It seems like part and parcel of Jewish life is delicious kosher food: chicken soup, gefilte fish, falafel and pastrami. So what's behind all this scrumptious food?

The Hebrew word "kosher" literally means "prepared." Foods that are permitted by the Torah, and prepared according to Jewish law are kosher.1

Actually the word kosher can be applied to any item that is prepared in accordance with halacha. Thus we find such expressions as kosher tefillin, a kosher mezuzah, and a kosher etrog – meaning that they satisfy the requirements of Jewish law for ritual use. An ethical person who lives his life in accordance with Torah teachings is called an Adam Kasher (lit: kosher man). In English, the word has gained colloquial usage as meaning "correct" or "proper" – e.g. a kosher deal.

Similarly, the word "treif" is often used to designate anything which is not kosher, although the term technically applies only to an animal whose organs are damaged or diseased. (see below)

In this lesson, we'll give a broad overview of what makes food "kosher," and at the end we'll examine some of the philosophical underpinnings of the kosher concept.

Kosher Species

1. Animals

The Torah says that two signs identify an animal as a kosher species: fully split hooves, and chewing the cud (rumination).2 Kosher animals are always mammals and herbivores. The kosher animals commonly eaten today are the cow, goat and sheep – and sometimes deer and buffalo.

2. Birds

The Torah enumerates 24 forbidden species of birds3 which includes, among others, all birds of prey (vulture, hawk, eagle). In practice today, we eat only those birds for which there is an established tradition that the bird is kosher – e.g. chicken, turkey, duck and goose.

3. Fish

The Torah teaches that a kosher fish must possess both fins and scales.4 (Fins help the fish swim, and scales are a covering over the body.)5 Even if the fish has only one scale or one fin, it is permitted. For example, tuna has very few scales and is kosher. Other popular kosher fish are: bass, carp, cod, flounder, halibut, herring, mackerel, trout and salmon.

Crustaceans (such as lobster and crab) and other shellfish (such as clams) are not kosher, because they lack scales. Further, all aquatic mammals (e.g. whales and dolphins) are not kosher.

And yes, there are kosher varieties of sushi and caviar – providing it's from a kosher species (fins and scales), and that it was prepared with kosher utensils (knife, cutting board, etc.).

4. Insects

Many are surprised to discover that four species of grasshoppers are kosher.6 However, all other insects are not kosher. One might think that this has little practical application to our modern eating habits. But in truth, many leafy vegetables (lettuce, broccoli) often contain insects and must be carefully examined before they can be eaten. Some fruits like raspberries and strawberries are also problematic. Instruction booklets are available that describe specific methods to properly check these fruits and vegetables for insects.

Kosher Slaughtering

1. Shechita

Besides being from a kosher species, kosher meat requires that the animal/bird be slaughtered in the manner prescribed by the Torah (Shechita).7 (Fish do not have this requirement.)8 In this procedure, a trained kosher slaughterer (shochet) severs the trachea and esophagus of the animal with a special razor-sharp knife.9This also severs the jugular vein, causing near-instantaneous death with minimal pain to the animal.

2. Bedika

After the animal/bird has been properly slaughtered, if there is reason to believe that the internal organs are damaged, they should be inspected for any physiological abnormalities that may render the animal non-kosher (treif).10 The lungs are always checked, being that they commonly have adhesions (sirchot) which may be indicative of a puncture in the lungs.11

3. Nikkur

Animals contain many veins (e.g. Gid HaNashe)12 and fats (chelev)13 that are forbidden by the Torah and must be removed. The procedure of removal is called "Nikkur," and it is quite complex. In practice today, the hind quarter of most kosher animals is simply removed and sold as non-kosher meat.

4. Melicha

The Torah forbids eating of the blood of an animal or bird;14 fish do not have this requirement. Thus in order to extract the blood, the meat is subject to a process called melicha.15 The meat is rinsed and then the entire surface is covered with coarse salt. It is then left for an hour on an inclined or perforated surface to allow the blood to flow down freely. The meat is then thoroughly washed to remove all salt. Meat must be koshered within 72 hours after slaughter so as not to permit the blood to congeal. (An alternate means of removing the blood is through broiling on a perforated grate over an open fire.)

Additional Prohibitions

1. Meat and Milk

The Torah forbids eating meat and milk in combination, and even forbids the act of cooking them together (as well as deriving benefit from such a mixture).16 As a safeguard, the Sages disallow the eating of meat and dairy products at the same meal, or preparing them with the same utensils. Therefore, a kosher kitchen must have two separate sets of pots, pans, plates and silverware – one for meat/poultry and the other for dairy foods.

The Hebrew terms for meat and milk are basar and chalav. In Yiddish, the terms are fleishig and milchig.

