Community medicine chapters
Micronutrient deficiencies
The micronutrient deficiencies that matter most in Pakistan (iron, iodine, vitamin A, zinc, vitamin D and folic acid), their features, the WHO grading of xerophthalmia, and the public health measures used to prevent them.
- Micronutrient deficiencies ("hidden hunger") are common in Pakistan: anaemia affects over half of young children and about four in ten women of reproductive age (National Nutrition Survey 2018).
- Iodine deficiency causes goitre and cretinism (prevented by iodised salt); vitamin A deficiency causes night blindness and xerophthalmia (prevented by six-monthly high-dose capsules from 6 months to 5 years).
- Zinc shortens and prevents diarrhoea; vitamin D prevents rickets; folic acid before conception prevents neural tube defects.
On this page
Overview
Micronutrients are vitamins and minerals needed in small amounts. Their deficiency is called hidden hunger because people may look well fed yet be deficient. They harm growth, immunity, learning, pregnancy outcomes and work capacity.
Pakistan's National Nutrition Survey (NNS) 2018 found high levels of anaemia, vitamin A, vitamin D and zinc deficiency. Check the latest survey for current figures.
Iron deficiency anaemia
The commonest micronutrient deficiency worldwide and in Pakistan.
Causes: poor intake (little meat, tea with meals), blood loss (hookworm, heavy periods), increased needs (infancy, adolescence, pregnancy), repeated pregnancies.
Effects: tiredness, poor school and work performance, low birth weight and maternal deaths, impaired child development.
WHO haemoglobin cut-offs for anaemia (at sea level):
| Group | Anaemia if Hb below |
|---|---|
| Children 6–59 months | 11 g/dL |
| Children 5–11 years | 11.5 g/dL |
| Non-pregnant women (15+ years) | 12 g/dL |
| Pregnant women | 11 g/dL |
| Men (15+ years) | 13 g/dL |
Prevention: iron-folic acid supplements in pregnancy, deworming, dietary advice (meat, pulses, vitamin C with meals, avoid tea with meals), fortification of wheat flour, delayed cord clamping, birth spacing.
Pregnant women are anaemic below 11 g/dL; non-pregnant women below 12 g/dL.
Iodine deficiency disorders (IDD)
Iodine is needed for thyroid hormones. Deficiency occurs where soil is poor in iodine, classically in mountainous and flood-prone areas (northern Pakistan was historically endemic).
Spectrum of IDD:
- Fetus: abortion, stillbirth, congenital anomalies, cretinism (intellectual disability, deaf-mutism, short stature).
- Child and adolescent: goitre, hypothyroidism, poor school performance.
- Adult: goitre, hypothyroidism, reduced work capacity.
Iodine deficiency is the world's commonest preventable cause of brain damage (intellectual disability).
Indicators: goitre prevalence in school children (a total goitre rate of 5% or more indicates a public health problem) and median urinary iodine concentration (adequate at about 100–199 µg/L in school children).
Prevention: universal salt iodisation: iodised salt is the main strategy. Iodised oil for high-risk areas.
Vitamin A deficiency
Vitamin A is needed for vision (rhodopsin), healthy epithelium and immunity.
Causes: poor diet, measles, diarrhoea, malnutrition.
Effects: night blindness, xerophthalmia, blindness, and higher deaths from measles and diarrhoea.
WHO classification of xerophthalmia
| Grade | Sign |
|---|---|
| XN | Night blindness (the earliest symptom) |
| X1A | Conjunctival xerosis |
| X1B | Bitot's spots (foamy, triangular patches on the conjunctiva) |
| X2 | Corneal xerosis |
| X3A | Corneal ulceration or keratomalacia covering less than a third of the cornea |
| X3B | Keratomalacia involving a third or more of the cornea |
| XS | Corneal scar |
| XF | Xerophthalmic fundus |
Night blindness is the earliest symptom; Bitot's spots are X1B; keratomalacia is a blinding emergency.
