Chapter 2 — Food and Nutrition

Why study food and nutrition?
Food and nutrition is the study of what we eat and how the body uses food to maintain life, grow, repair tissues and provide energy for activity. For adolescents, nutrition is especially important because this is a period of rapid physical growth, cognitive development and changing social patterns. Understanding nutrition helps you make practical decisions: what to eat at school, how to prepare balanced home meals, and how to avoid common errors such as skipping breakfast or relying heavily on processed snacks.

Basic definitions
A nutrient is any substance in food that the body uses for growth, energy, tissue repair or regulation of body processes. A diet is the combination of foods a person eats over time. A balanced diet supplies the right amounts of energy and nutrients to keep the body healthy. Malnutrition refers to poor nutritional status resulting from too little or too much of one or more nutrients. Micronutrients are vitamins and minerals needed in small amounts, while macronutrients—carbohydrates, proteins and fats—are needed in larger quantities.

Why it matters for daily life
Nutrition affects stamina, concentration and immunity. A student who eats a nourishing breakfast is more alert in class; an adolescent with adequate iron avoids fatigue and supports learning. Food choices also influence long-term health: excessive intake of energy-dense, nutrient-poor foods can increase the risk of obesity and diabetes, while chronic deficiencies of iron or vitamin A can impair growth and resistance to infections.

Connection to culture and economy
Food habits are shaped by culture, religion and availability. A practical nutrition plan respects those traditions while improving nutrient quality—using local foods, seasonal vegetables and simple cooking techniques to increase nutrient intake. Cost matters too: nutritious meals can be prepared using affordable staples like millets, legumes and seasonal produce. Understanding basic nutrition helps families make cost-effective choices that maximise health per rupee spent.

Approach for this unit
The unit will examine each nutrient group, their functions, food sources and deficiency signs. It will move from science to practice: digestion and absorption, reading food labels, meal planning across life stages, food safety and preservation, assessment methods and common diet-related disorders. You will be asked to practise menu planning, read labels and make small changes at home to improve family nutrition.

Overview of nutrient classification
Nutrition organises nutrients by the amounts needed and by their roles in the body. Two broad categories are macronutrients and micronutrients. Macronutrients—carbohydrates, proteins and fats—are needed in larger quantities because they supply energy and structural material. Micronutrients—vitamins and minerals—are needed in smaller amounts but are essential for enzymatic reactions, immunity and growth. Water and dietary fibre are also essential components even though fibre yields no energy.

Function-based grouping
Nutrients are also grouped by the roles they play: energy-giving, body-building and protective. Energy-giving nutrients (carbohydrates and fats) supply calories required for bodily functions and activities. Body-building nutrients (proteins and minerals such as calcium) help in growth and tissue repair. Protective nutrients (vitamins, minerals and fibre) maintain metabolic balance, protect against infections, and ensure smooth digestion. While useful for planning meals, remember many foods provide nutrients from multiple groups; for example, milk offers protein, fat, calcium and riboflavin.

Macronutrients in detail
Carbohydrates are the main fuel for the brain and muscles. Proteins supply amino acids for enzymes, hormones and structural tissues. Fats are dense energy sources, provide essential fatty acids and help absorb fat-soluble vitamins. The body needs these in varying proportions depending on age, activity and health. Energy needs are commonly expressed in kilocalories (kcal), and each macronutrient contributes a specific calorie per gram: carbohydrates and proteins at about 4 kcal/g, fats at 9 kcal/g.

Micronutrients and their roles
Vitamins are organic compounds that function as coenzymes, antioxidants or regulators of growth; they are classified as water-soluble (B-complex and C) and fat-soluble (A, D, E, K). Minerals are inorganic elements such as calcium, phosphorus, iron, iodine and zinc, necessary for bone health, oxygen transport, thyroid function and immune response. Although needed in small amounts, deficiencies can have serious consequences: iron deficiency causes anaemia, iodine deficiency leads to goitre and cognitive deficits in children.

Water and fibre
Water is the medium for metabolic reactions, helps in temperature regulation and waste removal. Fibre, the indigestible part of plant foods, supports gut motility, acts as a substrate for beneficial gut bacteria and can help control blood glucose and cholesterol levels. Different types of fibre (soluble and insoluble) have distinct physiological effects.

Practical planning implications
For meal planning, use simple food groups: cereals/millets, pulses, vegetables, fruits, dairy, fats/oils and sugars. Aim to include sources from each group daily to cover macronutrients and micronutrients. Consider cultural patterns and availability: combine pulses with cereals to improve protein quality; include green leafy vegetables and citrus fruits to support iron absorption. Understanding classification helps choose balanced, varied and culturally acceptable diets that meet nutritional needs.

What are carbohydrates?
Carbohydrates are organic compounds made of carbon, hydrogen and oxygen. They are the main source of energy for most daily activities and are central to many food patterns. In the body, carbohydrates are broken down to glucose, which is the preferred fuel for the brain and red blood cells. Carbohydrates occur in many forms in foods: simple sugars, disaccharides, starches and dietary fibre. Understanding these types helps make healthier choices.

Types of carbohydrates

• Monosaccharides (simple sugars): include glucose, fructose and galactose. These are absorbed directly into the blood and provide quick energy. Fruits and honey contain monosaccharides.
• Disaccharides: two monosaccharides linked together, examples are sucrose (table sugar), lactose (milk sugar) and maltose. These require digestion to monosaccharides before absorption.
• Polysaccharides: long chains of glucose units such as starch (plant storage form) and glycogen (animal storage form). Starch is found in cereals, roots and tubers and provides sustained energy because it digests more slowly than simple sugars.
• Dietary fibre: structural components of plant cell walls such as cellulose and hemicellulose, resistant starches and certain oligosaccharides. Fibre is not digested by human enzymes but plays important roles in intestinal health.

Functions of carbohydrates
Primary functions include supplying energy (4 kcal per gram) for daily activities and metabolic processes. Carbohydrates have a protein-sparing effect: when enough carbohydrates are available, the body spares protein for growth and repair instead of using it for energy. Carbohydrates also support the storage of energy as glycogen in liver and muscles for short-term needs and exercise. Dietary fibre helps maintain bowel regularity, supports a healthy gut microbiome through fermentation in the colon, and can contribute to lowering blood cholesterol and moderating blood glucose response after meals.