One must wait up to six hours after eating meat products before eating dairy products.17 However, meat may be eaten following dairy products (with the exception of hard cheese, which also requires a six-hour interval).18 Prior to eating meat after dairy, one must eat a solid food and the mouth must be rinsed.19

A food that contains neither meat nor milk is called pareve. Pareve foods may be eaten with either dairy or meat products. Pareve foods include: fish, eggs, and everything grown from the soil (vegetables, fruits, grains).

2. Limb of Live Animal

The Torah prohibits eating a limb that was removed from an animal before it was killed.20 In Hebrew, this is called Ever Min HaChai. (This requirement is actually one of the Seven Noahide Laws that apply to non-Jews as well.)21

3. Chalav Yisrael

A rabbinic law requires supervision during the milking process, to ensure that the milk comes from a kosher animal. In the United States, many people rely on the Department of Agriculture's regulations to fulfill the rabbinic requirement for supervision. Many people, however, do not rely on this, and will only eat dairy products that are designated as Chalav Yisrael (literally, "Jewish milk").

4. Bishul Akum

Bishul Akum is a Hebrew term meaning, "cooked by a non-Jew." As a rabbinic safeguard against assimilation, certain foods cooked by a non-Jew are considered not kosher. While the details of this law are many, the basic rule is that food cooked by a non-Jew may not be eaten if it: 1) could not have been eaten raw, and 2) is important enough to be served at a fancy meal table.

If a Jew assists with lighting the fire or the cooking, the food may be eaten even if it was cooked by a non-Jew (assuming, of course, that the food itself was kosher in every other way).22

It is also prohibited to drink wine that was touched by a non-Jew, unless the wine had first been boiled.23

5. Derivatives of a Non-Kosher Species

Products which come from non-kosher creatures are also not kosher.24 In other words, kosher eggs must come from a kosher bird, kosher milk from a kosher animal, and kosher fish oil from a kosher fish.

The exception to this rule is honey from bees, which is in fact kosher.25 Bees produce honey from the nectar of flowers. Even though bees bring the honey into their bodies, it is only stored, but not produced there.

[By the way, although the Torah praises the Land of Israel as "flowing with milk and honey,"26 the verse actually refers to fig-honey!)27

6. Non-Kosher Vessels

If a cooking or eating utensil (pot, fork, etc.) comes into contact with [hot] non-kosher food, then the utensil itself becomes non-kosher through the absorption of taste.28 These laws are quite complex, and will vary depending on the material the utensil is made of (i.e. metal, plastic, glass, earthenware, etc.), among other factors.

The possibility of making a utensil "kosher" again also depends on a variety of factors. But by way of example, a metal pot that became non-kosher can be made kosher again by being thoroughly cleaned, left for 24 hours, and then immersed into boiling water. This process is called hagalah.29

Kosher Produce

Although grains, fruits and vegetables are generally presumed to be kosher, there are a few important issues to be aware of:

1. Grains

The Torah says that if a grain (such as wheat) was harvested prior to Passover, then we may not eat that grain until after (the second day of) Passover.30

This means that we have two kinds of grain: grain that hasn't celebrated its first Passover is (temporarily) forbidden as Chadash (lit: new), while grain that has been around long enough to already have a Passover under its belt is permitted as Yashan (lit: old).31

Another grain-related issue is Challah. (This is not to be confused with the braided bread that we eat on Shabbat.) When one kneads a significant amount of dough (over 2.5 pounds) for baking purposes, a small portion of the dough is removed and burned.32 (In the times of the Holy Temple, this portion was given to a Kohen.) Once challah has been separated from the larger dough, the dough is "kosher" for baking into bread or other items.

2. Fruits

Fruit that grows during the first three years after a tree is planted is called Orlah and is not kosher to be eaten.33 This law applies to trees both in Israel and the Diaspora.34 If you plant a fruit tree in your backyard, you cannot eat the fruit for three years, and there is a special procedure to render the fruit permissible to eat in the fourth year.35 (Consult with a rabbi for details.)

3. Israeli Produce

Trumah and Maaser are terms for various tithes that apply to Israeli-grown produce. (In Temple times, these were given to the Kohen and Levi.) Even today, untithed foods are called Tevel and are not kosher to be eaten.36 If you're visiting Israel, or even if you're buying Israeli oranges or tomatoes in your local supermarket, you should make sure that proper tithes have been taken from all grains, fruits and vegetables.

The Torah says that every seven years, agricultural work must cease in the Land of Israel.37 This is called Shmita – the seventh, sabbatical year. Today, with the return of a Jewish agricultural industry to Israel, the laws related to Shmita are once again very relevant.38 So if you're buying Israeli produce, make sure that the laws of Shmita were properly observed.

Kosher Supervision

When shopping for kosher food, it is not enough to simply "read the ingredients." Food processing has become highly sophisticated and labeling practices may be misleading to the kosher consumer. For example, certain emulsifiers may be manufactured with non-kosher animal fats.

Further, just because a product is labeled with a "K" does not necessarily mean that it's kosher. In America, there is no law barring a manufacturer from putting any letter they want on a label, whether ice tea or pork rinds.

