Environmental biology is one of the critical Biology Topics that involves understanding how humans impact the environment and how to address environmental issues.
Different Components of Food That Provide Nutrients
A substance which is essential for maintaining life and for growth is called a nutrient. Our food has five major nutrients : Carbohydrates, Fats, Proteins, Vitamins and Minerals. In addition to these nutrients, water and roughage (dietary fibre) are also important parts of our food. Water and roughage do not have any food value, so they are not considered to be nutrients. Thus, when we talk of components of food, we mean five nutrients plus water and roughage.
Our food has seven components. These are :
- Roughage (or Dietary fibre)
Each component of food has its own function in the body. We will now discuss all the components of our food in detail, one by one. Let us start with carbohydrates.
Glucose, canesugar (ordinary sugar), and starch are examples of carbohydrates. Carbohydrates provide energy to our body. We eat very little of glucose or canesugar everyday. The main carbohydrate that we eat in our food is starch and it comes from cereals like wheat and rice. Food from wheat is prepared in the form of chapatti (roti), bread and noodles, etc.
Rice is used as such or in the form of dosa and idli. So, when we eat the food items like chapatti (roti), bread, noodles, rice, dosa and idli, etc., then we take starch carbohydrate into our body. And this starch carbohydrate provides energy to our body. Even potatoes which we eat almost everyday in one form or the other, contain a lot of starch carbohydrate.
Some of the common sources of carbohydrates in our food are : Cereals (like Wheat, Rice, Maize, Pearl millet), Potatoes, Sweet potato, Sugar, Jaggery (Grid), and Honey. Fruits like banana, mango, melon and papaya also contain carbohydrates. Please note that the carbohydrates in our food are obtained mainly from plant sources.
Like carbohydrates, fats also provide energy to our body. In fact, fats provide us twice as much energy as that provided by the same amount of carbohydrates. For example, a little butter (which is a fat) provides us much more energy than a large slice of bread (which is a carbohydrate). Butter, ghee, groundnut oil, mustard oil, sunflower oil and coconut oil are the common fats used by us in everyday life. Fats are the richest source of energy but they are more expensive than carbohydrates. Since both, fats as well as carbohydrates provide energy, therefore, the foods containing fats and carbohydrates are called ‘energy giving foods’.
Fats are supplied to our body by many foods such as : Butter, Ghee, Milk, Cheese (Patieer), Oil (Groundnut oil, Mustard oil, Sunflower oil and Coconut oil, etc.), Egg yolk (yellow of an egg), Meat, Groundnut, Cashew, and Soybean. Please note that fats and oils are similar substances, the only difference being that fats are solids at room temperature whereas oils are liquids at room temperature.
Fats can be obtained from plants as well as from animals. Some of the plant sources of fats are : Groundnut oil, Mustard oil, Coconut oil, Sunflower oil, Soyabean oil, Groundnuts, Til and Nuts. And some of the animal sources of fats are : Butter, Ghee, Milk, Cream, Cheese (Paneer), Eggs and Meat.
Proteins supply the body with materials to make new cells which build the body and make it grow. Proteins also give materials which repair the damaged body cells (as that during the healing of wounds). Thus, proteins are needed for the growth and repair of our body. In fact, foods containing proteins are known as body building foods. Children need more proteins than adults (in comparison to their body weight) because of the rapid growth of their body.
The various foods which are rich in proteins are : Milk, Cheese (Patieer), Pulses (Dal), Peas (Matar), Beans, Soyabean, Groundnut, Fish, Meat, Chicken and Eggs. All these are body building foods. The names of some of the pulses (or dais) which contain a lot of proteins are : Bengal gram (Ghana), Black gram (Urad), Green gram (Moong) and Lentil (Masoor). Proteins can be obtained from plants as well as animal foods.
- The foods such as pulses (dal), peas, beans, soyabean, and groundnut are good sources of plant proteins.
- The foods like milk, cheese, fish, meat, chicken and eggs are the main sources of animal proteins.