Sources in Indian diets
Cereals such as rice and wheat, millets like ragi and bajra, starchy vegetables like potatoes and sweet potatoes, legumes, fruits and milk are primary carbohydrate sources in Indian cuisine. Refined carbohydrates like white rice, polished wheat flour and sugar provide energy but fewer micronutrients and less fibre. Whole grains and minimally processed foods retain more fibre, vitamins and minerals.

Glycaemic considerations and portion control
The glycaemic index measures how quickly carbohydrate foods raise blood glucose. Foods with high glycaemic index (white bread, refined sugar) produce rapid spikes, while low-glycaemic foods (whole grains, legumes) produce slower, steadier increases. For long-term health, especially to prevent diabetes and obesity, prefer whole grains, combine carbohydrate sources with protein and fat to slow absorption, and control portion sizes to balance energy intake with expenditure.

Practical recommendations
Include cereals or millets at meals but choose whole grain or less-refined options when possible. Pair starchy foods with pulses, vegetables and some fat to improve nutrient balance and reduce the speed of glucose absorption. Limit sugary beverages and snacks; replace them with fruits, nuts or traditional roasted snacks to maintain energy without excess sugar.

What are proteins?
Proteins are complex macromolecules made of chains of amino acids linked by peptide bonds. Each protein’s structure determines its function: structural proteins build tissues, enzymes catalyse metabolic reactions, transport proteins carry molecules, and antibodies protect against pathogens. Proteins are essential for growth, repair and maintaining body systems. The body recycles amino acids but also requires dietary protein to supply essential amino acids that it cannot synthesise.

Amino acids and essentiality
There are about twenty amino acids used to build proteins. Some are considered essential because the body cannot make them; these must be provided by the diet. Non-essential amino acids can be formed in the body. The pattern of essential amino acids in a protein determines its quality. Animal proteins (milk, eggs, meat, fish) generally have a balance of essential amino acids and are called high-quality or complete proteins. Most single plant proteins are limited in one or more essential amino acids but can be complemented by combining foods—e.g., cereals low in lysine but high in methionine can be combined with pulses which are high in lysine—to provide a complete amino acid profile.

Functions of protein
Proteins build and repair body tissues such as muscles, skin, hair and nails. They form enzymes that speed chemical reactions, hormones that regulate physiological functions, and transport molecules like haemoglobin for oxygen transport. Proteins maintain fluid balance between blood and tissues, contribute to immune defence as antibodies, and can be used as a secondary energy source when carbohydrate intake is inadequate (4 kcal/g). Protein needs are higher during periods of rapid growth (childhood, adolescence), pregnancy and lactation, and during recovery from illness or injury.

Protein quality and biological value
Protein quality can be measured by biological value (BV), net protein utilisation and protein digestibility-corrected amino acid score (PDCAAS). These measures consider digestibility and amino acid composition. For practical meal planning, combining cereals and pulses (rice and dal, roti and chana) helps obtain high-quality protein on vegetarian diets. Dairy and eggs provide excellent protein for vegetarians who consume them.

Sources and daily requirements
Good protein sources include pulses, legumes, milk and dairy products, eggs, fish, poultry and lean meat. For adolescent students, recommended protein intake generally ranges from about 0.8–1.2 g per kg body weight depending on activity and growth; specific RDAs vary. Excessive protein intake is rarely needed and may burden the kidneys if sustained over long periods, especially in those with pre-existing kidney disease.

Cooking and protein preservation
Proteins are sensitive to extreme heat and prolonged cooking may reduce digestibility slightly, though normal cooking methods improve safety and make proteins more digestible. Methods like moist heat cooking preserve protein quality and reduce damage; avoid excessive frying that may add unnecessary fats. Combining protein sources with vitamin C-rich foods improves iron availability from plant sources and contributes to overall nutrient absorption.

Why fats are important
Fats, also called lipids, are essential nutrients that supply concentrated energy (9 kcal per gram), provide essential fatty acids, protect organs, insulate against heat loss and support absorption of fat-soluble vitamins A, D, E and K. Fats are components of cell membranes and are involved in hormone synthesis and signalling pathways. However, all fats are not equal; quality and quantity matter for long-term health.

Types of fatty acids

• Saturated fatty acids are mainly found in animal fats (ghee, butter, fatty meat) and some tropical oils (coconut oil, palm oil). They are generally solid at room temperature. High intake of saturated fats is associated with raised LDL (“bad”) cholesterol and increased cardiovascular risk.
• Unsaturated fatty acids include monounsaturated and polyunsaturated fats found in vegetable oils (mustard, sunflower, soybean), nuts and seeds. These fats can help maintain healthy blood lipid profiles when they replace saturated fats in the diet.
• Polyunsaturated fats include omega-6 (linoleic acid) and omega-3 (alpha-linolenic acid) fatty acids. Omega-3s, found in flaxseed, walnuts and fish, are important for brain and cardiovascular health.
• Trans fatty acids are produced by industrial hydrogenation and are found in some bakery goods, margarine and fried snacks. Trans fats raise LDL cholesterol and lower HDL (“good”) cholesterol and should be avoided.

Functions of fats
Besides energy provision, fats are essential for absorption of fat-soluble vitamins, provide essential fatty acids required for cell function and nervous system health, and contribute to taste and satiety in meals. Fats are stored in adipose tissue and act as a reserve energy source during fasting or prolonged exercise.

Healthy choices and cooking tips
Prefer oils high in unsaturated fats and low in trans fats. Use mustard, soybean, groundnut or sunflower oil for daily cooking and include sources of omega-3 such as flaxseed, walnuts or fish where culturally appropriate. Limit deep-fried foods and commercially prepared snacks that may contain hidden trans fats. For high-heat cooking choose oils with suitable smoke points and avoid repeatedly heating oils. Replace visible fat with healthier options: use curd or mashed vegetables instead of cream in some recipes, and choose lean cuts of meat or remove excess fat before cooking.

