Basic Nutritional Requirements

Energy & Macronutrients - Fuel & Builders

• Energy: Unit Kcal. 1 Kcal = heat to raise 1kg water by 1°C.
  • Fuel Values (Kcal/g): CHO 4, Protein 4, Fat 9. (Alcohol 7 Kcal/g).
• BMR: Minimum energy at rest. SDA/TEF: Energy to metabolize food (Protein highest ~30%).
• Macronutrients (% daily energy):
  • Carbohydrates (CHO): 50-60%. Primary fuel.
  • Proteins: 10-15% (0.8-1 g/kg/day). Body building.
    • 📌 Essential AAs: PVT TIM HALL.
  • Fats: 20-30%. Concentrated energy; EFA (Linoleic $\omega$-6, Linolenic $\omega$-3) deficiency → phrynoderma.

⭐ Atwater General Factors for physiological fuel values: Carbohydrates 4 Kcal/g, Proteins 4 Kcal/g, Fats 9 Kcal/g.

Fat-Soluble Vitamins - ADEK Superstars

• Absorbed with fats; stored (liver, adipose); risk of toxicity. 📌 Mnemonic: "Fat ADEK".
• A (Retinol): Vision, epithelial integrity, immunity.
  • Deficiency: Night blindness, Bitot's spots, xerophthalmia.
  • Prophylaxis: 1L IU (6-11mo), 2L IU (1-6yr) q6mo.
• D (Calciferol): $Ca^{2+}/PO_4^{3-}$ balance, bone health.
  • Deficiency: Rickets, osteomalacia.
  • Sources: Sunlight ($D_3$), diet ($D_2, D_3$).
• E (Tocopherol): Antioxidant, cell membrane protection.
  • Deficiency: Rare; hemolytic anemia, neuropathy.
• K (Phylloquinone/Menaquinone): Clotting factors (II, VII, IX, X, C, S).
  • Deficiency: Bleeding; Hemorrhagic Disease of Newborn (HDN).
  • HDN Prophylaxis: 1 mg IM at birth.

⭐ Vitamin A deficiency is a leading cause of preventable childhood blindness globally.

Water-Soluble Vitamins - B-C Vitality

• General: Not stored (except B12); excess excreted. Coenzymes.
• B-Complex:
  • B1 (Thiamine): TPP (carb metabolism). Deficiency: Beriberi, Wernicke-Korsakoff.
  • B2 (Riboflavin): FAD/FMN (redox). Deficiency: Ariboflavinosis (cheilosis, glossitis).
  • B3 (Niacin): NAD/NADP (from tryptophan). Deficiency: Pellagra (3Ds: Dermatitis, Diarrhea, Dementia).
  • B6 (Pyridoxine): PLP (amino acid metabolism). Deficiency: Neuropathy, sideroblastic anemia. Isoniazid ↑need.
  • B9 (Folate): THF (DNA synthesis). Deficiency: Megaloblastic anemia, NTDs. RDA (Pregnancy): 600 mcg.
  • B12 (Cobalamin): DNA synthesis, myelin. Needs intrinsic factor. Deficiency: Megaloblastic anemia, neurological damage.
• Vitamin C (Ascorbic Acid): Antioxidant, collagen synthesis, ↑non-heme Fe absorption. Deficiency: Scurvy.

⭐ High dose niacin (B3) is used for hyperlipidemia but can cause flushing (prostaglandin-mediated).

Essential Minerals - Micro Mighty

• Iron (Fe): O₂ transport (Hb, Mb); enzyme cofactor. Deficiency: Microcytic anemia, koilonychia, pica. RDA: Men 8 mg, Women 18 mg (pre-menopause).
• Iodine (I): Thyroid hormones ($T_3, T_4$). Deficiency: Goiter, cretinism, hypothyroidism. RDA: 150 µg.
• Zinc (Zn): Cofactor for >300 enzymes; immunity, wound healing, taste/smell. Deficiency: Growth retardation, acrodermatitis enteropathica, ↓immunity, delayed wound healing.
• Selenium (Se): Antioxidant (glutathione peroxidase); thyroid hormone metabolism. Deficiency: Keshan disease (cardiomyopathy), Kashin-Beck disease.
• Copper (Cu): Iron absorption/transport; enzyme cofactor (e.g., lysyl oxidase, cytochrome c oxidase). Deficiency: Menkes kinky hair syndrome, anemia. Excess: Wilson's disease.
• Fluoride (F⁻): Dental/bone health; prevents caries. Optimal water fluoridation: 0.7 ppm. Excess: Dental & skeletal fluorosis.
• Chromium (Cr): Glucose tolerance factor; potentiates insulin action.
• Manganese (Mn): Enzyme activator (e.g., mitochondrial superoxide dismutase).
• Molybdenum (Mo): Cofactor for xanthine oxidase, sulfite oxidase.

⭐ Zinc deficiency is classically associated with acrodermatitis enteropathica, characterized by periorificial and acral dermatitis, alopecia, and diarrhea.

High‑Yield Points - ⚡ Biggest Takeaways

• A balanced diet is crucial, supplying macronutrients (carbohydrates, proteins, fats) and micronutrients (vitamins, minerals).
• Average adult energy requirement (sedentary Indian male): ~2100-2300 kcal/day.
• Protein RDA: 0.8-1 g/kg body weight/day; requirements ↑ during growth, pregnancy, and lactation.
• Essential Fatty Acids (EFAs) like linoleic acid and alpha-linolenic acid must be diet-derived.
• Recommended Dietary Allowances (RDAs) are average daily nutrient intake levels sufficient for most healthy individuals.
• Basal Metabolic Rate (BMR) accounts for the largest portion (~60-70%) of total energy expenditure.
• Specific Dynamic Action (SDA), or thermic effect of food, is highest for proteins (~30%).