The Role of Protein Proteins provide amino acids for growth and repair.
They can also be converted into glucose to be used for energy when there is a strict supply of carbohydrate and during starvation.
This is why restricting carbohydrate or following a high protein diet can be disadvantageous, as it might force the body to use protein for energy production, which is not its prime physiological role.
There are two types of protein - animal and vegetable.
Animal proteins, found in meat, fish, poultry, game, eggs, cheese and milk, have high biological value because they contain all the amino acids required for protein synthesis.
However, the nutritional advantage of animal foods over vegetable foods is in the presence of nutrients such as vitamin B12, Iron, Zinc and vitamin A than in protein content.
Because of the lack of storage facilities for excess amino acids in the body, they are most efficiently utilised if a complete assortment is supplied to the body at about the same time.
Eating a mixed diet at each meal and ensuring that the total energy content of the diet is adequate can achieve this.
Therefore, mixtures of vegetable protein foods such as beans on toast or of animal and vegetable foods such as fish and new potatoes, an egg sandwich and breakfast cereal with milk would have a sound physiological basis.
Plant protein e.
g.
legumes and lentils are generally low in or lack one or two of the essential amino acids.
As a result, it is referred to as low biological value protein.
The quality of a protein is judged by its ability to supply all the essential amino acids in the amounts needed for protein production, rather than its source.
Mixtures of such plant protein foods, however, complement each other and are of greater benefit, so that even amongst those who eat little or no animal protein, protein deficiency is rarely a problem (provided that they eat a variety of foods from all the main four food groups).
This is essential for those with a small appetite, during the period of rapid growth for children, during periods of physiological stress such as pregnancy and lactation and for those recovering from surgery or any serious illness, including infections and trauma.
Sources of Protein in the Diet About one third of the protein in the average UK diet comes from plant sources and two thirds from animal sources.
The amount of protein in nuts, dried beans and pulses is very high and similar to that found in meat, fish and dairy produce (see table below).
The proportion of plant protein available is reduced when pulses are soaked in water, but regardless they still remain an excellent source of protein.
Cereal grains, including wheat, maize, millet, rice, pasta and potatoes, are also good sources and represent the main sources of protein for many people in various parts of the world.
Alternative Sources to Animal Proteins There is a growing demand for sources of protein that can replace animal based proteins in the diet all over the world, but especially in Western societies.
This may partly be due to vegetarianism, as well as some people's desire to limit their fat intake by consuming protein-rich foods that contain no saturated fat or animal protein.
Consequently, the food industry has responded by developing a number of products that can be consumed as an alternative to meat.
For instance, Soya based products such as Tofu (bean curd), which are traditionally used in far Eastern cuisine, are now becoming increasingly more available in the UK.
In addition to Tofu, other products have become available that can be used instead of meat, by vegetarians and non-vegetarians alike.
Some of these products are suitably fortified with vitamins and minerals, such as Iron, Zinc and some of the B-vitamins, which normally occur in meat and meat products.
Textured Vegetable Proteins Textured vegetable proteins are developed by concentrating or isolating the proteins from a number of plants such as Soya and converting them directly into products such as Soya "mince" or Soya "chunks".
Mycoprotein Mycoprotein is another product that can be used as an alternative to meat e.
g.
the Quorn range which incorporated into a wide range of retail products.
Indeed, regardless of the source (animal or plant), the amount and type of protein in any diet will not exactly balance the requirements for growth, development, maintenance and repair.
There will always be excess amino acids and total protein.
Consequently, these will be converted by the liver into glucose or directly oxidised to release heat and energy.
If the energy provided by the diet is insufficient to meet energy demands, the oxidation of amino acids for energy tends to take preference over their fundamental role for rebuilding body proteins.
This is why it is important to ensure that all diets, whether for weight reduction or weight maintenance, contain sufficient energy in the form of complex carbohydrate to avoid the use of protein as a source of energy by the human body.
Only then can these proteins be properly utilised for body functions and fulfil their purposes, which no other nutrient can.
Also, balancing the diet in terms of protein and carbohydrates is an absolute necessity in weight reducing diets in order to prevent the breakdown of muscle proteins, which results in unsafe weight loss.
