IGCSE Biology 0610 - 7.1 Human Nutrition - Diet

Objective: State the causes and effects of vitamin D and iron deficiencies.

Vitamin D Deficiency

Vitamin D is crucial for the absorption of calcium and phosphorus, which are essential for strong bones and teeth.

Causes of Vitamin D Deficiency

• Insufficient exposure to sunlight: The skin synthesizes vitamin D when exposed to UVB radiation from sunlight.
• Inadequate dietary intake: Few foods naturally contain significant amounts of vitamin D.
• Malabsorption: Certain medical conditions (e.g., cystic fibrosis, Crohn's disease) can interfere with the absorption of vitamin D from food.
• Darker skin pigmentation: Melanin reduces the skin's ability to produce vitamin D from sunlight.
• Older age: The skin's ability to synthesize vitamin D decreases with age.

Effects of Vitamin D Deficiency

• Rickets (in children): Causes soft and weak bones, leading to skeletal deformities. Bone growth is impaired.
• Osteomalacia (in adults): Similar to rickets, but affects adults. Causes bone pain, muscle weakness, and increased risk of fractures.
• Increased risk of osteoporosis: Weakened bones are more prone to fractures later in life.
• Weakened immune system: Vitamin D plays a role in immune function. Deficiency can increase susceptibility to infections.
• Potential link to other health problems: Research suggests a possible association with increased risk of certain cancers, heart disease, and autoimmune disorders, although more research is needed.

Iron Deficiency

Iron is a component of hemoglobin, which carries oxygen in red blood cells. It's also essential for energy production.

Causes of Iron Deficiency

• Insufficient dietary intake: Not consuming enough iron-rich foods.
• Poor absorption: Certain conditions (e.g., celiac disease, bariatric surgery) can impair iron absorption.
• Increased iron requirements: During periods of rapid growth (e.g., childhood, adolescence, pregnancy) or menstruation.
• Blood loss: Chronic blood loss (e.g., from heavy menstruation, ulcers, or internal bleeding) can deplete iron stores.
• Poor diet: A diet lacking in iron-rich foods.

Effects of Iron Deficiency

• Iron Deficiency Anemia: Reduced production of hemoglobin, leading to fewer red blood cells and reduced oxygen delivery to tissues.
• Fatigue and weakness: Reduced oxygen to muscles causes tiredness and lack of energy.
• Pale skin: Lower hemoglobin levels can cause paleness.
• Shortness of breath: The body tries to compensate for reduced oxygen carrying capacity.
• Headaches: Reduced oxygen supply to the brain.
• Brittle nails: Iron deficiency can affect nail growth and strength.
• Pica: Unusual cravings for non-food items (e.g., ice, dirt).
• Impaired cognitive development (in children): Iron is crucial for brain development.

Summary Table

Nutrient	Causes of Deficiency	Effects of Deficiency
Vitamin D	Insufficient sunlight, inadequate diet, malabsorption, darker skin, older age	Rickets/Osteomalacia (children/adults), osteoporosis, weakened immune system, potential link to other diseases
Iron	Insufficient diet, poor absorption, increased requirements, blood loss, poor diet	Iron Deficiency Anemia, fatigue, weakness, pale skin, shortness of breath, headaches, brittle nails, pica, impaired cognitive development (children)