Epidemiology- Nutrition

1. Epidemiology-Nutrition Mbongue N. Germaine S., Msc. Ph.D. (finalization) Muenster University of Applied Sciences, Germany/ Charité-Universitätsmedizin Berlin, Germany /University of Dschang Cameroon

2. Course outline • Major public health relevant nutritional problems • Case study: developing countries • Protein Energy Malnutrition (Dr. Zambou) • Micronutrient deficiency (Mbongue) • Obesity (Mbongue)

3. Vitamin A • What is Vitamin A • Is a lipid soluble organic compound, essential in the diet in small amounts and that are involved in fundamental functions in the body • Vitamin A includes provitamin A carotenoids, that are dietary precursors of retinol

4. Functions of Vitamin A • Vision: • Released all-trans retinol is converted to all-trans retinol, which can be transported across the inter photoreceptor matrix to the retinal epithelial cell to complete the visual cycle. • Inadequate retinal available to the retina results in impaired dark adaptation known as ‘Night blindness

5. Functions of Vitamin A • Gene expression: • Vitamin A may interacts with thyroid hormone and vitamin D to influence gene transcription. • Through the stimulation and inhibition of transcription of specific genes, retinoic acid plays a major role in cellular differentiation, the specialization of cells for highly physiological roles. • Integrity of epidermal and mucosal surfaces, and thus the physical barrier against the environment

6. Function of Vitamin A • Red blood cell production: • Red blood cells, like all blood cells, are derived from precursor cells called stem cells, which are dependent on retinoids for normal differentiation into red blood cells.

7. Functions of Vitamin A • Nutrient interaction: • Vitamin A and Zinc • Zinc deficiency is thought to interfere with vitamin A metabolism in several ways. Zinc deficiency results in decreased synthesis of retinol binding protein(RBP),which transports retinol through the circulation to tissues (e.g.,the retina). (health consequencies of zn deficiency on Vitamin A unclear) • Vitamin A and Iron • Vitamin A supplementation has been shown to have beneficial effects on iron deficiency anemia and improve iron nutritional status among children and pregnant women.

8. Functions of Vitamin A • Immunity: • Vitamin A and retinoic acid (RA) play a central role in the activation of macrophages and differentiation of white blood cells (moncytes), that play critical roles in the immune response. • Growth and development: • Retinol and retinoic acid are essential for embryonic development and has been found to regulate expression of the gene for growth hormone

9. Micronutrient deficiencyworld wide • Statistics: • 2 billion cases of vitamin and mineral deficiency in both developing and developed countries (WHO 2000) • Examples: Vitamin A, Fe, Vitamin B12, Iodine, Folic acid, Zn

10. Micronutrient deficiency in Developing countries • Main examples: • Vitamin A deficiency • Fe-deficiency • Iodine deficiency

11. Vitamin A deficiency • Statistics: • 14 Mio children under 5 years (WHO) • 6 to 7 Mio new cases yearly • Prevalence: South and East Asia, part of Africa and Latin America, middle East

12. Vitamin A deficiency • Vulnerable group: • Pregnant women • Lactating mothers • Preschool children

13. Vitamin A deficiency • Clinical features: • Xerpthalmia: • Night blindness • Bitot'sspots: Foamy accumulations on the conjunctiva (inner eyelids), that often appear near the outer edge of the iris • Corneal xerosis: Dryness, dullness or clouding (milky appearance) of the cornea • Keratomalacia: Softening and ulceration of the cornea. sometimes followed by perforation of the cornea, leading to permanent blindness.

14. Vitamin A deficiency • Clinical features • Low levels of blood vitamin A • Malnutrition in children • Increased infection rate • Decreased growth rate • Increase rate of fatigue

15. Vitamin A deficiency • Determinants: • Nutritional habit • Low dietary intake (e.g. maternal undernutrition) • Nutritional habits differs from the north to the south of the country. • Westernization of local meals • Geographical and regional variation • Palm oil, green vegetable for example rich in Vitamin A is scarce in the northern region compared to the south

16. Vitamin A deficiency • Determinants: • High rates of infections e.g. diarrheas, Measles and HIV/AIDS • Infection stimulates a vicious cycle, since inadequate vitamin A leads to a poor nutritional status with increased severity and likelihood of death from infectious disease.