Balancing fat intake
Fat is energy-dense; controlling portion size is important to prevent excess energy intake and weight gain. Aim to obtain fats mostly from plant oils, nuts, seeds and fish, and restrict saturated fat sources such as ghee and fatty meats. During growth and active periods, moderate fat supports energy needs; for sedentary lifestyles, reduce fat-rich foods and focus on nutrient-dense choices.

Understanding vitamins
Vitamins are organic compounds required in small amounts to regulate various biochemical processes. They do not provide energy directly but are essential for growth, immunity, wound healing and maintenance of tissues. Vitamins are classified by solubility into water-soluble (B-complex and vitamin C) and fat-soluble (A, D, E, K) groups. Each vitamin has specific roles, deficiency signs and food sources.

Water-soluble vitamins

• Vitamin C (ascorbic acid) acts as an antioxidant, helps collagen synthesis, improves iron absorption and supports immunity. It is abundant in citrus fruits, guava, amla, tomatoes and green chillies. Deficiency leads to scurvy—bleeding gums, poor wound healing and weakness.
• B-complex vitamins include B1 (thiamine), B2 (riboflavin), B3 (niacin), B6, B12, folate and others. They play diverse roles in energy metabolism, synthesis of red blood cells, nerve function and DNA synthesis. Sources include cereals, pulses, green leafy vegetables, milk and animal foods; B12 is mainly in animal products and must be supplemented or obtained through fortified foods for strict vegetarians.

Fat-soluble vitamins

• Vitamin A (retinol and provitamin A carotenoids) is essential for vision, growth and immunity. Foods rich in vitamin A include liver, milk and egg yolk; provitamin A carotenoids are abundant in orange-coloured fruits and vegetables (carrot, pumpkin, mango) and dark green leafy vegetables.
• Vitamin D helps calcium absorption and bone mineralisation. The skin synthesises vitamin D on exposure to sunlight; dietary sources include fortified milk, fish and egg yolk. Deficiency causes rickets in children and osteomalacia in adults.
• Vitamin E is an antioxidant protecting cell membranes; found in vegetable oils, nuts and seeds. Vitamin K is important for blood clotting and bone health; sources include green leafy vegetables and some vegetable oils.

Deficiency and excess
Vitamin deficiencies produce characteristic signs—night blindness for vitamin A, scurvy for vitamin C, beriberi for thiamine deficiency and neural tube defects with folate deficiency in pregnancy. Fat-soluble vitamins can accumulate and cause toxicity if taken in large supplemental doses; therefore supplementation should follow medical guidance, especially for vitamins A and D. Water-soluble vitamins are less likely to reach toxic levels but still require caution with high-dose supplements.

Improving vitamin intake
Use a variety of foods: include fruits and vegetables of different colours daily to cover vitamin A and C; include dairy, eggs or fortified foods for B vitamins and vitamin D; cook vegetables with minimal water and short times to preserve heat-sensitive vitamins like vitamin C and some B vitamins. Food fortification (iodised salt, fortified flour, vitamin D fortified milk) is a public health tool to reduce deficiencies in populations.

What are minerals?
Minerals are inorganic elements that perform structural and regulatory functions in the body. They are classified as macrominerals (needed in larger amounts) and trace minerals (needed in minute quantities but essential). Important macrominerals include calcium, phosphorus and magnesium; key trace minerals include iron, iodine, zinc, selenium and copper. Each mineral has specific roles, and imbalances affect health and development.

Calcium and phosphorus
Calcium is essential for bone and teeth formation, blood clotting, nerve conduction and muscle contraction. Dietary sources include milk, curd, paneer, small fish with bones, sesame seeds and leafy greens. Phosphorus works with calcium in bone mineralisation and is present in many foods including cereals, dairy and meat. A proper calcium-to-phosphorus ratio supports bone health. Adolescents need higher calcium during growth spurt years.

Iron
Iron is needed for haemoglobin formation and oxygen transport. Dietary iron exists as heme iron (in animal foods) which is more bioavailable, and non-heme iron (in plant foods) which is less easily absorbed. Good sources include red meat, liver, fish, pulses, green leafy vegetables, jaggery and fortified cereals. Vitamin C enhances non-heme iron absorption, while phytates, tannins and calcium can inhibit it. Iron deficiency causes anaemia, leading to fatigue, poor concentration and weakness—common in adolescent girls due to menstrual blood loss.

Iodine and zinc
Iodine is required for thyroid hormone synthesis which regulates metabolism and growth. Iodised salt is the primary prevention tool against iodine deficiency disorders, which include goitre and impaired cognitive development in children. Zinc supports growth, wound healing and immune function; sources are meat, pulses, nuts and dairy. Zinc deficiency can impair growth and immunity, particularly in children.

Magnesium, selenium and others
Magnesium is needed for enzyme activity, nerve conduction and muscle function; sources include nuts, seeds, green leafy vegetables and whole grains. Selenium is an antioxidant mineral found in nuts (especially Brazil nuts), cereals and fish. Copper and manganese play roles in enzyme systems and connective tissue formation. Though required in small amounts, their deficiencies or excesses can be harmful.

Bioavailability and improving mineral uptake
The amount of a mineral in food does not always equal the amount absorbed; bioavailability is affected by food matrix and interactions. Phytates in whole grains and legumes bind minerals and reduce absorption; simple household methods like soaking, sprouting, fermentation and cooking can reduce phytates and increase availability. Combining iron-rich plant foods with vitamin C-rich fruits or vegetables elevates iron absorption, while separating high-calcium foods from iron-rich meals may assist iron uptake when needed.

Practical planning
For adolescents, ensure dietary variety to meet mineral needs: include dairy or calcium-rich plant sources, pulses and green leafy vegetables for iron and zinc, iodised salt for iodine, and nuts/seeds for magnesium and selenium. Use fortified foods where appropriate and follow public health supplementation programmes to prevent widespread deficiencies.

