I can haz cheeseburger? The kosher conundrum of cultured meat

Rabbi Daniel Nevins, The Conservative Movement's Committee on Jewish Law and Standards; Yoreh De'ah 81.2017, "The Kashrut of Cultured Meat." You can find the full responsum at www.rabbinicalassembly.org.

Why promote cultured meat (vs pastured meat)?

• Ethics. Conventional methods for producing meat cause animal suffering at each stage of the process. Cultured meat would not involve a nervous system, and thus there would be no animal suffering.

• Health. Pastured meat often contains antibiotics and growth hormones, as well as contaminants such as Salmonella and E Coli. Cultured meat would be cultivated in sterile conditions with no need for such additives and a lower risk of contamination. It might be possible to include healthful components.

• Environment. Animals raised for meat pollute the environment through waste- products, particularly carbon dioxide and methane emissions. Cultured meat would have no excrement or emission of methane.

• Ecology. The land and quantities of freshwater dedicated to livestock production could be used to cultivate diverse fruits and vegetables, enriching human nutrition; fields could also be fallowed and returned to nature. Wildlife could benefit from the reduction of herds and flocks raised for meat.

• Energy efficiency. Although there is not yet a commercial operation producing cultured meat that can be critically assessed, cultured meat’s proponents claim that in ideal conditions, it should require far less energy to produce than does the system of raising animals (especially cattle) for slaughter and then butchering them for sale.

These general concerns are aligned with the classical rubrics of minimizing animal suffering (tzar ba'alei chayim), promoting human health (v'nishmartem me'od et nafshoteichem), and protecting natural resources and the enrionvment (bal tashchit).

Halakhic concerns should focus on:

• production methods
• the species of animal used as a source of cells to culture meat
• the prohibition of removing a limb or even flesh from a living animal
• the kashrut of ingredients used in the growth medium and as additives for flavor, texture and shelf-life
• whether it should be considered to be “meat” in halakhic terms, or rather neutral (pareve).

Must the original cells used to produce cultured meat come from a kosher animal?

1. Collect a sample of stem cells from a living animal
2. These cells are manipulated in a lab setting called a bioreactor to induce proliferation.
3. They are then coaxed into differentiating to form muscle fibers and are subjected to tension in order to develop into tissue that can be layered into meat.

• We assume the samples will be taken from a living animal. Taking them from a kosher animal right after slaughter would have halakhic implications.
• It is conceivable that in the future, there could be the technology to create muscle and fat cells from non-biological sources, which remove most concerns, but for now, cultured meat will be coming from live animal sources.

Since the resultant “edible biomass,” or meat will never have been part of an animal, the established signs of kosher species (split hooves and rumination for mammals; fins and scales for fish; traditional identification of birds) will not be observed.

The harvested cells may be compared to eggs and milk, which are collected from a fully formed specimen and inherit the species status of their source.

Simply put, cells from a non-kosher species may not be used to produce kosher food.

אבר מן החי / A Limb Taken From a Living Animal

In our case, the cell collection for the purpose of culturing the meat does not constitute a limb, the source animal is not permanently injured, and the targeted cells are skeletal stem cells, not forbidden fats, which also are forbidden in general.

What constitutes the limb that it is forbidden to detach from a living animal?

The sages discuss two types of “limb.” One is a body part which includes flesh, bone and sinew, such as a hand or leg. Another type of “limb” is actually an organ which is entirely “flesh,” such as the tongue, spleen, kidney etc. The limb ban seems to apply only when the entire limb is removed.

Some say that to elicit punishment, the entire limb must be eaten, but the halakhah sets a minimum for Jews at consumption of an olive’s bulk of any part before liability is established.

Rabbi Zvi Ryzman claims that stem cells are not considered “alive” but rather, “just water,” and thus not “flesh” that could trigger either the limb ban or the flesh ban. He concludes: "Therefore it appears that a cell taken from a pure animal is not considered to be 'a limb from a living animal' or 'flesh from a living animal,' for it is actually “just

water,” and is not a limb or flesh."

While a human fetus before 40 days may be largely unformed, and is indeed not considered by halakhah to be an independent life until birth, the cow from which stem cells are harvested is very much alive in the world....It does not appear that calling biopsied cells “simply water” will suffice to permit their consumption.

Rather, another approach seems preferable. It is forbidden to eat even a minute amount of flesh taken from a living animal, but with cultured meat, there is no intention to consume the source cells themselves. The act of “eating” is said to involve הנאת גרון, pleasure in the throat, but these cells will never be placed in a human throat, and would be undetectable if they were. They certainly do not meet the halakhically significant threshold of נותן טעם, giving flavor.

