4. Epidemiology of malnutrition and nutritional deficiencies
- 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.
- Descriptive studies – an observational study that describes the characteristics of a population
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
- Kwashiorkor
- Chronic malnutrition
- Shortness
- Cognitive dysfunction
- Acute malnutrition
- 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
- Iron 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