A healthier brew? EFSA roasts DNA damage claim as coffee study reveals temperature differences
03 Apr 2020 --- The European Food Safety Authority (EFSA) has rejected the claimed effect put forward by German coffee retailer Tchibo that consuming an Arabica roast coffee blend could reduce DNA damage occurring in white blood cells. This ruling was taken considering the lacking cause and effect relationship between the consumption of Coffee C21 and the protection of DNA from strand breaks. In other jittering research, a study to be presented at the American Chemical Society found that dark-roasted hot-brewed coffee contains more antioxidants from the grind than its counterpart.
The EFSA took into account a study that provided some evidence that daily consumption of Coffee C21 (750 ml per day) for four weeks decreases DNA strand breaks in habitual coffee drinkers after coffee withdrawal over the previous four weeks. However, a subsequent study conducted under similar conditions was not able to replicate the same results. 
“No studies performed in a different setting, from which conclusions could be drawn, were available. No evidence has been provided for a mechanism by which coffee, including Coffee C21, would reduce DNA damage in human cells by reducing DNA strand breaks,” the EFSA concluded. Moreover, the EFSA panel states it considers that the protection of DNA from strand breaks is a “beneficial physiological effect.”
“The panel considers that Coffee C21, a coffee standardized by its concentration of caffeoylquinic acids (CQA), trigonelline and N‐methylpyridinium (NMP), is sufficiently characterized in relation to the claimed effect,” the food authority highlights.
The antioxidant content of hot- and cold-brew coffee is much larger for a darker roast, says Dr. Rao.Hot versus cold brew
Regardless of the EFSA ruling, coffee does contain certain nutritionally beneficial elements, including antioxidants. Researchers at the Thomas Jefferson University roasted Columbian beans at five different temperatures – from light roasting at 174℃ to dark roasting at 209℃ – to study the impact on acidity, antioxidants and other natural chemicals in hot- and cold-brew coffee.
Filling the gap in cold-brew coffee research, they found that hot-brewed coffee made from dark roasts produces a “potentially healthier drink” containing higher levels of antioxidants and more kinds of acids and total dissolved solids in darker brews. Meanwhile, the pH level remains fairly similar for both hot and cold brews at equivalent roast.
Reproducing that “equivalent roast” presented itself as a particular research challenge, Dr. Niny Rao, the study’s principal investigator, outlines. “We have performed experiments in which we're using the same beans, the same machine, the same settings and it came out not quite the same as the previous batch. The same goes for brewing. To create a cup that’s consistent every time is difficult,” Rao stresses.
To overcome this hurdle, the research team rigorously standardized their processes to streamline their brewing procedures. This included the meticulous detailing of when the water should be added to the ground coffee, how to pour the water and for how long, how to shake the solution, how to press the brewed coffee and how to analyze it. These highly controlled research parameters were delineated by time limits for each step, with margins of just a few seconds and ultimately produced “much more reproducible results.”
While lighter roasts showed no substantial differences to the content of caffeine and antioxidants between hot and cold brews, this was more so the case with darker roasts. “Hot brewing extracts more antioxidants from the grind than cold-brew and this difference increases with the degree of roasting,” says Dr. Rao.
“My advice to consumers has always been to drink what they like,” Rao says. “But if you want to craft a coffee beverage with antioxidants or acidity in mind, you may want to pay attention to roast. If you want a low-acid drink, you may want to use a darker roast, but the gap between the antioxidant content of hot- and cold-brew coffee is much larger for a darker roast,” Dr. Rao concludes.
Edited by Anni Schleicher
