Diet plays an important part in general health. Food needs to provide the body with adequate amounts of the necessary nutrients. These nutrients are protein, carbohydrates, fats, fibre, vitamins, minerals and water.
Protein
Protein is needed by the body for growth and repair, and replacement of cells. It is made up of substances called amino acids. Protein in food is digested and broken down into individual amino acids. These are then absorbed into blood and used to build different proteins for blood tissues (for example, muscle, hair, skin, blood cells ). Most food contains some protein.
Foods from animals provide all amino acids required to make body proteins. These are known as complete protein foods (for example, meat, fish, cheese, eggs, milk). Plant foods may have one or more amino acids missing. These are known as incomplete protein foods (for example, cereal foods, bread, pulses, nuts). Proteins from plant foods can be combined to make complete proteins (for example, baked beans on toast).
Carbohydrates
Carbohydrates are the body's main source of energy. There are 2 main groups:
1. Starches - found in many foods (for
example, flour, grains, pasta
bread, pulses).
2. Sugars - found in many fruits and
some vegetables, as well as jams,
cakes and sweet drinks.
Fats
Fats are a concentrated source of energy, providing more calories than any other food. Certain foods which contain fat are important as they contain the essential vitamins A, D, E and K. The body is very efficient at converting food into energy and it rarely wastes anything. If the body gets too much food, it converts excess into fat and stores it. This can lead to a weight problem.
Some body fat is necessary as it cushions and protects organs like the liver and kidney, and helps to keep us warm. However, too much body fat can lead to health problems, so it may be necessary to reduce fat intake. Another problem is that if you eat a lot of saturated fat, the body is stimulated to produce extra cholesterol in the blood. This can have a serious effect on your health.
Cholesterol
Cholesterol is an odourless, white, fatty substance. It is made by the body and a certain amount is essential for health. Among other things, we need cholesterol for the formation and repair of body cells. It is a part of many of the key hormones produced in the body. It also helps digestion as an ingredient in the bile acids.
Problems begin when not all of the cholesterol is processed in beneficial ways. Excess cholesterol continues to circulate in the blood and may eventually be deposited in the walls of the arteries. Over years, a plaque forms on the interior walls of the arteries. As a result, the arteries become narrower and narrower. This is known as atherosclerosis or 'hardening of the arteries'.
A blood clot may form on the plaque, break free and enter the circulation system. If it blocks a blood vessel, it stops the blood flow. If this happens in a coronary artery, a coronary heart attack will result. Tissues in part of heart supplied by the blocked artery will die. If the clot blocks a blood vessel in the brain, a stroke will result. Preventive measures are the answer. You need to control your level of cholesterol. It may be necessary to introduce certain permanent changes in your diet...
There are 2 main types of cholesterol in blood:
1. Low density lipoprotein
cholesterol's (LDL) - these
encourage deposits on artery walls.
2. High density lipoprotein cholesterol's (HDL) - these have the opposite effect and can prevent deposits.
Therefore, it is best to have more HDL and less LDL in blood to counteract the hardening or furring up of arteries. The balance between HDL and LDL can be affected by diet. A diet, low in saturated fats, can reduce LDL Ð the harmful type of cholesterol. It is important to know which foods contain saturated fats and which ones contain unsaturated fats.
Saturated fats, or saturates, are those which are hard or solid at room temperature:
lard, dripping, suet, hard
margarine's
most meats, especially hard fat
round chops
sausages and pate
dairy products, milk, cream, cheese
and butter
some vegetable fats (for example,
coconut oil, palm oil)
cakes, biscuits, chocolates, sauces
and puddings
Sometimes, these fats are listed in the ingredients as hydrogenated vegetable fat or oil.
Unsaturated fats include polyunsaturated fats, or polyunsaturates, very soft/liquid at room temperature:
nuts and seeds (for example,
sunflower seeds)
sunflower oil
oily fish (for example, mackerel,
herring, trout)
some margarine and oil
Products which contain a high proportion of polyunsaturated fats are clearly labelled. Products high in polyunsaturates are also low in saturated fats.
For a healthy diet, choose skimmed or semi-skimmed milk, low fat natural yoghurt, low fat cheese, lean meat, poultry or fish.
Cholesterol is a major contributor to the poor condition of many people's arteries and heart. Arteriosclerosis and its consequence, coronary heart disease, is responsible for the deaths of 550,000 Americans each year according to the National Institute of Health. 5,400,000 Americans have symptoms of coronary heart disease.
