Increased in Carbon Isotope Ratios of Brazilian Fingernails Are Correlated with Increased in Socioeconomic Status.

High δ 13C in human tissues in Brazil indicate high consumption of C4-based sources due to the consumption of highly processed food and animal protein. The significant positive correlation between the human developed index (HDI) developed by the United Nations Development Program, and fingernail δ 13C at the county level proved to be useful as a new proxy in tracking human nutrition. Regions with higher HDI are those with higher consumption of highly processed food.