For the body or the soul: Possible reasons for keeping kosher

The laws of keeping kosher have no immediately obvious rationale behind them. Yet we assume that observance of all the mitzvot in the Torah are beneficial to us. Therefore, for generations, Jewish thinkers have formulated various approaches to the benefits of keeping kosher. In this lesson we consider four approaches to the physical and spiritual benefits of observing the laws of kashrut.

Resource Ages: 15-18


Rabbi Shmuel ben Meir (Rashbam), Leviticus (Vayikra) 11:3
(1085–1158) Commentator on Torah and Talmud in Northern France.

All of the domesticated and non-domesticated animals, the birds, fish, locusts, and crawling things that God forbade the people of Israel to consume, are detestable. They are unhealthy and cause the body to overheat. Therefore, the Torah refers to them as tamei.

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Foundations for Planning

Essential Questions

  • How do values and tradition impact my Jewish practice?
  • How do family traditions play an important role in our lives?
  • How do Jewish practices reflect Jewish values?
  • How do Jewish rituals and practices enrich the way I experience my life and the world?
  • Why/how might Jewish practices be meaningful for me even if I don’t define myself as “religious”?
  • How does being Jewish affect what I do in my daily/weekly life?

Content Questions Related to the Essential Questions

  • What does the phrase “You are what you eat” mean to you?
  • In what ways might the laws of kashrut be a more mindful way to live and eat?
  • In what ways might what we eat have a spiritual or religious impact on us?
  • From what you understand of the laws of shechita, would you say it is a cruel or a compassionate way to slaughter animals for food?

Background for Teacher

Rabbi Shmuel ben Meir (Rashbam), Leviticus (Vayikra) 11:3 Non-Kosher animals are unsafe: Rashbam explains why, in his view, certain types of animals were prohibited by the Torah. He claims quite simply that the prohibited animals are loathsome, and that they destroy and overheat the...

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Rabbi Shmuel ben Meir (Rashbam), Leviticus (Vayikra) 11:3

Non-Kosher animals are unsafe: Rashbam explains why, in his view, certain types of animals were prohibited by the Torah. He claims quite simply that the prohibited animals are loathsome, and that they destroy and overheat the body. In other words, certain animals possess physical characteristics that are injurious to humans. This is why Jews are enjoined from eating them.

Contemporary questions to this approach: If this approach is correct, one may wonder about the applicability of these laws today. Does modern science corroborate the notion that the prohibited animals are the least healthy? This approach is also troubling theologically. Jews, throughout the generations, have sought the guidance of the Torah in matters of morality and faith but not, generally, in practical matters such as diet and the maintenance of good health. Is the Torah, in fact, a health manual? One must also wonder, on a moral level, if these animals are unhealthy for consumption, why would the Torah not prohibit them also to the non-Jew as one of the Noachide Laws? 

Note on the text: The word tamei ( טמֵָא ) cannot be properly translated into English. Some have used the word pollution, while others impure. While it is beyond the scope of this lesson to explore the meaning of this word, suffice it for here to note that it generally signifies a spiritual state that prevents one from coming into contact with things that are kadosh (holy or sacred) until one is no longer in that state and one becomes tahor ( טָהורֹ ). What is so interesting about Rashbam then is how he defines the word tamei in a physical rather than a spiritual sense. 

Rabbi Shlomo Ephraim Luntschitz, Kli Yakar, Leviticus (Vayikra) 11:1, 4

Proof against keeping kosher for reasons of physical health: Referring to Rashbam and to other commentators who argue that the rationale for the laws of kashrut is to neutralize a health concern, the Kli Yakar not only disagrees, but affirms it is factually wrong. There are many who do not observe the laws of keeping kosher who are healthy and strong. He then proposes that the reason for these laws is to ensure the health of the soul, not that of the body.

Danger of non-kosher animals to moral character: In his commentary to verse 4 of the same chapter, the Kli Yakar discusses those animals who have only one of the two required kosher markers (such as the pig). Having only one marker for him is worse than no markers; one marker allows these animals to try to deceive people into thinking they are kosher, when they are not (an idea raised by the Midrash Bereshit Rabbah 65:1). While the Kli Yakar clearly does not take this literally, as animals do not deceive or act hypocritically in this way, he does believe that eating these animals would introduce into the person traits that manifest as deceptiveness and hypocrisy.

