From Rough Diamond to Polished Gem

Kuhnle discusses the study of Jessica Johnson and colleagues, in which they investigated whether the nitrogen stable-isotope ratio of amino acids in plasma or red blood cells provides a better option to determine meat and fish intake when compared to the nitrogen stable-isotope ratio of the whole tissue. They show that in many cases, amino acid stable-isotope ratios in whole tissue are sufficient to determine meat and fish intakes in a population with a typical US diet, but that in other settings with different diets, whole-tissue analyses might not be specific enough. Previously, stable-isotope ratios have been likened to a rough diamond. Diane O'Brien's group has transformed this rough diamond into a polished gem. Alas, they are still severely underused, as they do not fit within the traditional types of biomarkers. There needs to be a closer collaboration between nutrition researchers and experts in the field of stable-isotope ratios to make sure this technique receives the attention it deserves.