For reliable supervision, you should look for a "symbol" indicating that the product has been reliably supervised. Star-K, O-U and Kof-K are some of the most common symbols in America; Bedatz is popular in Israel. There are many others, some good and some not-so-good. If you have a specific question, you should check with a knowledgeable rabbi.

Why Keep Kosher?39

In today's modern world, why should we keep kosher?

Of course, the ultimate answer is "because God said so." Beyond this, however, there are practical, observable benefits to keeping kosher:

1) Spiritual Growth: The soul is like an antenna that picks up waves of spiritual energy, and non-kosher food has a negative effect on a Jewish soul. Eating kosher leads a person to holiness.40 Kashrut requires that one must wait between milk and meat, and we may not eat certain animals or combinations of foods. (Even when you're hungry!) All of this instills self-discipline, and enables us to elevate our spiritual side, by making conscious choices over animal urges.

In eating only kosher food, we habituate ourselves to becoming the type of person who makes discriminating choices. This sets a standard of behavior for all areas of life, where we can wisely choose what types of books, conversation, and other influences we permit ourselves to ingest.

2) Moral Lessons: We are taught not to be cruel – even to animals. A mother and her young are forbidden to be slaughtered on the same day,41 and of course we "don't boil a kid (goat) in its mother's milk." We must not remove the limb of an animal while it is still alive (a common practice, prior to refrigeration). When we slaughter an animal, it must be done with the least possible pain. And we are reminded not to be vicious, by the prohibition to eat vicious birds of prey.

Critics of kashrut are heard to remark that "it's not what goes into your mouth that counts, but what comes out." Actually, what comes out may very well be determined by what goes in. The food people eat (or more importantly, abstain from eating) influences a person's character, values, and moral-ethical sensitivity.42

3) Health Reasons: With its extra supervision, kosher food is perceived as being healthier and cleaner. After slaughter, animals are checked for abscesses in their lungs or other health problems. Blood – a medium for the growth of bacteria – is drained. Shellfish inhabit parts of the seabed which are contaminated with hepatitis virus and other pathogens. Milk and meat digest at an unequal rate and are difficult for the body to process. Certain types of meat are prone to tapeworm infestation, and of course, pigs can carry trichinosis.

4) Tradition: One of the keys to making a Jewish home "Jewish" is the observance of keeping kosher. When we keep kosher in the home, our attachment to Judaism and the sacrifices that we make become ingrained on our children's minds forever. And with food so often the focus of social events, keeping kosher provides a built-in hedge against assimilation.43 For many, the bridge between past and future is the spiritual aroma of a kosher kitchen.

Ultimately, we cannot fathom the full depth of "Why keep kosher." For as the saying goes, there is more to keeping kosher than meets the palate...


  1. For more details on this topic, see our 30-part Pathways course on Kashrut.
  2. Leviticus 11:3
  3. Leviticus 11:13-19
  4. Leviticus 11:9
  5. Maimonides (Ma'achalot Asurot 1:24); Yoreh De’ah 83:1,4
  6. Leviticus 11:22
  7. Deut. 12:21
  8. Numbers 11:12
  9. Talmud – Chullin 27a; Yoreh De'ah 21:1
  10. Yoreh De’ah 39:1
  11. ibid.
  12. Genesis 32:33
  13. Leviticus 7:23-24
  14. Leviticus 7:26
  15. Yoreh De’ah 69
  16. Exodus 23:19, 34:26, Deut. 14:21; Yoreh De’ah 87:1
  17. Yoreh De’ah 89:1
  18. Yoreh De’ah 89:2
  19. ibid.
  20. Deut. 12:23
  21. Talmud – Sanhedrin 58b
  22. Yoreh De’ah 113:1,6
  23. Yoreh De’ah 123:1,3
  24. Talmud – Bechorot 5b
  25. Yoreh De’ah 81:8
  26. Deut. 8:8
  27. Rashi (Sukkah 6a)
  28. Mishnah Berurah 451:40
  29. Orach Chaim 451:5; 452:2
  30. Leviticus 23:14
  31. Yoreh De’ah 293:2
  32. Orach Chaim 456:1; Y.D. 322:4,5; 324:1
  33. Leviticus 19:23
  34. Talmud – Kiddushin 37a; 38b; Yoreh De'ah 394:8
  35. Leviticus 19:24; Rambam (Ma'achalot Asurot 10:16,17)
  36. Leviticus 22:15; Talmud – Zevachim 11b
  37. Leviticus ch. 25
  38. see Chazon Ish (Shvi'it 10:6); Minchat Shlomo 1:44
  39. based on Shabbat Shalom Weekly by Rabbi Kalman Packouz
  40. Leviticus 11:44
  41. Leviticus 22:28
  42. Igeret HaKodesh by Ramban 4; Shach (Yoreh De'ah 81:26)
  43. Minyan HaMitzvot by Rambam, introduction to Sefer Kedusha