fats, fibres, proteins and carbs

The 7 components of food: Functions and Sources

What is food?

Food, put simply is any nutritious substance taken into the body for the maintenance of life and growth. Food is comprised of different components, and we all eat food to get energy. So, this energy can be used for the growth and repair of our bodies, as well as to do work.

Ultimately, the food we eat in a day comprises of varieties like pasta, eggs, butter, rice, bread, meat, cheese, milk, etc.

an image showing healthy food, balanced diet, components of food
Different varieties of food

Sources of Food

There are two primary sources of food, namely; plant and animal sources of food

Plant source of food

These foods are from plants. For example, rice, vegetables, wheat, fruits, etc

Animal source of food

These categories of foods are from animals. For instance, they are milk, meat, eggs, fish, honey, etc.

Balanced Diet

Ultimately, what makes its way into our stomachs in a day is called a diet. It varies for each individual. A balanced diet is a diet that is composed of the right proportion of essential nutrients. Therefore, whatever we eat must contain all the nutrients and provide the required energy.

Varieties of food items have varying proportions of nutrients present in them. Hence, the nutrient requirement of an individual varies, depending on gender, age, and health conditions. Nonetheless, the absence of these essential nutrients in our diet for extended periods may result in certain diseases.

Importance of a Balanced Diet

The benefits of a balanced diet are numerous, To illustrate, some of them include; helping in proper body growth and increasing the body’s ability to resist or fight diseases. As well as leads to excellent mental and physical health.

7 Components of food

In brief, our food is made up of different components, and these components take part in vital functions in the body. The main components of the food we eat are listed below:

  1. Carbohydrates
  2. Protein
  3. Fats
  4. Vitamin
  5. Mineral (salts)
  6. Water
  7. Dietary fiber (Roughage)

The components of food can be divided accordingly into energy(calories) and non-energy components.

The energy components of food are three, and they are:

  • Fats (lipids)
  • Carbohydrates (starches and sugars)
  • Proteins

The non-energy components of foods are listed as follows:

  • Water
  • Dietary fiber (Roughage)
  • Minerals
  • Vitamins

The food nutrients are carbohydrates, fats, proteins, vitamins, minerals. These are crucial for our survival. The detailed information on the different components of foods are:

Carbohydrate food components

Carbohydrates are one of the components of foods. It is the primary energy provider in our diet, hence the alternative name, energy-giving foods. Carbohydrates comprise hydrogen, carbon, and oxygen. In summary, carbohydrates fall into three categories, namely:


These are simple sweet-tasting carbohydrate. For example, glucose, milk, fruits such as banana, apple, grapes, oranges, etc


These are complex carbohydrates that are colorless and tasteless. Examples of starch providing foods are wheat, rice, potato, etc.


This is a complex carbohydrate that humans cannot digest. And it is usually present in a plant cell wall.

Functions of Carbohydrates

Indeed carbohydrates perform a lot of functions in the body. The main functions of this food component in the human body are energy production, sparing protein, energy storage, building macromolecules, and assisting in lipid metabolism.

bread, pasta, rice,  carbohydrates
examples of some carbohydrate component of food

Carbohydrate Sources

The source of carbohydrates in our diet are from plant sources.  For example, rice, wheat, potatoes, bread, beans, pasta, and fruits.

Recommended daily intake

This component of food, carbohydrates should make up 60% of one’s diet.

Proteins food component

Proteins consist of oxygen, carbon, hydrogen, nitrogen, and some elements like phosphorus and sulfur. This component of food, proteins, consists of smaller molecules called amino acids and they are joined together by peptide bonds to make up proteins.

Proteins are typically referred to as bodybuilding foods, as they find use in body growth and repair of body tissues. All in all, it is because of the bodybuilding function of protein, that they are greatly recommended as an integral part of the diet of pregnant ladies and growing children.

Functions of proteins

In addition to being a bodybuilding component of food, proteins also assist in supplying some energy to the body. Most enzymes and hormones are made up of proteins, as well as other essential structures that are composed of proteins. The functions of these crucial proteins are as follows:


Enzymes catalyze the biochemical reactions that take place in the body. For instance, biochemical reactions like digestion. Examples of these enzymes are trypsin and pepsin.


Hormones regulate various body functions. For example Insulin is a protein hormone.

Transport proteins

Transport proteins aid in carrying different substances from the blood to the various parts of the body, where needed. For example Hemoglobin is a transport protein. 

