Nutritional Epidemiology: Micronutrient malnutrition

1. Nutritional Epidemiology: Micronutrient malnutrition Asst. Prof. Dr.Sumattana Glangkarn

2. Micronutrient malnutrition: a public health problem • Micronutrient malnutrition (MNM) is widespread in the industrialized nations, but more in the developing regions • Can affect all age groups, but young children and women of reproductive age tend to be among those most at risk of developing micronutrient deficiencies • MNM has many adverse effects on human health, even moderate levels of deficiency (detected by biochemical or clinical measurement) sumattana glangkarn

3. Nutrition problems in Thailand include; - Protein energy malnutrition (PEM) - MNM; Iron deficiency anemia (IDA) Iodine deficiency disorder (IDD) Vitamin A deficiency. sumattana glangkarn

4. Iron-deficiency anemia • Iron-deficiency anemia (IDA) is the most common nutritional disorder in the world • Women in the reproductive age group and young children in tropical and subtropical regions • IDA affects over 2 billion people in the world • Average prevalence is higher in pregnant women (51%) than non-pregnant women • High prevalence in south and south-east Asia sumattana glangkarn

5. Stage of iron depletion Decrease in iron stores Stage I  Ferritin Biochemical indicators of low iron stores Transferrin saturation  Erythrocyte protoporphyrin Stage II Stage III Iron-deficiency anemia  Hemoglobin sumattana glangkarn

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7. องค์ประกอบของฮีโมโกลบินองค์ประกอบของฮีโมโกลบิน sumattana glangkarn

8. Iron nutritional status Biochemical and hematological tests • Serum iron concentration • Total iron binding capacity • Transferrin saturation • Protoporphyrin • Serum ferritin • Transferrin receptors sumattana glangkarn

9. Serum iron concentration • In IDA, serum iron may either be low or even normal • The normal value between 50 and 175 µg/dl • There is a considerable diurnal variation; the levels are highest in the morning and lowest during the night • It is reduced in inflammation, malignancy and during menstruation sumattana glangkarn

10. Total iron binding capacity • Total iron binding capacity (TIBC) and transferrin saturation indicate iron supply to issues • The normal value is about 300 µg/dl • TIBC is lowered in chronic disease and raised in iron deficiency Transferrin saturation • This is a ratio of serum iron and TIBC, normal value is 33% • In iron deficiency, there is a decreased saturation, while in chronic diseases the saturation is normal sumattana glangkarn

11. Protoporphyrin • Protoporphyrin is the precursor of heme • Free red blood cell (RBC) protoporphyrin is raised when there is an insufficient supply of iron for heme synthesis • It is high in IDA, caused by lead toxicity and other sideroblastic anemia sumattana glangkarn

12. Serum ferritin • Serum ferritin reflects the status of total body iron stores • A value below about 10 ng/ml is considered as diagnostic of iron deficiency • Its levels are raised in inflammation, infections and liver disease • Serum ferritin is a sensitive indicator of iron stores, particularly in areas where the incidence of infections is very high; the developing countries of south-east Asia sumattana glangkarn

13. Transferrin receptors • Transferrin receptors become elevated on cell surfaces and in plasma whenever there is insufficient iron supply to cells or iron depletion. Because of the cost implications for multiple biochemical tests, the parameter used to indicate iron status in population studies of IDA is measured by hemoglobin. sumattana glangkarn

14. Hemoglobin (Hgb) ค่าปกติ (g/dl) ชาย 14-18 หญิง 12-16 เด็ก 11-16 ทารก 10-15 แรกคลอด 14-24 sumattana glangkarn

15. Hematocrit : Hct Hct. = 3 (Hgb) ค่าปกติ (/100 ml.) ชาย 42-52 หญิง 37-47 เด็ก 31-43 ทารก 30-40 แรกคลอด 44-64 sumattana glangkarn

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18. Centrifuge sumattana glangkarn

19. Clinical features of iron-deficiency anemia • The symptoms of IDA depend on the rate at which anemia develops in an individual • Symptoms may relate to rate of fall in hemoglobin • Lowering of hemoglobin affects oxygen carrying capacity; in IDA, any physical exertion leads to shortness of breath • Initially, most patients complain of increasing lethargy and fatigue • More unusual symptoms are headache, tinnitus and disturbance in test sumattana glangkarn

20. As the severity of deficiency increases, the patients develop pallor of conjunctiva, tongue, nailbeds and soft palate • In IDA of longer duration, there may be papillary atrophy of the tongue and, the nail may become spoon shaped (koilnychia) • In children, chronic IDA may lead to behavioral changes; they may have impairment of cognitive function and short attention spans and appear withdrawn sumattana glangkarn

