Micronutrient malnutrition II

Vanessa Velazquez-Ruiz, MDEmergency Medicine Global Health Fellow

St. Luke’s-Roosevelt Hospital

Today schedule….

Zinc Deficiency

Iodine deficiency

Are you ready!!!!!!

Lets begin the second part of our journey

Zinc Deficiency

Common but overlooked problem in developing countries

Important role in biological processes

Gene expression

Cell development

Replication

Immune function

Growth and development

Overview

Intakes of zinc are commonly lower than recommended

Adaptation mechanisms preclude the development of severe deficiencies

Many consequences to adaptation states to low zinc levels

Overview

Probably affects a quarter or a third of pre school children and their mothers

Lack of simple quantitative markers for zinc deficiency

Overall, 20.5% of the world population is at risk of zinc deficiency

Estimated to be responsible for 800,000 deaths/year from diarrhea, malaria, pneumonia in children under five

One of the ten largest contributors to the burden of disease in developing countries

Zn deficiency in world crops: major areas of reported problems (adapted from Alloway, 2008a

Overview

Incidence and prevalence have not been defined

Lack of sensitive, practical, accepted indicators for zinc deficiency

Population-based surveys have not been done

Marginal deficiency is not characterized as a specific syndrome

Severe clinical deficiency is not seen owing to adaptation or death

Risk factors for zinc deficiency

Insufficient dietary intake (low protein diet)

High phytate and/or fiber intake (vegetarians)

Diarrheal disease

Malabsorption syndromes

Parasitosis

Hot, humid climate

Lactation

Rapid multiplicative cell growth (pregnancy, infancy, adolescence)

Genetic disease (acrodermatitis enteropatthica, Sickel cell anemia)

Close geographical linkage between soil zinc deficiency and human zinc deficiency

Zinc Metabolism

Zinc absorption

Absorbed at all levels of the small intestine

Intestine must recover zinc from both diet and endogenous sources

Total body zinc content maintained with absorption of 5mg/day

Zinc Storage

No specific organ for storage

60% striated muscle

20% in bone

5% in blood and liver

3% in the skin and GI tract

Zinc excretion

Mostly in feces

Through urine

In tropical countries, sweat losses can be considerable

Turnover of skin, hair and nails

Menstrual blood and semen

Lactation (2-3mg per day in the first several weeks)

Sources of zinc

Animal products, seafood, cereals Oysters and shellfish

Absorption impaired by phytates and fiber.

Protein acts as anti-phytate

Clinical presentation

Severe deficiency

Growth retardation

Impaired immune system

Skin lesions in extremities and perioral area

Hypogonadism

Anorexia

Cognitive dysfunction

Alopecia

Mild to moderate

Increases susceptibility to infection

Growth retardation

Failure to thrive

Impaired taste (hypogeusia)

During pregnancy

Birth defects

Spontaneous abortions

Fetal growth retardation

Low birth weight

Preterm delivery

Increase complications during delivery

Impairs estrogen-dependent gene expression in the uterus (via zinc-finger protein)

Lack of estrogen impairs the conversion of uterus from passive state to one capable of concerted contractions with sufficient force to expel fetus

Zinc and diarrheal disease

Strong evidence that supplements improves the prognosis (reduces severity and duration) of children treated for diarrheal disease

Zinc supplement + oral rehydration treatments been explored

UNICEF recommends packs of ten tablets of 20mg Zinc/daily for tx of diarrhea

Zinc and respiratory diseases

Regular zinc supplements have shown to prevent respiratory diseases in children with lower birth weights

Pool analysis of randomized controlled trails showed reduction of pneumonia by 41% in preschool children supplemented with zinc

One trial in Bangladesh showed reduced duration of severe pneumonia by 30% with zinc as adjunct therapy

Zinc and malaria

Gambia: 32% fewer clinic visits for malaria due to Plasmodium falciparum in young children supplemented with Zinc

69% reduction for malaria episodes accompanied by high levels of parasitemia (>10,0000 parasites/μL)

Zinc and HIV

Low serum Zinc identifies in 29% of hospitalized AIDS patients

Some studies showed that low zinc levels may reflect HIV replication and the possibility that Zinc may enhance viral replication, however,

Daily zinc supplementation for 30 days has proven to reduce infectious disease morbidity in AIDS patients in other studies

http://www.zincsaveskids.org/

http://www.youtube.com/watch?v=vN_qQPxPK3Q

Assessment

Plasma and Serum Zinc concentration

Circulating zinc less than 0.2% of total body

Cut-off values to assess risk of zinc deficiency Below 10.71 μmol/L for fasting sample and less

then 9.95μmol/L for non fasting

Dietary assessment

Food intake distributions of a population

Analysis of local staple foods

Recall of an individual for food consumed

Weighed food records by research assistants

24-hr dietary recall

Local food composition tables if available

Other

Hair zinc concentrations

Diminished taste acuity (hypogeusia)

Composite index for predicting the national risk of zinc deficiency- uses a combination of stunting rates and adequacy of zinc in the national supple

Replacement and treatment

Table 1: Recommended Dietary Allowances (RDAs) for

Zinc Age Male FemalePregnancy Lactation

0–6 months 2 mg* 2 mg*    

7–12 months 3 mg 3 mg    

1–3 years 3 mg 3 mg    

4–8 years 5 mg 5 mg    

9–13 years 8 mg 8 mg    

14–18 years 11 mg 9 mg 12 mg 13 mg

19+ years 11 mg 8 mg 11 mg 12 mg

* Adequate Intake (AI)

Recommended nutrient intakes (RNIs) for dietary zinc (mg/day) to meet the normative storage requirements from

diets differing in zinc bio-availability

Treatment

To combat zinc deficiency, five intervention strategies can be used:

Supplementation using medicines

Food fortification through the incorporation of zinc additives in food

Dietary modification/diversification

Genetic biofortification through plant breeding

Agronomic biofortification through zinc fertilization.

