Cholesterol as a new source of palaeodietary information: Experimental approaches and archaeological applications

Cholesterol and its diagenetic congeners have been detected in a wide range of human and animal bones dating to the Mesolithic period. Using isotope ratio monitoring-gas chromatography/mass spectrometry (irm-GC/MS), it is possible to determine accurately compound specific δ¹³C values of preserved cholesterol with high precision (±0.4‰). The δ¹³C value of cholesterol provides information complementary to that derived from collagen and apatite stable isotopes for use in palaeodietary studies. Potential advantages of using cholesterol are that: (1) the δ¹³C value will be biased towards the original isotopic composition of the carbohydrates and fats in the diet, (2) its δ¹³C value will retain isotopic integrity, i.e., will not be diagenetically altered, provided its carbon skeleton is characterized, and (3) that its relatively rapid rate of turnover provides a means of investigating carbon cycling on a shorter time scale than collagen. Laboratory animal feeding experiments have shown that cholesterol faithfully derives its isotopic signature from the diet and has a faster turnover rate than collagen. This paper reviews aspects of the methodologies employed in recording δ¹³C values from cholesterol preserved in skeletal materials and presents new results obtained from modern and archaeological humans, and studies of experimental animals.