Protein content of selected foods expressed as g/100g.
Food item Protein (g) -- Food item Protein (g) Beef sirloin, lean only, roast 27.
6 -- Potatoes, baked, flesh & skin 3.
9 Beef rump steak, lean only, grilled 28.
6 -- Baked beans, canned in tomato 5.
2 Lamb, leg, lean only, roast 29.
4 -- Blackeye beans, dried, raw 23.
5 Lamb, chops, lean only, grilled 27.
8 -- Chick peas, whole, dried, raw 21.
3 Chicken, roasted, meat only, light 26.
5 -- Lentils, green and brown, dried, raw 24.
3 Chicken, roast, meat only, dark 23.
1 -- Tofu, Soya bean, steamed 8.
1 Partridge, roast, meat only 36.
7 -- Eggs, boiled 12.
5 Duck, roast, meat only 25.
3 -- Peas, boiled in unsalted water 6.
7 Turkey, roast, meat only 28.
8 -- Brown rice, raw 6.
7 Venison, roast, meat only 35.
0 -- Brown rice, boiled 2.
6 Halibut, steamed, middle cuts 23.
8 -- White rice, raw 7.
3 Lemon sole, steamed, flesh only 20.
6 -- White rice, cooked 2.
6 Mackerel, smoked, flesh and skin 18.
9 -- Noodles, egg, raw 12.
1 Salmon, smoked 25.
4 -- Spaghetti, raw 12.
0 Prawns, boiled 22.
6 -- Granary bread 9.
3 Mussels, boiled 17.
2 -- White bread, average 8.
4 Milk, whole, pasteurised 3.
2 -- Wholemeal bread 9.
2 Milk, skimmed, pasteurised 3.
3 -- Almonds 21.
1 Soya milk, plain 2.
9 -- Mycoprotein, Quorn 11.
8 Cheese, cheddar, average 25.
5 -- Muesli, no added sugar 10.
5 Cottage cheese 13.
8 -- Red kidney beans, dried, raw 23.
9 Copyright 2012: Therapia: All Rights Reserved: Therapia is a Registered Trademark
They can also be converted into glucose to be used for energy when there is a strict supply of carbohydrate and during starvation.
This is why restricting carbohydrate or following a high protein diet can be disadvantageous, as it might force the body to use protein for energy production, which is not its prime physiological role.
There are two types of protein - animal and vegetable.
Animal proteins, found in meat, fish, poultry, game, eggs, cheese and milk, have high biological value because they contain all the amino acids required for protein synthesis.
However, the nutritional advantage of animal foods over vegetable foods is in the presence of nutrients such as vitamin B12, Iron, Zinc and vitamin A than in protein content.
Because of the lack of storage facilities for excess amino acids in the body, they are most efficiently utilised if a complete assortment is supplied to the body at about the same time.
Eating a mixed diet at each meal and ensuring that the total energy content of the diet is adequate can achieve this.
Therefore, mixtures of vegetable protein foods such as beans on toast or of animal and vegetable foods such as fish and new potatoes, an egg sandwich and breakfast cereal with milk would have a sound physiological basis.
Plant protein e.
g.
legumes and lentils are generally low in or lack one or two of the essential amino acids.
As a result, it is referred to as low biological value protein.
The quality of a protein is judged by its ability to supply all the essential amino acids in the amounts needed for protein production, rather than its source.
Mixtures of such plant protein foods, however, complement each other and are of greater benefit, so that even amongst those who eat little or no animal protein, protein deficiency is rarely a problem (provided that they eat a variety of foods from all the main four food groups).
This is essential for those with a small appetite, during the period of rapid growth for children, during periods of physiological stress such as pregnancy and lactation and for those recovering from surgery or any serious illness, including infections and trauma.
Sources of Protein in the Diet About one third of the protein in the average UK diet comes from plant sources and two thirds from animal sources.
The amount of protein in nuts, dried beans and pulses is very high and similar to that found in meat, fish and dairy produce (see table below).
The proportion of plant protein available is reduced when pulses are soaked in water, but regardless they still remain an excellent source of protein.