21. Conjunctiva Normal appearing conjunctiva sumattana glangkarn

22. Spoon finger sumattana glangkarn

23. Iron metabolism • Human body requires iron for the synthesis of the oxygen transport proteins, hemoglobin and myoglobin in the body • Total body iron in men ~ 3.8 g, in women ~ 2.3 g. • Approximately 2/3 of total iron is functional, serving either a metabolic or an enzymic function; in the form of hemoglobin, circulating with in RBC • The factor influencing iron balance are intake of iron, iron stores and iron loss • Adult males require ~ 1 mg of absorbed iron daily to replace the losses in gut secretions, epithelial cells, urine and skin • In menstruating females this can increase to 1.4 sumattana glangkarn

24. Factor influencing iron absorption • Type of food consumed; meat, eggs • Interactions between foods; iron absorption enhancers (vitamin C), iron absorption inhibitors (i.e. calcium phosphate, bran) • Regulatory mechanisms in the intestinal mucosa • Bioavailability; utilization of ingested iron for metabolic functions • Amount of iron stores: liver, reticuloendothelial, bone marrow • Rate of production of red blood cells sumattana glangkarn

25. Iron losses • In healthy individuals occur primarily in feces (0.6 mg/day), bile and desquamated mucosal cells, and in minute quantities of blood • Urinary losses are small • Women of reproductive age, in addition to the basal losses; lose iron in menstruation • The median menstrual blood loss is about 30ml/day, an additional requirement of 0.5 mg of iron per day sumattana glangkarn

26. In the tropical countries, hookworm infestation is a major cause of gastrointestinal blood loss contributing to iron deficiency in older children and adults. • In the developed world, among adults, chronic use of drugs such as aspirin, bleeding tumors and ulcers contribute to iron losses. sumattana glangkarn

27. Risk factors for anemia • Poor iron stores • Dietary inadequacy • Increased demands • Malabsorption and increased losses • Hemoglobinopathies; thalassemia, sickle cell anemia (non-nutritional factor) • Drug and other factors; anticancer drug, radiation therapy sumattana glangkarn

28. Prevention and control of iron-deficiency anemia • Provision of iron supplements • Fortification of commonly consumed food with iron • Nutrition education • Horticulture-based approaches to improving the iron bioavailability of common foods sumattana glangkarn

29. Iodine and Iodine-deficiency Disorders • The epidemiology of iodine deficiency disorders (IDD) is currently in a transitional phase because of the great progress seen during the 1990s in the battle against IDD • Mainly in the form of national salt iodization programs • The diagnosis of iodine deficiency should be seen as a group, community or population diagnosis rather than an assessment on the individual level; interpretation of IDD status sumattana glangkarn

30. Definition of iodine status of a population sumattana glangkarn

31. Thyroid size by palpation • Grade 0: no palpable or visible goiter • Grade 1: a mass in the neck that is consistent with an enlarged thyroid that is palpable but not visible when the neck is in the normal position (Ia), but move upwards in the neck as the subject swallows and visible when neck fully extended (Ib) • Grade 2: a swelling in the neck that is visible when the neck is in a normal position and is consistent with an enlarged thyroid when the neck is palpated sumattana glangkarn

32. Thyroid size by ultrasonography is a safe, noninvasive, specialized technique, which provides a more accurate measurement of thyroid volume than palpation • Thyroid-stimulating hormone (TSH) and thyroglobulin can be used as indicators to assess IDD, or as surveillance indicators • Thyroid hormones thyroxine (T4) and triiodothyronine (T3) tests are cumbersome, more expensive and less sensitive than other indicators sumattana glangkarn

33. WHO/UNICEF/ICCIDD recommended dietary intake for iodine (2001) sumattana glangkarn

34. Management of iodine deficiency • Use of iodized salt • Iodination of drinking water • Fortification of infant formulas • Fortification of other food sumattana glangkarn

35. Xerophthalmia Vitamin A Deficiency sumattana glangkarn

36. Vitamin ADeficiency • Vitamin A deficiency is the most common cause of childhood blindness • Causing 250,000-500,000 children to go blind every year, half of whom will die within the year • Vitamin A deficiencydisorders occur when body reserves are depleted to the limit at which physiological functions are impaired • Xerophthalmia; the pathological eye signs of Vitamin A deficiency sumattana glangkarn