Contractile proteins

Contractile proteins help in the contraction and expansion of cells and muscles in the body. For instance, myosin and actin are examples of contractile proteins
Structural proteins, For example collagen, form the structural elements that make up the cells and tissues of our body.

Protective proteins fight infections in our body. The gamma globulins found in the blood, for intance, is an example of a protective protein.

an image of poultry, lean beef, meat, fish
Some protein sources

Sources of proteins

Protein sources include both plant and animal sources.

To clarify, some examples of the plant’s sources of proteins are; Beans, Ground-nuts, Lentils, Chickpeas, Whole Cereals like
Maize and Wheat etc.

While, some examples of the animal sources of proteins are; Fish, Meat, Eggs, Cheese, and Milk.

Recommended daily requirement

The maximum daily need for protein in a diet is 50 grams of protein for a typical adult.

Fats food component

Fats are a component of food, that are esters of glycerol and long-chain fatty acids. Consequently, they are made up of three elements, namely; hydrogen, carbon, and oxygen. They are members of a group known as lipids. Lipids are a group of heterogeneous organic compounds. The body stores excess energy (calories) as fat. Thus fat is said to be the energy bank of our bodies. Accordingly, the stored fat produces energy by the body when needed.

Fats have the same elemental composition as carbohydrates. Hence, they provide energy. But the difference is that fat provides more energy. This difference lies in the fact that fats are made up of a higher percentage of hydrogen and carbon, and a lesser percentage of oxygen, compared to the carbohydrate. Accordingly, this leads to a slower energy release, hence a more steady energy source.

Functions of fats

Fats, by all means, are necessary for a lot of things in the body. For example absorption of vitamins such as A, D, E, and K in the body. Fats also store energy, as mentioned already. They insulate the body and protect vital organs. As well as act as messengers, assisting proteins in doing their jobs. More importantly, fats also start chemical reactions involved in immune function, growth, reproduction, and basic metabolic functions.

Sources of fats

Our bodies get fat from foods. For example, foods such as; milk, butter, ghee, nuts, egg yolk, and cooking oils.

image showing fats, fibers, proteins and carbs component of food
fiber, fats, and some other components of food

Recommended daily intake

Nutritionists say an adult needs about 35 grams of fat daily.

Vitamins food component

The vitamins components of food are necessary for healthy growth and functioning of the body. Thus, vitamins are complex organic compounds needed in our diets. The human body can only make two vitamins, namely Vitamins D and K. Other vitamins A, C, E, and B-complex must eaten into our bodies.

Even though vitamins are essential for the normal functioning of the body, they are however only needed in minute quantities. Vitamins do not provide energy, unlike other components like carbohydrates and fats that do.

Classification of Vitamins

Vitamins are divided into two categories, which are;

Water-soluble vitamins

These are vitamins that dissolve in water, for example, Vitamin-C and Vitamin B-complex.

Fat-soluble vitamins

Fat-soluble vitamins are vitamins that are soluble in fat, that is they cannot dissolve in water, but fat. For example Vitamin-K, Vitamin-A, Vitamin-E, Vitamin-D.

Functions of Vitamins

Indeed, vitamins are essential for a lot of things in the body such as good vision, normal growth, good health, healthy teeth and gums, proper digestion, strong bones, and maintenance.

vitamins wheel
A vitamin wheel

Sources of vitamins

Vitamins sources, For examples are meat, milk, liver, eggs, carrots, kale, spinach, poultry, fish, nuts, seeds, vegetable oils, etc

Minerals food component

Minerals arise from non-metals, metals, and their salts from the soil, through plants. Accordingly, plants take these minerals through their roots from the ground and supply them to man and animals via the food chain. Thus, even the minerals gotten from animals, are obtained from the plants, that the animal consumes.

Minerals do not supply energy to our bodies, but they aid the normal functioning of the body. ultimately, the deficiency of minerals in our diets leads to diseases. Examples of some of the essential minerals required in the body are phosphorus, iron, calcium, iodine, potassium, magnesium, etc.

Functions of Minerals

Minerals as components of food aids in the normal functioning of the body, assists in maintaining good health, and proper growth. Furthermore, some minerals are needed to help enzymes work. Most importantly, minerals are necessary for the body to build bones and teeth, coagulation of blood, and the formation of red blood corpuscles.

Sources of minerals

Our diets can be enriched with minerals, through the inclusion of foods rich in minerals. For example, seafood, leafy vegetables, milk, fish salts, etc.

