polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) form in meat when it's cooked at a high temperature (that char marks contain pure HCAs). Nether of these are good for you, both being carcinogens, PAHSs are also in cigarette smoke and car exhaust for example. But it turns out that another manly ingredient can make grilling safer: beer. Marinating your meat in beer is proven to reduce the PAHs, the darker the beer the better.
The Journal of Agricultural and Food Chemistry posted a 2014 study from the American Chemical Society where beers were used as marinades for meat and compared to unmarinated meat. Dark beer, black beer was used, showed a 68% scavenging activity of PAHs with lighter beers coming in around 30%. Dark beer as part of the study was deemed as providing a 'proper mitigation strategy' for the prevention of PAHs.
If you add an acid to the marinade, and most marinades include it anyway, like lemon juice or vinegar, you an also reduce the HCAs by keeping them from forming on them while cooking by creating an anti-oxidant barrier.
Having a beer while grilling and eating your meat is always satisfying, but now having beer in your meat is good for you as well. Here is an example of a marinade that includes dark beer and lemon juice to double up your cancer-prevention.