Fundamentals of Food and Nutrition
Fundamentals of Food and Nutrition
Introduction
·
Food and nutrition form the cornerstone of human
health, growth, and survival. Food refers to any substance consumed to
provide energy and nutrients for growth, repair, and maintenance of the body.
·
Nutrition is the science that deals with
the interaction of nutrients and other substances in food in relation to
growth, reproduction, health, and disease.
·
Proper nutrition ensures physical well-being,
mental development, disease prevention, and enhanced quality of life.
·
Malnutrition, whether due to undernutrition or
overnutrition, can lead to serious health concerns.
·
Thus, understanding food, nutrients, their
classifications, metabolism, and role in disease prevention is essential for
healthcare and public health.
Classification of Food
a) Based on Origin
- Plant-based
foods: Cereals, pulses, vegetables, fruits, oils,
nuts.
- Animal-based
foods: Milk, eggs, meat, fish, poultry.
b) Based on Function
- Energy-giving
foods: Cereals (rice, wheat, maize), fats, oils,
sugars.
- Body-building
foods: Pulses, legumes, meat, eggs, fish, milk, nuts.
- Protective
foods: Vegetables, fruits, milk (rich in vitamins and
minerals).
c) Based on Nutrient Content
- Cereals
and millets – rich in carbohydrates, moderate
protein.
- Pulses
and legumes – good protein source, vitamins,
minerals.
- Fruits
and vegetables – high in vitamins, minerals, fiber.
- Animal
products – proteins, fats, vitamins, and
minerals.
- Fats
and oils – concentrated energy source,
essential fatty acids.
d) Based on Processing
- Natural
foods – unprocessed (fresh fruits, vegetables).
- Processed
foods – minimally or highly processed (bread,
biscuits, canned foods).
- Fortified
foods – enriched with nutrients (iodized salt,
fortified flour).
Classification of Nutrients & Their
Importance
A. Macronutrients (required in large
amounts)
- Carbohydrates
- Importance:
Primary source of energy (4 kcal/g). Required for brain function,
muscular activity, and maintaining blood glucose.
- Sources:
Cereals, roots, tubers, sugars, fruits.
- Digestion
& Absorption: Broken down by salivary and
pancreatic amylase → maltose → glucose → absorbed in small intestine.
- Metabolism:
Glucose undergoes glycolysis, Krebs cycle, and oxidative phosphorylation
to yield energy. Excess stored as glycogen (liver, muscles) or fat.
- Proteins
- Importance:
Body-building nutrient, repairs tissues, forms enzymes, hormones,
hemoglobin, antibodies (4 kcal/g).
- Sources:
Animal (milk, meat, fish, eggs) and plant (pulses, legumes, nuts, soy).
- Digestion
& Absorption: Proteins → peptides → amino
acids via pepsin, trypsin, peptidases → absorbed in small intestine.
- Metabolism:
Amino acids used for protein synthesis, excess undergoes deamination in
liver, nitrogen excreted as urea.
- Fats
(Lipids)
- Importance:
Concentrated source of energy (9 kcal/g), essential fatty acids,
fat-soluble vitamin absorption, insulation, hormone synthesis.
- Sources:
Ghee, butter, oils, nuts, seeds, meat, fish.
- Digestion
& Absorption: Emulsified by bile salts →
hydrolyzed by pancreatic lipase into glycerol and fatty acids → absorbed
as micelles.
- Metabolism:
Fatty acids undergo β-oxidation → acetyl-CoA → ATP generation. Excess
stored as adipose tissue.
B. Micronutrients (required in small
amounts)
- Vitamins
– Organic compounds essential for metabolic functions.
- Classification:
- Fat-soluble:
A, D, E, K (stored in liver).
- Water-soluble:
B-complex, C (not stored, excreted in urine).
- Functions:
Enzyme cofactors, antioxidant defense, vision, bone health, immunity.
- Minerals
– Inorganic elements essential for growth, metabolism, and structural
functions.
C. Functional Classification of Nutrients
- Energy-yielding
nutrients: Carbohydrates, fats, proteins.
- Body-building
nutrients: Proteins, minerals.
- Protective
nutrients: Vitamins, minerals, fiber,
antioxidants.
A balanced diet provides all essential nutrients in
appropriate amounts to maintain health, growth, and vitality.
- Components:
- 55–65%
energy from carbohydrates
- 10–15%
energy from proteins
- 20–30%
energy from fats
- Characteristics:
- Includes
all food groups in proper proportion.
- Matches
individual’s age, sex, activity, and physiological status.
- Provides
adequate calories, macronutrients, and micronutrients.
- Emphasizes
variety, moderation, and nutrient density.
Role of Nutrition in Disease Prevention
and Management
·
Nutrition plays a critical role in both
prevention and treatment of diseases
- Prevention
- Adequate
nutrition prevents malnutrition, anemia, osteoporosis, obesity, diabetes,
cardiovascular diseases, and certain cancers.
- Balanced
diet enhances immunity and reduces risk of infections.
- Management
- Diabetes:
Controlled carbohydrate intake, high fiber, low glycemic index foods.
- Hypertension:
Low salt, high potassium, DASH diet.
- Obesity:
Calorie-restricted diet, balanced with exercise.
- Cardiovascular
disease: Low saturated fat, high omega-3,
fruits, vegetables.
- Renal
disease: Controlled protein, sodium,
potassium, fluid.
- Cancer:
High antioxidants, fruits, vegetables, phytochemicals.
- Definition:
Substances that neutralize free radicals (unstable molecules causing
oxidative stress and cell damage).
- Types:
- Endogenous:
Enzymes (superoxide dismutase, catalase, glutathione peroxidase).
- Exogenous
(dietary):
- Vitamins:
A, C, E.
- Minerals:
Selenium, zinc.
- Phytochemicals:
Flavonoids, carotenoids, polyphenols.
- Role
in Diet:
- Protect
against oxidative stress, aging, cardiovascular diseases,
neurodegenerative disorders, and cancer.
- Found
in colorful fruits, vegetables, green tea, nuts, seeds, whole grains.
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