37. Sources of vitamin A • Common dietary sources of performed vitamin A are liver, milk and milk products, eggs and fish • The richest sources are liver oils of fish, such as shark, halibut and cod, and of marine mammals, such as polar bear • The livers of ox, sheep, calves or chicken also contain vitamin A at concentrations comparable to cod liver oil • Eggs, milk and other dairy products: butter and cheese, are all moderate sources • Provitamin A carotenoids are found in yellow and orange fruit and vegetables, and in dark green leafy vegetables sumattana glangkarn

38. Consequences of vitamin A deficiency • Xerophthalmia represents the ocular consequences of vitamin A deficiency that include night blindness (XN), conjunctival xerosis (X1A), Bitot’s spots (X1B), corneal xerosis (X2), ulceration (X3A) or necrosis/keratomalacia (X3B) • Immunocompetence: effects on the immune system, infection sumattana glangkarn

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40. Epidemiology Magnitude of the problem • Vitamin A deficiency is, after PEM and iron-deficiency anemia, the most widespread and serious nutritional disease among young children • In 1994, global estimate indicated that 2.8 million preschool children are clinically affected by vitamin A deficiency • Asia and Africa account for nearly 90% of the global problem sumattana glangkarn

41. Risk factors • As a public health problem, vitamin A deficiency occurs within an environment of social, economic and ecological deprivations in which people live in the transitional and developing economics of the world • It is imperative to understand the local conditions when designing appropriate and effective intervention programs to improve the situation • Some underlying factors: age, gender, physiological status, diet, disease patterns, socioeconomic conditions sumattana glangkarn

42. Age • Varying levels of vitamin A deficiency, from subclinical forms to the severe form of blinding malnutrition (keratomalacia), can occur at any age • However, vitamin A deficiency, particularly severe deficiency, affects children of preschool age • The requirements for growth are high, while the dietary intake of vitamin A is often low • Children under 12 months of age, corneal disease is relatively rare event, largely because breast-feeding is protective sumattana glangkarn

43. Gender • In healthy human adults, both plasma retinol and RBP (retinol binding protein) are found at levels 20% higher in males than females • Nevertheless, males have generally been found to be at higher risk of night blindness and Bitot’s spot than female during the preschool and early school-age years • Less gender difference in severe xerophthalmia sumattana glangkarn

44. Physiological status • Vitamin A needs are increased during periods of rapid growth, younger children are the most vulnerable group • The demands for vitamin A are also increased during the period of gestation and lactation • Night blindness during pregnancy and lactation is especially common in south Asia (15-20% of all pregnancies) • Studies have shown, breast milk of women with poor vitamin A could subsequently contribute to increased susceptibility of the infants sumattana glangkarn

45. Diet • The basic underlying cause of vitamin A deficiency is a diet lacking adequate amounts of vitamin A, either preformed or provitamin A carotenoids, to meet the requirement • Vitamin A deficiency is common wherever diets are of relatively low quality • Breast-feeding, the quality of complementary feeding and the quality of the children diet are all important factors in maintain vitamin A status ; xerophthalmia protective sumattana glangkarn

46. Diet • Epidemiological studies support a progressive of appropriate complementary feeding that has been shown to guard children from xerophthalmia through the preschool year • Intake of yellow fruit (mango and papaya) is strongly protective in the second and third years of life • Dark green leafy vegetables play a more important role from the third year onwards • After infancy, routine consumption of animal foods with preformed vitamin A (eggs, dairy products, fish and liver) is highly protective sumattana glangkarn

47. Disease patterns • Vitamin A deficiency increase the risk of infectious morbidity; diarrhea, respiratory infection, measles • Intestinal worms such as Giardia and Ascaris have been reported to lead to reduced absorption of vitamin A sumattana glangkarn

48. Socioeconomic conditions • Vitamin A deficiency is confined largely to relatively impoverished countries • Studies have shown that households with mildly xerophthalmic children have smaller landholdings, poorer housing conditions, fewer draft and grazing animals, and lower economic standing • Low education levels of the father or mother are a further risk factor sumattana glangkarn

49. Prevention • Food-based approaches, including dietary diversification, nutrition education and fortification of staple and value-added food • Supplementation with vitamin A capsules • Breast-feeding, treatment of infectious diseases • Modification of the political, socioeconomic, physical environment sumattana glangkarn

50. Food fortification • Food fortification refers to the addition of micronutrients to processed foods. • Salt iodization was introduced in the early 1920s in both Switzerland and the USA. • From the early 1940s onwards, the fortification of cereal products with thiamine, riboflavin and niacin became common practice • Margarine was fortified with vitamin A in Denmark. • Milk with vitamin D in the United States sumattana glangkarn