Saturday, July 23, 2011

Nutrition 101

If you buy a food supplement that contains an enzyme (such as super-oxide-dismutase, SOD) designed to work in your blood or in your cells, you are wasting money. Your digestive enzymes will split up this enzyme and reduce it to amino acids. The body will use these amino acids according to its own priorities, not necessarily those that you may have had in mind. Remember; dietary protein is digested by enzymes in your intestine to amino acids, amino acids are reconstructed by cellular enzymes to body protein.

Amino acids, if not used for protein synthesis or other purposes, lose their nitrogen (amino group) and are metabolized for energy. The body get rid of ammonia, which contains the nitrogen (from amino groups), by converting it to urea in the liver. The blood carries the urea to the kidney, where it is excreted in the urine. Some amino acids are also used for synthesis of hormones or other chemical compounds. Tryptophan can serve as a precursor for serotonin, a neurotransmitter. Tryptophan can also be converted to a vitamin, niacin. Certain amino acids are also converted to glucose, if the body does not receive sufficient carbohydrates. Starving or fasting people make their glucose this way.

Essential amino acids
We cannot make essential amino acids in sufficient quantities for optimal nutrition in our own body. We therefore need to get them from food. Eight amino acids are essential for adults; nine are essential for children. The remaining amino acids are just as important for protein synthesis, but our body can synthesis them from the carbon skeletons of fats, carbohydrates, other amino acids, and the nitrogen from amino acids already present.

Complete protein is a colloquial term for proteins of high nutritional quality. High quality proteins are dietary proteins that provide all the essential amino acids in the right proportions. Animal proteins usually resemble our own proteins more than plant proteins, and therefore are usually of high quality. Many plant proteins are of lower quality. These differences are not surprising because plants have different needs and properties than animals and, therefore, need different types of protein.

Plant seed proteins, such as grains, rice and corn, are usually low in one or two essential amino acids. Most animal proteins, gelatin is an exception, contain all the essential amino acids in the proper proportions.
Egg protein is one of the highest quality proteins. Other protein sources are therefore compared to egg protein regarding their nutritional value. The relative quality of protein, or its usefulness for the human body is called the “biological value.” A high quality protein would have a high biological value.

Proteins with the required proportions of essential and non-essential amino acids have a high biological value, and can be used for protein synthesis with little waste.We can get good quality protein by combining different plant proteins. This is especially important for vegetarians. For example, one plant protein may be low in one amino acid, while another plant protein may be high in that amino acid. If these two plant proteins are combined and eaten together, they complement each other, delivering all essential amino acids in sufficient amounts.
Some examples:
Rice is low in lysine , an essential amino acid. Beans are low in methionine, another essential amino acid. Since both contain reasonably balanced proportions of the other essential amino acids, rice and beans complement each other to make better quality protein. Rice and beans are staple foods of many countries and of vegetarians.
Good nutrition is essential for a heathy life.  For more helpful, healthy hints go to:

1 comment:

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