Most of the food materials usually contain more than one nutrient. However, in a given food material, one particular nutrient may be in much larger quantity than the other nutrients. For example, rice contains much more carbohydrate than fat and protein. So, rice is said to be a carbohydrate-rich food. Similarly, butter is a fat-rich food whereas fish is a protein-rich food.
Vitamins are necessary for good eyesight; healthy teeth, gums and bones ; proper digestion ; normal growth; and good health. In fact, vitamins help in protecting our body against diseases. Though vitamins are needed by our body in very small quantities but their presence is essential in our food.
Many vitamins are known at present. The vitamins are represented by the letters of the alphabet such as A, B, C, D, E and K. In those cases where the same letter is used to represent more than one vitamin, we put the digits 1, 2,…. etc., just after the letter in a little lower position so as to distinguish between them. For example, vitamin B-one is written as vitamin B, and vitamin B-two is written as vitamin B2.
Some of the important vitamins are : Vitamin A, Vitamin Bj, Vitamin B2, Vitamin B6, Vitamin B12, Vitamin C, Vitamin D, Vitamin E and Vitamin K. The vitamins B1, B2, B6 and B12 taken together are known as Vitamin B-complex. Our body needs all these vitamins in small quantities to remain healthy. We will now give the functions of some of the vitamins in our body. We will also give the names of the foods in which these vitamins are present in good amounts.
Vitamin A protects the eyes, skin and hair. So, vitamin A is necessary for good eyesight, healthy skin and hair. The various sources of vitamin A are the foods such as: Milk, Butter, Carrot, Fish liver oil, Eggs, Green vegetables, Mango and Papaya. All these food materials contain good amount of vitamin A.
Vitamin B1 is essential for growth, and proper functioning of the digestive system, heart, nerves and muscles. Vitamin Bj is present in good amounts in the following foods : Milk, Eggs, Meat, Wholegrain cereals (like wheat grains and rice), Potatoes, Yeast and Green Vegetables.
Vitamin C is necessary for keeping teeth, gums and joints healthy. Vitamin C also increases the resistance of our body to infection and helps to fight diseases. Vitamin C is present in : Citrus fruits (such as Oranges, Lime and Lemon), Amla (Indian gooseberries), Tomato,
Guava, and Green vegetables. Actually, almost all the fresh fruits and vegetables contain some vitamin C.
Vitamin D is necessary for the normal growth of bones and teeth. Vitamin D helps our body to absorb calcium mineral from the food. And this calcium makes the bones and teeth hard and strong. Vitamin D is present in foodstuffs such as : Milk, Fish, Egg, Butter and Fish liver oil. Some vitamin D is also made in our body when the skin is exposed to sunlight. In our country, the newborn babies are exposed to sunshine everyday. This is done to produce vitamin D in their body (which prevents a disease called rickets in children).
Our body needs minerals for its proper functioning, normal growth, and good health. Minerals are needed to build bones and teeth; formation of blood; coagulation of blood; and functioning of muscles, nerves and thyroid gland, etc. Minerals are needed by our body in small amounts. Some of the important minerals needed by our body are : Calcium, Phosphorus, Iron, Iodine, Sodium and Potassium. These minerals are used by our body in the form of their salts and not as elements. So, when we talk of ‘minerals’ as a component of food, it actually means ‘mineral salts’. We will now give the functions of some of the minerals in our body. We will also give the names of the foods in which these minerals are found in good amounts.
Calcium and Phosphorus
Calcium is needed for making bones and teeth. Calcium also helps in the proper functioning of heart and other muscles, as well as in the clotting of blood. Children need more calcium than adults in comparison to their body weight because they grow fast and their bones and teeth are to be made largely from calcium salts. Some of the foods which are good sources of calcium are : Milk, Cheese, Eggs, Green leafy vegetables, and Fish. Wheat and rice contain very little of calcium.
