Though the title sounds ominous about the health benefits of grass-fed beef, the content actually reflects a myth about E. coli.

Industrial cattle production typically uses grain (corn) as feed. Since cows did not evolve to eat corn, their stomachs reach a lower pH (more acidic) than cows fed grass. Corn-fed cows have a greater tendency to become sick; this is one of the reasons that the industrial plants supplement their feed with antibiotics. An externality of this process is that bacteria naturally found in a cow’s intestinal track is killed off. By itself, this is not necessarily a bad thing, but bacteria like E. coli are remarkably adept at evolving into new, hardier strains.

This is exactly how E. coli O157:H7 is believed to have come into relative dominance.

A few years ago, proponents of grass-fed beef brushed off the E. coli threat, saying that grass-fed cows with natural digestive pH levels are not carriers of hardy O157:H7. This no longer appears to be the case. A recent study examined the acid-resistance of O157:H7 in grass-fed cows versus that in corn-fed cows and found no difference.

Unfortunately, this means that grass-fed beef is not inherently safer than industrial, corn-fed beef. When preparing ground beef, regardless of the source, the meat should be well-cooked to protect its eaters (the FDA recommends an internal temperature of 160 degrees).