Genetic Food Modification and Kosher Law Are They Compatible?

“It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness,”from Charles Dickens’ classic book, A Tale of Two Cities.

The author’s famous words aptly sum up how our high-tech generation relates to genetically modified foods (GM foods grown with scientifically modified DNA).

Although this innovative process enhances positive characteristics of foods, such as size and taste, as well as making them more resistant to disease, drought and spoilage, genetic engineering has stirred a worldwide debate. There are those who laud it as an important scientific breakthrough, while others question its safety, as well as the possible health repercussions. Some object to genetic engineering on religious or ethical grounds, disapproving of tampering with nature.

OU Kosher has had to address the ramifications of genetic engineering on the kosher status of these foods. Is it permissible to certify genetically modified foods as kosher? Does kosher law allow this type of modification?

The issue raised three key questions. Fortunately, OU Kosher had the great privilege to discuss them with Rabbi Yisroel Belsky (of blessed memory), who was one of the preeminent authorities on kosher law and served as a consultant for OU kosher for over 25 years.

1. Does kosher law permit the manipulation of DNA even if no foreign DNA is introduced?

Rabbi Belsky explained that, although it is clear from many sources that while it is not considered a virtue to tamper with nature, it is not a prohibition. As such, he ruled unequivocally that genetically modified foods are to be considered kosher. It should be noted that this is not an endorsement of the health benefits of such foods, but simply acknowledging that none of the kosher laws are being violated.

2. Does kosher law permit splicing together genetic material from different kosher organisms (e.g. mixing DNA from tomatoes and blueberries)?

This question is slightly more complex. There is a Biblical prohibition to graft a branch from one species of fruit tree onto another. However, if one did so, the fruit may be eaten and one may benefit from the offspring. Similarly, one is not permitted to breed animals from different species together. For example, in the case where a sheep and a goat (both of which are kosher animals) had been used to create a hybrid, there is no prohibition to consume the offspring.

Rabbi Belsky gave several reasons to why splicing together DNA from different species might be more lenient and might not be included in the Biblical prohibition at all, but he concluded that even if it would, the resulting foods would definitely be permitted. As such they may be certified kosher.

3. Splicing DNA from a non-kosher source into a kosher food (e.g. mixing the DNA from an eel (which is not kosher) into the DNA of salmon (a kosher fish)?

This question is the most complex of the three and requires a case-by-case evaluation. Rabbi Belsky was asked about a salmon (a kosher fish) that was engineered with genes from an eel (non-kosher), enabling it to grow faster. Kosher fish are identified by their fins and scales. Therefore salmon is kosher, because it possesses both fins and scales. An eel is not kosher, since it does not have fins and scales. In this situation, Rabbi Belsky ruled the genetically modified salmon is kosher, since it physically resembles a salmon, and it exhibits the signs of a kosher fish i.e. it has fins and scales. However, this leniency should not be extended to other cases. For example, if one were to take a gene from a non-kosher bird and splice it into the DNA of a kosher bird, this would be a serious concern.

The fascinating new field of genetic engineering demands the guidance of rabbinic leaders to help educate OU Kosher manufacturers and consumers in an appropriate, ethical, and safe manner. It necessitates Torah scholars, with extensive knowledge pertaining to science and kosher law, to rule on the myriad of involved questions that will undoubtedly continue to arise. As the key player in kosher supervision, OU Kosher can be relied upon to understand every vital nuance within food production’s scientific advances.


Rabbi Eli Gersten, OU Kosher rabbinic coordinator and recorder of OU policy, is a regular contributor to BTUS. His “Chiltis – One Powerful Spice!”appeared in the Fall 2017 issue.

Rabbi Eli Gersten
Rabbi Eli Gersten serves as OU rabbinic coordinator and recorder of OU policy.