Animal Nutrition (LC 2026) (Leaving Cert Biology): Revision Notes

Balanced Human Diet

Importance of a Balanced Diet

• Provides the right amounts of carbohydrates, proteins, fats, vitamins, minerals, fibre, and water needed for health.
• Supplies energy for daily activities and body functions.
• Supports growth and repair of tissues.
• Helps maintain a healthy immune system, reducing risk of illness.
• Prevents deficiency diseases (e.g., scurvy from lack of vitamin C, rickets from lack of vitamin D).

Negative Effects of an Unbalanced Diet

• Too little food → weight loss, weakness, poor immunity, nutrient deficiencies.
• Too much food (especially fats and sugars) → obesity, type 2 diabetes, heart disease, high blood pressure.
• Low protein intake → stunted growth, muscle loss, weakened repair of tissues.
• Vitamin and mineral deficiencies → anaemia (iron), weak bones (calcium/vitamin D), poor vision (vitamin A).
• Lack of fibre → constipation, increased risk of bowel disease.

A balanced diet contains the correct proportions of the following 7 components:

1. Proteins
2. Fats
3. Carbohydrates
4. Vitamins
5. Minerals
6. Water
7. Fibre

The total amount of food required depends on factors such as:

8. Age
9. Activity levels
10. Gender
11. Health

Food Groups

Food is divided into 4 groups with recommended daily servings:

• Cereals, bread and potatoes (6)
• Fruit and vegetables (4)
• Milk, cheese and yoghurt (4)
• Meat, fish and beans (2)

Key Nutrient Breakdown

• Carbohydrates → broken down into glucose and transported to the liver via the hepatic portal vein.
• Protein → broken down into amino acids and transported to the liver via the hepatic portal vein.
• Lipids → broken down into fatty acids and glycerol and transported via the lymphatic system (lacteals).