Prevention: high-dose vitamin A supplementation
| Age | Dose |
|---|---|
| 6–11 months | 100,000 IU once |
| 12–59 months | 200,000 IU every 6 months |
Also: vitamin A for children with measles, breastfeeding, vitamin A-rich foods (green leafy vegetables, carrots, mangoes, liver, eggs), fortification of cooking oil and ghee.
High-dose vitamin A must be avoided in pregnancy because it is teratogenic.
Zinc deficiency
Zinc is needed for growth, immunity and repair of the gut lining.
Effects: stunting, more infections, more severe and longer diarrhoea, delayed wound healing, skin lesions.
Zinc in diarrhoea (WHO/UNICEF): with ORS, give zinc 20 mg daily for 10–14 days (children over 6 months), or 10 mg daily for infants under 6 months. It shortens the episode and reduces further episodes for two to three months.
ORS plus zinc is the standard treatment for childhood diarrhoea.
Vitamin D deficiency
Very common in Pakistan despite sunshine (indoor living, covered clothing, darker skin, poor diet).
Effects: rickets in children (bowed legs, widened wrists, delayed teeth), osteomalacia and bone pain in adults, maternal deficiency affecting the newborn.
Prevention: sunlight exposure, vitamin D supplements (for example 400 IU daily for infants, per common guidance), fortified foods.
Folic acid and vitamin B12
- Folic acid deficiency causes megaloblastic anaemia and, around conception, neural tube defects. Women planning pregnancy should take 400 µg daily from before conception to 12 weeks (higher doses for those at high risk). Wheat flour fortification helps.
- Vitamin B12 deficiency is common in vegetarians and those with poor absorption (pernicious anaemia); causes megaloblastic anaemia and nerve damage.
Other micronutrients
- Vitamin C: scurvy (bleeding gums, poor wound healing).
- Thiamine (B1): beriberi, Wernicke's encephalopathy.
- Niacin: pellagra (dermatitis, diarrhoea, dementia), linked with maize diets.
- Fluoride: too little causes dental caries; too much causes fluorosis (mottled teeth, bone changes).
Public health strategies
- Supplementation: iron-folic acid in pregnancy, vitamin A capsules, zinc in diarrhoea.
- Food fortification: iodised salt, wheat flour with iron and folic acid, edible oil and ghee with vitamins A and D.
- Dietary diversification: education, kitchen gardens, breastfeeding.
- Public health measures: deworming, immunisation (measles), clean water and sanitation.
- Biofortification: breeding crops with more nutrients (for example zinc-enriched wheat).
Expect: iron as the commonest deficiency, WHO anaemia cut-offs, the spectrum of IDD and iodised salt, the xerophthalmia grades (XN earliest, X1B Bitot's spots), vitamin A doses by age, zinc dosing in diarrhoea, vitamin D and rickets, and folic acid for neural tube defects.
Quick revision
- Iron: commonest; Hb cut-offs 11 (child, pregnancy), 12 (women), 13 (men).
- Iodine: goitre, cretinism; universal salt iodisation.
- Vitamin A: night blindness earliest; Bitot's spots X1B; 100,000 IU (6–11 months), 200,000 IU 6-monthly (12–59 months).
- Zinc with ORS: 20 mg/day for 10–14 days (10 mg under 6 months).
- Vitamin D: rickets and osteomalacia.
- Folic acid 400 µg/day before conception prevents neural tube defects.
Written by The House Job from Excel Community Medicine and Park's Textbook of Preventive and Social Medicine (named in the UHS PGET syllabus), with WHO cut-offs and dosing schedules and Pakistan's National Nutrition Survey 2018. Follow current national guidance for doses.
FAQ
What is the earliest sign of vitamin A deficiency?
Night blindness.
How is iodine deficiency prevented in a population?
By universal iodisation of salt.
What dose of zinc is given to a child with diarrhoea?
20 mg daily for 10–14 days for children over 6 months, or 10 mg daily for infants under 6 months, together with ORS.
What haemoglobin level defines anaemia in pregnancy?
Below 11 g/dL, according to WHO.