Kashrus Kurrents, Spring 2022

There is a basic principle in Halacha: kol hayotzei m’tamei tamei, kol hayotzei m’tahor tahor. The crux of that principle is that a product derived from a non-kosher animal will be deemed not kosher (e.g., pig milk or ostrich eggs), while a product derived from a kosher animal will be kosher (e.g., chicken eggs and goat milk). This definition needs more investigation when it comes to stem cells.

Before we proceed with this discussion, let’s first step back to the Beginning, to the Source of all that ‘stems.’

In the Beginning … There Was Change

Change is sometimes beneficial, at times detrimental, frequently challenging, and often intriguing. If we take a closer look, change is actually the underlying force behind brias ha’olam (creation).

The Ramban offers a riveting insight into unlocking the secret of brias ha’olam when he draws us close and says, “and now, let me tell you the secret of creation. The Ribono shel Olam created the world yesh mi’ayin – ex nihilo – Something out of Nothing.” What exactly did He create? In the Ramban’s words: yesod dak me’od – what we would call a single element: הִיוּלִי  (hiyuli).

In Hashem’s creation of hiyuli, He changed, shaped, expanded, molded, designed, and refined the entire briah – v’hinei tov me’od! As we can clearly see from the Ramban’s perspective, change is the fundamental driving force behind all matter that envelops us.

Let’s illustrate the power of change with a few simple examples. Take two basic elements – hydrogen (H) and oxygen (O). Combine two parts hydrogen with one part oxygen, and the result is water, H₂O, the elixir of life. Highly beneficial! Add the element sulphur (S) to the hydrogen and oxygen, and the result is sulfuric acid, H₂SO₄, a corrosive acid that can damage skin, eyes and lungs. Potentially harmful!

Change in the World of Kashrus

In the world of kashrus, we are constantly dealing with change and transformation. Combining water and barley flour transforms the starch into a sugary liquid called wort or malted barley. Combine the wort with yeast and you brew beer. Distill the beer, and the water and alcohol separate into vapors. The alcoholic vapor condenses into a chometzdik liquid called neutral grain spirits. Fascinating!

Take non-kosher grape wine seeds, wash them, dry them and extract the oil from the seeds. You now have kosher grapeseed oil. Intriguing!

Some products are grown and propagate from a small test tube filled with nutrients known as growth media. This is the initial growth stage of fungi, popularly known as yeast. Yeast cells grow from test tubes to laboratory flasks, to fermentation tanks, to tanks that may have the capacity to hold 60,000 gallons of yeast. What happens to all that yeast if the protein nutrient in the original test tube came from pork? The yeast would be considered not kosher. Disappointing!

So is the Stem Cell Fleischig? Is It Even Kosher?

As we clearly see in the world of kashrus, not all transformations are created equal. In fact, one of the most fascinating kashrus questions before us today ‘stems’ from recent developments in the area of stem cell research.

Let’s begin with a working definition of stem cells and how they could relate to kashrus.

Stem cells are an organism’s basic raw material – undifferentiated cells from which all other cells with specialized functions are generated. Undifferentiated cells are pluripotent – they have the capacity to become any kind of cell. Stem cells, under the right conditions, can divide into more cells called daughter cells. Daughter cells can themselves become more stem cells or differentiate to become specialized cells – such as blood, brain, bone, fat, or muscle cells.

Mammalian stem cells may be harvested from early animal embryos (at the so-called blastocyst stage) or from certain adult animal sources like bone marrow. Such stem cells could, in principle, be used to grow tissues or organs – like Black Angus steer muscle (and fat) that could, in principle, be fashioned into a lab-derived steak. 

With researchers discovering new methods to direct stem cells to become specific types of cells, we can engage in an interesting thought exercise. Theoretically, what would be the kashrus status of a bovine stem cell taken from a Black Angus steer that you let grow into a stem cell rib steak? Does the possibility exist to propagate beef stem cells and grow them into a geshmak stem cell rib steak?

Indeed, it is an intriguing prospect. Researchers approached Rabbi Moshe Heinemann, shlit”a, STAR-K’s Rav Hamachshir, for his opinion about stem cell beef. Rabbi Heinemann clearly maintained that kosher embryonic stem cells would have to be grown from a beheima shechuta, an animal that was properly slaughtered. As the Rav has opined with genetically modified tomatoes, if it looks like a tomato and tastes like a tomato, it’s a tomato.

‘Stem cell’ meat would be no different. When a stem cell is propagated, you are actually growing an animal, and not something that emanates from the animal. Since the stem cell and the actual beheima are one and the same, the kashrus status and gender of the stem cell follow suit. Unlike a pareve egg that comes from a chicken or dairy milk that comes from a goat, a kosher bovine stem cell is unquestionably fleishig.

The author wishes to thank Dr. Arie Michelsohn for his assistance with this article. Dr. Michelsohn is a patent attorney and molecular biologist who earned his PhD at Caltech, where he conducted stem cell research and wrote his dissertation on the topic.