Wednesday, 5 June 2019

Nutrition and their benefits


Nutrition and their benefits
Nutrition and their benefits

From low-level to high-level, from single-celled organisms to higher animals and plants, from living in the water to living on land, living in different environments and ecology. As a result, the nutrients needed and the way they are fed are different.
The nutrients required by the organism, the elemental composition, and the large amount of hydrogen, oxygen, nitrogen and carbon. These are the main elements that make up the protein and energy stored in the organism. In addition, there are small amounts of sulfur, phosphorus, calcium, magnesium, potassium, sodium, chlorine and various trace elements. Some trace elements have only trace amounts in the body.
Plants and microorganisms containing chlorophyll and purpeptin can absorb these inorganic compounds directly from the outside through roots, leaves or cell membranes, and use the energy of sunlight to synthesize organic substances such as proteins, lipids and proteins required for life activities such as growth and development. Carbohydrates (sugars), etc. An organism having such a nutritional form is called an autotrophic or inorganic nutrient type organism. Other organisms (such as animals) cannot directly use the external inorganic matter to synthesize the organic matter needed for their own life, and must obtain nutrients from autotrophic organisms or other similar organisms. Through the metabolic process, the ingested substances are converted into organic substances such as proteins, lipids, and carbohydrates required by themselves. A creature with such a nutritional form is called a heterotrophic organism.
Nutrition is the science of studying the effects of food on living things. In the process of its development, nutrition not only includes changes in food entering the body, such as participating in biochemical reactions and binding to tissue cells; it also includes guiding people on how to choose food to ensure the normal growth, development and reproduction of the body. Therefore, in addition to its biological significance, nutrition has its socio-economic significance.
Nutrients are food ingredients that are required to ingest organisms for normal life activities. The study of nutrients in modern nutrition is mainly aimed at the nutrient needs of humans and livestock. Nutrients are classified into seven major categories: proteins, lipids, carbohydrates (sugars), vitamins and minerals (inorganic salts), water, and cellulose.


The cellular components of the body tissues are mainly proteins, and the body fluids also contain proteins. The nutritional role of protein lies in its various amino acids. There are more than 20 kinds of amino acids that make up food proteins. Several of them cannot be synthesized in humans and animals, but must be obtained from food. These amino acids are called "essential amino acids", namely methionine, lysine, tryptophan, and threonine. Acid, valine, phenylalanine, leucine and isoleucine. In addition, histology requires histidine for growth, and birds such as chicken require arginine and glycine. Other amino acids other than these essential amino acids are called "non-essential amino acids" because they can be synthesized in the body.
The amino acid types and contents of various proteins are different. Some proteins lack certain essential amino acids. For example, gelatin does not contain tryptophan, and zein does not contain lysine. Therefore, to evaluate the nutritional value of a food protein, it should be mainly based on whether the amount of essential amino acids contained in it can meet the needs of the body. Insufficient, the body can not effectively synthesize body protein, other kinds of amino acids can only be metabolized by deamination, produce sugar (glycogen) and supply heat as fuel. It can be seen that the amino acid pattern of food protein is the key to determining the quality of its quality. Internationally, the hypothetical model of the essential amino acid pattern of whole eggs, or the essential amino acid pattern in human milk, or the amount of amino acids necessary for the human body, is used as a criterion for evaluating the nutritional value of food proteins. This is the chemical evaluation method for the so-called protein nutritional value. In addition, there is also a biological evaluation method that performs nutritional evaluation based on the utilization rate of food protein in the body. Commonly used are "protein physiological value" (abbreviated as BV, the percentage of nitrogen retention and nitrogen uptake in the body), "net protein utilization" (abbreviated as NPu, the percentage of nitrogen retention and nitrogen intake in the body, That is, the digestibility of BV × protein), or the "protein potency ratio" (abbreviated as PER, is the weight gain per gram of protein).