Describe the components of a balanced diet.
P6 – Sports Nutrition P6 - Describe the components of a balanced diet. Carbohydrates Carbohydrates are a main source of energy; they are the body's fuel. Most of a balanced diet should be made from carbohydrates. If eaten in an excess of the dietary requirements carbohydrates are easily stored as fats in the cells. Sources of carbohydrates such as starch are rice, potatoes, wheat and other cereals. Sugars are also carbohydrates, sources of sugars are refined sugar - sucrose, which is a food sweetener and preservative and fruit sugars - fructose. If the diet lacks carbohydrate stores of fat are mobilised and used as an energy source. Proteins Protein is not a direct source of energy in the body, it is used primarily for growth and repair of body tissues although can be used as an energy source as a last resort. Proteins fulfil a wide variety of roles in the body they are broken down in the stomach and intestines to amino acids which are then absorbed. The body can only form 8 amino acids to build proteins from the diet must provide Essential Amino Acids (EAA’s) which are synthesised into proteins which can be structural. Sources of protein include meat, fish, eggs and pulses. The diet needs to provide 8 EAA’s as the body is unable to synthesis proteins without these molecules. Cells draw upon a pool of amino acids for protein synthesis which either come from dietary protein digested and absorbed in the gut and the breakdown of body protein such as muscle. However, unlike fats and carbohydrates there is no store of amino acids for cells to draw on, any amino acid in excess of immediate bodily requirements is broken down into urea and excreted. It is therefore important to maintain the dietary intake of protein everyday. If the body lacks protein, muscle wasting occurs as muscle is broken down. Vitamins Vitamins cannot
be synthesised by the body so must be supplied by diet. Vitamins have no common structure or function but are essential in small amounts for the body to be able to utilise other dietary components efficiently. Vitamins fall into two categories, fat soluble vitamins such as vitamin A, D, E and K which are ingested with fatty foods and water soluble vitamins such as the B group vitamins and vitamin C. Vitamins are known as micronutrients because only small quantities are required for a healthy diet. Water soluble vitamins such as vitamin C and B groups vitamins can be excreted ...
This is a preview of the whole essay
be synthesised by the body so must be supplied by diet. Vitamins have no common structure or function but are essential in small amounts for the body to be able to utilise other dietary components efficiently. Vitamins fall into two categories, fat soluble vitamins such as vitamin A, D, E and K which are ingested with fatty foods and water soluble vitamins such as the B group vitamins and vitamin C. Vitamins are known as micronutrients because only small quantities are required for a healthy diet. Water soluble vitamins such as vitamin C and B groups vitamins can be excreted in the urine if in excess in the diet. Vitamins carry out a wide range of functions and prevent specific deficiency diseases. A diet that lacks a certain vitamin is not a balanced diet vitamins have vital roles in the maintenance of a healthy body. Vitamin A is found in some animal foods such as milk, eggs, liver and fish. A lack of vitamin A results in dry, rough skin, inflammation of the eyes, a drying or scarring of the cornea. Vitamin D is another fat soluble steroid vitamin which functions to stimulate calcium uptake from the gut and its deposition in bone. Vitamin D acts as a hormone when converted by enzymes in the gut and liver into an active form "active vitamin D", which stimulates epithelial cells in the intestine to absorb calcium. Vitamin D is therefore essential in growing children's diets to enable the growth of strong bones. Without the right amounts of vitamin D children can develop rickets which is the deformation of the legs caused when they lack calcium to strengthen the bones. In adults a lack of vitamin D in the diet can lead to osteomalacia, a progressive softening of the bones which can make them highly at risk to fracture. Vitamin D is made by the body when exposed to sunlight and is stored in the muscles however if the skin is rarely exposed to the sunlight or is dark little vitamin D is produced. Foods such as eggs and oily fish are all rich in vitamin D. Vitamin K is found in dark green leafy vegetables such as spinach and kale. It is a fat soluble vitamin which is involved in the clotting process of blood. In the intestines bacteria synthesise a number of important clotting factors which need vitamin K. Without vitamin K cuts can fail to heal and internal bleeding can occur. Vitamin C is a water soluble vitamin. It is found in citrus fruits such as oranges and lemons and also in potatoes and tomatoes. The main function of vitamin C is the formation of connective tissues such as collagen. B group vitamins have a wide range of roles acting as co-enzymes in metabolic pathways. They