Classes of Food
I. Carbohydrates:
Carbohydrates are the primary source of energy for the body.
They are composed of carbon, hydrogen, and oxygen.
Two main types:
Simple Carbohydrates: Sugars (e.g., glucose, fructose, sucrose)
Complex Carbohydrates: Starches and fibers (e.g., in potatoes, bread, and vegetables)
Role in the body: Providing quick energy for daily activities.
Deficiency: Lack of carbohydrates can lead to fatigue and a decrease in energy levels.
II. Proteins:
Proteins are essential for growth, repair, and the overall functioning of the body.
Composed of amino acids, which are the building blocks of life.
Sources: Meat, fish, eggs, dairy, legumes, and nuts.
Role in the body: Repair and maintenance of body tissues, enzyme production, and immune system
support.
Deficiency: Protein deficiency can result in stunted growth, muscle wasting, and weakened immune
system (e.g., kwashiorkor).
III. Fats (Lipids):
Fats are a concentrated source of energy.
Composed of fatty acids and glycerol.
Types of fats: Saturated (solid at room temperature) and unsaturated (liquid at room temperature).
Sources: Butter, oils, nuts, avocados.
Role in the body: Energy storage, insulation, protection of vital organs.
Deficiency: Long-term fat deficiency can lead to skin issues, hair loss, and difficulty absorbing fat-
soluble vitamins (e.g., vitamin A, D, E, K).
IV. Vitamins:
Essential organic compounds required in small quantities.
They do not provide energy but are necessary for various body functions.
Examples: Vitamin A, C, D, etc.
Role in the body: Support metabolism, immune system, and overall health.
Deficiency: Vitamin deficiencies can result in diseases like scurvy (vitamin C deficiency) and night
blindness (vitamin A deficiency).
V. Minerals:
Inorganic nutrients required in small quantities.
Essential for various bodily functions.
Examples: Calcium, iron, potassium, etc.
Role in the body: Bone and teeth health, muscle function, and maintaining electrolyte balance.
Deficiency: Mineral deficiencies can lead to conditions like anemia (iron deficiency) and osteoporosis
(calcium deficiency).
VI. Roughage (Dietary Fiber):
Roughage, also known as dietary fiber, is an important component of the diet.
It is primarily found in plant-based foods such as fruits, vegetables, and whole grains.
Role in the body: Promotes healthy digestion, prevents constipation, and contributes to a feeling of
fullness.
Deficiency: Insufficient dietary fiber can result in digestive issues, including constipation and
diverticulitis.
VII. Water:
Water is essential for life and makes up a significant portion of our body.
It is involved in various biochemical reactions and helps transport nutrients.
Role in the body: Regulating body temperature, digestion, and waste removal.
Deficiency: Dehydration can lead to various health issues, including kidney problems and electrolyte
imbalances.
NB:
A balanced diet should include all classes of food in appropriate proportions, and deficiencies should be
avoided to maintain good health.
Understanding these classes of food and their associated deficiency diseases is crucial for promoting
overall well-being and preventing health problems.
Heterotrophic Nutrition
Heterotrophic nutrition is one of the two primary modes of nutrition; the other being autotrophic
nutrition.
Heterotrophic organisms rely on consuming other organisms or organic matter to obtain the necessary
nutrients.
I. Types of Heterotrophic Nutrition:
Holozoic Nutrition:
Organisms ingest whole food, which is then broken down internally through digestion.
Examples: Humans, animals.
Role of specialized structures (e.g., teeth and stomach) in the digestion process.
Saprophytic Nutrition:
Organisms feed on decaying or dead organic matter.
Role in decomposition and recycling of organic material.
Examples: Fungi like mushrooms and some bacteria.
Parasitic Nutrition:
Organisms derive nutrients from a host organism, causing harm to the host.
Adaptations to attach to or enter the host.
Examples: Parasitic worms, some insects.
II. Process of Heterotrophic Nutrition:
Ingestion: The process of taking in food, often involving the use of specialized structures (mouth,
beaks, etc.).
Digestion: Breaking down complex food into simpler substances that can be absorbed.
Absorption: The uptake of nutrients by the organism, typically occurring in the small intestine.
Assimilation: Incorporating absorbed nutrients into the organism's cells and tissues for energy and
growth.
Egestion: The elimination of undigested or waste materials from the body.
III. Benefits and Challenges of Heterotrophic Nutrition:
Benefits:
Ability to consume a wide variety of foods.
Efficient energy acquisition and utilization.
Allows for complex and mobile organisms.
Challenges:
Dependence on finding and capturing food sources.
Competition for limited food resources.
Risk of ingesting harmful substances or pathogens.
