Expression of the dietary isotope signal in the compound‐specific δ¹³C values of pig bone lipids and amino acids

Abstract

Pigs were raised on six isotopically controlled diets to examine the dietary macronutrients used in the synthesis of bulk bone biochemical components (apatite, collagen and lipids) and individual compounds (bone fatty acids, cholesterol and amino acids from collagen). δ 13 C values of apatite and bulk bone lipids reflected those of the whole diet, with 13 C apatite-whole diet = 10.2 ± 1.3‰ and 13 C bone lipids-whole diet = −2.4 ± 0.7‰. A wide variation observed in the 13 C collagen-whole diet values (0.5 to 6.1‰) was hypothesized to reflect the relative importance of (i) the direct incorporation of essential amino acids, and (ii) the balance between direct incorporation and de novo synthesis of non-essential amino acids. Linear regression (n = 6) was used to assess the relationship between the δ 13 C values of whole diet and bulk bone components and individual compounds. Whole diet δ 13 C values showed a strong correlation with those of bone cholesterol (R 2 = 0.81) and non-essential fatty acids (0.97 ≤ R 2 ≤ 0.99). Not surprisingly, bone linoleic acid δ 13 C values correlated well with dietary linoleic acid (R 2 = 0.95). Mass balance calculations using the δ 13 C values of single amino acids accurately predicted the δ 13 C value of whole collagen. The δ 13 C values of whole diet were well correlated with those of the non-essential amino acids, alanine (R 2 = 0.85) and glutamate (R 2 = 0.96) in collagen. The essential amino acids leucine ( 13 C collagen leu-diet leu = 0.5 ± 1.2‰) and phenylalanine ( 13 C collagen phe-diet phe = −0.6 ± 0.6‰) showed little isotopic fractionation between diet and bone collagen.

Multi-isotopic analysis of first Polynesian diet (Talasiu, Tongatapu, Kingdom of Tonga)

“…Stable carbon isotope ratios in human bone hydroxyapatite (or apatite, δ 13 C ap ), on the other hand, reflect the total diet including carbohydrates and lipids as well as protein and thus can be used to assess non-protein sources in the diet, particularly plant consumption (Ambrose and Norr, 1993;Schwarcz, 2000;Kellner and Schoeninger, 2007;Fernandes et al, 2014). Estimates of carbon isotope fractionation between diet and bone apatite range from 9.5 to 13‰ (Howland et al, 2003;Tykot et al, 2009;Warinner and Tuross, 2009;Fernandes et al, 2012); we adopt an offset of 10‰ (Fernandes et al, 2012). Our overall conclusions would not change substantially if a different value in this range were used.…”

Isotope evidence for the use of marine resources in the Eastern Iberian Mesolithic

“…Because of slow collagen turnover, collagen stable isotope values reflect an average diet representative of the last 10e15 years of life . In addition, they mainly reflect the isotopic signals of the main dietary protein sources rather than that of a diet as a whole, especially for nitrogen (Ambrose and Norr, 1993) since carbon may be derived from other dietary macronutrients like sugars and fats (Howland et al, 2003;Jim et al, 2006).…”

Neanderthal diets in central and southeastern Mediterranean Iberia

“…Also, collagen stable isotope ratios reflect the isotopic signals of the main dietary protein sources rather than that of diet as a whole, especially for nitrogen (Ambrose and Norr, 1993). Depending on dietary protein levels, carbon may be derived from other dietary macronutrients (sugars and fats) (Howland et al, 2003;Jim et al, 2006).…”