A nutrient is actually a chemical substance essential for an organism to survive and develop. In other words, a nutrient may be described as a substance that is utilized during the metabolic process of an organism and that is necessarily obtained from the environment of the organism. Nutrients are employed to develop as well as mend the tissues, control the various processes within the body and are also transformed into energy for carrying out the various functions of the organism. It is worth mentioning here that there are various methods of nutrient ingest. For instance, animals as well as protists (single-celled organisms) consume foods that are assimilated by means of an internal digestive system. The manner of ingestion of nutrients by majority of the plants is different. They obtain their nutrients directly from the soil by means of their roots and also from the atmosphere.

Nutrients are of several types. Nutrients that are known as organic comprise carbohydrates, vitamins, fats and proteins (or amino acids, which are their building blocks). Inorganic nutrients comprise chemical compounds like water and dietary minerals. Even oxygen is considered to be a valuable nutrient. Any nutrient is considered to be essential or 'indispensible' provided it is necessarily obtained from outside sources for two reasons - either the organism is unable to produce it or produce it in sufficient amounts. Similarly, nutrients that the organism requires in minute amounts are known as micronutrients, while those that are required in large amounts are known as macronutrients. The consequences of ingestion of these nutrients rely on the dosage and whenever there is a shortage of any nutrient in the organism, it is called a deficiency.

Categories of nutrients

There are various different ways to describe macronutrients.

In effect, oxygen, carbon, nitrogen, hydrogen, sulfur and phosphorus are the chemical ingredients that the human beings intake in large amounts. On the other hand, the categories of chemical amalgams consumed by human beings in maximum amounts and those that supply them with immense energy include carbohydrates, fats and proteins. In addition, water as well as oxygen obtained from the atmosphere too need to be ingested in large amounts, but these are not always referred to as nutrients or foods.

Occasionally, the list of macronutrients also include sodium chloride (common salt), calcium, potassium, magnesium, in addition to sulfur and phosphorus since they are needed in large amounts in comparison to different other minerals and vitamins. Therefore, they are every so often called macro minerals.

Substances that supply energy

Carbohydrates are basically compounds comprising various kinds of sugars. In effect, carbohydrates are categorized depending on the number of sugar units contained by them - monosaccharide (e.g. glucose and fructose), disaccharides (e.g. lactose and sucrose), polysaccharide (e.g. starch, cellulose and glycogen), and oligosaccharides.

Another macronutrients, proteins are also organic compounds that comprise amino acids attached by peptide bonds. The human body is unable to produce a number of amino acids (which are called essential amino acids), which need to be provided through one's diet. As far as nutrition is concerned, proteins are broken down by proteases by means of digestion to form free amino acids again.

Fats are made up of a glycerin molecule along with three fatty acids binded together. In effect, fatty acids are undivided hydrocarbon chains that are linked by means of just a single bond (for instance, saturated fatty acids). Alternately, they are attached by single as well as double bonds (for instance, unsaturated fatty acids). Fats are required to maintain the proper functioning of the cell membranes, to maintain a stable body temperature, to insulate the organs of the body against shock, as well as to sustain a healthy skin plus hair. It may be noted that the human body does not produce specific fatty acids, which are called essential fatty acids, and these need to be supplied through our diet.

Essential and non-essential nutrients

Quite often nutrients are classified into two groups - essential and non-essential. Essential nutrients are those which the body is unable to synthesize by itself or does not produce them according to its requirements or at all. Therefore, it is must for organisms to obtain these nutrients from the environment to fulfill their requirements. On the other hand, non-essential nutrients are those that are produced by the body, but may also be ingested from foods. Most of the animals eventually obtain their essential nutrients from plant sources. However, there are other animals who intake minerals from the soil with a view to append their diet.

In the case of humans, the essential nutrients include vitamins, essential amino acids, essential fatty acids and some other specific dietetic minerals. While water and oxygen are also absolutely indispensible for the existence of the humans, usually they are not referred to as foods when they are taken in separately.

It may be noted that the human beings have the aptitude to obtain energy from an assortment of carbohydrates, fats, proteins as well as ethanol. In addition, they are able to synthesize additional required amino acids obtained from other essential nutrients.

It is worth mentioning here that even non-essential substances enclosed in the foods we ingest may also have considerable consequences on our health - both helpful as well as toxic. For instance, majority of the dietary fibers ingested by us are not assimilated by our digestive system. Nevertheless, they are vital for the digestion as well as assimilation of substances that are otherwise detrimental for our health. Recently, people's interest in phytochemicals, also known as phytonutrients, has increased. It is worth mentioning here that phytochemicals comprise numerous non-essential materials that may possibly be beneficial for our overall health.

