Protein

• Protein constitutes at least 50% of our dry weight and is the most abundant organic substance in the body
• The term "protein" was derived from the Greek "proteios", meaning 'of first importance'
• Proteins are essential components of muscle, skin, cell membranes, blood, hormones, antibodies, enzymes, genetic material, and almost all other body tissues and components
• Proteins are made up of chains of amino acids, which are nitrogen-containing compounds
• When 2 or more amino acids link to form a protein, it is the side chain characteristics of the amino acids that determine the protein's specialized function and shape
• There are different classifications of amino acids: essential, nonessential, and conditionally essential
• Proteins play various roles in the body such as transporting substances, providing structure, building hormones, enzymes, antibodies, maintaining fluid balance, promoting acid-base balance, assisting in blood clotting, and providing energy and glucose
• Proteins are important for nutrient transport, muscle contractions, energy source, maintaining healthy skin, hair, and nails
• Protein digestion begins in the stomach and absorption primarily occurs in the jejunum and ileum of the small intestine
• Protein sources include animal (meat, poultry, fish, egg, milk) and plant sources (legumes & nuts)
• Complete proteins contain all essential amino acids, while incomplete proteins lack or contain very low amounts of one or more essential amino acids
• Protein quality is determined by the essential amino acids it provides, its digestibility, and its efficiency in usage by the body
• Protein energy malnutrition (PEM) is a deficiency of protein, energy, or both, including conditions like kwashiorkor, marasmus, and a mix of both
• PEM is most prevalent in poor countries experiencing food insecurity, but can also be found in developed countries among specific populations like the homeless, elderly, and individuals with chronic infections
• PEM can be classified into acute PEM (recent severe food restriction) and chronic PEM (long-term food restriction)
• Marasmus is characterized by severe weight loss and muscle wasting, while kwashiorkor involves edema, fatty liver, and changes in hair color due to protein deficiency
• The combination of marasmus and kwashiorkor results in edema and wasting, often leading to heart failure and infections