Indirect methods: vital statistics, ecological factors and food balance sheets
Indirect methods judge a community's nutrition from records, not bodies: death and illness rates, ecological conditions, and the food balance sheet showing food available per head.
Vital statistics as indicators
| Indicator | Why it reflects nutrition |
|---|---|
| Infant mortality rate (IMR) | Many infant deaths involve low birth weight, poor breastfeeding and infection on top of malnutrition |
| Under-five mortality rate | Undernutrition is an underlying cause in a large share of deaths of young children |
| 1-4 year mortality rate | The most sensitive mortality index of child malnutrition: deaths at weaning age reflect PEM and infection |
| Low birth weight rate | Babies below 2500 g reflect the mother's nutrition and health in pregnancy |
| Maternal mortality ratio | Anaemia and poor nutrition add to maternal deaths |
| Morbidity records | Cases of diarrhoea, measles, TB and deficiency diseases in PHC and hospital records |
| Life expectancy | Rises as nutrition and health improve |
Ecological factors (Jelliffe)
- Conditioning influences: infections and parasites (diarrhoea, measles, worms) that worsen nutrition.
- Food consumption: what and how much families actually eat, found from diet surveys.
- Cultural influences: food habits, taboos (e.g. avoiding certain foods in pregnancy), cooking and feeding practices, breastfeeding customs.
- Socio-economic factors: income, food prices, family size, the mother's education, employment.
- Food production: crops grown, soil, irrigation, storage losses, seasons of plenty and scarcity; climate, floods and drought.
- Medical and educational services: PHCs, anganwadis, schools, water, sanitation, PDS.
The food balance sheet
A food balance sheet shows the total food available for human use in a country in a year, divided by the population to give the amount available per person per day (in grams, and as energy, protein and fat). It is usually prepared in the FAO format. Supply = production + imports + stocks drawn out; then subtract exports, stocks added, seed, animal feed, industrial use and wastage. It shows whether the nation has enough food, but not how it is shared among states, families or family members.
Worked example: availability of pulses per person
In a year a country produced 25 million tonnes of pulses and imported 3 million tonnes. Exports were 0.5 million tonnes, and seed, feed and wastage took 2.5 million tonnes. Stocks did not change. The population was 1400 million. Find the net availability of pulses per person per day. (Figures are made up for practice.)
- Net available = 25 + 3 − 0.5 − 2.5 = 25 million tonnes a year.
- In grams: 1 tonne = 1,000,000 g, so 25 million tonnes = 25 × 10¹² g.
- Per person per year = 25 × 10¹² ÷ (1400 × 10⁶) = 17,857 g (rounded to the nearest gram).
- Per person per day = 17,857 ÷ 365 = 48.9 g, rounded to one decimal.
About 49 g of pulses per person per day. This is a national average; the poorest families may get far less, so it must be read with diet surveys.
Merits vs limitations of indirect methods
A district nutrition officer who studies 1-4 year deaths, low-birth-weight rates and the season of food scarcity can decide where to open extra anganwadi centres or NRCs even before a full survey is done.
2 marks: “What is a food balance sheet?” A statement of a country's total food supply for human use in a year, expressed as availability per person per day.
5 marks: “Explain how vital statistics are used to assess nutritional status.” IMR, under-five and 1-4 year mortality (most sensitive), LBW rate, MMR, morbidity records; why each reflects nutrition; limitations of the data.
10 marks: “Discuss the indirect methods of assessing the nutritional status of a community.” Vital statistics table; Jelliffe's ecological factors; food balance sheet with its formula and a worked example; merits and limitations.
Indirect methods are V-E-F: Vital statistics, Ecological factors, Food balance sheet. They read records, not bodies.