are found in most plant and animal tissues involved in metabolism therefore foods such as liver and dairy products are all rich in B group vitamins.Minerals Some minerals are considered to be macronutrients as they are required in fairly large amounts in the diet to maintain a healthy body. Minerals are required in their ionic state in the diet. Calcium is a major component of bones and teeth and is required to keep bones strong. It is required in blood clotting as an activator of various plasma proteins and is also involved in muscle contraction. A good source of calcium is in dairy products, eggs and green vegetables. Chlorine is required to maintain the osmotic anion / cation balance of the body and the formation of HCl in the stomach. It is found in table salt and is rarely deficient in the diet as it is used as a preservative to many foods. Sodium is also found in table salt as well as dairy foods, meat, eggs and vegetables. Sodium is used in conjunction with chlorine in the maintenance of the osmotic anion / cation balance. It is also needed in nerve conduction and muscle action. Potassium is yet another mineral required in nerve and muscle action it also has a role in protein synthesis. It is found in meat, fruit and vegetables. Phosphorus, in the form of phosphate, PO43- is a constituent of nucleic acids, ATP, phospholipids in cell membranes, bones and teeth. It is present in dairy foods, eggs, meat and vegetables. Magnesium, Mg2+, is an important component of bones and teeth and is also an enzyme activator. It is found in meats and green vegetables. Micronutrients are minerals needed in trace quantities. Despite the small quantity required, they are still essential to a healthy balanced diet. Iron, in the forms of Fe2+ and Fe3+, are required in the formation of haemoglobin and myoglobin. Iron is a constituent of many enzymes as a prosthetic group and also as an electron carrier in mitochondria. Red meat, liver and green vegetables are all sources of iron. Iron supplements are taken by people who suffer from anaemia. Iodine, I-, is a component of the growth hormone thyroxine. A lack of iodine in the diet can cause hypothyroidism which results in weight gain and in extreme cases a lack of physical and mental development known as cretinism. A swelling of the neck can occur which is called goitre if iodine is deficient in the diet. Iodine can be found in seafood such as shellfish, seaweed and fish. Iodine has also been added to water supplies in areas where it is deficient in the main water system. Copper manganese and cobalt are all needed in the diet to form co-factors for enzymes. Copper is also needed for bone and haemoglobin formation and cobalt is needed for the production of red blood cells, manganese is also a growth factor in bone development. They are found in meat and liver as well as some dairy products. Fibre Fibre is not digested by the body but is involved in maintaining the health of the gut and is therefore an essential part of a balanced diet. Fibre is mostly made up of cellulose and is indigestible as the stomach and gut do not contain the correct enzymes. Fibre aids prevent constipation. It also aids the peristaltic movement in the intestine and has been linked to the prevention of bowel cancer. Fibre also removes some saturated fats and cholesterol therefore protecting the body a little from the build up of plaques in blood vessels. Fruit, vegetables and cereals are a good source of dietary fibre. Water The diet must provide water which is required as a solvent. Water in fact makes up about 70% of the total body weight of humans. Water is needed as it is lost constantly from our bodies in urine, sweat and evaporation from lungs. An average person requires 2-3 litres of water a day which is supplied through drinks and liquid foods. Without water or food the longest anyone has ever survived is 17 days, however, with water the longest anyone has survived is 70 days, this illustrates the importance of water in the diet. As you can see a balanced diet is very important to maintaining a healthy body. People who choose to be vegetarians and vegans therefore must make sure that their diet contains all the correct nutrients to avoid any deficiencies that may occur as well as people living in countries where their diet lacks certain important food groups. A diet can easily be adequate without being a properly balanced diet and since everyone has different metabolic rates everyone's ideal diet is unique therefore generalised guidelines have been established to aid people in obtaining a good diet. Vitamins and minerals are required in small amounts to carry out a variety of essential specific functions fat and carbohydrates are the main fuel that the body runs on, whilst protein is needed in large amounts for growth and repair. The diet must also provide adequate quantities of essential fatty acids and amino acids which are required for the body to metabolise into proteins and are fundamental for health. Over eating of one food group is considered to be a form of malnutrition because the diet is not balanced. Ladien Cunningham