Like most cells, these will eventually degrade and die. Far more significantly, the final product is extremely unlikely to contain remnants of the original stem cells. It is only much later—after their descendant cells will have transformed from stem into muscle and fat cells, multiplied by the trillions within a growth medium, and been structured under tension to form strips of muscle tissue and then layered into meat—that an edible product will emerge....In any given portion of the end-product it is exceedingly unlikely that there will be consumption of the actual source cells taken from an animal.

Although it is theoretically possible that one or more of the original cells might survive into the final product and be unwittingly eaten by someone, liability for the limb ban for Jews is triggered only with the consumption of an olive’s bulk. A kosher consumer could be confident that the cultured meat they consume will contain no cells that ever lived in an animal....In our case, any portion of cultured meat is extremely unlikely to contain one of the original source cells.

מה טיבו של זה? / The Question of Identity Across Generations

Although we have found precedent for maintaining the species identity of cells derived from permitted and forbidden animals, just as is done with milk from mammals, and eggs from birds and fish, it is reasonable to ask how much individual history those source cells convey with them.

Species identity across generations is compelling for several reasons. First, this is the default position of both biology and halakhah, summed up nicely in the Mishnah at Bekhorot 1:2. Second, we might compare the live DNA preserved in these cells to the halakhic concept of a “sustaining substance.” (davar ha-ma'amid) In rabbinic sources this is a minute additive that nevertheless has a pronounced, durable and readily discernible impact, such as rennet on cheese or gelatin on gelatinous foods.

If species identity can be preserved across the generations, what about other attributes of the source cells? If the original cells were cut from a live animal, do the successor cells inherit the status of “torn flesh,” even though they were never part of a living specimen? This is a fundamental question. Those who would apply the limb ban to descendant cells—a trillion or more cells cultured from an original animal cell—are claiming that the descendants are identical to the source, not only in genotype but in phenotype. This is false on both scientific and halakhic grounds.

The successor cells are transformed by their own “experience”—the material environment in which they are nurtured, differentiated, and multiplied. They have transformed cell type, grown in a distinct environment, and become far removed in generation and experience from the animal in which the first cells grew. They do not bear a “flesh memory” of the original cells,53 and as Dr. Post has observed, the descendant cells might not be recognized by the original animal’s immune system were they to be returned by autologous transplant. The DNA may be the same, but everything else is different. They are like eggs collected from a chicken—the same DNA, but different substance and halakhic status.

It is possible that a gene editing technology such as CRISPR-Cas9 will be employed to modify the DNA of the harvested cells. This could be done to increase yield by modification of the myostatin gene (whose mutation leads to a condition called “double muscling”), or perhaps to augment the nutritional content of the meat. The halakhic concept of a “novel entity" (d'var chadash) is usually applied to a substance that has passed through an inedible state, but in this case the product would be modified at the genetic level, so that the descendant cells might arguably be deemed a new substance However, single-gene modifications do not suffice to change the species identity of the organism.

Rabbi Ze’ev Weitman

"However, it appears that the matters are indeed comparable, for just as the earth provides a plant with the nutrients needed for it to grow and develop, exactly so with cultured meat—there the growth and development are made possible due to the materials that nourish the cell and serve it as a growth platform. And if a plant which grows and develops from a seed is considered to be a new entity (lit. new face) it would appear that so too meat which grows and develops from a cell may be considered like a new entity."

We would go further and say that the stem cells are comparable to a plant whose seed desists—the original cells will die, and only with intensive interventions from lab technicians will new cells grow and develop in the desired fashion. Therefore, the model from replanted tithes fails to establish the transmission of ritual status between generations of cells.

Germline cells from a species convey the same qualities to their genetic heirs, even with the mutations that attend all reproduction. The DNA is like a sustaining substance, and the species identity is reproduced at the cellular level. Culturally too we recognize later generations of plants and animals as belonging to the same species even with the minor variations that are readily observed.

However, it is less coherent to claim that later generations of cells should inherit the ritual status of “torn meat” (טריפה) from their source cells, which themselves have long since perished. The later generations of cells never were connected to a living animal, even as later generations of plants were not part of the original physical plant.

In other words, cells that are cultured over time to produce beef remain identified with the same species of cow, but not with the experience of the specific cow or cows from which they ultimately derived, just as ears of barley lose the ritual tithing status of earlier generations, while remaining barley.

In Pesahim 22b), there is a comprehensive prohibition on eating the limb or flesh or blood taken from a living animal, there is no prohibition on benefiting from it. These microscopic cells may be cultured in a lab setting to produce muscle cells and other components that will eventually resemble meat. The harvesting process will not render the original animal as “mortally wounded” and so Rabbi Moshe Isserles (the Rema) taught, there is no true limb ban, but only a stringency.

