Protein

Man needs a wide range of nutrients to stay healthy and perform various functions. One such important nutrient is protein which is present in the food we eat daily. Proteins are defined as “the basic chemicals that make up the structure of the cells and are essential for growth and repair of tissues”. Proteins are present in every cell and are essential to plant and animal life. They make up about 15% of the mass of an average person.

How do proteins work?

The human body is largely made up of proteins. In fact proteins consitute most of the body’s weight apart from water. They enable the cells in the body to detect and react to hormones and toxins, and form a chief ingredient in antibodies, which help resist infection.

Unlike other nutrients like carbohydrates and fats, protein is used as a source of emergency energy if carbohydrates or fats don’t meet the immediate needs of the body. However, the body does not use protein from food directly. Once it is ingested, the enzymes in the digestive system break down the proteins into separate amino acids, which go into the bloodstream from where it is transported to the cells. The cells incorporate the amino acids and begin building proteins from them. Proteins are present in every cell and tissue proteins promote growth and repair everywhere in the body be it the bones, muscles, tissues, blood or organs.

What do proteins do?

• Proteins are an important constituent of tissues and cells of the body.
• They are an important component of muscle.
• They are the basic building blocks of the body.
• They control vital biochemical reactions in the body.
• Proteins supply body building material and hence are important for growth and tissue repair.
• Proteins are essential to body’s structure and proper functioning.
• Proteins as enzymes promote chemical reactions in the body.
• Proteins as antibodies help the body to defend against infection.

Thus, proteins are vital to the living process and carry out a range of bodily functions.

What are proteins made up of?

Proteins are large, complex molecules made up of smaller units called “amino acids”. Though there are thousands of different proteins required by the body, only 20 amino acids are assembled into these varied proteins. These different types of amino acids can be combined in various ways to form long chains called polypeptides. A few polypeptides are straight, but most are bent into complex three dimensional shapes. The sequence of amino acids determines each protein’s unique 3-dimensional structure and its specific function.

Foods That Contain Protien

Protien is found in abundance in meat, fish, poultry, milk products, grains, beans and nuts. Proteins in foods which have all essential amino acids are known as complete protein. Foods with complete protien include meat – mutton, beef, lamb, pork, poultry, fish, shellfish, eggs, milk, and milk products.

Proteins in food products that do not supply all the essential amino acids is called an incomplete protein. Foods such as grains, fruits, and vegetables are called incomplete protein because they lack one of the essential amino acids. However, such food, when eaten in combination can include all of the essential amino acids and form complete protein. For example, consuming rice, beans, milk and wheat cereal provides complete protein.

However, a combination of incomplete proteins can provide all the amino acids when used judiciously. For example, a cereal grain can be combined with a legume to complement the amino acids lacking in each. However, the two foods must be eaten together to provide the correct balance of amino acids.

Nutrition

Proteins are an essential part of the diet. The recommended dietary intake is one gram per kilogram of body weight per day. So a man weighing 70 kgs must include 70 gms of protein in his diet and a woman weighing 52 kgs must get 52 gms of protein per day. Both children and pregnant and lactating women require higher amounts of protein because of their special conditions.

Insufficient protein in the diet may cause lack of energy, stunted growth and lowered resistance to infections giving rise to a condition called Kwashiorkor. If the diet is very low in calories, the body starts using protein as an energy source and the protein in the muscles is converted into calories. Important muscle mass is lost in this way and leads to weakness. On the other hand, too much protein can also cause problems in people already having liver and kidney problems. Also, if the main source of protein in the diet is from red meats and dairy products high in saturated fats, it can lead to increase in blood cholesterol levels.

Protein deficiency can lead to a number of health problems like loss of muscle mass, lower body immunity, slower growth – particularly in children and adolescents. Protein malnutrition can also lead to the condition known as Kwashiorkor. The lack of specific proteins in the brain may be linked to such conditions like Alzheimer and Creutzfeldt-Jakob diseases.

Excess protein intake the diet can to high cholesterol or other diseases, such as gout. It can strain the kidneys which have breakdown the extra waste matter to be excreted in the urine. Also to counterbalance the excess protein the body requires additional calcium.

Protein requirement

The adult requirement of egg protein is 0.7grams per kilogram body weight, while requirement in terms of mixed vegetable protein is 1.0 gram per kilogram body weight. Children require more protein per unit body weight than adults, because new tissues are being laid down during growth. Likewise, pregnant women and nursing mothers also have increased protein requirements.

Insufficient protein in the diet may cause lack of energy, stunted growth and lowered resistance to infections giving rise to a condition called Kwashiorkor. If the diet is very low in calories, the body starts using protein as an energy source and the protein in the muscles is converted into calories. Important muscle mass is lost in this way and leads to weakness. On the other hand, too much protein can also cause problems in people already having liver and kidney problems. Also, if the main source of protein in the diet is from red meats and dairy products high in saturated fats, it can lead to increase in blood cholesterol levels.

Thus, to sum up, the diet should include a variety of foods to ensure the supply of all amino acids, a healthy balance between calories and proteins should be maintained and healthier choices of protein foods should be made. For example, skim or low fat dairy products should be substituted in place of high fat versions and leaner cuts of meat in place of those containing high saturated fats.

Did You Know?

• Cooking can alter the composition of amino-acid, but it enhances flavour and there isn’t much nutritional loss.
• A can of tuna usually has 20 to 35 grams of protein in a single serving.
• To maintain a healthy body weight, consume 0.5 grams of protein per pound to help you maintain a healthy body weight.
• Protein Deficiency is rare in the U.S.
• Most Americans Consume 50% more protein than needed.
• The Best Protein choices are low in saturated fat.

Healthy Living With Proteins

A balanced diet is good enough for a peson to get adequate protein intake.

• Go for healthier choices in protien be it lean meant or skimmed milk. Nuts, soy, beans, lentils, whole grains are rich sources of protein. They also have fiber and micronutrients, which are both essential and healthy, so ensure that your diet includes all these foods.
• Vegetarains can get all their proteins, if they eat a proper combination of plant proteins so make sure you have a combinatin of grains, lentils, vegetables, fruit and nuts in your diet.
• Don’t go overboard on protein. A high-protein and low saturated fat diet is good for both the heart and the waistline.

References

• What are proteins?
• Learning about Proteins
• What is the function of carbohydrates?
• The Nutrition Source: Carbohydrates
• Medical Encyclopedia: Carbohydrates
• Nutrition Fact Sheet: Protein
• Protein Power