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Results | Food Web and its Function | Interesting Isotopic Studies

Interesting Isotopic Studies

HUMAN STUDIES: Animal Protein Consumption, International Differences, Organ Differences and Paleodiet Changes Over Time

human hair and protein consumption chart
Fig. 1. The d15N and d13C values of human hair depend on how much animal protein we eat. More frequent protein consumption results in higher d15N and d13C. Note the very low d15N values of vegans, who eat no animal protein. View larger image.

human hair chart human organs chart
Fig. 2. Average diets vary among people living in different countries, and these differences are recorded in the isotopic composition of our hair. Note the isotopic shifts (particularly d13C) of the Japanese people who lived in other countries for one year. With a hair sample, one could reasonably guess where they had lived! View larger image.
Fig. 3. The d13C values of human organs vary widely. This is why isotope-related diet studies need to compare similar organs and tissues among individuals. View larger image.

Estimating human paleodiet
Fig. 4. The d13C values of collagen from human bones (both fossil and modern) can be used to estimate the amount of C4 plants (e.g., maize) versus C3 plants (e.g., wheat) in the diet of native populations. The study above calculated this percentage over the last 4000 years using a “mass balance” formula with average values for C3 and C4 plants and the known isotopic offset between a person’s diet and their bone collagen. The importance of C4 plants in human diets has increased dramatically, from less than ~10% before 500 AD to ~30-60% between 1000 AD and 1600 AD.


Using stable isotopes for research
Animal and Diet Studies
Human and Diet Studies
Results | Food Web and its Function | Interesting Isotopic Studies

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