To get energy to do work, the human body needs food, which is broken down by the body system and releases energy that can be utilized by the body for functioning. It provides nutrients which are important for us, and if proper food is not taken, it may cause several deficiencies in our body. Now it depends entirely upon us what we eat? If we eat healthy food such as fruits, vegetables, and legumes etc., they provide all the essential components to our body that may be required for metabolism, growth or any other functioning. But if you are eating junk or processed food, whilst it may appeal to you and fill your appetite, it does not result in a healthy body. Unhealthy food may lead to obesity which is the precursor of various diseases such as hypertension, heart disease and diabetes. To live a healthy life, one should consume healthy food and balanced diet.
What is food?
Everything that is edible and can provide us nutrition is food. Food can be obtained from various sources either organic/ inorganic or plants/animals. The major nutrients of food are carbohydrates, proteins, fats/lipids, vitamins, and minerals. What happens when we ingest food? Though this is a simple question, it contains a complex mechanism to convert food into energy, several enzymes and thousands of reactions occur in the body to break down food. This process is simply known as digestion. Different enzymes are present in the body to digest different foods such as lipase for fats, protease for proteins etc.
Plants provide us with fibre, carbohydrates, vitamins and sometimes proteins like legumes and fats from vegetable oils while animal sources are more rich in fats and protein. All of the food components are important for a balanced diet and healthy living.
Protein
Proteins are complex molecules/ macromolecules which are essential for the human body. They are formed by repeated subunits of amino acids by a peptide bond. There are a total of 20 – 22 amino acids that are required by the human body for various functioning. Protein is the only nutrient which contains nitrogen. When 1g of protein is broken down, it releases 4 kcal of energy that can be used by the human body.
Amino acids
Amino acids are the building blocks of protein. They are made from carbon, nitrogen, hydrogen and oxygen. Amino acids are of three types: essential, non-essential and conditional. Essential amino acids are those amino acids that the human body can’t make on its own, therefore it must fulfil this demand by food. They are a total of 9 in number. Non-essential amino acids are those amino acids which are prepared by the body on its own, while conditional amino acids are required by the body during stressed conditions or illness.
Major sources of proteins
Protein can be obtained from various sources such as meat, dairy products, meats, nuts, sea food, legumes, and eggs. Both plant and animal sources are produced by nature to fulfil the protein requirement of body.
Role of protein in human body
Protein plays a variety of roles in the human body such as:
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- Protein helps to develop and repair body tissue such as hair, nail, and skin;
- Proteins are highly important in the immune system because immunoglobulins are made up of protein. They have a role in providing immunity to the body to fight diseases;
- They have a role in transportation and storage of certain molecules;
- Enzymes are made up of proteins and they speed up the chemical reaction;
- Blood, plasma and organs are also made up of protein;
- There are various hormones that are protein in nature that have different function in the human body such as insulin regulates blood sugar, and secretin helps in digestion.
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Actually, protein makes up 20 % of our body!
A protein deficiency in the body leads to muscular pains, dizziness, depression, mood swings and less immunity.
Fat
Fats are commonly known as triglycerides because they consist of three fatty acids and glycerol. As an essential nutrient, fat is required by the human body in small quantities to maintain body functioning and disease prevention. They provide twice more energy than protein because 1g of fat produces 9 kcal energy and helps absorb vitamins – K, E, D, A. Fats are hydrophobic and soluble in organic solvents and insoluble in water.
Types of fats
Fats can be classified in the following categories:
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- Unsaturated fats: Those fats which are liquid at room temperature are known as unsaturated fats. They are good fats because they provide “good cholesterol” to our body and decrease “bad cholesterol” levels. They can be monounsaturated fats and polyunsaturated fats. Monounsaturated fats are found in a variety of plant foods and oils such as olive oil, canola oil, sesame oil, peanut oil and sunflower oil. These fats are good because they provide vitamin E and prevent stroke and heart diseases. Polyunsaturated fats are mostly found in oils like soybean oil, rapeseed oil, flaxseed oil, nuts and fatty fish (salmon, mackerel, and trout). Polyunsaturated fats also decrease “bad cholesterol” and contain essential fatty acids like omega3 and omega 6;
- Saturated fats: Those fats which are solid at room temperature are known as saturated fats. They are mostly obtained from animal sources and a few plants like coconut. Saturated fats provide us with energy. If you eat too much, they raise the “bad cholesterol” level. Major sources of saturated fats are: beef, butter, milk cream, pork fat, chicken fat, and coconut oil;
- Trans fats: They are commonly known as trans fatty acids. They are bad, don’t eat them because they increase the “bad cholesterol” level. Trans fats are blamed for many diseases. Manufacturers create trans fats by a process known as “hydrogenation”. In simple words, hydrogenation is a process by which vegetable oils are solidified by the addition of the hydrogen atom. The major sources of trans fats are: cakes, brownies, cookies, icing, and margarines.
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In our diet we need monounsaturated, polyunsaturated and saturated fats at a ratio of about 1:1:1. In that ratio, we can take fats from variety of sources.
Cholesterol
Cholesterol is aunique type of fat and is produced by mainly animal cells. It is the major component of animal cell membrane and has a main role in maintaining the structural integrity and fluidity of cell membrane. Cholesterol acts as precursor for biosynthesis of bile and hormones.
Cholesterol can be transported in the body via lipoproteins. These lipoproteins can be Low density lipoproteins (LDL) or High density lipoproteins (HDL):
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- HDL is known as “good cholesterol” because it carries cholesterol from the body to liver, which removes cholesterol from the blood.
- LDL is known as “bad cholesterol” because it builds up cholesterol deposits in arteries that may lead to atherosclerosis or narrowing of the arteries. If your body has high LDL concentration, then talk to your doctor and change your lifestyle.
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Cholesterol is a precursor of various biochemical pathways that produces steroid hormones, and vitamin D. The major hormones produced by the human body that are fatty in nature are: cortisol, aldosterone, progesterone, estrogen, and testosterone.
Fats in excess
Fats give more energy but they should be consumed with care else they may cause harm to the body if they are in excess. Very little concentration of fat is required for the body. The rest deposit under skin and in arteries as plaque formation that may block the arteries resulting in stroke, heart failure, and myocardial infraction.
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