17. Vitamin A deficiency • Determinants: • GIT disorders: Malabsorption of vitamin A by the body due to sprue, celiac disease, obstructive jaundice, cirrhosis, giardiasis, cystic fibrosis • Poverty • Animal products which are a rich source of Vitamin A are expensive for a majority in developing countries

18. Vitamin A deficiency • Consequences : • Xerophthalmia : major cause of blindness in young children • 20% of survivors being totally blind • 50-56% of survivors being partially blind • Childhood diseases • Maternal and 20-30% childhood mortality • Increases HIV-mother to child transformation (MTCT) (needs further investigation)

19. Vitamin A deficiency • Daily requirement: • Babies 0-12 months: • 0.5-0.6 mg retinol eq./day • Children under 1-5: • 0.6 - 0.7 mg retinol eq./day • Pregnant women: • 1.1 mg retinol eq./day • Breast feeding mothers: • 1.5 mg retinol eq. /day • RNI: 700ug (no official RNI) since amount depends on fat content of food Eq. =equivalent, RNI: required nutrient intake

20. Sources of Vitamin A • Free retinol is not generally found in foods. Retinylpalmitate, a precursor and storage form of retinol, is found in foods from animals. • Plants contain carotenoids, some of which are precursors for vitamin A (e.g.,Alpha-carotene and B-carotene). • Common sources are: oil, fortified cereal, egg, butter, whole milk, sweet potato, carrot etc.

21. Sources of Vitamin A

22. Vitamin A deficiency • Intervention: • Vit A intake through food such as egg, whole milk, liver, dark green vegetable, red palm oil • RDA of 0.9 mg is present in: • 3l whole milk, 200g margarine, 8 eggs, 2-3 kg meat, 200g thon fish, 5-10g liver, 150g caviar,

23. Vitamin A deficiency • Intervention: • Supplementation (treatment with palmitate-30mg) • Short-term solution • Liquid gelatin filled capsule given orally or intravenously • Reducing child mortality to 23% overall • Reducing Measles infection to about 50%

24. Vitamin A deficiency • Intervention • Fortification • Medium –term solution • Increase nutrient in specific food (margarine, oil, sugar, carotenoid- rich bananas) • Requires commitment from government , food industry, legislation, consumer and research facilitators

25. Food fortification Vitamin A fortified cereals

26. Vitamin A-deficiency • Intervention: • Diet diversification • Long term solution • Should run parallel to short term solution • Increases variety and frequency of micronutrient rich food • Modifies food production, consumption and distribution • Cost effective and would’t lead to hypervitaminose • Long term commitment from participants

27. Vitamin A deficiency • Intervention: • Diet diversification • Through education of the population, home garden and improved methods of preparation and preservation • Nutritional Education • Long term commitment from the participants • Education of mother and children on how to eat a well balanced diet • Improved local access to VA-rich food • Requires economic, political, operational, behavioral sustainability

28. Iron deficiency

29. Iron deficiency • Statistics: • Over 2 billion people world wide suffer from some form of iron deficiency • 25% of the world’s children under age 3 have Fe-deficiency anemia with higher rates in developing countries • Africa & South Asia have the highest overall incidence of anemia, followed by Latin America & East Asia

30. Fe-types • Iron intake and absorption • Two forms of iron occurs in the diet: • Hem (organic): greater absorption than non-hem iron • Sources include: meat, liver, fish and eggs • Non-hem (inorganic) • Sources include: cereals, legumes, green vegetable, nuts, dried fruits and chocolate

31. Fe-intake and absorption • Iron intake and absorption • Iron absorption is tightly controlled to match the body’s need, as iron is toxic to cells because of its pro-oxidant properties • Ingested iron not immediately required remains in the enterocytes, and is shed at the end of their life cycle in the faeces • Up to 25-30 mg of iron is transported in the body per day from sites of absorption or release for storage or utilization

32. Iron stores in the body • Iron stores in the body: • Hemoglobin: 60% (total of 4g) of body’s iron content • Bone marrow: 15% • Ferritin (in liver): contains up to 4000 atoms of iron • Functional enzymes • Muscles (as myoglobin) • In circulation: attached to transferrin

33. Factors influencing Fe absorption • The absorption of Fe from food is influenced by multiple factors: • Form of Fe: Hem Fe from animal sources is better absorbed than non-hem Fe from plant origin • The absorption of non-hem iron can be improved when a source of hem iron is consumed in the same meal. • Fe absorption-enhancing food: e.g. Ascorbic acid-rich fruits and vegetable (orange, orange juice, grape, spinach, fruits); lean beef, liver. Maria Kapsokefalou and Dennis D. Miller 1993. J.Nutr.