The role of water
Water is the most essential nutrient; the human body cannot store large amounts and needs regular intake to sustain life. It provides the medium for biochemical reactions, aids digestion and absorption, transports nutrients and wastes, regulates body temperature through sweating and respiration, lubricates joints and cushions organs. Water balance depends on intake, losses through urine, sweat, respiration and stool, and on environmental and activity factors. Adolescents, especially those who play sports or live in hot climates, must increase fluid intake to avoid dehydration.

Daily water requirements
Daily needs vary by age, sex, body size, activity level and climate. A rough guideline is 30–40 ml per kg body weight from all sources (plain water, beverages and water contained in foods). Foods like fruits, vegetables, soups and milk contribute to total water intake. Encourage sipping water throughout the day rather than consuming large volumes infrequently, and increase fluids during illness, fever or heavy physical exertion.

Dehydration: signs and prevention
Mild dehydration leads to thirst, dry mouth, decreased urine output, headache and reduced concentration—important considerations for students. Severe dehydration can cause dizziness, rapid pulse and heat-related illnesses. Prevent dehydration by drinking water regularly, avoiding excess caffeinated sugary drinks that may promote fluid loss, and replacing electrolytes during prolonged sweating with appropriately salted beverages or oral rehydration solutions when indicated.

Dietary fibre: types and actions
Dietary fibre is the indigestible part of plant foods and comprises soluble and insoluble fractions. Soluble fibre (found in oats, apples, beans) dissolves in water to form a viscous gel that slows gastric emptying and glucose absorption, helps lower blood cholesterol and supports beneficial gut bacteria. Insoluble fibre (found in wheat bran, vegetable skins, whole grains) adds bulk to stool, speeds intestinal transit and helps prevent constipation. Both types contribute to satiety, aiding weight control by reducing overeating.

Health benefits of fibre
Fibre supports regular bowel movements, reduces the risk of haemorrhoids and constipation, and contributes to a lower risk of colorectal cancer. Soluble fibre helps regulate blood glucose, which is important in diabetes management, and can lower LDL cholesterol, protecting heart health. Fibre-rich diets also promote a healthy gut microbiome that produces short-chain fatty acids beneficial for colon health and systemic metabolism.

Sources and practical tips
Include whole grains (brown rice, whole wheat, millets), legumes, fruits (with skins where edible), vegetables and nuts for fibre intake. Increase fibre gradually to prevent bloating and ensure sufficient water intake to aid fibre function. For students, replace polished cereals and refined snacks with wholegrain options and fruit snacks. Simple changes—like choosing chapati made from whole wheat, eating fruit instead of sweet biscuits, and adding lentils and vegetables to meals—can raise fibre intake significantly.

Purpose of digestion
Digestion is the process by which foods are broken down into smaller units that the body can absorb and use. It includes mechanical actions (chewing, grinding) and chemical actions (enzymes and acids) that transform complex carbohydrates, proteins and fats into absorbable molecules—monosaccharides, amino acids and fatty acids respectively. Understanding where and how digestion occurs helps explain why certain foods need particular preparation and why some conditions (e.g., lactose intolerance) affect diet choices.

Major stages of digestion

• Mouth: Mechanical digestion begins with chewing, which increases food surface area. Salivary glands secrete saliva containing salivary amylase that starts starch digestion to maltose and dextrins. Well-chewed food forms a bolus that is easier to swallow and digest.
• Oesophagus and stomach: The bolus travels through the oesophagus by peristalsis into the stomach. The stomach’s acidic environment (hydrochloric acid) denatures proteins and activates pepsin, a protease that begins protein breakdown into peptides. The stomach also churns food to mix it with gastric juices, producing chyme. Some absorption occurs for water, alcohol and certain drugs, but most nutrient absorption awaits the small intestine.
• Small intestine: The duodenum, jejunum and ileum are the main sites for digestion and absorption. The pancreas secretes digestive enzymes—pancreatic amylase continues carbohydrate digestion, proteases (trypsin, chymotrypsin) digest proteins into peptides and amino acids, and pancreatic lipase digests triglycerides into monoglycerides and free fatty acids. Bile from the liver emulsifies fats to increase surface area for lipase action. Intestinal brush-border enzymes (maltase, lactase, sucrase, peptidases) complete digestion into monosaccharides and amino acids which are then absorbed through enterocytes into the blood or lymph.
• Large intestine: The colon absorbs water and electrolytes, forming semi-solid stool. Gut bacteria ferment some undigested carbohydrates and fibre, producing short-chain fatty acids that are used locally by colon cells and may provide metabolic benefits. The large intestine also houses a complex microbiota important for immunity and nutrient metabolism.

Absorption specifics
Carbohydrates are absorbed as monosaccharides (glucose, fructose, galactose) via transporters in the intestinal mucosa; proteins are absorbed as amino acids and small peptides; fats are absorbed as fatty acids and monoglycerides, reassembled into triglycerides and transported in chylomicrons via the lymphatic system. Water-soluble vitamins and minerals are absorbed at various sites; fat-soluble vitamins require dietary fat for efficient absorption.

Factors affecting digestion and absorption
Chewing thoroughly, eating balanced meals, and including some fat with fat-soluble vitamin-rich foods improve digestion and nutrient uptake. Antinutrients like phytates and tannins reduce mineral absorption; techniques like soaking, fermenting, sprouting and combining foods (vitamin C with iron-rich foods) enhance bioavailability. Conditions such as pancreatic insufficiency, celiac disease, or infections can impair digestion and require dietary adjustments or medical treatment.

Practical tips
Encourage slow, mindful eating to aid digestion, include fibre for bowel regularity, and combine foods sensibly to enhance nutrient absorption—e.g., pairing vitamin C sources with iron-rich plant foods. Recognise symptoms like bloating, persistent diarrhoea or unexplained weight loss as signals to seek medical advice.

Why focus on local foods?
Nutrition education is most effective when it is grounded in familiar foods and customary recipes. Indian cuisines are diverse, with cereals, millets, pulses, vegetables, fruits, dairy, legumes, fish and meat contributing to nutrient intake. Understanding the nutrient composition of these common foods helps plan balanced meals that respect taste, cultural practices and availability while meeting nutritional needs.

