Stable isotopes ((13)C and (15)N) track socioeconomic differences among urban Colombian women

BENDER, RICHARD L; DUFOUR, DARNA L; VALENZUELA, LUCIANO O; CERLING, THURE E; SPONHEIMER, MATT; EHLERINGER, JAMES R

Minneapolis

Encuentro; The 80th annual meeting of the American Association of Physical Anthropologists (AAPA).; 2011

American Association of Physical Anthropologists

The stable isotope composition of mammalian tissues, such as hair, can serve as an indicator of dietary composition. Here, we present stable isotope data for hair samples taken from 38 urban Colombian women from two different socioeconomic status (SES) groups. The goal is to determine whether the two SES groups differ in stable isotope composition, and whether these differences track with long-term indicators of nutritional status, including BMI, five body circumference measures, and six skinfold measures. Hair samples were analyzed for δ13C and δ15N. There is a significant positive, but weak, correlation between δ13C values and δ15N values (r2=0.23, p<0.01). The higher SES group has significantly greater mean δ13C (-16.4 ± 0.5) and δ15N (10.3 ± 0.4) values than the lower SES group (-17.2 ± 0.8 and 9.6 ± 0.6) (Kruskall-Wallis, p<0.05). Discriminant function analysis using only δ13C values and δ15N values correctly classifies 79% of subjects into the two SES groups, further indicating a substantial difference in isotope composition along socioeconomic lines. On the other hand, there are no SES differences in any of the 12 anthropometric measures. Furthermore, neither δ13C values nor δ15N values are significantly correlated with any of these variables. Contrary to expectations, stable isotope composition is a stronger predictor of SES than traditional indicators of long-term nutritional status in this sample. The Observed differences reflect either variation in the isotopic composition of the diet, or variation in the isotopic spacing between diet and tissues as a result of differing dietary quality or nutritional status.