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Study: Grass-Fed not Safer than Conventional Beef

According to a recent study done by investigators from Purdue University in Indiana and Zhejiang University in Hangzhou, China, there is no safety advantage to consuming grass-fed beef over conventionally raised beef. 

Researchers investigated a modest sample of U.S. retail beef products and found that marketing which claims that grass-fed beef is safer than conventionally raised beef is not necessarily true.  

The study was released in the magazine Foodborne Pathogens and Disease in July.

cow-grazing-featured.jpgReviewed by professors at the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, researchers found that there were no significant differences in the presence of total coliform bacteria, Escherichia coli, or Enterococcus species between grass-fed and conventionally fed beef.

Alternatively, researchers found evidence that indicates conventional beef has an increased resistance to bacteria when compared with grass-fed beef.

“Taken together, these data indicate that there are no clear food safety advantages to grass-fed beef products over conventional beef products,” says the report by investigators from Purdue University in Indiana and Zhejiang University in Hangzhou, China.

According to the authors, though results of the study show no clear advantages to grass-fed cattle over conventionally raised cattle, other factors play a large roll in affecting the safety of the meat.  These factors include how the beef is processed, whether cattle are fed preventative antimicrobials, and other factors.  The authors explain that grass-fed cattle are more likely to be processed in small facilities and are less likely to be given preventative antibiotics.  

Testing showed no difference in overall coliform contamination of the sample sets. Likewise, solid cuts and ground beef did not differ in coliform levels.

Enterooccus species were isolated from 62 percent of the conventional samples and 44 percent of the grass-fed samples, a difference that did not reach significance.  However, the difference was greater for ground beef: 75 percent for conventional versus 41 percent for grass-fed.

The two sample sets had equal overall levels of E. coli contamination, at 44 percent. For solid cuts of meat, the conventional products had a higher level of E. coli than the grass-fed products, but this was reversed for ground beef.  Neither difference was significant.  No E. coli O157:H7 or Salmonella was found in any of the samples.

Additionally, the investigators found no differences in the percentages of resistant E. coli from conventional versus grass-fed beef.  However, Enterococcus species from conventional beef were more frequently resistant to daptomycin and linezolid than were the same species from grass-fed beef, they report.  They also found that both E. coli and Enterococcus from conventional beef showed higher resistance to several antibiotics than the same species from grass-fed beef, in terms of the amount of drug needed to inhibit the organism.

Though researchers found few significant differences between grass-fed and conventional beef,  they concluded that there was an “overall trend” for more Enterococcus species found in conventional beef while more E. coli was found in grass-fed beef.  Findings on resistance indicate, “a possible trend for bacteria isolated from conventional products to be more antimicrobial-resistant.”

Director of education at the University of Minnesota Center for Animal Health and Food Safety Scott J. Wells said study results were intriguing, but the small sample size limits the applicability conclusions.

“The low sample size limits inference generally as well as limits authors from further evaluating differences between specific subtypes of retail beef products,” he wrote.  Wells also added that the low prevalence of E. coli O157 and Salmonella in the beef supply means that a much larger sample would be needed to compare levels in grass-fed versus conventional beef.

Wells also wrote that ”Contamination of retail beef samples by certain bacterial pathogens is a complex process, with multiple points of potential contamination . . . and several risk factors that could potentially mitigate the outcome. It’s not likely to be as simple as grass-fed vs conventional fed.”

In addition, Wells observed that other factors including farm size and type of farm management system can contribute to the level of bacteria in beef. “In short, the article is interesting but I’m left with more questions,” he said.

The study abstract is available online.

© Food Safety News
  • hhamil

    Your article has no description of the “modest sample.” We don’t know its size nor how it was selected nor how it was collected.
    Without this information there is no way to evaluate what you have written and whether or not your or the authors apparently broad conclusions are warranted.
    Just like polls, all “scientific” studies are far from equal. Studies and their “peer” review (or lack thereof) seem to be increasingly biased so that they will be reported in mainstream media in a certain way. The food safety arena has been replete with it.
    One of the worst examples occurred last fall in CSPI’s “The Ten Riskiest Foods Regulated by the U.S. Food and Drug Administration.” The “study” didn’t even make a semblance of a peer review and it contained ONLY raw data that was deceptively displayed. It contained NO measurement of risk.
    I urge “Food Safety News” to show greater discretion is its reporting of “studies” or it will mirror the poor journalism of most of American mainstream media.

  • Michelle

    1. Foodborne Pathogens and Disease, the journal that published this study is a peer-reviewed, international journal.
    2. Between July 2008 and March 2009, investigators collected and analyzed fifty conventional samples from retail stores in Illinois and Indiana and fifty grass-fed samples from 10 sources including retail stores, farm stores, and farmers’ markets. Around two thirds of the samples in each set were solid cuts of beef (such as steaks) while the rest of the samples were ground beef.

