Is kosher also healthy? Kosher chicken contains high concentrations of antibiotic-resistant strains of the E. coli bacteria, according to a new study conducted in the United States and published by the Jewish Telegraphic Agency (JTA).

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The research's abstract, published in the British F1000Research website, notes that while retail poultry products are known sources of antibiotic-resistant Escherichia coli, kosher chicken had the highest frequency of antibiotic-resistant E. coli, nearly twice that of conventional products.

According to the researchers, Prof. Bruce Hungate, a biology professor at Northern Arizona University, and Lance Price, a microbiologist with Translation Genomics Research Institute in Phoenix, the study's findings “belie the historical roots of kosher as a means to ensure food safety.”

Is kosher food healthier?

According to JTA, the study's initiator is Jack Millman, a 17-year-old Jewish boy from New York City. After his sister's bat mitzvah, he began asking himself whether kosher food was healthier. In order to explore the issue, he recruited his uncle, Prof. Hungate, who connected him to Price.

From April 2012 to June 2012, the three collected 213 samples of four types of raw chicken – conventional, organic, kosher and those raised without antibiotics – purchased at 15 locations in the New York area.

The study found kosher chicken, regardless of brand, had the highest frequency of antibiotic-resistant E. coli, nearly twice the amount in conventional products. It also found no difference in levels of antibiotic resistance between strains found on organic and conventional chicken.

The researchers noted that "unlike for organic and RWA (raised without antibiotics), kosher poultry is not regulated by Federal laws but rather by private certification organizations, and thus the specific practices vary.”

According to the researchers, "These results indicate that production methods influence the frequency of antibiotic-resistant E. coli on poultry products available to consumers. Future research to identify the specific practices that cause the high frequency of antibiotic-resistant E. coli in kosher chicken could promote efforts to reduce consumer exposure to this potential pathogen."

They did not, however, recommend that consumers stop buying kosher poultry.

Wrong point of departure

The study, published about a month ago, sparked a wave of reactions in the US scientific community. Timothy D. Lytton, a professor of law at Albany Law School, and Joe M. Regenstein, a professor of food science in Cornell University’s Department of Food Science, say the study fails to answer the question whether the use of kosher slaughter had a direct link to the high concentrations of E. coli bacteria.

In an editorial published in the Food Safety News website, the two argue that in light of the study's findings, it is unclear whether the kosher slaughter industry in the US makes intensive use of antibiotics, and the reason for the high frequency of resistant strains in poultry, or whether the Jewish slaughter process itself is responsible for the high concentrations.

According to Lytton and Regenstein, the research will be better informed if it is based on a better understanding of kosher poultry production and regulation. The study's point of departure, that kosher-certified food is safer, is wrong, they say.

"The 'historical roots' of kosher dietary practice have more to do with religious concepts of ritual purity, ethical treatment of animals, and Jewish identity than with food safety," the two professors write.

However, they say, the growing popularity of kosher food in America among Jews and non-Jews is a response to a more general cultural anxiety about industrialization of the food supply.

"The image of a rabbi overseeing production and hand-slaughtering the animals — motivated by a deep religious commitment to the ritual purity of food — diminishes the unease many feel about eating food produced in large-scale industrial production."

Difference stems from water temperature

Regenstein and Lytton say the difference in the concentration of bacteria lies in the kosher method of feather removal. "Most poultry is placed in scalding water before plucking, but kosher poultry is dry plucked or soaked in very cold water due to restrictions prohibiting any form of cooking before the meat has been soaked and salted."

"That's a known weak spot," says a senior veterinarian who served in the past as the supervisor of slaughterhouses in Israel

"Non-kosher poultry is placed in hot water and the bacteria die, and with kosher poultry the water has to be cold. There are ways to overcome this, like a strong flow of water or using very cold water to prevent the development of bacteria, but sometimes the bacteria remain in the chicken until it is cooked. We are aware of it in Israel, and that's why the water is taken care of very well," the veterinarian clarifies.

He adds that in Israel frequent examinations are conducted on the concentration of bacteria in slaughtered poultry.

Dr. Ari Zivotofsky of the Multidisciplinary Brain Research Center at Bar-Ilan University, who is a slaughterer himself, says the bacteria found in the American study are not the result of contamination, but exist naturally in the intestines of human beings and animals.

The cold water may be a possible explanation for the high concentrations of the bacteria, but in any case the findings cannot point to a risk to public health.

"Although (the researchers) took types of kosher poultry from different brands, it's possible that we are talking about chickens which came from one slaughterhouse or two. So I am not at all sure that this points to a general problem with kosher meat," says Dr. Zivotofsky.

"In addition, they checked the frequency of E. coli. E. coli is a problem in red meat, not in chicken. It's very rare to get infected with this bacterium from chicken. Salmonella is a much more common possibility, and so it is checked in eggs, but they didn't check that at all."

Better worry about salmonella

"In my humble opinion, the bacteria's presence in the chicken does not cause any damage," says Dr. Zivotofsky. "I'm not a microbiologist, but I'm not sure I have to be one to say this."

He says he has doubts over the way the study was conducted. "A 17-year-old boy collected the poultry, and it's unclear under what conditions. I'm not saying it's a fraud, everything could be okay, but something in this study's methodology bothers me."

In your opinion, doesn't the study have any practical significance for kosher meat consumers in the US?

"In my opinion, and my colleague Joe Regenstein has said the same, you can calm down. There is no room for concern. In any case, cooking removes all bacteria, and whoever eats raw chicken had better worry about salmonella."

And what do you think about the situation in Israel?

"In Israel the supervision is much tighter, and I'm saying that as someone who is familiar with the system. I didn't even know that polio is checked in the sewage system, and you see that is also checked routinely. Chickens are examined here all the time, and if there were E. coli, it would have been taken care of immediately."

The Israeli State Veterinary Services and Animal Health (VSAH) offered the following statement in response: "To this day no link has been proven between antibiotic-resistant strains of the E. coli bacteria in poultry and public health. The finding has no implications on public health and no conclusions should be made from it about the kosher slaughter in Israel."

The VSAH clarified, in addition, that Israel does not import any chicken from the United States.