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Proteins I Hi, How has the winter being treating you? There have been lots of sniffing customers at the shop lately; I hope that you have escaped the miseries of the flu. We have so far discussed the role of carbohydrates and enzymes, shall we move on to PROTEINS? Here goes; PROTEINS IN THE DIET ( by Mike Benton ) The body for 2 reasons needs protein: growth and for tissue repair & replacement. Protein is not necessary for muscular energy, increased activity or as a source of fuel. Perhaps the role of protein in growth is best exemplified in the development of babies and newborn animals. A relatively high amount of protein is found in the milk of lactating mothers to insure healthy tissue growth in the young child. The protein needs are high when growth is fastest. For instance, compare the protein content in mother's milk after the first 6 months of birth: Time after birth Percent protein From the 8th to 11th day 2.38 From the 20th to 40th day 1.79 From the 70th to 120th day 1.49 At the 170th day and later 1.07 The highest protein contents occur during the earliest stages of growth to allow for rapid development of the baby. It is interesting to note that the percentage of protein found in mother's milk is approximately the same as the protein content of most fruits and vegetables. For example, grapes have a 1.3% protein content. Raspberries 1.5%, dates 2.2% etc… We can also find a relationship between the protein content of milk of lactating animals and the growth rate of their young by studying the following chart: No of days for newborn to double its weight-----Average protein % in mother's milk Man 180 1.6 Horse 60 2.0 Calf 47 3.5 Kid 19 4.3 Pig 18 5.9 Lamb 10 6.5 Dog 8 7.1 Cat 7 9.5 The second role of protein is the repair of tissues or replacement of worn-out cells. After an organism reaches its full growth ( usually between 18 and 22 years for humans ) protein is needed only to supply the loss incidental to tissue waste. Protein is not used directly as fuel for the body or for muscular activity. In muscular work, excretion of nitrogen, as a result of protein usage, increase only very slightly. Instead, it is the excretion of carbonic acid and absorption of oxygen that increase. These changes indicate that an expenditure of energy is derived mainly from non-nitrogenous foods ( such as carbohydrates and fats ) and not from protein. It is true that the body can use protein to generate fuel for physical activity, but it does so by breaking the protein down into carbohydrate form. Protein is used as fuel only when there is either an excess of proteins or a lack of carbohydrates. When this occurs, the body splits off the nitrogenous matter from the protein molecule and uses the remaining carbon contents to produce fuel. This process not only involves a nett loss of energy, but it also places an unnecessary strain on the liver, kidneys and other organs to eliminate the unusable nitrogenous waste. It is for this reason that the popular high protein, low carbohydrate diets result in weight loss and also why they are dangerous. Since the body has to expend so much energy in converting the excess protein into the needed carbohydrates for fuel, a nett loss occurs in the body and the dieter loses weight. At the same time, he also places a heavy burden on his kidneys to eliminate all the uric acid generated by this protein breakdown and simultaneously overworks an already exhausted liver. During the last 60 years, several independent researchers proved that between 6.7% and 4.65% of the total food intake was all the protein necessary to maintain good health. These percentages are equivalent to about 24 to 30 grams of protein, or about 1 gram per 2.5 Kg of body weight. We know now why we need proteins in our diet, but what actually are proteins? There are many different types of proteins within the bodies of animals and plants. For example, all plants have at least 2 different types of protein, and within the human body are over100,000 different kinds of proteins. Although all of these proteins differ in their molecular structure, they all have approximately the same chemical composition of 53%carbon,22% oxygen, 17% nitrogen, 7% hydrogen and 1% sulphur, iodine etc… The principal vegetable protein are: Albumin ( found in fruits & vegetables ) Gluten ( found in wheat & cereals ) Legumin ( found in peas & beans ) Globulin ( found in nuts ) Mucleo-protein ( in seeds ) Casein ( found in milk & dairy products ) Gelatin ( in bones & tendons ) Fibrin ( in blood ) Myosin ( in the flesh of animals ) All these proteins are composed of Amino acids but since this letter is so mind boggling, let's leave the Amino-acids for next week See you then, The Crazy Nut team.