Protein: Importance, RDA for Adults & Pregnant Women, Protein Needs and Functions in the Human Body
Protein is one of the most vital macronutrients required by the human body for survival, growth, maintenance, and overall physiological functioning. Unlike carbohydrates and fats which primarily provide energy, proteins serve as the building blocks of life. Every cell in the body—from skin, hair, muscles, and bones to internal organs and immune cells—contains protein.
Proteins are made up of smaller units called amino acids, often referred to as the building blocks. There are 20 amino acids, out of which 9 are essential, meaning the body cannot synthesize them and must obtain them from diet.
Understanding protein requirements, especially in adults and pregnant women, is crucial for maintaining good health and preventing deficiency-related disorders.
What is Protein?
Protein is a complex organic compound composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. It is an essential nutrient that plays structural and functional roles in the body. Proteins help in formation and repair of tissues, production of enzymes, hormones, antibodies, and various biological molecules.
Proteins differ from fats and carbohydrates because they contain nitrogen, which is necessary for cell growth and regeneration.
Amino Acids: Building Blocks of Protein
Proteins are composed of amino acids, and based on dietary importance they are classified as:
Type of Amino Acid Description Examples
Essential Amino Acids Must be obtained from food Lysine, Methionine, Leucine, Isoleucine, Phenylalanine, Threonine, Tryptophan, Valine, Histidine
Non-Essential Amino Acids Synthesized by the body Alanine, Glutamic acid
Semi-Essential (Conditionally Essential) Required in special conditions like illness, growth Arginine, Glutamine
Types of Protein Based on Source
Source Examples Quality
Animal Protein Eggs, meat, milk, fish, poultry Complete protein (contains all essential amino acids)
Plant Protein Pulses, beans, peas, nuts, seeds Often incomplete (except soy, quinoa), may require combining foods
Examples of complementary plant protein combinations:
• Rice + Dal
• Chapati + Milk
• Peanut + Jaggery
Functions of Protein in the Human Body
Protein performs numerous essential roles:
1. Growth and Repair of Tissues
Required for muscle development, wound healing, and cell replacement.
2. Enzyme and Hormone Formation
Enzymes aid digestion and metabolism; hormones regulate growth, reproduction, mood, etc.
3. Immunity
Antibodies are proteins that defend the body against infections.
4. Structural Role
Proteins like collagen and keratin provide structure to skin, hair, nails, and bones.
5. Transport and Storage
Hemoglobin (a protein) transports oxygen; ferritin stores iron.
6. Maintains Fluid and pH Balance
Proteins regulate acid-base status and prevent fluid leakage from blood vessels.
7. Energy Source (When Needed)
In absence of carbohydrates and fats, protein can be used to provide energy (4 kcal/g).
Protein Requirements (RDA)
RDA = Recommended Dietary Allowance = minimum protein intake required to maintain health.
RDA for Adults
Category RDA (g/day)
Adult Male 60 g/day
Adult Female 55 g/day
RDA for Pregnant and Lactating Women
Physiological State RDA (g/day)
Pregnancy (2nd & 3rd trimester) ~65–75 g/day (approx. +15g to normal)
Lactation (0–6 months postpartum) 75 g/day
Lactation (6–12 months postpartum) 70 g/day
Pregnant women need more protein for:
• Growth of fetus
• Development of uterus, placenta, breast tissue
• Increased maternal blood volume
Protein Needs in Special Conditions
Condition Protein Requirement
Athletes / Bodybuilders 1.2 – 2.0 g/kg body weight/day
Surgery / Injury / Burns Higher protein for healing (up to 2.5 g/kg/day)
Elderly People Slightly increased intake to prevent muscle loss
Best Dietary Sources of Protein
Animal Sources (High Quality)
• Eggs
• Milk and milk products (paneer, cheese)
• Chicken and fish
• Meat
• Yogurt and curd
Plant Sources
• Beans, lentils (dal), chickpeas, rajma, soybeans
• Peanuts, almonds, cashews, walnuts
• Pumpkin seeds, chia seeds, flax seeds
• Quinoa, oats, whole grains
Symptoms of Protein Deficiency
Mild Deficiency Symptoms Severe Deficiency (Kwashiorkor/Marasmus)
Weakness, tiredness Stunted growth
Hair fall, brittle nails Swelling (edema)
Poor concentration Skin depigmentation
Muscle wasting Frequent infections
• Excess Protein Intake: Possible Risks
Although protein is essential, excessive intake can cause:
• Kidney strain
• Digestive issues
• Dehydration
• Increased fat storage if protein is consumed with fats (e.g., red meat)
Moderation is key.
Simple Daily Protein Meal Plan (Indian Diet)
Meal Protein-Rich Options
Breakfast Milk + Oats + Nuts / Eggs / Sprouts
Lunch Rice + Dal + Curd + Green Vegetables
Snacks Roasted chana / Peanuts / Yogurt
Dinner Chapati + Dal/Soya/Paneer + Salad
Tips to Improve Protein Intake
• Include protein in every meal
• Choose healthy plant and animal protein mixtures
• Replace refined grains with whole grains
• Add nuts and seeds to breakfast and snacks
• Include eggs or milk products daily if non-vegetarian options are limited
Conclusion
Protein is essential for maintaining life, supporting growth, building tissues, strengthening immunity, regulating hormones, and repairing cells. Ensuring adequate intake of protein is crucial for adults, pregnant women, children, and individuals with increased physiological needs. A balanced diet containing both plant and animal protein sources can effectively meet daily protein requirements.
Frequently Asked Questions (FAQs)
1. How much protein do adults need daily?
Adult males require about 60 g/day, while adult females need 55 g/day.
2. Why do pregnant women require extra protein?
They need protein for fetal growth, placenta formation, and supporting increased maternal tissue.
3. What are good vegetarian protein sources?
Dal, rajma, chana, peanuts, almonds, quinoa, soy products, and mixed grains.
4. Can protein help in weight loss?
Yes, protein increases satiety and reduces hunger, supporting weight management.
5. What happens if protein intake is too low?
Deficiency can lead to muscle loss, weaker immunity, hair fall, and severe malnutrition disorders
I hope that you liked this article.
Thanks!! 🙏 😊
Writer: Vandita Singh, Lucknow (GS India Nursing Group)