Also a large, but undetermined number of others, have arteriosclerotic disease at present undiagnosed. Therefore, it is vital to be aware of the content of your diet and control your intake of saturated fats. To get the maximum benefit, it is wise to have your body's cholesterol levels checked and evaluated regularly.
Fibre
Essential for the healthy functioning of the digestive system. It's a form of carbohydrate found naturally in cell walls of plants and is the substance which gives structural support, without which, plants wouldn't be able to stand upright. There are 2 groups of fibre: soluble and insoluble. Most fibre rich foods contain a mixture of both.
Insoluble fibre is important in helping the passage of foods through the body. It absorbs water causing the fibre to swell. This makes us feel full and stimulates the digestive system. It increases rate at which food passes through intestines. It removes toxic substances from the body at the same time. It's valuable in helping prevent constipation, haemorrhoids (piles), varicose veins, bowel cancer and appendicitis. Found mainly in wheat products like flour, bread, breakfast cereals and bran. Also in fibrous fruit and vegetables such as carrots.
Soluble fibre performs a different role. It slows the absorption of nutrients from food. It does this by forming a gel which results in food passing through the body more slowly. By delaying the uptake of sugar by blood, it allows a moderate amount of sugar into the blood over an extended period. This is one of the ways, an almost continuous blood sugar level is maintained.
Therefore, soluble fibre is an important part of diet for people who have diabetes. The feeling of hunger is associated with a low blood sugar level, so soluble fibre can delay the onset of hunger. Another important function is that it can bind with cholesterol from food and assist in its elimination from the body.
In this way it can help people at risk of developing coronary heart disease because of high levels of blood cholesterol. It's found in most fruits and vegetables. The richest sources are pulses like red kidney beans, baked beans, dried peas and lentils. Also products containing oats, barley or rye, such as porridge and rye bread.
The fibre values of foods are often reduced by cooking, processing or refining. For example, at an early stage in the milling of white flour, the outer bran coating is removed. This takes away some of the natural fibre from the grain; this would remain in wholegrain or wholemeal flour.
The cooking of fruit and vegetables may also reduce the fibre content. This happens when an apple is converted into apple sauce. The fibrous structure is further broken down if the apples are pressed to produce apple juice.
The fibre in your diet should be increased gradually. If this is done too quickly you may suffer physical discomfort, such as stomach ache. Also, it is important to drink plenty of fluid when eating more fibre.
Food Additives
Substances which are added to food in order to preserve it and affect its appearance, texture, taste, smell and so on. Some food additives are natural, such as salt and spices. Others are manufactured chemicals. Example categories of additives are: preservatives, anti-oxidants, emulsifiers, stabilisers and colourings.
Preservatives
They stop microbes from spoiling food or making it unsafe. Microbes such as moulds, yeast's and bacteria are present in small, harmless quantities in or on fresh food. In time they multiply. This affects food in various ways. As the microbes feed, they break down the food, making it taste and smell bad. Fruit juice becomes fizzy when yeast's in the air get into it and breed.
Bread becomes mouldy and slowly disintegrates. Microbes can be dangerous in large quantities as they and/or their waste products are poisonous.
Preserving food will kill microbes or slow down their activity. This means food will keep longer and there is less waste. This leads to many practical benefits, shops can keep some foods longer, meaning lower prices for the consumer. Foods are available out of season and can be safely imported from abroad. Preservatives are therefore important for both health and practical reasons.
Anti-oxidants
Any food prepared with fats or oils, such as butter or salad cream, is likely to contain an anti-oxidant. Anti-oxidants stop fats and oils from combining with oxygen and becoming rancid, that is having an unpleasant smell and taste. Vitamin E and vitamin C are examples of anti-oxidants.
Emulsifiers
These mix together ingredients that would normally separate (for example, oil and water). Stabilisers prevent them from separating again. Both are useful in making low-fat table spreads. They have many other uses in both sweet and savoury foods.
One sort of emulsifier stops sauces such as mayonnaise from separating, stabilisers are added to instant desserts and toppings making them foamy when mixed. There are also substances called polyphosphates which are added to cured ham and frozen poultry to keep them tender and juicy. On the whole, emulsifiers and stabilisers are natural substances or are chemically related to them.
Colouring
Colouring is added to some foods because they have lost their natural colour during processing. Other foods are coloured in order to make them appear to contain ingredients which they don't, or simply to make them look more attractive (for example, fizzy orange drink contains artificial colour and flavouring, but no oranges).
