Nutrition, Vitamins & Health Sciences
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Nutrition, Vitamins & Health Sciences — Complete Study Guide
Introduction to Nutrition
Nutrition is the science that studies the relationship between food and living organisms. It involves the intake of food, absorption, transport, utilization, and excretion of nutrients. A balanced diet is one that contains all nutrients (carbohydrates, proteins, fats, vitamins, minerals, water, and fiber) in the correct proportions needed by the body for normal functioning, growth, and maintenance of health.
1. Macronutrients — The Energy Providers
A. Carbohydrates:
- Primary and quickest source of energy for the body
- Composed of Carbon (C), Hydrogen (H), and Oxygen (O)
- Formula: Cₙ(H₂O)ₙ — hence called "carbohydrates" (carbon + water)
- Provide 4 Kcal per gram
- Sources: Rice, wheat, maize, potato, sugar, fruits
Types:
| Type | Examples | Digestion |
|---|---|---|
| Monosaccharides | Glucose, Fructose, Galactose | No digestion needed — absorbed directly |
| Disaccharides | Sucrose (table sugar), Lactose (milk sugar), Maltose | Digested to monosaccharides |
| Polysaccharides | Starch (plant storage), Glycogen (animal storage), Cellulose (dietary fiber) | Starch & Glycogen digested; Cellulose not digested |
Diabetes Mellitus: When the pancreas cannot produce enough insulin → blood glucose rises uncontrolled. Type 1: Autoimmune — no insulin produced. Type 2: Insulin resistance — lifestyle disease.
B. Proteins:
- Building blocks of the body — used for growth, repair, enzyme production, antibodies
- Made of Amino Acids — there are 20 amino acids, of which 9 are Essential Amino Acids (cannot be synthesized by body, must come from diet)
- Provide 4 Kcal per gram
- Sources: Pulses (lentils, peas, beans), eggs, meat, fish, soybean, dairy
Protein Deficiency Diseases:
- Kwashiorkor: Severe protein deficiency in young children (1–3 years). Symptoms: Swollen belly (edema), thin limbs, skin lesions, growth failure. Common in sub-Saharan Africa.
- Marasmus: Combined protein AND calorie deficiency. Severe wasting — child looks like a skeleton (skin and bones). Can affect infants from birth.
C. Fats/Lipids:
- Concentrated energy stores — provide 9 Kcal per gram (highest among macronutrients)
- Functions: Energy storage, insulation (body temperature), protection of organs, fat-soluble vitamin absorption
- Sources: Butter, ghee, oil, nuts, avocado, meat
Types:
- Saturated Fats: No double bonds — solid at room temperature. Found in animal products (butter, ghee). Excess → heart disease.
- Unsaturated Fats: Have double bonds — liquid at room temperature = oils. Healthier. Found in nuts, avocado, olive oil.
- Trans Fats: Artificially hydrogenated unsaturated fats (vanaspati/margarine). Most harmful — raise LDL (bad cholesterol), lower HDL (good cholesterol).
Cholesterol:
- LDL (Low-Density Lipoprotein): "Bad cholesterol" — deposits in arteries → atherosclerosis
- HDL (High-Density Lipoprotein): "Good cholesterol" — removes LDL from arteries
2. Vitamins — The Micronutrients
Vitamins are organic compounds required in small quantities. They are divided into Fat-Soluble (A, D, E, K) and Water-Soluble (B complex, C) vitamins.
Fat-Soluble Vitamins: Stored in fatty tissues and liver. Can accumulate to toxic levels if taken in excess.
| Vitamin | Chemical Name | Deficiency Disease | Rich Sources |
|---|---|---|---|
| Vitamin A | Retinol | Night Blindness (Nyctalopia); severe deficiency → Xerophthalmia (dry eyes) → Keratomalacia (corneal ulcers → blindness) | Carrot, papaya, mango, liver, egg yolk |
| Vitamin D | Calciferol (D₂=Ergocalciferol, D₃=Cholecalciferol) | Rickets (children — soft, bent bones); Osteomalacia (adults — soft bones) | Sunlight (skin synthesis), fish oil, milk |
| Vitamin E | Tocopherol | Sterility (infertility), muscle weakness, hemolytic anemia | Vegetable oils, nuts, green vegetables |
| Vitamin K | Phylloquinone (K₁ from plants), Menaquinone (K₂ from bacteria) | Impaired blood clotting (excessive bleeding) | Green leafy vegetables, liver |
Water-Soluble Vitamins: Not stored; excess excreted in urine. Must be consumed regularly.
