Stable carbon isotopic evidence for differences in the dietary origin of bone cholesterol, collagen and apatite: Implications for their use in palaeodietary reconstruction

Rats were raised on a variety of isotopically controlled diets comprising 20% C3, C4 or marine protein and C3 and/or C4 non-protein or energy (i.e. sucrose, starch and oil) macronutrients. Compound specific stable carbon isotope ( C) analysis was performed on the cholesterol isolated from the diet (n 7) and bone (n 15) of these animals and the values compared with bulk C measurements of bone collagen and apatite. The dietary signals reflected by these three bone biochemical components were investigated using linear regression analysis. C values of bone cholesterol were shown to reflect whole diet C values, collagen to reflect mainly dietary protein values and apatite to reflect whole diet values. Further correlations between dietary protein-to-energy spacings ( Cprot-engy Cprotein – Cenergy) and whole diet-to-bone component fractionations ( Cbcomp-wdiet Cbone component – Cwhole diet) indicates that for hypothetical diets where protein C values are equal to energy values, fractionations between whole diet and bone biochemical fractions are –3.3‰ for cholesterol, 5.4‰ for collagen and 9.5‰ for apatite. Moreover, the narrow range of variation observed in apatite-to-cholesterol spacings ( Capat-bchol) suggests that cholesterol C values can potentially also be used as an independent test for the isotopic integrity of apatite C values. These insights into bone cholesterol, collagen and apatite dietary signals, diet-to-bone fractionations and bone component-to-bone component spacings provide the basis for more accurate interpretations of the dietary behaviour of archaeological populations and food webs when the C analysis of bone is employed. Copyright © 2004 Elsevier Ltd