Animals have character traits which can affect those who eat them: What Kli Yakar states here seems to be an expansion of an idea that Ramban (Rabbi Moshe ben Nachman; 1194–1270) stated. Ramban points out that the mammals and birds permitted by the Torah are calmer and less violent than the ones forbidden for consumption. And fish that have fins and scales tend to stay closer to the surface of the sea where there is more oxygen, and so contain less of the harmful humors (bodily fluids central to an ancient theory of medicine) present in the sea creatures found in the deeper, murkier waters. Eating the prohibited animals will thus impact psychologically and will introduce into the person a tendency to bad personality traits, or will upset a healthy balance of humors in the body. The overall effect, though, is either to transform the body into something abominable for God’s service or will ward off any sense of holiness from that person, as stated and implied by the verses in Vayikra 11 (43–44). (This idea is also the focus of Maimonides below.) One should note that in addition to the psychological and spiritual detriments to eating prohibited foods, Ramban also believes these foods can cause physical harm to the individual. Thus, unlike Kli Yakar, Ramban presents both a physical and a spiritual rationale for these prohibitions.

A modern voice that parallels the Kli Yakar: Rabbi Shimshon Raphael Hirsch (1808–1888) wrote that eating non-kosher foods may provide you with better physical nourishment, however, as these are absorbed into the body, especially such foods coming from prohibited animal sources, the animal instinct that exists in every person will be aroused, leading one to act in more animal-like ways. The human heart, then, becomes apathetic and dulled instead of being an instrument to seek out holiness.

While the commentators mentioned in this analysis do not see eye-to-eye on all points, it does seem to hold true that for each of them, “you are what you eat” is not just a slogan. The traits of the animals you consume can potentially become part of who you are as a person. 

Professor Baruch A. Levine, The Meaning of the Dietary Laws

Kashrut categories are about how animals feed themselves: In searching for a common denominator with regard to the prohibited birds, Levine discovered that they are: “birds of prey, by day or by night, who feed on carrion and tear the flesh of other living creatures in their pursuit of food.” The other birds feed mostly on grain.

Preference for non-animals of prey: Kosher animals, according to the Tanakh, must have cleft hoofs and must chew their cud. Why is this significant? Animals with cleft hoofs are generally herbivores, while those with paws are carnivores, generally ripping apart the flesh of their prey. Fish with scales and fins are generally not scavengers. Thus, the Tanakh shows a preference for animals that do not prey on other living creatures. As Jews (and also humankind) are prohibited from eating flesh torn from a living creature, it seems reasonable that they should not eat animals that sustain themselves in ways prohibited to the Jews.

Jews are to be as humane as possible in their acquisition of food: The second criterion is consistent with the first. By chewing their cud, the animals – which might have obtained their food in ways forbidden to the Jews – are making sure that it is digested as thoroughly as possible. Apparently, the message is that Jews are to be as humane as possible in their acquisition of food. If they cannot sustain themselves by the produce of the earth, they are permitted to slaughter animals, but Jews must limit themselves to those that behave “humanely” in their eating habits. Thus, the dietary laws serve an important humanitarian function – they are not intended merely to preserve one’s health and physical well-being; they are intended to elevate the individual spiritually by preventing barbaric behavior and by enhancing humaneness.

Maimonides (Rambam), Moreh Nevukhim (Guide for the Perplexed) 3:48

The laws of kashrut are a response to idolatry: Consistent with his general approach to the dietary laws, Rambam suggests here that the prohibition of boiling meat in milk is a reaction to idolatrous practices. Although he was not able to confirm such a practice, he assumed that a milk and meat mixture was probably offered during some idolatrous ceremonies. He adduces support for this theory from the Torah itself. The Torah presents the prohibition in the context of the pilgrimage festivals. In other words, the Torah is warning the Jews not to observe the festivals in a manner similar to the pagans.

Moral basis to shechita: Additionally, Rambam considered that the slaughtering of an animal had to be done with a moral approach, without tormenting it. This is consistent with some of Rambam’s other writings where he proposes that animals are prone to emotional pain similar to humans: “there is no difference . . . between the pain of humans and the pain of other living beings, since the love and tenderness of the mother for her young ones is not produced by reasoning, but by imagination, and this faculty exists not only in humans but in most living beings.”

A modern-day application of these values: It is this idea, that kashrut requires from Jews a moral approach to the food they eat, that the Magen Tzedek (“Shield of Justice”) Commission was started in 2008 following “conversations between the Rabbinical Assembly and the United Synagogue of Conservative Judaism over a period of years.” It was launched on the heels of a report on inappropriate working conditions at the Agriprocessors kosher meat plant in Postville, Iowa in 2007. The commission was formed to create a “set of standards that would certify that kosher manufacturers in the US operate according to Jewish ethics and social values.” The Magen Tzedek hekhsher assures “consumers and retailers that kosher food products have been produced in keeping with exemplary Jewish ethics in the area of labor concerns, animal welfare, environmental impact, consumer issues and corporate integrity,” therefore being proper (kosher) for a Jew to eat.

