cfbv

1. Nutrition & Infection
Malimu .E Z
KIU

2. Session outline
 Historical background
 Relationship between infection and nutrition
 Effects of nutrition on resistance to infection
 Effects of infection on nutritional status
 Mechanisms of infection-nutrition

3. Historical background
 1950s textbooks of nutrition – little/no mention of a relation to infection
 Same was true for articles on infectious diseases
 Studies in experimental animals and clinical observations were pointing out
the role of infection in precipitating nutritional disorders

4. Historical background
 Clinicians and nutritionists did not recognize the importane of the
relationship
 Late 1950s – field and metabolic studies demonstrated the synergism in
humans
 Effects were then extensively investigated

5. Historical background
 Explosion in knowledge of cell-mediated immune mechanisms led to an
understanding of how malnutrition lowers body resistance
 Interaction – leading cause of morbidity and mortality in children – Africa,
Asia, Latin America
 Malnutrition – infection complex remains the most prevalent PH problem
globally

6. Malnutrition – infection interactions
 Relationship is reciprocal and synergistic
 Infection leads to a deterioration in nutritional status and at the same time
 Malnutrition increases susceptibility to infections

7. Malnutrition – infection
interaction – reciprocal and
synergistic
Nutritional Status
Health status
Nutritional and Health status are closely related
Disease contributes to malnutrition
While malnutrition makes an individual more susceptible
to disease

8. This vicious cycle is known as the malnutrition-infection cycle
Inadequate dietary Intake Weight loss, growth faltering, and
reduced immunity, which lower
the body’s ability to resist infection
Loss of appetite,
malabsorption of nutrients,
altered metabolism and
increased nutrient needs
Longer, more severe and more
frequent disease episodes
This causes
This results
Leads to
Leads to

9. Effects of Malnutrition on resistance to infection
• Malnutrition may reduce body’s resistance to infection by reducing
• Antibody formation especially PEM
• Production of nonspecific protective substances e.g. Interferons, lysosomes,
hydrolytic enzymes
• Phagocytic activity of macrophages
• Non specific resistance to bacterial toxins
• Inflammatory response
• Wound healing and collagen formation

10. Effects
 Example of effects of micronutrient deficiency
 VAD reduces leukemia numbers, lymphoid tissue weights, T-cell function,
etc
 Iron deficiency – reduces cytotoxic activity of phagocytes and proliferation
of T helper cells

11. Effects
 Vitamin B deficiency reduces lymphocyte numbers, lymphoid tissue weight,
antibody response and depresses phagocyte function and T cell
proliferation
 Zinc deficiency reduces T cell development and function

12. Effects of infection on nutritional status
 Profound effects on the intake, metabolism and excretion of most nutrients
 Cause protein catabolism
 Increase resting energy metabolism
 Reduces serum vitamin A concentration, precipitating xeropththalmia

13. Effects
• Metabolic responses to infections – have deep effects on utilization of food
and endogenous nutrient stores – leading to malnutrition
• Increased energy expenditure, 10-15% per 1oC rise in BT
• CHO stores for energy are rapidly depleted
• Increased fecal losses and/or poor absorption of nutrients
• Increased permeability of intestinal mucosa
• Macroscopic blood loss – certain parasites e.g. Schistosoma haematobium
 IDA

14. Examples of disease affecting nutritional status
• Malaria – frequent effects - anaemia, growth failure
• Measles – weight loss is obvious
– Poor food intake - anorexia, dehydration, fever, buccal lesions
– Virus may damage GI mucosa – causing malabsorption and protein loss
– Severe metabolic disturbances in the acute phase

15. • Hookworm – IDA, proteins
• A. Lumbricoides – wight loss
• T. Trichura - abdominal pain and diarrhoea, weight loss, anaemia
• S. Stercoralis – anorexia, malabsorption, loss of endogenous nutrients
• Schistosoma – anaemia, poor growth and reduced proteins
• G. lamblia – diarrhoea, malabsorption

16. Effects of HIV/AIDS on nutritional status
• Depressed appetite, poor nutrient take and limited food availability
• Fever, nausea, vomiting and diarrhoea
• Depression
• Increased energy requirements – 20-30% in symptomatic HIV and AIDS
• Side effects from drugs – opportunistic infections
• Chronic infections, malabsorption, metabolic disturbances, muscle and
tissue catabolism

17. General mechanisms – infection-malnutrition
1. Shifts in the types and quantities of foods consumed (custom or loss of
appetite)
2. Adverse effects of treatment on nutrition
– Purgatives to children with diarrhoea or worms
– Prolonged antibiotics may interfere – synthesis of vitamin K and B vitamins
1. Impaired absorption – diarrhoea-proteins, Vitamin A, Vitamin B12 and
Folate
2. Energy, protein and micronutrient needs are elevated in order to fight off
infection

18. 5. Parasitic organisms – malaria or schistosomiasis or intestinal worms divert
nutrients for their own use
6. Increased urinary loss
– Nitrogen, vitamin A, ascorbic acid, Fe, Zn as a result of stress response
– Urinary schistosomiasis – loss of Fe and protein
7. Increased fecal loss
– Leaking gut phenomenon in hookworm infestation leads to loss of nitrogen and Fe
8. Sweat loss
– Loss of amino acids, nitrogen, minerals

19. END