34. Fe-absorption: factors affecting absorption of non-hem iron

35. Fe-deficiency stages • Pre-latent • Reduction in iron stores without reduced serum in iron level • Hb (N), MCV (N), iron absorption (), transferin saturation (N), serum ferritin (), marrow iron () • Latent • iron stores are exhausted, but the blood hemoglobin level remains normal • Hb (N), MCV (N), TIBC (), serum ferritin (), transferrin saturation (), marrow iron (absent)

36. Fe-deficiency stages • Iron deficiency anemia • blood hemoglobin concentration falls below the lower limit of normal • Hb (), MCV (), TIBC (), serum ferritin (), transferrin saturation (), marrow iron (absent)

37. Fe-deficiency anemia • Iron deficiency anemia (IDA): • Is the most common nutritional deficiency in the world, with a range of pathological consequences. • These can include changes to the digestive tract, loss of appetite, reduced work capacity and eventually heart failure • IDA can also affect the function of white blood cells, reducing their ability to destroy invading organisms

38. Iron def. anaemia • Prevalence: • The most affected are young children between 8 and 16 months and women of reproductive ages • In dev. countries: • About 40% women between 15 and 40 years of age • e.g. 32% in Cameroon Ray Yip and Usha Ramakrishnan 2002. Journal of Nutritional

39. Fe-deficiency • Vulnerable group: • Women of reproductive age • Pregnant and lactating women • Malaria infected persons • Vegetarians • Sick persons (tuberculosis, HIV/AIDS, Malaria)

40. Causes of Fe def. anaemia • Low dietary Fe intake • Food of animal sources such as beef, fish, poultry, liver are rich sources of iron • Not all causes of anaemia are nutritional in origin; yet anaemia linked to iron and/or folic acid deficiency is among the world’s major nutritional disorders

41. Causes of Fe def. anaemia • Iron absorption inhibitors in food such as: • Phytates • Oxalates • Carbonates • Phosphates • Dietary fibres • Others Fe- inhibitors : milk, eggs and tea, coffee Reduces the bioavailability of Fe in the body, a single cup of tea taken with meal reduces iron absorption by up to 11%. Morck et al. 1983. Am.J. Nutr.

42. Causes of Fe def. anaemia • Parasitic infectionssuch as: • Malaria • HIV/AIDS • Hookworm • Schistosomiasis • Tuberculosis WHO 2009; Nutrition Topics: Iron deficiency anaemia

43. Causes of Fe def. anaemia • Chronic bleeding : • Menstrual blood loss (20mg to 60mg) • Gastrointestinal tract (stomach/intestinal cancer, haemorrhoids) • Blood in sputum (rare)  Tuberculosis • Urinary blood loss (rare) Ray Yip and Usha Ramakrishnan 2002. Journal of Nutrition

44. Causes of Fe def. anaemia • Increased Fe utilization: • Pregnancy • Lactation • Infancy • Adolescence

45. Fe-deficiency anemia • Signs and symptoms: • Dry pale skin • Fatigue • Dizziness • Headache • Irritability • palpitation • Etc.

46. Iron deficiency anemia Angular cheilosis or stomatitis

47. Fe- deficiency anemia • Consequences: • Reduces work capacity, thus productivity, earnings & ability to care for children • Contributes to 20% of all maternal deaths • Retards fetal growth, causes low birth weight (LBW) & increases infant mortality • Impairs ability to resist disease; in childhood, reduces learning capacity • Learning disabilities and psychomotor development • Inability to maintain body temperature

48. Iron deficiency • RDA: • Men: 8.7 mg • Women: 14.8 mg • Dietary sources: • beef, liver, fish, dairy products, Green vegetables, lentils • For 15 mg : 350 g nuts, 750g lean meat, 100g pig liver, 400g spinach, 200g leguminous fruits

49. Dietary sources of Iron Hem iron: Beef Non-hem iron: Lentils

50. Interventions to control Fe def. anaemia • Supplementation: • Fe could be supplied to the vulnerable group in the form: • Tablets • Capsuls • Syrups