4. Epidemiology of malnutrition and nutritional deficiencies

From greek.doctor
  • Micronutrient deficiency is widespread in developing countries, affecting 2 billion people worldwide
  • Deficiency affects the most vulnerable groups most commonly
  • Most common deficiencies
    • Iron
    • Vitamin A
    • Iodine
  • Malnutrition = inadequate or excess intake of a nutrient, leading to infections and disorders
  • Underweight malnutrition – large problem in the developing world
    • Affects mainly children and women
    • Malnutrition increases risk for children to die from malaria, meningitis, pneumonia, gastroenteritis

Epidemiology of malnutrition

  • Epidemiology is the study of the distribution and determinants of diseases and other health outcomes in human populations
  • Types of studies in nutritional epidemiology
    • Descriptive studies – an observational study that describes the characteristics of a population
      • Describes the nutritional state of a population
      • National surveys are often used
    • Ecological studies – an observational study that measures the incidence of a disease in a population
      • Can compare how the incidence of a disease in a population changes over time
      • Can study whether certain populations have higher incidence of disease (like certain ethnicities, religions)
      • Can study immigrants to assess the contributions of genetic and environmental factors
    • Case-control studies – a retrospective observational study that compares people with a disease and without a disease and looks for possible risk factors
    • Cohort studies – a prospective study that compares two groups, one group with a risk factor and another group without and compares their incidence of disease
    • Intervention trials – a double blind experimental study where random subjects are assigned into two groups. One group receives a treatment, the other not. Health outcomes are compared.

Types of malnutrition

  • Growth failure
    • Acute malnutrition
      • Kwashiorkor
        • Severe protein malnutrition but without total calorie deficiency
        • Symptoms
          • Oedema
          • Pigmentation changes of skin and hair
          • Impaired growth and development
          • Ascites
          • Liver disease
      • Marasmus
        • Severe protein and calorie malnutrition
        • Symptoms
          • Growth retardation
          • Wasting of subcutaneous fat, muscle
    • Chronic malnutrition
      • Shortness
      • Cognitive dysfunction
  • Micronutrient malnutrition
    • Iron deficiency
      • Most common nutritional disorder – 2 billion people worldwide
      • Causes anaemia
      • Very prevalent in pregnant women and preschool children in developing countries
      • Aggravated by parasite infection, malaria, HIV, TB
      • Health effects
        • Fatigue
        • Poor pregnancy outcome
        • Impaired physical and cognitive development
        • Increased morbidity in children
      • Prevention
        • Increase iron intake
        • Control infection
        • Improve nutritional status
    • Vitamin A deficiency
      • Major cause of blindness in Africa, south-east Asia
      • Affects mostly children and pregnant women
      • Prevention
        • Supplementation
        • Increased breastfeeding
        • Promotion of vitamin A-rich diet
        • Fortification of food
          • Golden rice – a type of rice fortified with vitamin A
    • Iodine deficiency

Cachexia

  • = a complex metabolic syndrome characterised by loss of muscle with or without loss of fat, due to an underlying illness
  • Frequently seen in COPD, chronic kidney disease, cancer
  • Causes weight loss
  • Anorexia, inflammation, insulin resistance and protein catabolism as associated with cachexia
  • Not the same as starvation!
  • Increases morbidity

Intervention of malnutrition and nutritional deficiencies

  • Determine etiology of malnutrition
    • Parasite
    • Infection
    • Increased demand
    • Poor diet
  • Effective measures
    • Improve water supply, sanitation, hygiene
    • Improve access to adequate amounts of healthy food
    • Supplementation
      • When deficiency is severe
      • Can be used as preventative measure in high-risk populations
      • Cost-effective
    • Fortification of foods (adding nutrients to foods)
      • Not appropriate in severe deficiency
      • Requires participation of the food industry
    • Diversify the diet
      • Introduce nutrient-rich foods in the diet
      • Change dietary habits
    • Change agricultural habits