Amino acids

Introduction

Amino acids play many important roles in the body. They are required in necessary processes like building neurotransmitters, proteins and hormones. Amino acid is an organic compound categorized into three types: essential, conditionally essential and nonessential. Amino acids are made of nitrogen, carbon, hydrogen, and oxygen. Every protein has its unique sequence of or chain of amino acids. 

Classification of Amino Acids

Amino acids can be categorised into three types depending on their functions and requirements. 

• Essential amino acids
• Nonessential amino acids
• Conditionally essential amino acids

Essential Amino Acids

The body makes hundreds of amino acids daily, but it cannot make nine. These nine amino acids have to be absorbed by the body through food. They each have their importance and source. The nine essential amino acids are, 

Leucine: This is one of the three Branched-chain amino acids. It is crucial for making protein and growth hormones. Leucine also helps in muscle repair, wound healing, and blood sugar level regulation. 

Isoleucine: This amino acid is also a Branched-chain amino acid concentrated in muscle tissue. It plays a part in the body’s muscle metabolism and immune function. Hence, it also contributes to the production of haemoglobin and energy regulation. 

Methionine : It is vital for metabolism, tissue growth and detoxification. Methionine also helps in absorbing zinc, selenium and many other essential minerals. 

Histidine: This amino acid aids in producing Histamine, a neurotransmitter essential for immune response, digestion, sexual function and sleep-wake cycle. Methionine is also vital for maintaining myelin sheath. 

Threonine: It is integral to the structural protein, collagen and elastin. Collagen and elastin are essential components of skin and connective tissue. Threonine also helps in fat metabolism, immunity, and blood clot functioning.

Phenylalanine: This is required for the production of tyrosine, dopamine, norepinephrine and epinephrine, which are the chemical messengers of the brain. It is also essential for the functioning and producing enzymes, proteins and other amino acids.

Valine: This is the last of the three Branched-chain amino acids. Valine is responsible for muscle growth, making energy and tissue regeneration. 

Tryptophan: It helps in maintaining the nitrogen in the body. Tryptophan also helps make a brain chemical called serotonin, which helps regulate mood, appetite, and sleep.

Lysine: Lysine has several purposes. They include calcium absorption, energy production, immune function, hormone production, enzyme production, collagen, elastin production and protein synthesis. 

Nonessential Amino Acid

The body can produce the nonessential amino acids on its own, so they are not required and necessary for them to be present in food. Some of the nonessential amino acids are:

• alanine
• arginine
• asparagine
• aspartic 
• cysteine
• glutamic 
• glutamine
• glycine
• proline
• serine
• tyrosine

Conditionally Essential Amino Acid

Conditionally essential amino acid is generally unnecessary for the human body except during stress, injury or sickness. Conditionally essential amino acid includes,

• arginine
• cysteine
• glutamine
• tyrosine
• glycine
• ornithine
• proline
• serine

Food sources for Amino Acids

Amino acids are found in many foods. However, all essential amino acids are found in specific foods and are called complete proteins. There are foods with two or three amino acids present, and they can be completed by adding other foods that might have the missing amino acids. Foods that have a few amino acids are called incomplete proteins. 

Sources of complete protein are,

• Meat
• Seafood
• Poultry
• Eggs
• Dairy products
• Whole grains (like brown rice or whole-wheat bread)
• Soy and pea protein
• Sources of incomplete protein are,
• Nuts 
• Seeds
• Vegetables
• Legumes (lentils, peas, and beans). 

Conclusion

Amino acids play an essential part in the human body. An individual must take enough essential amino acids through a proper diet to stay healthy, as this is the only way to get essential amino acids. Conditionally essential amino acid is needed during illness, stress or injury; at this time, the physician might advise the individual to take supplements.

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