Investigating the Influence of Marine Protein Consumption on Multiple Stable Isotopic Proxies from Bone and Soft Tissues

Abstract

This work investigates the influence of a marine protein diet on the isotopic signals of different body tissues using a controlled feeding study of pigs. Using a multifaceted approach, looking at how increasing amounts of marine protein consumption effects the routing and synthesis of carbohydrates, lipids and proteins throughout numerous body tissues. This was accomplished with a systematic analysis of carbon and nitrogen isotopes from bone collagen, muscle, and liver and extracted tissue lipids obtained by GC, GC/MS and GC/C/IRMS. The percentage of marine protein in the diet was found to be directly correlated to the δ13C isotopic values and the δ13C tissue-whole diet offsets of bone collagen, muscle and liver. This is due to the increased routing of dietary protein to tissue synthesis. The δ13C tissue-whole diet offsets seen in this study show a larger than previously reported range (-0.4±0.2‰ to +7.6±0.4‰), which suggests that tissue-whole diet offsets may be susceptible to extreme diets. There was also a strong linear correlation in the δ15N isotopic values in response to marine protein in the five tissues studied. Marine protein consumption was determined to be diagnostic over 25% marine dietary protein intake. Isotopic evidence was obtained to suggest a causal link between dietary marine protein and the δ13C values of C16:0, C18:0, C18:1. No link between C18:2 and marine protein was observed. The δ13C values of the non-essential and essential fatty acids more closely reflected the isotopic signals of whole diet, but with larger than expected isotopic offsets. Cholesterol was found to become increasingly enriched with the incorporation of marine protein. At an optimized marine protein intake virtually no cholesterol-whole diet offset occurred. This suggests that cholesterol is a better proxy for whole diet in situations of omnivorous dietary intake, which could be important in paleodietary analysis.

Date of Award	7 Mar 2017
Original language	English
Awarding Institution	University of Bristol
Supervisor	Richard P Evershed (Supervisor) & Ian D Bull (Supervisor)