Nutrition In Human Beings: Six Essential Nutrients and Their Functions

Organisms need various raw materials for the growth and maintenance of their body. They also need the energy to perform various activities. These raw materials and energy are provided by the food that they eat. Nutrients are the compounds in the food that maintain the body and make it work. In this article, we shall study the topic of Nutrition in Humans. 

Carbohydrates, proteins, and fats are the major nutrients needed by our body, also called macronutrients. Minerals and vitamins are needed in fewer quantities and hence are called micronutrients. Along with these fibre and water are also required for the body. The process of consuming food and using it is known as nutrition. Our diet should contain a mix of raw materials that provides all necessary nutrients in the right amounts, Such a diet is called a balanced diet. 

Key Terms: Nutrition, Carbohydrates, Proteins, Fats,  Macronutrients

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Nutrition in Human Beings

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Nutrients required by the human body are as follows :

• Carbohydrates

Carbohydrates are the sugars, starches, and dietary fibre which are found in foods such as pasta, bread, beans, rice, potatoes, and cereals. Our body breaks down carbohydrates into glucose, the body’s main source of energy.

Carbohydrates

• Vitamins and Minerals

Vitamins and minerals maintain a strong immune system, build strong bones and muscles, support normal growth and development, and help cells and organs do their jobs. Vitamins mean "Vitals for life" and are required in tiny amounts, therefore called Micronutrients. They are found in fruit, vegetables, fish, meat, dairy products, and eggs. Minerals include calcium and iron amongst many others, which also help the body perform optimally. They are found in vegetables, dairy products, meat, nuts, and fish.

Vitamins and Minerals

• Fats

A small amount of fat is necessary for a healthy balanced diet. Fat is a source of fatty acids that are used as an energy source and to make cell membranes. Foods high in fat include Dairy products, meat, palm oil, Coconut oil, seeds, Cakes, nuts, and vegetable oils.

Fats

• Proteins

Proteins are made up of smaller units called amino acids and include biological compounds such as enzymes, hormones, and antibodies. They perform most of the work in cells and helps in structuring, functioning, and regulating the tissues and organs of the body. Foods high in proteins include fish, meat, poultry, and beans. 

Proteins

• Water

Water helps in regulating body temperature, lubricate joints, maintain blood volume, flush toxins, and circulate nutrients throughout the body. 

Function of Water in the Body

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Digestion in Human Beings

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Humans are omnivorous and have a complex digestive system. The human digestive system contains the alimentary canal and accessory glands. The alimentary canal constitutes the oesophagus, stomach, small intestine, large intestine, rectum, and anus. The salivary gland, liver, and pancreas are the accessory glands that lie outside the alimentary canal. Digestion is an important process in humans, which provides energy by breaking down the large food molecules. 

Digestion in Human Beings

The step-wise process of nutrition in humans are as follows: 

Ingestion: In human beings, food is put into the mouth with the help of hands. Saliva (Watery Liquid) is secreted by salivary glands located under the tongue. It contains digestive enzymes like salivary amylase, which digests the starch (carbohydrate) present in the food into Maltose, a simple sugar (Chemical digestion).

• The teeth grind the ingested food into tiny pieces. This process is called mastication (Physical digestion). 
• The tongue helps in rolling food and mixing saliva in the food while masticating. The semi-solid form of food in the mouth is known as Bolus.
• The food from the mouth then goes down the oesophagus, which is the food pipe, to the stomach, through the movement of walls of the oesophagus (peristalsis).

Digestion: It is the process to break down the ingested food into molecular parts. 

Digestion

• The food from the mouth goes down the food pipe called the oesophagus, through the contraction and expansion movements of walls of the oesophagus called peristaltic movement. 
• The stomach mixes the food with various digestive juices. The inner lining of the stomach secretes :

1. Hydrochloric acid – Hydrochloric acid kills any germs which may be present in our food. Moreover, it creates an acidic medium which is necessary for gastric enzymes to work.
2. Digestive enzyme –The enzyme pepsin, secreted in the stomach, does partial digestion of protein. It breaks down protein into simpler substances. 
3. Mucus – It protects the lining of the stomach from getting damaged from hydrochloric acid.

• The food from the stomach eventually moves into the small intestine. The complete digestion of proteins, fats, and carbohydrates occurs here in the small intestine. It gets intestinal juices from two different glands – the liver and pancreas that help in the further digestion of food.
• The liver is the largest organ of the body and manufactures bile juice. Bile juice gets stored in the gallbladder and has a significant role in the digestion of fats. From the gallbladder, bile is released as and when required.
• The pancreas secretes enzymes that help in the total digestion of all food components. 

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Absorption: This is a stage where nutrients from the digestive food are distributed to the body’s tissues. Several finger-like projections called villi at the inner lining of the Small Intestine increase the surface area for absorption. The villi have a rich supply of blood vessels which acts as the medium to take the food to each and every cell of our body. In the cells, the food is utilized to obtain energy, build new tissues and repair the old ones. 

Absorption

Egestion: This is the final process where waste material is excreted from our bodies. Undigested food goes into the large intestine which is smaller than the Small Intestine. Excess water and salt are absorbed by the walls of the large intestine. After that, the undigested food goes to the rectum and finally excreted through the anus.