Modern-day relevance of Rambam’s approach?: Rambam’s explanation for the prohibition against mixing milk and meat may have been relevant in the era of idolatry, but what meaning could it have today? His attempt to give a historical explanation for this and similar prohibitions risks making them seem quite obsolete in a world no longer troubled by the existence of such idolatrous practices, unless one argues that the Torah laws of kashrut had specific purposes in the time in which they were given and now have taken on other purposes. His approach to slaughtering, however, could still be relevant.

See “Additional Text” below for a source that could be used to explore the “because God commanded them” approach to why keep the laws of kosher, in addition to these sources which present logical rationales for their observance.

Optional Hooks
In-Depth Discussion
Suggested Activities
  • This lesson presents four texts that approach the laws of kashrut from the perspective of the impact that our food has on us when we eat it. They can all be summed up with the well-known phrase “You are what you eat”. This video that presents a historical and scientific approach to this can be used as a hook to consider this concept (the first 1:32 particularly). 
    • Here are a few suggestions for techniques that could help focus your students while watching the videos in order to help them extract the information: 
      • 3-2-1 – Gauge students’ understanding and interest in a topic by asking them to write down takeaways, questions, and something they enjoyed about a text
      • Close Viewing Protocol: Teach your students to become critical viewers of film with this four-step procedure.
      • Rapid-Fire Writing – Help students unpack their responses to a text or video using this structured protocol that requires alternating between thinking and writing.
      • S-I-T: Surprising, Interesting, Troubling: Use this quick way for students to demonstrate their engagement with a text, image, or video by having them identify what they find surprising, interesting, and troubling.
      • Think, Pair, Share: Facilitate thoughtful group discussions by having students first share their ideas in writing and with a partner.
    • You could ask your students questions on this video follow up questions such as:
      • What does the phrase “You are what you eat” mean to you?
      • Did you learn anything new from the video about this?
      • Is there a connection between the historical approaches mentioned to food and the modern scientific approach?
      • How do you think the laws of keeping kosher factor in this?

Click here to view our consolidated list of suggested interactive pedagogies for classroom discussion.

  • The first source (the Rashbam) suggests that non-kosher animals are tamei (a term that usually means spiritually impure) because of physical reasons. You could use the following questions to encourage your students to consider and critique this source:
    • Do you think non-kosher animals are physically unhealthy for humans to heat? Can you prove your answer?
    • Does science back the Rashbam’s position? If not, how can we approach the laws of kashrut?
    • If the position of the Rashbam is correct, how can we explain God not ensuring non-Jews also don’t eat them?
    • Why do you think the Rashbam feels the need to find a reason why the Torah prohibits the eating of these animals?
  • The Kli Yakar takes a similar approach, that the laws of kosher are about the impact the food has on the eater, but instead of suggesting it is physically harmful, he argues non-kosher animals are spiritually harmful on those who eat them. You could use the following questions to encourage your students to explore this source:
    • Do you think foods that we eat can have a spiritual or impact on us?
    • Do you believe there is a connection between our physical and mental/emotional/spiritual selves?
    • How can eating non-kosher animals make us cruel according to the Kli Yakar?
  • Professor Levine’s position is somewhere between the two, suggesting that we are both concerned about the physical impact the animals have on us (if they have eaten something that is unacceptable then we will also indirectly consume this undesirable element) and the spiritual (the aggressive nature of animals of prey could rub off on us). You could use the following questions to help your students to understand this source:
    • What are the concerns that the Jewish law has that explain which animals are kosher according to this source?
    • Is Professor Levine worried about a physical or spiritual impact on those who eat non-kosher animals?
    • What is the ultimate value behind kashrut according to Professor Levine?
  • For Rambam, the reason behind the laws of not mixing milk and meat  are probably connected to ancient pagan practices that no longer exist, and the laws of shechita are out of compassion for the animal. You could use the following questions to help your students to understand this source:
    • What two reasons does the Rambam give fior the laws of kashrut?
    • Are they both still relevant today?
    • If the rationale behind a law seems to no longer apply, is there still a reason to observe the law?
    • Were these reasons applicable at Rambam’s time during the Middle Ages? If not, then why do you think he still gave them as a reason (wasn’t this a risk)?
  • Using the diagrams below, ask your students to summarize the four approaches to the laws of kashrut, by labelling the diagrams as if they were scientific illustrations (e.g. draw a line from the hoof of the pig and describe the Kli Yakar’s approach to why a pig is unkosher, because it demonstrates deceit by stretching out its hooves to show it is kosher).