| Vitamin | Chemical Name | Deficiency Disease | Sources |
|---|---|---|---|
| B₁ | Thiamine | Beri-Beri (nerve & heart damage) | Rice bran, whole grains, pork |
| B₂ | Riboflavin | Ariboflavinosis (skin cracks, sore throat, redness of eyes) | Milk, eggs, green vegetables |
| B₃ | Niacin | Pellagra (3 D's: Dermatitis, Diarrhea, Dementia) | Meat, fish, groundnut |
| B₅ | Pantothenic Acid | Burning feet syndrome, paresthesia | Found in most foods |
| B₆ | Pyridoxine | Microcytic anemia, convulsions | Poultry, fish, potatoes |
| B₇ | Biotin | Hair loss, dermatitis (rare) | Egg yolk, liver, nuts |
| B₉ | Folic Acid | Megaloblastic Anemia; neural tube defects in fetus (spina bifida) | Green leafy vegetables, legumes |
| B₁₂ | Cobalamin | Pernicious Anemia, nerve damage | Animal products only — absent in plants |
| C | Ascorbic Acid | Scurvy (gums bleeding, joint pain, no wound healing) | Amla (richest source), lemon, orange, guava |
Key Vitamin Facts for Exams:
- Vitamin C is the most heat-sensitive vitamin — destroyed by cooking
- Vitamin D is the only vitamin produced by the body (skin + sunlight)
- Vitamin B₁₂ is found ONLY in animal products — risk for strict vegetarians
- Folic acid is critical during pregnancy to prevent neural tube defects
- Vitamin K is produced by intestinal bacteria (E. coli)
3. Minerals
| Mineral | Function | Deficiency | Sources |
|---|---|---|---|
| Iron (Fe) | Part of Hemoglobin (carries O₂) & Myoglobin | Anemia (pallor, fatigue, breathlessness) | Spinach, liver, meat, jaggery, dates |
| Calcium (Ca) | Bone & teeth strength, muscle contraction, blood clotting | Rickets (children), Osteoporosis (adults) | Milk, curd, green vegetables |
| Iodine (I) | Essential for thyroid hormones (T₃ & T₄) | Goitre (enlarged thyroid gland) | Iodized salt, seafood, dairy |
| Phosphorus (P) | Bone & teeth, ATP (energy molecule), DNA | Weakness, bone pain | Meat, fish, dairy, nuts |
| Sodium (Na) | Fluid balance, nerve signals, blood pressure | Hyponatremia (weakness) | Salt, processed foods |
| Potassium (K) | Heart rhythm, muscle function | Hypokalemia (cramps, weakness) | Banana, potato, avocado |
| Fluoride (F) | Prevents dental caries (tooth decay) | Easy tooth decay | Fluoridated water, tea |
| Zinc (Zn) | Wound healing, immunity, growth | Stunted growth, poor immunity | Meat, shellfish, nuts |
4. Water — The Sixth Nutrient
- Makes up 60–70% of body weight
- Functions: Temperature regulation, transport of nutrients, chemical reactions, waste removal
- Dehydration: Loss of >1% body water → impaired performance. >3% → severe problems. >10% → life-threatening.
- The body needs 2–3 liters of water per day (also comes from food)
5. Major Health Conditions Related to Nutrition
A. Malnutrition:
- Undernutrition: Not enough food/nutrients
- Overnutrition: Too much food → obesity
- Hidden Hunger: Micronutrient deficiency even with adequate calories
B. Obesity:
- Excess calorie intake → fat storage
- BMI (Body Mass Index) = Weight (kg) / Height² (m²)
- Underweight: <18.5, Normal: 18.5–24.9, Overweight: 25–29.9, Obese: ≥30
- Increases risk: Type 2 diabetes, heart disease, some cancers, sleep apnea
C. Anorexia & Bulimia:
- Eating disorders linked to psychological issues with food and body image
D. Goitre:
- Enlargement of thyroid gland due to iodine deficiency
- Simple Goitre: No hormonal imbalance — just enlargement
- Prevented by using iodized salt (salt fortified with potassium iodate)
6. Food Preservation Methods
| Method | Principle | Examples |
|---|---|---|
| Refrigeration | Slows microbial growth | Milk, vegetables |
| Sun drying | Removes water (dehydration) | Papad, kari, amla |
| Pickling | Vinegar/oil creates acidic/anaerobic environment | Mango pickle, lemon pickle |
| Pasteurization | Heating at 63°C for 30 min or 72°C for 15 sec — kills pathogens | Milk, juice |
| Sterilization | High-heat killing of ALL microorganisms | Canned foods |
| Addition of salt/sugar | Creates hypertonic environment (osmosis kills microbes) | Jam, jelly, jerky |
| Smoking | Antimicrobial compounds from smoke | Fish, meat |
| Irradiation | Gamma rays kill microbes | Spices, potatoes (sprout prevention) |
Food Additives:
- Preservatives: Sodium benzoate (soft drinks), vinegar (acetic acid), salt, sugar
- Artificial Colors: Tartrazine (yellow), Erythrosine (red)
- Artificial Sweeteners: Saccharin (oldest), Aspartame (Diet Coke), Sucralose (Splenda)
7. Hormones and Metabolism (Related to Nutrition)
| Hormone | Gland | Function |
|---|---|---|
| Insulin | Pancreas (Beta cells) | Lowers blood glucose → stores glucose as glycogen |
| Glucagon | Pancreas (Alpha cells) | Raises blood glucose → breaks glycogen to glucose |
| Thyroxine (T₃, T₄) | Thyroid | Controls basal metabolic rate (BMR) |
| Leptin | Fat cells | Suppresses appetite (feeling of fullness) |
| Ghrelin | Stomach | Stimulates hunger |
Basal Metabolic Rate (BMR): Minimum energy needed to maintain vital functions at rest
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