Myth: Grass-Fed Beef Is Safer Than Beef From Cattle Finished On Corn And Grains


Extensive research has shown that beef from grass-fed and corn-finished cattle is equally safe. While some unreliable online sources claim that grass-fed cattle have lower levels of E. coli O157:H7 in their intestines, studies show that the there is no difference in the prevalence of E. coli O157:H7 in live animals fed a variety of diets. 1

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In fact, organic and natural methods don’t seem to impact bacteria in the gut either. In 2009, researchers examined the incidence of pathogenic E. coli O157:H7 in organic and naturally raised cattle and concluded, "Our study found similar prevalences of E. coli O157:H7 in the feces of organically and naturally raised beef cattle, and our prevalence estimates for cattle in these types of production systems are similar to those reported previously for conventionally raised feedlot cattle. 2

While a very small USDA study 3 of a handful of cattle in 1998 initially suggested that feeding cattle hay could reduce E. coli O157:H7, that small study’s findings were never able to be duplicated in larger research. More than a decade later, a large, accumulated body of research strongly suggests that E. coli O157:H7 appears to be a natural bacterium found in the gut of cattle regardless of production system.

  1. Fegan, N et. al., The prevalence and concentration of Escherichia coli O157 in faeces of cattle from different production systems at slaughter, 2004 (accessed July 19, 2010). Van Baale, MJ, et. al., "Effect of Forage or Grain Diets with or without Monensin on Ruminal Persistence and Fecal Escherichia coli O157:H7 in Cattle," 2004 (accessed July 19, 2010).
  2. S. Reinstein, J. T. Fox, X. Shi, et al., "Prevalence of Escherichia coli O157:H7 in Organically and Naturally Raised Beef Cattle," Environ. Microbiol. 75(16):5421-5423.
  3. Diego-Gonzales, F. et. al., Grain Feeding and the Dissemination of Acid-Resistant Escherichia coli from Cattle Science 11 September 1998: Vol. 281. no. 5383, pp. 1666 – 1668.