Nutritional status and adult mortality in a mid-20th century Gambian population: do different types of physical ‘capital’ have different associations with mortality?

Abstract

Measures of nutritional status are often used as markers of health, at both individual- and population-level. Different measures of nutritional status – such as height or weight, for example, – may have different associations with health outcomes because they reflect both current nutritional status and the accumulation of past health experiences, but the weighting of past and present experiences differs between different measures. Here, we present an analysis of a longitudinal dataset, collected between 1950 and 1974 in four Gambian villages, to investigate whether three different measures – height, body mass index (BMI) or haemoglobin level – are associated with adult mortality. We interpret these different measures as indicators of different types of physical ‘capital’ that vary in their liquidity. Adult height represents ‘illiquid’ capital, indicative of nutritional status in the past, during different periods of development. BMI, determined both by past childhood experiences and recent nutrition and health exposures, represents capital of intermediate ‘liquidity’. Haemoglobin represents ‘liquid’ capital, determined largely by recent environmental exposures. We find, not unexpectedly, that the more ‘liquid’ measures of capital show clearer associations with adult mortality: for haemoglobin there is a negative relationship with mortality risk for both sexes: BMI is also broadly negatively related to mortality risk for both men and women, though overweight individuals suffer a slightly increased risk of death. For men, there is no relationship between the ‘illiquid’ measure of height and adult mortality; but for women, there is a U-shaped relationship, with women of average height having the lowest mortality.