GRILLING meat gives it great flavour. This taste, though, comes at a price, since the process creates molecules called polycyclic aromatic hydrocarbons (PAHs) which damage DNA and thus increase the eater’s chances of developing colon cancer. For those who think barbecues one of summer’s great delights, that is a shame. But a group of researchers led by Isabel Ferreira of the University of Porto, in Portugal, think they have found a way around the problem. When barbecuing meat, they suggest, you should add beer.

This welcome advice was the result of some serious experiments, as Dr Ferreira explains in a paper in the Journal of Agricultural and Food Chemistry. The PAHs created by grilling form from molecules called free radicals which, in turn, form from fat and protein in the intense heat of this type of cooking. One way of stopping PAH-formation, then, might be to apply chemicals called antioxidants that mop up free radicals. And beer is rich in these, in the shape of melanoidins, which form when barley is roasted. So Dr Ferreira and her colleagues prepared some beer marinades, bought some steaks and headed for the griddle.

One of their marinades was based on Pilsner, a pale lager. A second was based on a black beer (type unstated). Since black beers have more melanoidins than light beers—as the name suggests, they give it colour—Dr Ferreira’s hypothesis was that steaks steeped in the black-beer marinade would form fewer PAHs than those steeped in the light-beer marinade, which would, in turn, form fewer than control steaks left unmarinated.

And so it proved. When cooked, unmarinated steaks had an average of 21 nanograms (billionths of a gram) of PAHs per gram of grilled meat. Those marinated in Pilsner averaged 18 nanograms. Those marinated in black beer averaged only 10 nanograms. Tasty and healthy too, then. Just what the doctor ordered.