Cereals and millets
Cereals such as rice and wheat are major carbohydrate sources in Indian diets and provide some protein and B vitamins. Millets (ragi, bajra, jowar) are traditional crops with higher fibre, calcium (especially ragi), iron and B vitamins compared to refined cereals. Whole grains retain bran and germ that supply fibre and micronutrients; polished grains lose much of these nutrients. Integrating millets in chapatis, porridges or dosa batters increases nutrient density.

Pulses and legumes
Pulses (toor, moong, masoor, chana) are primary vegetarian protein sources and also provide carbohydrates, fibre, vitamins and minerals. They are rich in lysine but low in methionine; combining them with cereals like rice and wheat complements amino acid profiles to form complete proteins. Sprouting pulses enhances protein digestibility and vitamin content and reduces antinutrients that impede mineral absorption.

Vegetables and fruits
Vegetables and fruits are crucial protective foods providing vitamins A and C, folate, potassium and fibre. Leafy greens (spinach, methi) are good sources of iron, calcium and vitamin A precursors. Orange-coloured vegetables and fruits (carrot, pumpkin, mango) supply beta-carotene. Seasonal fruits are important for vitamin C and variety. Cooking methods matter: steaming or light sautéing preserves vitamins better than long boiling.

Dairy, eggs, fish and meat
Dairy products (milk, curd, paneer) provide high-quality protein, calcium and riboflavin. Eggs are nutrient-dense offering complete protein, iron and fat-soluble vitamins. Fish and lean meats supply high-quality protein and bioavailable iron and zinc. For populations with limited animal foods, attention to combining plant sources, using iron absorption enhancers (vitamin C) and possibly fortified foods is important to meet micronutrient needs.

Nuts, seeds and oils
Nuts and seeds (almonds, peanuts, sesame) supply healthy fats, vitamin E, minerals and some protein. Traditional oils like mustard, groundnut and coconut vary in fatty acid profiles; mustard and groundnut oils are higher in unsaturated fats, while coconut oil is higher in saturated fats. Choosing oils and portion sizes wisely helps balance energy and fatty acid intake.

Practical food composition use
Maintain a simple chart of nutrient-dense, affordable local foods and their major nutrients. Use this chart when planning meals: ensure at least one green vegetable, one protein source (milk, dal, egg), a cereal or millet and fruit daily. Seasonal and local choices often provide better nutrient value and are cost-effective. Small changes—replacing polished rice with brown or adding a small bowl of curd—can improve nutrient intake substantially.

What is meal planning?
Meal planning is the process of selecting foods and organising meals so that they meet nutrient needs, suit family preferences and fit within time and budget limits. Effective planning ensures variety, balance and moderation across days and weeks. For adolescents, planning should address higher needs for energy, protein, calcium and iron as well as practical considerations like school schedules and physical activity.

Core principles

• Variety: Choose different foods across food groups and within a group to ensure a broad spectrum of nutrients and to prevent monotony. Rotate cereals, millets, pulses, vegetables and fruits through the week.
• Balance: Each day should include energy-giving (cereals, fats), body-building (proteins—milk, dal, eggs) and protective (fruits, vegetables, vitamins/minerals) foods in appropriate proportions.
• Moderation: Limit foods high in added sugars, saturated fat and salt. Portion control helps avoid excess energy intake leading to overweight.
• Suitability: Adapt meals to age, activity level, cultural practices, health conditions and budget. For example, active adolescents may need larger portion sizes and more frequent snacks.
• Palatability and acceptability: Food should be acceptable in taste and culturally appropriate to ensure adherence. Use spices and familiar recipes to make healthy changes acceptable to family members.

Steps to plan meals

• Assess nutrient and energy needs based on age, sex, activity and any health conditions.
• Select foods from each major food group to meet those needs; ensure sources of protein, iron, calcium and vitamins are included.
• Decide menu patterns—breakfast, mid-morning snack, lunch, evening snack and dinner—with portion sizes and preparation methods chosen to preserve nutrients.
• Consider convenience, storage and cost. Use seasonal produce and bulk cooking to save time and money.
• Review and adjust: monitor acceptance and actual intake, and modify menus to address gaps or preferences.

Practical tools and tips
Use the daily food group approach (cereals/millets, pulses, vegetables, fruits, milk/dairy, fats, sugar) with recommended number of servings from each group. Prepare a weekly menu including simple equations such as ‘one cereal + one pulse + one vegetable + one milk/dairy’ for each main meal to guide choices. Encourage nutrient-dense snacks—fruit, nuts, roasted chana—instead of processed packaged snacks. Include at least one green leafy vegetable and one source of vitamin C each day to support iron absorption. For students, emphasize breakfast and portable, nutritious tiffins that combine carbohydrate, protein and fibre to sustain energy and concentration.

Adapting for budgets and time
Affordable nutritious meals can be planned using local staples: combine rice with seasonal vegetables and dal, include eggs when possible, use milk for calcium, and prepare legumes in bulk. Minimal processing (soaking, sprouting) increases nutrient availability and reduces cooking time. Batch-cook soups, stews and khichdi to cover multiple meals and preserve nutrients carefully for safe consumption.

Adolescence: growth and special needs
Adolescence is a period of rapid physical and hormonal changes, requiring increased energy, protein, calcium and iron. Boys often need extra calories for lean body mass gain, while girls need more iron due to menstrual blood loss. Meal plans should prioritise nutrient-dense foods: milk and dairy for calcium, pulses and eggs for protein, green leafy vegetables and citrus fruits for iron and vitamin C. Encourage regular meals and healthy snacks to meet increased requirements rather than large single meals.

Pregnancy and lactation
Pregnant women need additional energy (depending on activity and trimester), more protein, iron, folic acid and calcium to support foetal growth and milk production. Meal plans should include extra servings from cereals, pulses, milk, fruits and vegetables. Folic acid before and during early pregnancy reduces neural tube defect risk. Frequent small meals help manage nausea. Iron supplementation is often recommended to prevent maternal anaemia. Lactating mothers need higher energy and fluid intake; nutrient-dense snacks and continued iron/calcium-rich foods are important.