  • Natalia

    I, too am troubled by the above-mentioned factors in the reporting in this article.
    Furthermore, why doesn’t your author question the “insignificance” of an 18% difference between “conventional” vs grass-fed beef re the enterococcus species isolated from same? And the even higher 34% difference in processed meats?) Since when is an 18% difference in rates of anything not statistically significant!?
    There are similar red flags in the rest of the article (re the antibiotic-resistance, etc., etc.) but I have no time to detail them now – However, a careful reading will bring them glaringly forth to anyone’s attention.
    If one is going to be a reporter, the first prerequisite, it seems to me, is a sceptical mind and also an informed one…

  • Harry Hamil

    Your article has no description of the “modest sample.” We don’t know its size nor how it was selected nor how it was collected.
    Without this information there is no way to evaluate what you have written and whether or not your or the authors apparently broad conclusions are warranted.
    Just like polls, all “scientific” studies are far from equal. Studies and their “peer” review (or lack thereof) seem to be increasingly biased so that they will be reported in mainstream media in a certain way. The food safety arena has been replete with it.
    One of the worst examples occurred last fall in CSPI’s “The Ten Riskiest Foods Regulated by the U.S. Food and Drug Administration.” The “study” didn’t even make a semblance of a peer review and it contained ONLY raw data that was deceptively displayed. It contained NO measurement of risk.
    I urge “Food Safety News” to show greater discretion is its reporting of “studies” or it will mirror the poor journalism of most of American mainstream media.

  • Doc Raymond

    To the responders, please forget the percentages and the discrepancies. Does it not bother you that the study showed that on average 50% of our steaks, roasts and ground beef were contaminated with bovine fecal material, to state it politely. And does it not concern you, Harry, that steaks are just as contaminated with bovine fecal material as ground beef is? I have always treated GB as a potential source of cross contamination, but not steaks. This is a study that may change how we look at fresh, raw beef in our homes and kitchens. Marler does not eat hamburger now, but will this change his perception of the safety of intact beef products in his kitchen?

  • http://www.sebagolakeranch.com Ben

    Yes it’s true that grainfed beef is not any healthier as far as E. coli is concerned, as long as it’s not contaminated during processing. Meat does not have E. Coli in it unless there is contamination with fecal matter. However, the health claim with grassfed is that grassfed animals have a much lower cell count of E. Coli then grain fed. It’s a difference of 20,000 vs 6.3 million cells per gram of manure. Therefore, if contaminated, there is a higher risk with grain fed.
    (Diez-Gonzalez, F., et al. (1998). “Grain-feeding and the dissemination of acid-resistant Escherichia coli from Cattle.” Science 281, 1666-8.)
    I’m not too worried about steak, all exposed surfaces that are potentially contaminated are cooked enough to kill E. Coli. The center I leave rare is not contaminated (unless it’s mechanically tenderized). Ground is all kinds of surface area mixed together,that is where the danger is.

  • sandra sheridan REHS

    Cattle raised on concrete or in feedlot pens have a much more contaminated environment than cattle raised on grass. Cattle raised on concrete or in feedlots are fed antibiotics to keep them healthy and other substances to allow them to put on weight since they are in a stressful environment. I see many discrepancies in this article that fly in the face of the facts and don’t make logical sense. Who wants to make money out of these findings. Heck the Chinese can’t keep melamine out of their infant formulas, do you expect me to believe this? well I don’t, and I am still going to buy grass fed beef for my family and friends.

  • trav45

    Many of the health claims for grass fed beef also have to do with the amount of saturated fat in grain fed vs. grass fed cattle. Grass fed cattle have significantly lower amount of saturated fats.

  • http://www.facebook.com/profile.php?id=1300627189 Valerie Valerie

    All you are talking about is one feature.   Standard meats are shot full of antibiotics to combat all the horrendous disease that is rampant in feed lots.   The poor creatures drop dead right there and are trampled on.  It’s filth.   By the time they are done permeating the bodies and meat tissues with medicines, yes, the leftover bacteria might be fewer.   But that does not make it healthier. 

    We are surrounded by bacteria.  If you had no bacteria in your gut, you would die post haste.  Bacteria is a part of life and the ecosystem.  Fear-mongers would have everyone believe you have to drench all life in a vat of Lysol to make it to your 30th birthday.  (Sterilize the baby bottle or something really bad will happen!  Ignore that the baby is picking up stuff off the floor continually and sucking on it.) 

    There are so many factors that contribute to the good health of naturally raised meats.   Bet this study was funded by businesses interested in the success of feed lots and the downfall of local, natural growers.