Mapping carbon and nitrogen isotopic composition of fingernails to demonstrate a rural–urban nutrition transition in theCenter‐West, Northeast, and Amazon regions of Brazil

Abstract

ObjectiveThe main objective of this study is to investigate diet patterns among rural and urban populations of the Center‐West, Northeast, and Amazon regions of Brazil through the carbon and nitrogen isotopic composition of fingernails, recognizing that the extent of market integration is a key driver of food consumption.Materials and methodsIn the Center‐West, Northeast, and Amazon regions of Brazil, fingernails were sampled in clusters encompassing a major city, town, and rural village. A total of 2,133 fingernails were analyzed. Fingernails were clipped by donors using fingernail clippers. In the laboratory, samples were cleaned then weighed in small tin capsules before being isotopically analyzed for carbon and nitrogen.ResultsThe overall mean δ13C and δ15N were −19.7 ± 2.8‰ and 10.6 ± 1.1‰, respectively. In the more remote villages, where access to food markets is more challenging, lower δ13C prevails, suggesting that Brazilian staple foods (rice, beans, and farinha) still dominate. In areas with easier access to food markets, δ13C values were higher, suggesting a change to a diet based on C4 plants, typical of a Brazilian supermarket diet. The variability among inhabitants in the same location expressed by a significant inverse correlation between δ13C and δ15N fingernail values suggested that “market integration” does not affect everyone equally in each community.Discussion and ConclusionThe nutrition transition has not yet reached some remote villages in these regions of Brazil or that the nutrition transition has not yet reached all residents of these remote villages. On the other hand, in several villages there is a considerable adherence to the supermarket diet or that some residents of these villages are already favoring processed food.

Impacts of market economy access and livelihood conditions on agro-food transition in rural communities in three macro-regions of Brazil

“…This study was carried out almost on the same geographical scale as Nardoto et al ( 2020 ) in household units (HU) from three macro-regions of Brazil (Amazon, Center-West, and Northeast) distributed along 15 counties, with 19 specific sites (Table 1 ) with at least one adult (i.e., ≥ 18 years) of each HU. Sampling was performed randomly, considering the availability for interviews and if the dwelling was inhabited.…”

“…We sorted the database and fingernail samples according to the type of source region and accessibility to urban areas, such as city, town, village, coast, and island. General sample units can be seen with more details in Nardoto et al ( 2020 ), whereas Jesus Silva et al ( 2019 ) demonstrate site-specific details for Kalunga villages.…”

“…The interviews were conducted without replication at each location, mainly due to difficulties accessing certain areas and limited availability of financial resources to cover all field samples. In this sense, any possible bias in data obtained from the questionnaires was overcome through the isotopic composition analysis of fingernail samples collected from each interviewee, which reflected their food habits directly over 4–6 months in a semiquantitative way (Nardoto et al, 2011 , 2020 ). More details about the advantages of this interdisciplinary method can be seen in Jesus Silva et al ( 2019 ).…”

“…Jesus Silva et al ( 2017 ) were pioneers in approaching the subject through multinomial logistic regression analyses of semi-structured questionnaire data to assess the relative influence of socioeconomic and environmental factors on local food habits. Recently, two relevant articles have been published on food transition in Brazil: one with this joint methodology but restricted to a specific slave-remnant rural community called Kalunga located in the Center-West region (Jesus Silva et al, 2019 ) and the other with an isotopic mapping of fingernail composition in several rural communities in the Amazon, Center-West, and Northeast regions (Nardoto, 2020 ).…”

“…We previously found a more homogeneous food habit based on plants that follow the C 4 photosynthetic metabolism (sugarcane, maize, and grasses) in urban areas (Jesus Silva et al 2019 ; Nardoto et al, 2011 , 2020 ). In general, while the δ 13 C values in C 4 plants vary from − 11 to − 15‰, in C 3 plants, they range from − 24 to − 38‰ (Farquhar et al 1989 ).…”