Cereal grains, including wheat, maize, millet, rice, pasta and potatoes, are also good sources and represent the main sources of protein for many people in various parts of the world.
Alternative Sources to Animal Proteins There is a growing demand for sources of protein that can replace animal based proteins in the diet all over the world, but especially in Western societies.
This may partly be due to vegetarianism, as well as some people's desire to limit their fat intake by consuming protein-rich foods that contain no saturated fat or animal protein.
Consequently, the food industry has responded by developing a number of products that can be consumed as an alternative to meat.
For instance, Soya based products such as Tofu (bean curd), which are traditionally used in far Eastern cuisine, are now becoming increasingly more available in the UK.
In addition to Tofu, other products have become available that can be used instead of meat, by vegetarians and non-vegetarians alike.
Some of these products are suitably fortified with vitamins and minerals, such as Iron, Zinc and some of the B-vitamins, which normally occur in meat and meat products.
Textured Vegetable Proteins Textured vegetable proteins are developed by concentrating or isolating the proteins from a number of plants such as Soya and converting them directly into products such as Soya "mince" or Soya "chunks".
Mycoprotein Mycoprotein is another product that can be used as an alternative to meat e.
g.
the Quorn range which incorporated into a wide range of retail products.
Indeed, regardless of the source (animal or plant), the amount and type of protein in any diet will not exactly balance the requirements for growth, development, maintenance and repair.
There will always be excess amino acids and total protein.
Consequently, these will be converted by the liver into glucose or directly oxidised to release heat and energy.
If the energy provided by the diet is insufficient to meet energy demands, the oxidation of amino acids for energy tends to take preference over their fundamental role for rebuilding body proteins.
This is why it is important to ensure that all diets, whether for weight reduction or weight maintenance, contain sufficient energy in the form of complex carbohydrate to avoid the use of protein as a source of energy by the human body.
Only then can these proteins be properly utilised for body functions and fulfil their purposes, which no other nutrient can.
Also, balancing the diet in terms of protein and carbohydrates is an absolute necessity in weight reducing diets in order to prevent the breakdown of muscle proteins, which results in unsafe weight loss.
Protein content of selected foods expressed as g/100g.
Food item Protein (g) -- Food item Protein (g) Beef sirloin, lean only, roast 27.
6 -- Potatoes, baked, flesh & skin 3.
9 Beef rump steak, lean only, grilled 28.
6 -- Baked beans, canned in tomato 5.
2 Lamb, leg, lean only, roast 29.
4 -- Blackeye beans, dried, raw 23.
5 Lamb, chops, lean only, grilled 27.
8 -- Chick peas, whole, dried, raw 21.
3 Chicken, roasted, meat only, light 26.
5 -- Lentils, green and brown, dried, raw 24.
3 Chicken, roast, meat only, dark 23.
1 -- Tofu, Soya bean, steamed 8.
1 Partridge, roast, meat only 36.
7 -- Eggs, boiled 12.
5 Duck, roast, meat only 25.
3 -- Peas, boiled in unsalted water 6.
7 Turkey, roast, meat only 28.
8 -- Brown rice, raw 6.
7 Venison, roast, meat only 35.
0 -- Brown rice, boiled 2.
6 Halibut, steamed, middle cuts 23.
8 -- White rice, raw 7.
3 Lemon sole, steamed, flesh only 20.
6 -- White rice, cooked 2.
6 Mackerel, smoked, flesh and skin 18.
9 -- Noodles, egg, raw 12.
1 Salmon, smoked 25.
4 -- Spaghetti, raw 12.
0 Prawns, boiled 22.
6 -- Granary bread 9.
3 Mussels, boiled 17.
2 -- White bread, average 8.
4 Milk, whole, pasteurised 3.
2 -- Wholemeal bread 9.
2 Milk, skimmed, pasteurised 3.
3 -- Almonds 21.
1 Soya milk, plain 2.
9 -- Mycoprotein, Quorn 11.
8 Cheese, cheddar, average 25.
5 -- Muesli, no added sugar 10.
5 Cottage cheese 13.
8 -- Red kidney beans, dried, raw 23.
9 Copyright 2012: Therapia: All Rights Reserved: Therapia is a Registered Trademark
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