What is Protein?
Protein is a nutrient whose structure comprises molecules of carbon, hydrogen, oxygen, and nitrogen elements. Apart from these elements, sulfur, zinc, copper, and phosphorus are also present in some proteins. These are the main components of protoplasm and are essential for physical development and various biological activities. According to the chemical composition, proteins are divided into three categories: simple, complex, and derived. Simple proteins are formed by amino acids and complex proteins are formed by combining molecules of some other substances with amino acids. Derived proteins are those proteins that are obtained by the breakdown of simple or complex proteins.
Why is protein important for our physical growth and health?
Proteins play an important role in our body’s development and growth. Proteins are essential nutrients for the development of our skin, blood, muscles, and bone cells. Some essential proteins for the body development of animals are enzymes such as hormones, transport proteins, contractile proteins, structural proteins, and protective proteins. The main function of proteins is to establish the basic structure of the body and to conduct the biochemical activities of the body in the form of enzymes. Proteins also provide us with energy as per requirement. We get about 4.1 calories of heat from the synthesis of one gram of protein. Antibiotics are produced in our body by proteins, which are the body’s immunity power.
Proteins were named by J.J. Mulder in 1840. 20 amino acids are required to make proteins. Plants can prepare all these amino acids in their different parts. Some cells of animals can prepare some of these amino acids, but the remaining amino acids that cannot be prepared by the cells are obtained by animals from their food. These amino acids are called essential amino acids whose scientific names are as follows: leucine, isoleucine, valine, lysine, tryptophan, phenylalanine, methionine, and threonine.
Sources of Protein
Plants prepare the amino acids they need on their own, but animals cannot do so. To fulfill their protein requirement, animals have to take some amino acids from outside in the form of food. The main sources of protein are fruits, dry fruits (nuts), green vegetables, pulses, cereals, meat, fish, eggs, milk, curd, cheese, and liver, which are described in detail below. We can classify protein foods into two parts 1. Vegetarian food, 2. Non-vegetarian food.
Among the foods obtained from plants, soybean contains the highest amount of protein. It contains more than 40 percent protein. Among the foods obtained from animals, chicken breast contains the highest amount of protein. It contains more than 30 percent protein. Boys in the age group of sixteen to eighteen years, weighing 57 kg, require 78 grams of protein daily. Similarly, for girls of the same age group weighing 50 kg, they require 63 grams of protein daily.
Vegetarian sources of Protein
1. Fruits
Fruits are one of the good sources of protein but they do not contain high amounts of protein. Fruits are one of the foods that are consumed the most by people. All fruits contain different amounts of protein, which is shown in the chart below.
| S.No | Fruits | Per 100 gram | Amount of Protein |
| 1 | Guava | 100 g | 2.6 g |
| 2 | Passion fruit (Granadilla) | 100 g | 2.2 g |
| 3 | Avocado | 100 g | 2.0 g |
| 4 | Jackfruit | 100 g | 1.7 g |
| 5 | Pomegranate | 100 g | 1.7 g |
| 6 | Apricots | 100 g | 1.4 g |
| 7 | Blackberries | 100 g | 1.4 g |
| 8 | Raspberries | 100 g | 1.2 g |
| 9 | Nectarines | 100 g | 1.1 g |
| 10 | Kiwi Fruit | 100 g | 1.1 g |
2. Nuts
Nuts are one of the best sources of protein. All nuts contain different amounts of protein. For example: 26 grams of protein is found in 100 grams of peanuts, 20 grams of protein is found in 100 grams of peanut butter, and 21 grams of protein is found in 100 grams of almonds. The protein content in other nuts is shown in the chart below.
| S.No | Nuts | Per 100 gram | Amount of Protein |
| 1 | Peanuts | 100 g | 26 g |
| 2 | Almonds | 100 g | 21 g |
| 3 | Pistachios | 100 g | 20 g |
| 4 | Cashews | 100 g | 18 g |
| 5 | Hazelnuts | 100 g | 15 g |
| 6 | Brazil Nuts | 100 g | 14 g |
| 7 | Walnuts | 100 g | 15 g |
| 8 | Pine Nuts | 100 g | 14 g |
| 9 | Pecans | 100 g | 9.0 g |
| 10 | Coconut | 100 g | 3.3 g |
3. Green Vegetable
Green vegetables, which people like to eat as a salad, are one of the good sources of protein. The chart below shows how much protein we get from green vegetables. The green vegetable with the highest protein content is green peas, which contain about 5 grams of protein per 100 grams of green peas.
