BIO103 Lecture 10 11

FOOD AND
NUTRITION
&
The Digestive
System
Lecture No. 10

FOOD AND NUTRITION

Food
 Food is any edible material that supports growth, repair and maintenance of the body.
 Foods are substances containing nutrients
 Nutrients are needed for:
• Cell repair
• Cell growth
• Energy
• Protection

Food
 Classification of foods:

A. According to the source of origin
1. Animal foods
2. Plant foods
B. According to the calorigenicity
1. Calorigenic foods
2. Non-Calorigenic foods
C. According to the main function
1. Energy yielding foods
2. Body building foods
3. Protective foods

Factors associated with Food
The important factors in relation to Food are:
1.
2.
3.
4.
5.
6.
7.

Energy Value
Quality and Quantity of Primary Foods
Variation in the diet
Digestibility
Cooking
Psychological factors
Cost

Nutrients
Nutrients are specific dietary constituents. They can be classified into:
Macronutrients
• Carbohydrate
• Protein
• Fat
• Trace elements
• Dietary fibre
• Water
Micronutrients
• Vitamins
• Minerals

Role of Proteins in the Diet
 Replacement of cells
 Growth
 Large molecules
 Smaller molecules called Amino Acids
 Source: meats, eggs, beans

Role of Carbohydrates
 Primary energy source
 Molecules of C, H, O
• Sugars ~ simple carbohydrates
• Starches ~ complex carbohydrates
• Fiber
 Sources: Rice, potatoes, sugar etc.

Role of Fats
 Provide energy/stores energy
 Absorb vitamins
 Make up cell membranes
 Sources: oil, cheese, butter and other milk product.

Vitamins
 Organic (contain carbon)
 Growth
 Regulate body functions
 Prevent disease
 No food has all vitamins
 Water soluble
 Fat soluble
 Sources: Vitamins are organic molecules.
They are water and fat soluble and found in vegetables, fruits, egg, milk etc.

Minerals
 Inorganic (no carbon)
 Control chemical reactions
 Build cells
 Conduct nerve impulses
 Carry oxygen

Sources of Minerals
 Calcium: Best sources of calcium are milk
,cheese, eggs, green vegetables, oranges, nuts, beans,