Cutting global tuberculosis by tackling adult undernutrition

Tuberculosis remains a major global health problem and current efforts to reduce cases are not enough. A team led by Peter J. Dodd examined one clear, changeable driver of tuberculosis: undernutrition in adults. The researchers focused on people aged ≥15 years because nutritional status in adults can strongly affect the chance of developing active tuberculosis. Rather than treating undernutrition as a simple yes-or-no risk, they used a continuous view of risk tied to body mass index (BMI). This approach allowed them to account for differences in nutritional status across countries, between men and women, and among age groups. The aim was to estimate how many adult tuberculosis cases could be prevented if low BMI were eliminated at the population level. Using available data on BMI distributions and a statistical model that links BMI to tuberculosis risk, the team built alternative, or counterfactual, BMI scenarios in which people with low BMI were redistributed to higher BMI values. The study therefore looks beyond clinical treatment and asks how much tuberculosis could fall if public health efforts successfully addressed undernutrition on a broad scale.

To quantify the potential impact, the researchers used a continuous risk framework and detailed BMI data. For each country, sex, and age group they generated BMI distributions and applied a bilinear model for the logarithmic relative risk of tuberculosis incidence at different BMI values. They then constructed counterfactual BMI distributions that redistributed those with low BMI to higher BMI, proportional to the remaining density, and assessed two scenarios: eliminating moderate/severe undernutrition (BMI<17kg/m2) and eliminating all undernutrition (BMI<18.5kg/m2). The results were substantial. Eliminating moderate/severe undernutrition was estimated to avert 1.4 million tuberculosis episodes globally (95%UI, 1.1-1.7), representing 16.8% (14.3-19.2) of global adult incidence. Eliminating all undernutrition was estimated to avert 2.3 million (1.8-2.7) episodes, a reduction of 26.5% (23.2-29.8). The analysis also found the largest proportional reductions in the African, South-East Asian, and Eastern Mediterranean regions, and among females, adolescents, and the elderly.

The findings suggest that undernutrition is a much bigger driver of adult tuberculosis than commonly appreciated, and that addressing it could prevent a large share of cases. The study estimates that over a quarter of global adult tuberculosis could be averted by eliminating undernutrition, a figure described as roughly three times higher than current estimates. This points to the potential value of population-level nutrition programs alongside conventional tuberculosis control measures. The authors highlight that scaling up nutritional interventions could bring many social and health benefits beyond preventing tuberculosis, and they call for research to determine the best ways to implement such programs and to measure their real-world impacts. The work was carried out without specific funding and emphasizes the need for urgent action to tackle an underlying, modifiable risk factor if global tuberculosis reductions are to accelerate.