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A Balanced Diet.

Extracts from this essay...

Introduction

A Balanced Diet By Iram 6L A balanced diet A balanced diet is one that provides an adequate intake of energy and nutrients for maintenance of the body and therefore good health. A diet can easily be adequate for normal bodily functioning, yet may not be a balanced diet. An ideal human diet contains fat, protein, carbohydrates, vitamins, minerals, water and fibre all in correct proportions. These proportions vary for each individual because everyone has different metabolic rates and levels of activity. Malnutrition results from an unbalanced diet, this can be due to an excess of some dietary components and lack of other components, not just a complete lack of food. Too much of one component can be as much harm to the body as too little. Deficiency diseases occur when there is a lack of a specific nutrient, although some diet related disorders are a result of eating an excess. An adequate diet provides sufficient energy for the performance of metabolic work, although the energy food is in an unspecified form. A balanced diet provides all dietary requirements in the correct proportions. Ideally this would be 1/7 fat, 1/7 protein and 5/7 carbohydrate. Energy is provided by carbohydrates, fats and proteins. Proteins are a provider of energy in an emergency, but are primarily used as building blocks for growth and repair of many body tissues. These energy providing compounds are needed in large quantities in our diet so are described as macronutrients. We also need much smaller amounts of other nutrients, such as vitamins and minerals. Because much smaller quantities are needed for a balanced diet these are known as micronutrients. Despite the small quantities needed these are essential to provide a healthy diet as they have specific roles in metabolic reactions and as structural components. Within the cells of our body, the nutrients ingested are converted to other compounds which are then used for metabolism and other cellular reactions.

Middle

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. An example of a deficiency is when the diet does not contain enough, or any vitamin A. Vitamin A is found in some animal foods such as milk, eggs, liver and fish liver oils, related compounds such as carotenoids e.g. b carotene, are in a wide variety of vegetables such as cabbages, carrots and spinach. Vitamin A is essential to the proper functioning of the retina in the eye and the epithelial tissues. A lack of vitamin A results in dry, rough skin, inflammation of the eyes, a drying or scarring of the cornea - xerophthalmia, which occurs when the secretion of lubricating tears is stopped, the eyelids become swollen and sticky with pus. Mucous surfaces of the eye may become eroded allowing infection to set in, leading to ulceration and destruction of the cornea. Night blindness - an inability to see in dim light can also occur. Rod cells in the retina of the eye detect light of low intensity, they convert vitamin A into a pigment, rhodopsin, which is bleached when light enters the eye. Rod cells resynthesis rhodopsin, but if there is a deficiency of the vitamin, rod cells can no longer function and the result is night blindness. Epithelial cells use retinol to make retinoic acid, an intracellular messenger used in cell differentiation and growth. Without retinoic acid epithelial cells are not maintained properly and the body becomes susceptible to infections, particularly measles and infections of the respiratory system and gut. Xenophthalmia is common among children who's diets consist of mainly cereals with little meat or fresh vegetables, this is common in Indonesia, Bangladesh, India and the Philippines.

Conclusion

Fibre aids the formation of faeces, preventing 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, a transport medium, a substrate in hydrolytic reactions and for lubrication. 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, evaporation from lungs and in faeces. 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 imperative 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.

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