Diseases from the deficiency of some Vitamins and Minerals

Vitamins: Vitamin A
Deficiency Diseases: Night blindness
Symptoms: Loss of vision in darkness, poor vision

Vitamins: Vitamin B1
Deficiency Diseases: Beriberi
Symptoms: Fatigue, Weak muscles, pain

Vitamins: Vitamin C
Deficiency Diseases: Scurvy
Symptoms: Bleeding gums, loose teeth

Vitamins: Vitamin D
Deficiency Diseases: Rickets
Symptoms: Bent bones, teeth deformities

Minerals: Calcium
Deficiency Diseases: Osteomalacia
Symptoms: Weak bones, tooth decay

Minerals: Iodine
Deficiency Diseases: Goitre
Symptoms: Swelling in neck, hoarseness

Minerals: Iron
Deficiency Diseases: Anaemia
Symptoms: General weakness, fatigue


Water is a polar solvent; it is odorless, colorless, and tasteless made up of zero calories and nutrients. Hence it is not considered a food. Furthermore, it is made up of two molecules of hydrogen and one molecule of oxygen.

The human body is two-thirds water, so one can say they are walking on water! Our bodies cannot survive water for an extended period. Water is needed for the normal functioning of the cells, without which they malfunction and die. Water, though not food, plays significant roles in one’s diet. For instance, it helps in digestion and assimilation of food by the body.

Functions of water in the body

Water as a food component has numerous roles to play in our bodies, some of which are:

  • It is a solvent for all the salts present in the body and acts as a medium for biochemical reactions to take place.
  • Water aids in dissolving food nutrients so the body can easily digest them, and also in dissolving waste materials for natural excretion.
  • This polar solvent helps in transporting dissolved food from the digestive tracts to the bloodstream.
  • Furthermore, an essential role of water in our body is the regulation of body temperature.
an image of a boy taking  water
A little boy drinking water

Sources of water in the body

The quantity of water required by the body is dependent on several factors such as; Climate, Age, and Occupation of an individual.

The body gets some of its water from most of the food we consume. For instance, fish, fruits, meat, and vegetables provide a lot of water to the body.

However, the majority of the water component of food required by the body comes from consuming ordinary water, coffee, milk, and tea. Other sources of water in the body comes from the by-product of oxidation of glucose in our food, during digestion. To clarify, one molecule of glucose gives six molecules of water on oxidation.

Recommended daily intake

 Suggested intake is a minimum of 8 glasses per day.

The dietary fiber food component

Dietary fiber, also known as roughage is any fibrous material that is indigestible in our foods. That is, it is indigestible. Roughage as a component of food aids in the prevention of constipation. Also adding bulk to the foods we eat, resulting in the sense of fullness after eating.

Dietary fiber is not classified as a food, as it neither gives energy nor adds anything to our bodies. But, it plays critical roles in balancing one’s diet, as it enables the normal functioning of the digestive system.

In brief, when we consume plants and plant materials, we get cellulose into our body, and our bodies cannot digest cellulose. So it usually remains as an undigested fibrous material passed into the intestine, absorbing water, which creates bulk, to assist the muscles in the intestine push out wastes.

Functions of roughage in the body

Functions of roughage in the body include:

  • Roughage helps in holding water in the body. The water retention ability is due to its fibrous nature, which allows it to absorb and retain water.
  • Dietary fiber prevents constipation by adding bulk to food. And, also by keeping the food on the move in the intestine, as it stimulates muscle contraction, that causes movement of food.

Sources of roughage

The roughage component of food can be added to our diet, by consumption of foods like vegetables, salad, fruits, sprouted grains, and wheat. These provide roughage to our diets, along with other nutrients.

Recommended daily intake

The suggested intake is around 30 grams per day.

SEE ALSO: Health challenges common to Children, Adults, Elderly

Frequently asked questions

What element makes protein different from carbohydrate and fat?

The element nitrogen makes the composition of protein different from carbohydrate and fat.

What are the classes of nutrients?

The classes of nutrients are carbohydrates, proteins, fats, vitamins, and minerals.

How many components of foods are there?

There are seven components of food.

What class of nutrients build tissues and make enzymes?

Proteins are a nutrient class that builds tissues and makes enzymes.

What nutrient class makes up 60% of one’s diet?

Carbohydrates consist of 60% of one’s diet.

What is the difference between fats and carbs?

Fats, provide more energy compared to carbohydrates

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