Infants and young children
Infants have high nutrient needs relative to body size. Exclusive breastfeeding is recommended for the first six months, followed by appropriate complementary feeding with nutrient-dense semi-solids while continuing breastfeeding. Complementary foods should be safe, age-appropriate in texture, and given frequently in small amounts. Use locally available nutrient-dense foods—mashed lentils, mashed vegetables, fruit purees—and avoid added sugar or salt for young infants.

Elderly individuals
Older adults may have lower energy needs but unchanged or increased requirements for some nutrients such as protein, calcium and vitamin D. Dentition issues, reduced appetite and digestive changes mean meals should be nutrient-dense and easy to chew or swallow. Small, frequent meals and snacks rich in protein (milk, curd, paneer), soft cooked vegetables, and fortified foods may be helpful. Hydration is also crucial due to reduced thirst sensation.

Special needs and medical conditions
Conditions like diabetes, hypertension, renal disease and food allergies require tailored meal planning. For diabetes, focus on consistent carbohydrate intake, portion control and whole grains; for hypertension, reduce salt and saturated fat and increase potassium-rich vegetables and fruits. Food allergies demand strict avoidance of allergens and careful label reading. For malnourished children, therapeutic feeding regimes and nutrient-dense diets are prescribed under health professional guidance.

Practical planning steps
Assess individual needs—age, sex, activity level, medical status—then select appropriate food groups and portion sizes. Account for cultural preferences and affordability by using local foods. Monitor acceptance and health outcomes and adapt plans accordingly. Use fortified foods and supplements where recommended by health programmes or clinicians, such as iron-folic acid supplementation for pregnant women or vitamin D for those at risk of deficiency.

Why food hygiene matters
Food hygiene and safety are crucial to prevent food-borne illnesses caused by bacteria, viruses, parasites and toxins. Unsafe food handling can cause outbreaks that affect individuals and communities, leading to stomach upset, dehydration, hospitalisation and in severe cases death. Students and home cooks must learn practical steps to keep food safe from purchase to plate.

Common pathogens and hazards
Pathogens such as Salmonella, E. coli, Staphylococcus aureus, and norovirus contaminate foods through contaminated water, improper cooking, poor personal hygiene, or cross-contamination between raw and cooked foods. Chemical hazards (pesticide residues, adulterants) and physical hazards (stones, glass) also pose risks. Recognising hazards helps apply proper preventive measures during food handling and storage.

Key safe practices

• Personal hygiene: Wash hands with soap before food preparation and after handling raw foods, using the toilet or touching pets. Keep nails short and avoid jewellery while cooking.
• Cleanliness of environment and utensils: Keep kitchen surfaces, cutting boards and utensils clean. Sanitize boards used for raw meat after use to avoid cross-contamination.
• Safe cooking: Cook foods thoroughly—especially meat, eggs and poultry—to recommended internal temperatures to kill microbes. Reheat cooked food to a rolling boil or adequate temperature.
• Separation: Store raw foods separately from ready-to-eat foods. Use different cutting boards for raw and cooked items where possible.
• Proper storage: Refrigerate perishable foods promptly at or below 5°C and keep hot foods above 60°C if they are to be served later. Do not leave cooked rice or other perishables at room temperature for long, which encourages Bacillus cereus and other bacteria to grow.

Water safety and washing produce
Use safe drinking water for cooking and washing raw vegetables and fruits. For produce that will be eaten raw, wash under running water and peel where appropriate. Soaking leafy greens in clean water and discarding the wash water can reduce surface contaminants. When in doubt about water quality, use boiled or bottled water for preparation of infant feeds and ready-to-eat items.

Food handling at functions and school
Temperature control during transport and service is important: use insulated containers and avoid long intervals between cooking and consumption. For tiffins, include ice packs for perishable items in hot weather if refrigeration is not possible. Teach food handlers about safe intervals for leaving cooked food at room temperature—generally no more than 2 hours in warm climates.

Recognising spoilage and safe disposal
Spoilt foods often show off-odours, slimy texture, visible mould or discolouration and should be discarded. Avoid tasting suspicious food to check safety. For leftovers, store promptly in clean, shallow containers to cool quickly and consume within 24–48 hours depending on the food and storage conditions. Educate family members about label dates: understand ‘use by’ (safety) vs ‘best before’ (quality) distinctions.

Food safety education and community role
Schools can teach and demonstrate safe hygiene through practical sessions on handwashing, safe cooking and storage. Communities should promote access to safe water, sanitation and proper waste disposal to reduce the risk of food-borne illnesses. Simple consistent habits—regular handwashing, clean utensils and correct storage—prevent most food-related illnesses and protect vulnerable groups such as young children and the elderly.

Purpose and principles
Food preservation aims to extend shelf life, reduce wastage and maintain an adequate supply of food beyond harvest or market availability. Preservation works by slowing or halting the growth of microbes, reducing enzymatic spoilage and preventing oxidation. Common household and traditional methods are practical for students to learn: drying, salting, pickling, fermentation, refrigeration and canning. Each method has advantages and limitations regarding nutrient retention, safety and cost.

Drying and dehydration
Drying removes water that microbes and enzymes need to grow. Sun-drying and oven or mechanical drying are traditional and modern approaches. Sun-drying fruits (mango slices, banana chips), vegetables and pulses is economical but requires hygienic conditions to prevent contamination. Proper drying reduces weight and volume for storage and transportation. However, some heat-sensitive vitamins, e.g., vitamin C, are lost during drying.

Fermentation
Fermentation uses beneficial micro-organisms (lactic acid bacteria, yeasts) to preserve food and often improve flavour and digestibility. Examples include curd, idli/dosa batter, pickles and fermented soy products. Fermentation can increase vitamin content (B vitamins), reduce antinutrients such as phytates, and add probiotic benefits that support gut health. Ensure clean equipment and controlled fermentation times to avoid spoilage organisms.

Salting, smoking and sugaring
Salting draws water out of foods by osmosis, inhibiting microbial growth; it is used for fish, meats and some vegetables. Smoking adds flavour and reduces surface microbial activity. Sugaring (jams, syrups) preserves fruit by creating high osmotic pressure that inhibits microbial growth. While effective, these methods often increase sodium or sugar content and should be balanced with health considerations.

