Worldwide stable carbon and nitrogen isotopes of Big Mac® patties: An example of a truly “glocal” food

The Big Mac®, McDonald’s® signature burger, is a global food served in over 100 countries. We measured carbon (δ13C) and nitrogen (δ15N) stable isotope ratios of Big Macs® from twenty-six countries. The δ13C values varied from −25.4‰ to −11.1‰, representing cattle-rearing systems based exclusively on C3 plants, exclusively on C4 plants, or both C3 and C4 plants. Median δ15N value was 6.6‰; the 25th and 75th percentile were 5.9‰ and 7.3‰, respectively. Calculated percentages of imported beef were consistent with the δ13C values of purchased Big Macs®. Japanese patties had higher δ13C values than expected based on that country’s C3 agriculture, however Japan imports beef from Australia, where C4 plants are prevalent. Lower latitude countries generally had higher δ13C values than higher latitude countries, reflecting the larger distribution of C4 plants in warm regions. Although Big Macs® are a global food, we conclude they also contain local components.