Iodine deficiency

Overview

Iodine is an essential constituent of the thyroid hormones (T4, T3)

Deficiency can lead to Goiter or cretinism depending on the severity

The ongoing global health effort to eliminate iodine deficiency through iodization of salt presents one of the largest public health efforts

By 1990, there were 1,572 million people worldwide consuming inadequate amounts of iodine

Iodine deficiency is the leading cause of mental retardation in the world

Problem is global, with mountainous regions and large river deltas the most well-known areas of endemic deficiencies

Epidemiology

Mountainous areas, high altitude and alluvial plains

Leaching of iodine form the soil due to erosion and heavy rain, deforestation, overgrazing lead to loss of iodine form soil and water

WHO Region Proportion of population with UI Population with < 100 µg/L (%)

UI < 100 µg/L (millions)

Africa 42.6260.3Americas 9.8 75.1South East Asia 39.8 624Europe 56.9435.5Eastern Mediterranean 54.1228.5Western Pacific 24 365.3Total 35.21988.7

192 WHO Members States Based on population estimates for the year 2002 (United Nations, Population Division, World Population Prospects: The 2002 Revision)

WHO 2003

Risk factors

Residency in an area where soil and water are poor in iodine

Ingestion of substances known as “goitrogens”( found in vegetables and fiber) that can interfere with metabolism

Cabbage, sweet potato, brussel sprouts, turnips

Cassava containing high concentration of thiocyanates

Role of iodine in biological functions

Metabolism

Growth and development

Synthesis of growth hormone

Normal bone cell growth and development

Brain development

Early growth and differentiation of the brain and nervous systems in the fetus

Immune function

Sources of Iodine

Seafood and seaweed

Crops grown on iodine rich soil

Iodized salt

Drinking water (less than 10%)

WHO recommended dietary requirements

Spectrum of iodine deficiency disorders

Fetus

Abortions

Stillbirths

Congenital anomalies

Increase perinatal mortality

Neurological cretinism: mental deficiency, deaf-mutism, spastic diplegia, squint

Myxoedematous cretinism: dwarfism, mental deficiency

Spectrum of iodine deficiency disorders

Neonate

Neonatal goiter

Neonatal hypothyroidism

Spectrum of iodine deficiency disorders

Child and adolescent

Goiter

Juvenile hypothyroidism

Retarded physical development

Spectrum of iodine deficiency disorders

Adult

Goiter

Hypothyroidism

Impaired mental function

Iodine-induce hyperthyroidism

Goiter

Enlargement of thyroid gland in response to insufficient iodine intake

Low iodine -> decrease T4 -> increase production of TSH -> stimulates hyperplasia of the thyroid -> increase uptake of iodine -> Goiter

Definition by palpation: enlargement of the thyroid such that lateral lobes are larger than the terminal phalanx of the thumb of the person who is being examined

Goiter Severity of goiter correlates with severity of the

deficiency

In areas of endemic goiter , the daily intake is less the 100 μg/day

Cretinism

Usually found where the prevalence of endemic goiter is more than 30%

Characterized by mental retardation

Two extreme types of cretinism:

Neurological

Myxoedematouse

Myxoedematous cretinism (hypothyroid cretinism): severe growth retardation, mental retardation not severe, coarse, dry skin, husky voice.

Neurological cretinism: stature is normal, mental retardation is severe, deaf-mutism, cerebral diplegia

Assessment of iodine status

Urinary iodine

Most useful/reliable indicator I status

24hr or random (30 samples) urine collection

Related to recent dietary I intake

Adequate 100-200 μg/L

Mild deficiency 50-99μg/L

Moderate Deficiency 20-49μg/L

Severe Deficiency Less than 20μ/L

Assessment of iodine status

Thyroid size (goiter surveys)

Palpation

Ultrasound (more reliable)

“Total Goiter Rate”, schoolchildren

Grade 0 No palpable or visible goiter

Grade 1 Palpable mass but not visible when neck in normal position

Grade 2 Visible, palpable swelling of the neck

Classification for Goiter

Mild 5-19.9

Moderate 20-30

Severe >30

Goiter by palpation or by thyroid volume by US (>97% of percentile)

*School-children

TSH screening programs

For early detection of congenital hypothyroidism

Useful epidemiology information, not cost effective

The degree of iodine deficiency can be evaluated on the basis of the frequency of neonatal blood TSH above the cutoff point of 3μU/ml

Mild deficiency TSH 3-19.9

Moderate deficiency TSH 20-40

Severe deficiency TSH > 40

Prevention

Iodized salt: “Universal salt iodization” (150μg of I/day)

Oral iodide oil

Adult : 1ml (480mg)

0.5ml (240mg)

Iodized oil injections

Prevention

Other:

Iodization of drinking and irrigation water

Iodine saturated silicon matrices placed in wells and hand pumps

Fortification of food

Conclusion

Iodine deficiency is the leading cause of preventable mental retardation

Great progress in providing access to iodized salt

WHO/UNICEF/ICCIDD report in 1999, from 5 billion people living in counties with iodine deficiencies, 68% now have access to iodized salt.

From 130 counties, 104 have intersectoral coordination and 98 have legislations about iodized salt

Much work needs to be done…

To be Continued…Stay tune for more on micronutrient deficiencies

next week… same channel, same time

Thanks

Any questions…

References

WHO website