IGCSE Biology 0610 - 7.1 Human nutrition – diet

Objective: Describe the effect of protein-energy malnutrition (PEM) on children: kwashiorkor and marasmus.

Introduction

Protein-energy malnutrition (PEM) occurs when the body doesn't receive enough protein and calories. This is a serious condition, particularly harmful to children, as it can significantly impair their growth and development. There are two main forms of PEM: kwashiorkor and marasmus, which have distinct characteristics and underlying causes.

Marasmus

Marasmus is primarily a deficiency in calories, leading to severe wasting of body tissue. It typically develops over a relatively short period.

• Cause: Insufficient intake of carbohydrates, fats, and proteins.
• Symptoms:
• Severe weight loss and wasting of muscle and fat.
• The child appears very old for their age.
• Lack of subcutaneous fat (fat under the skin).
• Growth retardation.
• Weakness and lethargy.
• Dry, thin skin.
• Physiological Effects: The body breaks down its own tissues (muscle) for energy.

Kwashiorkor

Kwashiorkor is primarily a deficiency in protein, even if calorie intake is relatively adequate. It usually develops after a period of calorie restriction.

• Cause: Insufficient protein in the diet.
• Symptoms:
• Edema (swelling), particularly in the abdomen, legs, and feet. This is due to low levels of albumin in the blood, which affects fluid balance.
• Growth retardation.
• Skin lesions (dermatosis), often appearing as reddish-brown patches.
• Hair loss and changes in hair color (often becoming thinner and more brittle).
• Irritability and apathy.
• Enlargement of the liver.
• Physiological Effects: The body prioritizes essential protein functions, leading to impaired growth and fluid retention issues.

Comparison of Marasmus and Kwashiorkor

Feature	Marasmus	Kwashiorkor
Main Deficiency	Calories (energy)	Protein
Appearance	Wasting of muscle and fat; appears very old	Wasting of muscle and fat; edema (swelling)
Edema	Absent	Present (especially in the abdomen, legs, and feet)
Skin	Dry and thin	Skin lesions (dermatosis)
Hair	Thin and sparse	Changes in color and texture

Long-term Effects

Both marasmus and kwashiorkor can have long-term consequences for children, including:

• Impaired cognitive development.
• Weakened immune system, increasing susceptibility to infections.
• Stunted growth.
• Increased risk of chronic diseases later in life.

Prevention

PEM can be prevented through:

• Ensuring a balanced diet with adequate protein, calories, vitamins, and minerals.
• Addressing underlying poverty and food insecurity.
• Providing nutritional education to families.
• Targeted feeding programs for vulnerable populations.