And even if the original flesh should be forbidden as a stringency, the amount taken is less than the olive’s bulk that is forbidden to Jews. And even if we nevertheless forbid the cells since non-Jews have a stricter standard, this would apply only to the original cells, not to the trillions of descendants. These later cells are the product of many inputs—DNA from the source, and nutrients from the growth medium. All aspects are essential; this triggers the principle of זה וזה גורם and renders the final product as permissible.

נותן טעם לשבח / Non-Kosher Additives

How does one develop an edible biomass (i.e., meat) of trillions of cells from just a few original stem cells?

• A sponge-like matrix that is perfused with a culture medium that provides nutrients and growth factors, most commonly such a medium contains an additive of fetal bovine serum.
• Gels used in Petri dishes are often made from porcine sources.
• Plant-based replacement additives are possible and desirable (cheaper, safer, vegetarian friendly)

  • Dr. Amit Gefen of Technion University has proposed using apples for the armature needed as a foundation for cultured meat

• For cultured meat to mimic pastured meat, it may be necessary to add ingredients to enhance taste, aroma, appearance, and bite, just as is done with plant-based meat products. These additives will also need to be kosher-certified.

Would fetal bovine serum render the product inherently non-kosher?

• The finished product would be removed from the medium. Just as food that is cooked in a forbidden substance is forbidden, so too is food that is soaked in a forbidden substance.
• The growth medium would not imbue the product with its taste, either for good or bad, which leaves moot the traditional concern of a whether a non-kosher admixture is tasty (נותן טעם לשבח) or repulsive (נותן טעם לפגם).
• In the final form, any residual amount of medium left in the meat would certainly be less than 1/60 of the product volume and, because there was no intention to retain it, could be considered retroactively nullified.

Should Cultured Meat Be Considered “Meaty” from a Kashrut Perspective?

Meat removed from a living animal, even a pure animal, is considered to be “treife” and is forbidden to be eaten. If, however, the flesh taken from the animal is not itself eaten, but is rather used as a source to create new generations of cells, are those subsequent cells which have never themselves been part of a living animal considered to be meat? We have argued that they should not be considered “limb meat,” but are they meat altogether?

Cultured meat will lack the features of an animal and not be subject to slaughter and inspection. It would be plausible to compare it to eggs laid by a live bird. They derive from an animal and in certain conditions would have the capacity to grow into an animal, but instead, they have been kept in a cellular state, and might be considered pareve, or neutral, like eggs or a vegetable. On the other hand, the end-product is intended to look, feel and taste like meat, and it will be biologically identical to meat. How could it be deemed pareve?

Precedent: Rennet and Gelatin

• Substances derived from an animal source, which are not themselves considered to be “meat”
• After extensive processing, considered by some halakhic authorities to have become דבר חדש, a “novel entity,” and therefore neutral/pareve.
• Rennet extracted from the lining of a calf’s stomach has precedent to be considered “like wood.”
  • May be nullified in a volume of ingredients 60 times greater than itself.
• Gelatin and rennet pass through an inedible and even a toxic stagehand have thus arguably removed the substance from the status of food and turned it into a new substance.

• Chymosin, a microbial enzyme harvested from ruminant animals, but since 1990 cultured through recombinant genetic engineering, is employed to produce kosher cheeses; chymosin itself is considered kosher and pareve.

But, cells gathered from a live animal will, despite all the manipulations, remain some sort of muscle cell. It is less plausible to dismiss the meaty status of a biological structure that never departs significantly from its original state.

Halakhic Conclusions

• Should cultured meat become a viable consumer product, it will be important to ascertain that it derives from a kosher species of animal and that the growth medium and any additives be plant-based or synthetic and certified kosher. Indeed, the entire process will require kosher supervision.

• Cultured meat derived from cells taken from a kosher species of animal will not be prohibited as a limb or flesh taken from a living animal, because the original cells will not be eaten, and they alone would not suffice to create the final product.

• While cultured meat might arguably be deemed pareve like eggs, this is a matter of doubt, and we rule stringently when in doubt over a biblical prohibition. Moreover, because the product is designed to mimic the biological structure and eating experience of pastured meat, it would be confusing for one meat to be “meaty” and another apparently identical meat to be pareve. Cultured meat should be designated as “meaty according to the rabbis” even though there will be no need for kosher slaughter, inspection for injury, deveining, soaking or salting to remove blood.

• If cultured meat fulfills the promises of being less cruel to animals, less destructive to the environment, and more healthful to consume, then it will be not only acceptable, but even preferable to eating conventional pastured meat.