The Importance of Good Nutrition

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The Importance of Nutrition for Human Health

The health of human beings is fundamental in ensuring that their bodies perform all functions in the right way. Nutrition can be described as the supply of food materials to the body cells to keep them alive, as well as how the body uses these nutrients. Every part of human's organism plays a specific role in the complex functions of the body. It is, hence, important that we take nutritious and balanced diets to enhance our body health. Food nutrients can be categorized into macronutrients and micronutrients. The macronutrients are needed in relatively larger amounts than the micronutrients (Grossi et al. 2016, p.214).

Good Nutrition and a Balanced Diet

Good nutrition and a balanced diet is the building block for body muscles, energy, fitness, and immunity to diseases. Water is also a major body requirement that should not be substituted for soft drinks or sugary drinks.


Macronutrients provide energy to the human body. They are proteins, fats, and carbohydrates, which benefit our bodies differently (Mathias 2016, p.132). They are needed in large amounts to assist organism in maintaining functions and enabling the daily life activities. A well-balanced diet requires that 55 percent of the plate are carbohydrates, 30 percent are fats and 15 percent are proteins (Denzel, et al., 2016, p. 87).


Carbohydrates are recommended to take up the greater percentage of all food intake per day. They are easily metabolized or rather broken down into glucose and used as the body’s main source of fuel. The glucose is easily absorbed (Langley-Evans 2015). It makes it easy for the other macronutrients to be used in the repair and growth of tissues. Internal body parts that heavily rely on energy from the carbohydrates to function effectively include the brain, kidneys, muscles, and the heart. Carbohydrates enable the synthesis of amino acids and the metabolisms of fats. They are found in foods rich in starch, such as grains, potatoes, some fruits, and milk. It is also available in lesser quantities in foods, such as vegetables, nuts, cheese, and seeds. They can have either simple or complex chemical structures, whereby the simple structured are sweet while the complex one’s taste savory (Insel et al. 2015, p.343). Fiber is also an indigestible type of carbohydrate, which helps in the digestion system and excretion of waste from our bodies. Foods rich in fiber include fruits, vegetables, and whole grains. They decrease the risks of obesity, cholesterol-related problems, and heart issues (Farooqui 2015, p.238).


The recommended fraction of proteins in any meal taken ranges between 10% - 35%. They play a vital role in the making of cells constituting 50 percent of the dry weight. It means that the human body is largely made from proteins. They help in the production of new tissues, repairing the ailing ones, as well as maintaining the daily body functions. They also make enzymes that catalyze digestion and other activities, as well as support the essential hormones that regulate the body activities. In cases where carbohydrates are not available, proteins can also be used as a source of energy. They are broken down into amino acids. 21 amino acids are needed by the human body, and nine of them are essential since they cannot be produced by the body. Nine essential amino acids are categorized as high-quality proteins and can be found in animal products. Those without the nine amino acids are low quality and are found in plant sources, such as legume plants (Moran and Lowe 2017).


People have a misconception that fat is harmful or always bad for human health. However, as a matter of fact, it is important in enhancing a healthy body. It is recommended that a person’s diet should have between 20 to 30% of fat. There are good fats and bad fats. Examples of bad fats include high-fat meats and sweets. Good fats are nuts, avocados, and plant-extracted oils (Coulston et al. 2017, p.76). Fat plays an essential role in keeping the body warm through insulation and cushioning body organs to maintain body temperature. It enhances the growth, development, and maintenance of cell membranes. It also lubricates a person’s joints and muscles keeping them loose and flexible as well as assisting in the absorption of certain fat-soluble vitamins such as vitamins A, D, E, and K (Gropper et al. 2017, p.210).


Unlike the macronutrients, these are required in smaller quantities but are still essential to the proper functioning of the body system for good health. Micronutrients are minerals and vitamins (Denzel et al. 2016, p.251). The first helps in fastening chemical reactions in the body. Sodium, for instance, ensures the proper functioning of cells, as well as maintaining water volume outside them. Potassium maintains fluid volume inside the cells. Calcium strengthens bones and teeth.

There is a wide variety of vitamins, categorized as fat soluble and water soluble. They are important for the functioning, development, and growth of the cell. Fat-soluble vitamins are vitamin A, D, E, K. Water-soluble vitamins are vitamin C, B-1, B-2, B-3, B-5, B-7, B-6, B-12. Each of them plays a different role from the other. Poor or lack of vitamins intake may lead to health problems. The richest vitamin food includes fruits, vegetables, beans, lentils, and fortified foods. Sometimes people can get vitamins not only from a meal. For example, vitamin D is produced by the body after basking in the sun for a considerable duration (Mann and Truswell 2012, p.45).