Pickling and acidification
Pickling preserves vegetables and fruits using acetic acid (vinegar) or lactic acid from fermentation plus salt and spices. Acidic environments prevent many spoilage organisms. Follow tested home recipes and hygiene practices to prevent botulism and ensure safety, especially with low-acid vegetables requiring heat treatment or proper vinegar concentration.

Cold storage (refrigeration and freezing)
Cooling slows microbial growth and enzyme activity. Refrigeration extends shelf life for perishable items such as milk, cooked meals and fresh produce when kept below about 5°C. Freezing halts microbial growth and preserves food for longer periods, although repeated thawing and refreezing can degrade quality and safety. Blanching vegetables before freezing preserves colour and some nutrients by inactivating enzymes.

Canning and heat processing
Canning uses heat to destroy microbes and seals food in sterile containers to prevent recontamination. Pressure canning is needed for low-acid foods to prevent botulinum toxin. Pasteurisation reduces microbial load in milk and juices and increases safety. High-heat methods can reduce heat-sensitive vitamins, so balance safety and nutrient retention by using minimal effective heat.

Modern methods and household considerations
Vacuum packing and controlled atmospheres reduce oxygen and slow oxidation and microbial growth. For household preservation, cleanliness, correct salt/sugar ratios, adequate heat treatment and proper storage containers are essential. Consider nutrient trade-offs: fermentation can improve bioavailability, while some heat methods reduce vitamin C. Educate families on safe home canning and storage techniques, avoiding ad-hoc preservation that may compromise safety.

Importance of food labels
Food labels are tools that give consumers essential information about what is inside packaged foods, how to store them and whether they are safe to eat. Informed reading of labels helps families choose healthier options, avoid allergens, and understand portion sizes. For students, learning to interpret labels supports better snack choices and can be a practical skill to carry into adulthood.

Key components of a label

• Product identity and net quantity: The name of the product and net weight or volume tell what the item is and the amount per package.
• Ingredients list: Ingredients are listed in descending order by weight. This helps identify dominant ingredients and potential allergens (nuts, milk, soy, wheat).
• Nutrition information: This usually shows energy (kcal), protein, carbohydrate (with sugars), fat (with saturated and trans fats), sodium (salt) and sometimes fibre and selected vitamins/minerals per serving or per 100 g. Compare similar products by standardising to per 100 g to evaluate nutrient density.
• Allergen declaration and additives: Many labels highlight common allergens and list preservatives, colourings or flavour enhancers. Be cautious if an individual has food allergies.
• Dates and storage: ‘Best before’ indicates quality; ‘use by’ indicates safety. Storage instructions (refrigerate after opening) guide safe handling.

How to use labels wisely
When comparing products, look for lower saturated fat, trans fat, added sugar and sodium. Prefer items with higher fibre and protein where appropriate. Check serving size: manufacturers may present small serving sizes to make nutrient numbers seem lower. For children’s snacks, choose options with less added sugar and salt and more wholegrain or nut content. Fortification claims (iron-fortified, vitamin D added) can be helpful for populations at risk, but fortified products are not a substitute for a varied diet.

Deceptive claims and marketing
Health claims such as ‘low fat’, ‘multigrain’ or ‘natural’ may be misleading. ‘Multigrain’ does not mean whole grain; the product may still contain refined flours and high sugar. Always read the ingredients and nutrition panel to verify claims. Labels with long lists of unfamiliar additives should be approached cautiously.

Practical classroom exercise
Teach students to collect labels from common snacks and beverages and compare them using a checklist: serving size, energy per 100 g, sugar, saturated fat, trans fat and sodium. Calculate how much of a nutrient a typical child would consume from a usual portion and decide if it fits into a healthy daily plan. This exercise builds numeracy and awareness about healthier substitutes.

Consumer rights and food safety marks
Be aware of food safety and quality marks where relevant and know how to check expiry dates. Consumers also have a right to safe and correctly labelled food; reporting adulteration or false labelling to local authorities helps protect the community. Encourage families to buy from reputable sources and store packaged foods according to label instructions.

Understanding malnutrition
Malnutrition refers to imbalances in nutrient intake—either too little (undernutrition) or too much (overnutrition). Both forms affect health at individual and population levels. Undernutrition includes wasting (low weight for height), stunting (low height for age), underweight, and micronutrient deficiencies such as iron-deficiency anaemia and vitamin A deficiency. Overnutrition describes overweight and obesity and their complications like type 2 diabetes, hypertension and cardiovascular disease. In many communities, both problems coexist—children with anaemia but adults with overweight—creating a double burden of disease.

Causes of undernutrition
Undernutrition results from inadequate dietary intake, poor food diversity, infectious diseases, poor maternal nutrition during pregnancy and socio-economic factors such as poverty, food insecurity and lack of access to health services. Inadequate breastfeeding and inappropriate complementary feeding practices contribute to undernutrition in infants and young children. Recurrent infections increase nutrient needs and reduce appetite and absorption, worsening nutritional status.

Causes of overnutrition
Overnutrition arises from excessive energy intake compared to energy expenditure, often due to increased consumption of high-calorie processed foods, sugary beverages and sedentary lifestyles. Urbanisation, changes in food systems, easy availability of packaged foods and reduced physical activity among youth contribute to rising overweight and obesity rates.

Health consequences
Undernutrition in childhood can cause stunted growth, impaired cognitive development, weakened immunity and higher risk of disease and death. Micronutrient deficiencies impair development and learning. Overnutrition increases the risk of metabolic diseases—insulin resistance, high blood pressure, fatty liver, early onset diabetes—and can cause psychosocial issues such as low self-esteem. Both under- and overnutrition have economic and social costs for families and health systems.

Detection and assessment
Simple anthropometric measures like weight-for-age, height-for-age and BMI help detect malnutrition. For adolescents, BMI-for-age charts are useful. Biochemical tests (e.g., haemoglobin for anaemia) and dietary assessments (24-hour recall, food frequency questionnaires) complement physical measurements to identify specific nutrient gaps. Community-level screening programmes and school health checks help detect problems early.