Like calcium, phosphorus is needed for the formation of bones and teeth. Some of the sources of phosphorus in our food are : Milk, Pearl millet (Bajra), Banana, Pulses (Dal), and Green leafy vegetables. Milk is one food item which contains both calcium and phosphorus minerals in good amounts. So, we should drink milk daily to get strong bones and teeth.
There is a thyroid gland situated in the neck of our body. It controls the growth of our body. Iodine is essential for the proper functioning of the thyroid gland which controls the growth of the body. Iodine helps thyroid gland to make a hormone which controls growth.
The various sources of iodine in our food are : Sea-food (like Sea-fish), Fruits, Vegetables and Iodised salt (The common salt which contains adequate amount of iodine salts is known as iodised salt). Iodine is also present in drinking water at Figure. Sea-food like sea-fish is a good most of the places (except in hilly areas). source of iodine.
Iron is needed to make haemoglobin present in red blood cells (which carries oxygen from the lungs to the body parts). Thus, iron is an important constituent of haemoglobin in the blood. Please note that iron is used by our body in the form of iron salts and not as iron element. Some of the sources of iron in our food are : Spinach (Palak, Saag), Other green leafy vegetables, Apples, Eggs, Liver, Cereals (like Bajra), Pulses and Groundnuts.
Water is essential for life but it has no ‘food value’ in our body. A person can live without food for several weeks but would die in a few days without water. Water provides a liquid in which other substances can dissolve and move within the body or eliminated from the body. Water is needed by our body :
- to transport digested food to the body cells
- to transport important chemicals such as hormones around the body
- to get rid of waste products from the body
- to control and regulate the temperature of body
Water dissolves the digested food which then passes into blood. Blood is mostly water. Water present in blood transports (carries) the digested food to each and every cell in all the parts of the body. The water in blood also carries chemicals like hormones around the body. Water also dissolves waste products of the body so that they can be removed through urine and sweat (pasina).
Water controls and regulates the temperature of our body by the process of sweating and evaporation. This happens as follows : When the outside temperature is high, water oozes out through the skin in the form of sweat. When this sweat evaporates from our body, it takes the heat required for evaporation from our skin. By losing heat, our skin cools down a little bit and we feel cool and comfortable.
Our body needs about 2 to 3 litres of water everyday. We get most of the water that our body needs by drinking water, milk, tea, coffee, and juice, etc. Many food materials themselves contain some water. The fresh fruits and vegetables also provide us a lot of water. For example, tomatoes, melons, cabbage and lettuce contain a lot of water. We also add water while cooking many food items. This water also goes into our body.
Before we go further and discuss roughage, we should know the meaning of three terms : wholemeal flour products, faeces and constipation. The flour made from the ‘entire wheat grains’ (or whole wheat grains) from which bran is not removed, is called wholemeal flour. Wholemeal flour products include ‘wholemeal chapatti’ and ‘wholemeal bread’.
The ‘waste matter’ remaining in our body after the food has been digested is called faeces. We discharge faeces when we go to toilet. Sometimes the faeces becomes hard and difficult to discharge. The difficulty in discharging hardened faeces from the body is called constipation. Constipation is known as ‘kabz’ in Hindi. Keeping these points in mind, we will now discuss roughage.
7. Roughage (Dietary Fibre)
Roughage is the fibrous matter in food which cannot be digested. Roughage is mainly made of an indigestible carbohydrate called ‘cellulose’, which is present in plant cell walls. Roughage is also called dietary fibre (‘Dietary fibre’ means ‘fibre which can be eaten’). Like water, roughage does not provide any nutrients to our body. Though roughage has ‘no food value’ but its presence is essential in our food. Roughage is needed for the normal working of the digestive system. This happens as follows.
Roughage provides bulk to the food, keeps the food and waste matter (faeces) moving along the intestines and helps to prevent constipation. Roughage is provided mainly by the plant products which we include in our food. Some of the good sources of roughage (or dietary fibre) in our food are : Fruits,
Vegetables and Wholemeal flour products (such as wholemeal chapatti and wholemeal bread). Before we go further and describe the tests for food nutrients such as carbohydrates, fats and proteins.