteins come mainly from plant foods such as peas, beans and lentils, whole cereals and nuts. These foods also contain fibre and are low in fat
Functions of Proteins The functions of proteins are: • Growth of new cells such as skin hair and blood. • Repair of damaged cells. • Production of heat and energy. • Manufacture of important body chemicals such as enzymes, hormones and antibodies.
RDA of Proteins • The RDA of protein depends on your body weight • For every kilogram of body weight one gram of protein per day is needed, e.g. if you weigh 60 kg you need 60 g of protein per day
Vitamins • The word "vitamin" comes from vita, the Latin for "life“ • Everybody must eat a certain amount of vitamins to stay healthy • Vitamins are chemicals found in very small amounts in many different foods. Tiny quantities are enough for the needs of the body • If people live on a very limited range of foods they may not get their proper share of vitamins
Classification of Vitamins • Vitamins, of which there are 14, are classified into two main groups: Water soluble and Fat soluble • Fat soluble – stored in bodies fat tissue • A, D, E & K • Water soluble – not stored in the body • B vitamins, folic acid & vitamin C
Vitamins • Fat soluble: • Vitamin A - needed for healthy vision, bone growth, reproduction and the immune system • found in dark green, orange and yellow vegetables, such as spinach, carrots, broccoli, mangos, apricots, vegetable soup and tomato juice.It is also found in meat and dairy products such as liver, beef, chicken, whole milk and eggs.
Vitamins • Fat soluble: • Vitamin D - controls the absorption of calcium and phosphorus, which are essential for bone growth and development • sardines and tuna, liver, egg yolks, some breakfast cereals and vitamin D-fortified milk. Vitamin D can also be made when the skin is exposed to sunlight
Vitamins Water soluble: • Vitamin C - helps to maintain skin integrity, absorb iron from the gut and heal wounds, and is important in immune functions • Vitamin C is found in citrus fruit and juices, tomatoes, spinach, potatoes, berries, green and red peppers, and broccoli
Vitamins Water soluble: • Folate (folic acid), also called vitamin B9 is essential for the normal formation of the red blood cells, protein metabolism, growth and cell division • Food sources include liver, citrus juices and fruits, beans, nuts, seeds, liver, dark green leafy vegetables.
Minerals • The human body requires about 20 mineral elements • Each has a specific function and is found in certain foods • A good varied diet should supply all essential minerals • Some minerals are described as trace elements because the are required in smaller amounts • Minerals are lost into the water during cooking
Macrominerals • Calcium - for muscle and digestive system health, builds bone, neutralizes acidity, clears toxins, helps blood stream • Found in milk, cheese, green leafy vegetables • Potassium – for growth of lean tissue • Found in bananas • Sodium – regulation of water balance in the blood • Found in table salt, bacon, snack foods • Sulfur • Magnesium • Phosphorus
Trace Minerals • Iodine – Needed for the formation of thyroxine, a hormone in the thyroid gland which controls metabolism • Found in vegetables and sea fish • Iron – Needed to make red blood cells • Found in red meat, liver & cabbage • Manganese – Processing of oxygen • Zinc • Cobalt • Copper
Water • Water is absolutely essential to life. Over 70% of the human body is made up of water. It is found in: • Muscles • Saliva • Blood • Digestive Juices • Mucus • Sweat
Composition of Water • Water contains the elements hydrogen and oxygen • They are present in the ratio 2:1, two parts hydrogen to one part oxygen • Pure water freezes at 0C and boils at 100C
Sources of Water • The main sources of water are drinking water and beverages like tea, coffee and alcoholic drinks • Water is also present in many other foods like meat and fish • Fruits and green vegetables are high in water. Almost all foods contain water, except those with a high fat content (butter), and dry foods (sugar and flour)
Functions of Water • It is the chief component of all body fluids. • It helps dissolve foods and aids digestion. • It helps remove waste material from the body. • It regulates body temperature by perspiration. • It is a source of dissolved minerals such as flourine and calcium. • It keeps the body fluids liquid so that they may flow easily.
RDA of Water • As 2-2.5 litres of water are lost daily by excretion, and perspiration, an equal amount is required daily by the body to avoid dehydration • 1.5 litres of water is obtained from beverages and 0.8 from food.