Further, by studying the levels of a particular heavier isotope of nitrogen, the researchers found that this corn-fed beef was relying on heavy applications of fertilizer as well as, potentially, animals surrounded by their own waste. "As metabolism proceeds, the nitrogen products become heavier and heavier," Jahrens explains. "Nitrogen is just cycling through the animal, including potentially ingestion of that waste or respiration. Our results are consistent with that."
Researchers at Johns Hopkins are now completing a study measuring the levels of carbon 13 in human blood, in an effort to understand how much of the corn in our meat and in the sweeteners (high fructose corn syrup) in our food and drink ends up in our bodies. The fast-food outlets did not return calls for comment.
As Jahren notes, Americans spend more than $100 billion a year on such fast food, making it a significant part of the diet. "Diet related disease is causing more and more suffering in this country and the information you can get is either vague or nonexistent," says Jahren, who spent the last two years trying to get information about what specifically goes into fast food at these chains and how it is made, with no success. "You shouldn't have to use stable isotopes to get the answer to what's in something I just spent my money on and am about to put in my body."