The impact of household expenditure on human nutrition in Dar es Salaam and Mbeya regions of Tanzania

Based on an earlier research project entitled “An empirical analysis of household demand for food and nutrition in Dar es Salaam and Mbeya regions of Tanzania”, a household survey on food and non-food expenditures was carried out in Dar es Salaam and Mbeya regions of Tanzania in 1998 and 1999. The results of the food demand analysis showed that households raise food expenditure as total expenditure increase.

However, households tend to improve the quality of the food consumed as their incomes increase, and their demand patterns shift within foods of different nutritive composition. Thus, households can increase their food budget without improving nutrient availability. Therefore, a direct analyses of the impact of household per capita expenditure and other demographics on availability of individual nutrients was carried out.

In a first stage, a nonparametric procedure was used to visualize the effect of per capita expenditure on per capita nutrient availability using logarithmic scales. The representation of the influence of expenditure on calorie availability is presented in the figure as an example. As can be seen, calorie availability continuously increases with raising expenditure.

In a second stage parametric estimations were carried out, to estimate nutrient-expenditure elasticities as well as the influence of other socio-demographic variables on nutrient availability. The figures in the table are the estimated nutrient-expenditure elasticities, which indicate the percentage increase of nutrient availability if household expenditure increase by one percent.

The results show that nutrient availability increases with increasing expenditure and thus with increasing household income. Availability of calories increases by 0.34%, and availability of protein by 0.44% when expenditures raise by 1%. This is a clear indication that households not only raise their food expenditure with increasing income, but also improve nutrient availability. Therefore, policies aiming at raising household incomes, especially of low income households are very likely to be effective in improving human nutrient availability.