All the above nutrients cannot be produced in the body but are crucial for the development of the body as well as prevention of diseases. Nutritional deficiency risks the body to diseases and health problems. It is when the body cannot absorb or get the required amount of nutrients (Fitzgerald 2014, p.256). Some of the consequences of nutritional deficiencies include anemia, which is a blood disorder caused by iron deficiency. Lack of vitamin A causes poor eye health and functioning. Deficiency of iodine affects the production and function of thyroid hormones (Insel et al. 2016, p.99). Poor amount of vitamin D and calcium causes muscle weakness, weak bones, poor growth or soft bones in children, and increases the risk of cancer. Lack of vitamin B-12 may lead to megaloblastic anemia, and impaired brain function. Vitamin B-5 and B-12 improve a person’s immunity and the nervous system. Their deficiency may lead to numbness and exaggerated reflexes (Farooqui 2015, p.85).


Malnutrition is a condition in both children and adults brought about by insufficient intake, absorption, and utilization of nutrients in the human body (Langley-Evans 2015, p.201). The two major forms of malnutrition are protein-energy and micronutrient deficiency diseases.

Protein-Energy Malnutrition

It is caused by the lack of glucose and proteins in an individual’s daily food. It is more prevalent in areas affected by hunger and can be lethal if it prolongs. It is because all body parts require chemical energy gotten from both carbohydrates and proteins to function properly (Farooqui 2015, p.97). In children, this form of malnutrition can be categorized into three types. The first is acute malnutrition, which is characterized by rapid wasting, thinness, and failure to gain weight in the normal way. The second is chronic malnutrition, which is characterized by stunted growth or failure to gain height. The third is acute and chronic malnutrition, which is characterized by the child being underweight (Bose 2013, p.100). Acute malnutrition in children can lead to diseases such as marasmus and Kwashiorkor. Abnormalities caused by protein-energy malnutrition can be reversed through nutritional therapy, but if the effects have been prolonged, they can lead irreversible body and organ changes (Denzel et al. 2016). Adults too can develop extreme wasting and edema but cannot have stunted growth.

Micronutrient Deficiency Diseases

It is a severe lack of vitamins and minerals that are of utmost necessity in the efficiency of various body processes. These nutrients include iron, iodine, vitamin D, selenium, zinc, iodine, folate, calcium, vitamins A, B, C, D. This form of malnutrition is more common and of great concern in developing countries. Zinc deficiency leads to sensory perception and poor immunity. Folate deficiency leads to slow growth. Lack of vitamin B-12 causes nerve degeneration and poor red blood cell formation. Deficiency of vitamin A causes poor vision and bone development. Lack of vitamin D causes bone development disorders and rickets. Deficiency of selenium weakens immunity and affects cardiac functions. Finally, lack of iron causes anemia and poor brain development (Gropper et al. 2017, p.253).

The Anatomy and Physiology of the Human Digestive System

The Mouth and Esophagus

The human digestive system is complex and uniquely made to convert food ingested into nutrients that can be absorbed by the body cells and organs. The absorbed nutrients are then used for energy, cell growth, and repairs of damaged tissues and cells. It is consistent with the digestive tract where food passes through into the bloodstream while waste materials are eliminated from the body. It starts at the lips and ends at the anus.

Food is ingested through the mouth and hence it marks the start of the digestion process. It consists of teeth, salivary glands, and the tongue. The mouth also has taste buds that help to give the vital perception of harmful or rotten food. Upon ingestion, food is processed through mastication and mixing it with saliva. The saliva has enzymes called amylase, which aid in the breaking down of carbohydrates. Mastication is the breaking down of large food particles into smaller particles, which are then lubricated by saliva to form a bolus or a ball of food easy to swallow (Brett 2015, p.105). The bolus is swallowed with the aid of the tongue through the throat to the esophagus. The esophagus is a muscular tube running from the throat to the stomach. It delivers food to the stomach through muscular contractions called peristalsis. At its end, it has a valve called "lower esophageal sphincter" which is a high-pressure zone that restricts the backward flow of food from the stomach.