Deficiency and toxicity

When an organism has lesser than the required nutrients, the condition is called a deficiency. Such deficiencies may occur owing to a variety of reasons, counting insufficient intake of nutrients - a condition called dietary deficiency, or conditions that obstruct the organism from using the nutrient effectively. A number of conditions that may come in the way of utilizing the nutrients include difficulties in absorbing the nutrients, conditions that may be responsible for destroying the ingested nutrient, substances that may result in a greater than usual requirement for nutrients as well as conditions that lead to more than normal excretion of nutrients.

It may be noted that nutrient toxicity may occur in an organism whenever excessive intake or presence of nutrients in the body proves to be detrimental for an organism.

As far as plants are concerned, they endure five most common types of deficiency symptoms. These symptoms include absence of fresh growth of the plant; accumulation of anthocynanin - a condition wherein a reddish or purple colorization of foliage and/ or stems is formed; chlorosis - a condition wherein the plant tissues turn yellow owing to deficiency of chlorophyll synthesis; necrosis - a condition that eventually results in the death of plant tissues; and stunting or diminished growth.

It may be noted that too much supply of plant sustenance in the environment may often result in unwarranted growth of plant as well as algae. This process is known as eutrophication and it has the potential to result in disparities in the population numbers as well as additional nutrients may prove to be detrimental for specific species. For instance, an algal bloom has the aptitude to exhaust the existing oxygen for the fish to respire. There are several causes for this, including contamination of water from sewage or overflow from the farms, which carries excessive agricultural fertilizers along with it. In addition, nitrogen and phosphorus have been found to be the most common factors that restrict the growth of plants and, thereby, are most prone to set off eutrophication when they are introduced unnaturally.

Why nutrients are necessary for us?

Now, the pertinent question is as to why organisms require nutrients. Answering this question in an uncomplicated way, we may simply say that the nutrients are the fuels for our body that enable the body to carry out its various functions, including movement and growth. Nutrients are akin to the fuel that is essential for the working of an internal combustion engine. When we take adequate amount of the requisite nutrients, our body will not only be healthy, but, in a number of cases, may also be capable of mending the damages caused by various factors.

One nutrient that is required by the body of all humans is water. However, technically water is not considered to be a nutrient like others, such as vitamins and minerals. Our body is mainly composed of water and this valuable fluid helps to maintain the blood circulation, assist in the functioning of the stomach, sustaining a supple skin and so on. In the absence of water, we would really become dehydrated and die.

Now, we shall discuss about the specific nutrients which are essential for us to survive. Vitamins belong to the category of nutrients which almost all people are very acquainted with. In effect, various dissimilar types of vitamins are essential for several dissimilar functions carried out by the human body. For instance, in order to have healthy teeth and gums, it is essential to ingest adequate quantities of vitamin C as well as calcium.

In order to survive, grow and remain healthy, we also require some minerals, particularly calcium and magnesium. These minerals are vital for the appropriate functioning of the brain. Researches undertaken by scientists on the brain have revealed that the signals sent from and to the brain actually work optimally when adequate quantities of magnesium are present in the body.

In addition to the nutrients mentioned above, the human body requires amino acids as well. Amino acids are important for the body as they help it to build proteins. As far as a healthy body as well as effectual metabolism are concerned, protein is the hub of all activities. If you try to learn more regarding proteins and enzymes, you will possibly find out the fundamental elements of life - the DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Humans also require particular types of fats that are converted into energy for being utilized by our body. It is worth mentioning here that fats and vitamins have a specific bond that is vital for the life of humans. It may be noted that there are specific vitamins that only work when they are digested as well as assimilated in the presence of particular fats.

Carbohydrates are also essential for humans for their survival, growth and wellbeing. The carbohydrates that we obtain from breads, grains as well as a number of other foods are valuable for the body to carry out its essential functions. The body converts the ingested carbohydrates into energy very fast and they are vital for sustained life as well as our health.

Hence, the primary reason why we require nutrients is that they supply us with the appropriate type of fuel for several complicated processes, which help us to remain alive. For instance, if we consume only one type of food, such as bread, we would actually be denying our body of the essential vitamins present in citrus fruits as well as the minerals found in dairy products. On the other hand, if we only consumed milk shakes, we will not be able to get sufficient amounts of carbohydrates that we require from the grains or the fats as well as proteins we obtain from lean meats. Therefore, the single manner by which we are able to supply the body with the correct nutrients and in appropriate quantities is to consume an assortment of fresh foods from every different food groups.

Any healthy individual will always follow a specific eating pattern and his/ her diet will comprise adequate amounts of fresh vegetables and fruits, lean meat, dairy products, poultry and the like. When we take these foods along with a few glasses of hygienic water daily, our body would be in a better position to convert the nutrients ingested through the foods into chemicals that are required for survival, development, maintenance of the body as well as our wellbeing.


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