Prevention and interventions
Preventing undernutrition involves improving maternal nutrition, promoting exclusive breastfeeding for six months, timely and appropriate complementary feeding, dietary diversification, micronutrient supplementation (iron, vitamin A) and treating infections. Food fortification (iodised salt, fortification of flour and oil) and school feeding programmes are effective public health measures. To prevent overnutrition, promote balanced diets, limit intake of sugary and high-fat processed foods, encourage regular physical activity and teach portion control. Behaviour change communication, policy measures such as taxation of sugary drinks and clearer food labelling support healthy choices.

Community and household role
Household practices—diversifying diets using local foods, ensuring safe water and sanitation, timely healthcare and appropriate feeding practices—play a central role in preventing malnutrition. Schools and community programmes that teach children and families about healthy eating, cooking demonstrations and kitchen gardens can improve long-term dietary habits and reduce both under- and overnutrition.

Diet and disease link
Many common illnesses are strongly influenced by diet. Some disorders result from nutrient deficiencies (anaemia, rickets), others from excesses or imbalanced diets (obesity, type 2 diabetes, hypertension), and some are caused by food-borne pathogens due to unsafe handling. Understanding the dietary causes and preventive measures helps in both personal health management and community education.

Micronutrient deficiency disorders

• Anaemia (iron deficiency) presents with fatigue, pallor and poor school performance; prevention includes iron-rich diets, vitamin C to enhance absorption, deworming where parasites are common, and supplementation when needed.
• Rickets and osteomalacia due to vitamin D and calcium deficiency lead to bone deformities in children and bone pain in adults; prevention involves sunlight exposure, dietary calcium and vitamin D, and supplementation in high-risk groups.
• Scurvy from vitamin C deficiency causes bleeding gums and poor wound healing and is prevented by citrus fruits, guava and tomatoes.

Chronic non-communicable diseases (NCDs)
Diet contributes to the risk of obesity, type 2 diabetes, cardiovascular disease and some cancers. Diets high in refined carbohydrates, saturated and trans fats, salt and sugar increase these risks. Preventive dietary measures include consuming whole grains, fruits and vegetables, limiting processed foods, reducing saturated fat and salt intake, choosing unsaturated oils, and maintaining healthy body weight through diet and physical activity.

Dental caries and oral health
Frequent intake of sugary foods and sticky snacks increases the risk of dental caries. Prevention involves limiting sugary snacks between meals, promoting proper oral hygiene (brushing twice daily), and intake of fluoride where recommended.

Therapeutic diets and lifestyle changes
Diet modification often complements medical treatment. For diabetes, a consistent carbohydrate plan, portion control and regular physical activity help control blood glucose. For hypertension, reduce sodium intake, increase potassium-rich produce, and maintain healthy weight. Individuals with food allergies must strictly avoid trigger foods and learn to read labels carefully.

Community prevention strategies
Schools and public health programmes play a key role: nutrition education, promoting school meals that meet nutrient standards, providing physical activity opportunities, fortification of staples to prevent deficiencies and screening programmes for early detection. Policy measures—limiting trans fats, regulating marketing of unhealthy foods to children and mandating clearer labels—support healthier food environments.

Practical tips for students
Adopt simple daily habits: eat a balanced breakfast, include fruits and vegetables, prefer water to sugary drinks, choose whole grains, avoid frequent fried snacks, and keep active. Small consistent changes reduce long-term risk of diet-related disorders and support academic and physical performance.

Purpose of nutrition assessment
Nutrition assessment helps determine nutritional status of individuals or populations and guides interventions. It uses multiple methods: anthropometry (measurements of body size and composition), biochemical tests (blood or urine measures), clinical examination (signs of deficiency), and dietary assessment (recall or food frequency). Combining methods increases accuracy because each method has limitations; for example, dietary recall may be affected by memory while biochemical tests are more specific but costlier.

Anthropometric measures
Common measures include weight, height, body mass index (BMI), mid-upper arm circumference (MUAC) and growth charts for children. BMI is calculated as weight in kilograms divided by height in metres squared and is used to classify underweight, normal weight, overweight and obesity in adults; for children and adolescents age-specific BMI-for-age percentiles are used. MUAC is useful for quick screening of acute malnutrition, especially in young children.

Biochemical and clinical assessment
Biochemical tests such as haemoglobin measure iron status; serum vitamin levels can detect deficiencies of vitamins A, D or B12. Clinical signs like pale conjunctiva (anaemia), swollen gums (vitamin C deficiency) or bitot’s spots (vitamin A deficiency) provide useful clues. However, clinical signs often appear late; biochemical tests and dietary assessments help identify problems earlier.

Dietary assessment methods
Common methods include 24-hour dietary recall, food frequency questionnaires and dietary records. A 24-hour recall asks the respondent to list all foods and beverages consumed in the previous day and is useful for quick assessments of energy and nutrient intake. Food frequency surveys estimate usual intake over longer periods. These methods require training to get accurate portion size estimates and to convert foods into nutrient values using food composition tables.

Recommended Dietary Allowances (RDAs)
RDAs are population-level recommendations that represent average daily nutrient intakes sufficient to meet the needs of nearly all healthy individuals in a specific group by age, sex and physiological status. RDAs guide meal planning, policy and supplementation programmes. They vary by lifecycle stage—children, adolescents, adults, pregnant and lactating women—and take into account energy expenditure and growth requirements. RDAs are not individual prescriptions; individual needs may differ due to illness, metabolic differences or activity levels.

Using RDAs in practice
To assess whether a diet meets RDAs, calculate nutrient intake from a 24-hour recall or planned menu and compare to RDA values. Identify shortfalls and suggest dietary adjustments or supplementation. For population programmes, aggregate data indicate common nutrient gaps to target with fortification or public health measures. For school menu planning, ensure average nutrient levels across the week meet RDAs for children and adolescents.

Limitations and ethical use
RDAs are averages and not designed for clinical treatment of individual disorders. Nutrient requirements also change with illness and activity. Use assessment data sensitively and provide culturally appropriate advice. When biochemical tests are unavailable, use combination of anthropometry and dietary assessment to inform practical, affordable strategies such as improving diet diversity and encouraging nutrient-preserving cooking methods.