The stomach is a hollow muscular sack that holds food for several hours as it is mixed with enzymes aiding the food breakdown. It is located between the esophagus and the small intestines. Rhythmical contractions of the stomach muscles aid in the churning of the food particles into even smaller bits that are more digestible in the intestines (Brett 2015, p.132). Its walls secrete acids and enzymes that speed up digestion. Enzyme pepsin enables the digestion of proteins. Other enzymes include gelatinase, lipase, and gastric amylase, alongside gastric acid and hydrochloric acid. The cells located in the stomach are mucous cells, parietal cells that secrete hydrochloric acid, chief cells that produce pepsin, and G cells that produce gastrin, which aids in the secretion of HCl acid. The stomach also protects itself from corrosion by the acids through a layer of mucus on its walls (Mason 2015, p.87). The stomach releases the food into the duodenum.

The Small Intestine

The small intestine consists of the duodenum, jejunum, and the ileum. The small intestine has many enzymes, which are produced by the pancreas, bile from the liver, and glands located on the intestine walls, which further aid the breakdown of proteins and starch (Marieb 2015). Peristalsis occurs here, stimulating the movement of food as they mix with the digestive juices. Most of the digestion in the small intestine takes place in the duodenum, while absorption of nutrients into the blood and other cells is handled by the ileum and jejunum (Green et al. 2014, p.432). As soon as food passes to the duodenum, pancreatic enzymes are released to digest protein, fat, and starch. Bile is also released from the liver by the gallbladder to help in fat digestion to form absorbable nutrients.

The jejunum and the ileum enable the absorption of carbohydrates, proteins, and fat into the bloodstream. The jejunum is the middle section and is about 3 to 6 feet. The ileum is the last part and is about 6 feet long. It is facilitated by finger-like projections on the small intestine walls called villi and microvilli that provide an increased surface area to maximize absorption (Midthun 2014, p.148). 90% of all ingested food nutrients are absorbed in the small intestine. Most water-soluble vitamins are absorbed in the ileum. The villi contain numerous tiny capillaries and lymphatic vessels that transport the nutrients to the blood supply and liver through the hepatic portal vein (Widmaier et al. 2014, p.201). In the small intestines, proteins and peptides are converted into amino acids, lipids are converted to fatty acids and glycerol, while carbohydrates are converted to monosaccharides or simple sugars, such as glucose and fructose (Widmaier et al. 2014). The nutrients in the blood supply are distributed to all body parts, while those in the liver are stored or converted into energy. The residue, which is in a liquid form, is then passed to the large intestine.

The Large Intestine (Colon)

The large intestine is a tube estimated to be 6 feet. It connects the small intestine to the rectum. The colon is made up of the cecum, the ascending colon, transverse, descending colon, and rectum. It is shorter and thicker than the small intestine. The colon, being the final section of the track, absorbs water and vitamins, making the residue solid. The water absorption allows the retention of the utilized water in the metabolism as well as absorbing ions dissolved in the water. It also helps in transmitting the remaining indigestible food from the body as feces (Leung 2014).

The colon is also home to commensal bacteria or rather gut bacteria that aids in the absorption of vitamins. They break down the undigested fibers and polysaccharides to form short-chain fatty acids, which are then absorbed through passive diffusion. These bacteria also help in the formation of vitamin K and biotin, especially when the vitamin intake from the ingested food is low. The mucosa layer of the colon produces bicarbonates that neutralize acidity, hence giving a conducive environment for the production of the fatty acids and other digestive components (Leung 2014, p.104). The lymphoid tissues in the large intestines also play a role in the forming of antibodies and cross-reactive antibodies that save the immunity and prevent infections (Ogden 2017). The solid feces are then stored in the rectum and eliminated through the anus in a process called defecation. The anal sphincter muscles control the bowel movements by holding or releasing stool.


The energy required for human beings to conduct their daily life activities is derived from the consumed food. From the above analysis, human's health is determined by the ratio of the macronutrients, micronutrients, and water intake that constitute diet. All the dietary portions are important and should never be ignored. The deficiency of any nutritional requirements can easily lead to diseases and malnourishment since the body processes and immunity highly depend on nutrients absorbed in our cells and muscles. The digestive system, on the other hand, is a complex tract that enables the ingestion, digestion, and absorption of nutrients in the bloodstream for storage or usage for the normal body functioning. Enzymes, saliva, mucus, and acids constitute some of the main catalysts of digestion, while villi and capillaries aid in absorption. The pancreas, liver, and gallbladder can be called accessory organs of the digestive process for their role in the production of enzymes and bile. Treatment can be an expensive affair; hence prevention can save us money and time by staying healthy.


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August 09, 2023

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