| S.No | Green Vegetable | Per 100 gram | Amount of Protein |
| 1 | Green peas | 100 g | 5.0 g |
| 2 | Alfalfa Sprouts | 100 g | 4.0 g |
| 3 | Brussels Sprouts | 100 g | 3.4 g |
| 4 | Corn | 100 g | 3.4 g |
| 5 | Artichoke | 100 g | 3.3 g |
| 6 | Mushroom | 100 g | 3.1 g |
| 7 | Kale | 100 g | 3.0 g |
| 8 | Spinach | 100 g | 2.9 g |
| 9 | Broccoli | 100 g | 2.8 g |
| 10 | Arugula | 100 g | 2.6 g |
4. Beans and Pulses
Beans and pulses are also one of the main sources of protein. They come under the category of legume crops. Many types of beans and pulses are grown which contain different amounts of protein. The chart below shows the types of beans and pulses that contain the highest amount of protein. Among all food items, soybean (36%) contains the highest amount of protein. We must include pulses and beans in our diet to fulfill the protein requirement.
| S.No | Beans and Pulses | Per 100 gram | Amount of Protein |
| 1 | Soya Chunks | 100 g | 36 g |
| 2 | Black Gram | 100 g | 25 g |
| 3 | Pink Lentils | 100 g | 25 g |
| 4 | Kidney Bean | 100 g | 24 g |
| 5 | Green Gram | 100 g | 24 g |
| 6 | Horse Gram | 100 g | 22 g |
| 7 | Pigeon Pea | 100 g | 22 g |
| 8 | Pinto Bean | 100 g | 21 g |
| 9 | Chickpeas | 100 g | 19 g |
| 10 | Lentils | 100 g | 9 g |
| 11 | Black-eyed Pea | 100 g | 8 g |
5. Cereals
Cereals are one of the sources of protein that is consumed by all people. Cereals come under the category of grass family which includes crops like wheat, rice, rye, barley, millet, and maize. All these whole grains contain different amounts of protein which is shown in the chart below.
| S.No | Cereals | Per 100 gram | Amount of Protein |
| 1 | Oats | 100 g | 17 g |
| 2 | Quinoa | 100 g | 16.5 g |
| 3 | Wheat | 100 g | 14 g |
| 4 | Barley | 100 g | 12 g |
| 5 | Sorghum | 100 g | 11 g |
| 6 | Maize | 100 g | 10 g |
| 7 | Millet | 100 g | 6 g |
| 8 | Rye | 100 g | 5 g |
| 9 | Rice | 100 g | 2.7 g |
6. Milk
Milk is one of the best sources of protein. We must include milk in our daily diet. 100 grams of cow’s milk contains 3.4 grams of protein which is very beneficial for our health. Apart from this, we find different amounts of protein in the milk of various animals. Every 100 grams of cow’s milk contains 3.4 grams of protein, buffalo’s milk contains 3.75 grams of protein, goat’s milk contains 3.6 grams of protein and sheep’s milk contains 6 grams of protein.
7. Curd
Curd is a milk product made by bacterial fermentation of milk but still contains more protein than milk. While 100 grams of cow’s milk contains 3.4 grams of protein, 100 grams of yogurt contains 10 grams of protein. This shows how important yogurt is in our diet.
8. Paneer
Paneer (a popular Indian cheese) is another milk product that is one of the best sources of protein. About 100 grams of paneer contains 18 to 20 grams of protein depending on the quality of the paneer. People who are vegetarian and do not eat meat or fish should definitely include paneer in their diet.
Non-vegetarian sources of Protein
1. Meat
Meat is one of the good sources of protein. Meat is the most commonly consumed food by people. It is not only a popular diet among non-vegetarians but is also the best source of protein. About 31 grams of protein is found in 100 grams of chicken breast, which is the second largest source of protein in the whole world. Meat of different animals contains different amounts of protein, like beef has 21 grams, pork has 27 grams and goat meat has 27 grams, etc.
2. Fish
If we talk about protein, then fish and seafood are one of the best sources of protein. There are many types of fish, due to which the amount of protein in different fish varies. If we talk about the fish with the highest protein, then it is tuna fish. About 29 grams of protein is found in 100 grams of tuna fish and 22 grams of protein is found in 100 grams of salmon fish.
3. Eggs
Those who are non-vegetarians and eat meat and fish should definitely consume eggs. About 13 grams of protein is found in 100 grams of eggs, which removes the protein deficiency in our body and maintains health.
4. Liver