One of the commonest colourings is caramel, which is made by over-cooking or chemically changing sugar. Beta carotene is a colouring which can be extracted from carrots and is a form of vitamin A. Some colourings are artificially produced. No colourings are allowed in baby foods.
E number
Preservatives, anti-oxidants, colourings, emulsifiers and stabilisers are given E numbers. These are codes for these additives (for example, colouring caramel has E number of E150). They are standard throughout all food manufacturers in U.K. and European Union.
Enhancer
Flavour enhancers make existing flavours seem stronger. They can be used when flavour is lost during processing. The best known is monosodium glutamate. It can be made from seaweed, but usually from sugar beet or wheat. It stimulates taste buds and has been used by the Chinese for centuries. Salt is another flavour enhancer.
Sweeteners
The best known sweetener is probably saccharin. It contains almost no calories, as do other sweeteners, and so is put in diet drinks and low calorie foods. Sugar is a preservative as well as a sweetener in some foods, such as jam.
Caking
Anti-caking agents are added to some foods (for example, icing sugar, powdered milk), to stop them clogging up. Firming agents, made from a substance called pectin, are added to some fruit and vegetables during processing. This stops them going soft. Flour improvers and bleachers make stronger dough or whiten flour.
Nutrients
Some foods have nutrients added to them. Vitamins are added to white flour to replace those which are lost during processing. Vitamins are added to margarine and cereals in the making of breakfast foods. All additives are tested before they can be used and they must go through a long process of approval.
Vitamins
Vitamins help to ensure that all cells and organs of the body are functioning well. Our bodies only need them in small quantities. A balanced diet should provide all the vitamins required. Fresh fruit and vegetables are very good sources of vitamins. There are about 20 vitamins. The most important ones are:
Vitamin A
Helps fight infections. It keeps the cell walls strong, thereby preventing bacteria and viruses from entering the body. It is also good for the skin and helps us to see in dim light. Sources: liver, carrots, green vegetables, eggs, butter, margarine.
Vitamin B
Consists a group of substances, such as Riboflavin (B2) and Folic Acid (B12). They help breakdown carbohydrate, protein and fat to release energy, and help make blood and nerves healthy. Bodies can't store B vitamins, therefore daily supply is important. Sources: milk, meat, fish, fruit, vegetables, cereals, eggs, nuts, bread.
Vitamin C
Helps fight infections, assists the absorption of iron from food and keeps skin healthy. Bodies can't store vitamin C, therefore daily supply is important. Sources: fresh and frozen fruit and vegetables.
Vitamin D
Is made by the body when sunlight falls on the skin. We need it to help us absorb and use calcium and phosphorous for strong bones and healthy teeth. Sources: produced by the body, in liver, fish oil, eggs, butter and margarine.
Vitamin E
Helps to protect cells in the body. Sources: many foods, especially vegetable oils, eggs, green vegetables.
Vitamin K
Is necessary for the clotting of blood. Sources: produced by the body, also in green vegetables, liver.
Minerals
Minerals are necessary to keep the body's organs, bones and muscles functioning properly. A balanced diet usually provides all the necessary minerals. There are many different minerals needed, such as calcium, sodium, potassium, iron, zinc and iodine.
Calcium forms the structure of bones and teeth. A regular supply of calcium is vital because it is constantly needed by the body. Sources: milk, cheese, fish, beans, green vegetables.
Iron is needed for the formation of red blood cells, which help to carry oxygen around the body. Sources: meat, liver, vegetables, peas, beans, fruit.
Trace elements are minerals which you need in minute quantities. Examples are selenium, chromium and silicon. They perform a variety of functions and are found in a wide range of foods (deficiency is very rare).
Minerals such as potassium, magnesium, phosphorous and common salt (sodium chloride) are needed to keep the balance of chemicals in body cells at the correct level. These are found in many foods and there is little danger of deficiency.
Iodine, manganese and zinc are needed to control certain chemical reactions in the body. Iodine is found in fish, zinc comes from wholegrain cereals, peas, beans, lentils and meat. Manganese comes from wholegrain cereals, leafy vegetables and nuts.
Water
Water is essential to life (66% of the body is water). Each cell in the body contains water. You take in about 3.5 pints (2 litres) of water/day. Half comes from drinks and the rest from food which contains various amounts (for example, bread 39%, eggs 75%, carrots 90%, cucumber 99%).
Even dry food, like flour and cereals, contain some water. Every day you lose about 2 pints in urine and the rest in sweat and in your breath.
