Kashrut (also kashruth or kashrus, כַּשְׁרוּת) is a set of dietary laws dealing with the foods that Jews are permitted to eat and how those foods must be prepared according to Jewish law. Food that may be consumed is deemed kosher (ər/ in English, Yiddish: כּשר‎), from the Ashkenazi pronunciation of the Hebrew term kashér (כָּשֵׁר), meaning 'fit' (in this context: 'fit for consumption').

Although the details of the laws of kashrut are numerous and complex, they rest on a few basic principles:

  • Only certain types of animals, birds and fish meeting specific criteria are kosher; the consumption of the flesh of any animals that do not meet these criteria, such as pork and shellfish, is forbidden
  • Kosher mammals and birds must be slaughtered according to a process known as shechita; blood may never be consumed and it must be removed from meat by a process of salting and soaking in water for the meat to be permissible for use
  • Meat and milk and their derivatives may never be mixed, and separate equipment for the storage and preparation of meat-based and dairy-based foods must be used

Every food that is considered kosher is also categorized as follows:

  • "Meat" products (also called b'sari or fleishig) are those that contain kosher meat, such as beef, bison or lamb, or kosher poultry such as chicken, goose, duck or turkey, or derivatives of meat, such as animal gelatin; non-animal products that were processed on equipment used for meat or meat-derived products must also be considered as meat (b'chezkat basar)
  • "Dairy" products (also called halavi or milchig) contain milk or any derivatives of milk such as butter or cheese; non-dairy products that were processed on equipment used for milk or milk-derived products must also be considered as milk (b'chezkat halav)
  • Parev products contain neither meat nor milk or their derivative ingredients, and include foods such as fish, eggs, grains, fruit and produce; they remain parev if they are not mixed with or processed using equipment that is used for any meat or dairy products.

While any produce that grows from the earth, such as fruits, grains, vegetables and mushrooms, are always permissible, laws regarding the status of certain agricultural produce, especially that grown in the Land of Israel, such as tithes and produce of the Sabbatical year, impact their permissibility for consumption.

Most of the basic laws of kashrut are derived from the Torah's books of Leviticus and Deuteronomy. Their details and practical application, however, are set down in the oral law (eventually codified in the Mishnah and Talmud) and elaborated on in the later rabbinical literature. Although the Torah does not state the rationale for most kashrut laws, some suggest that they are only tests of obedience,[1] while others have suggested philosophical, practical and hygienic reasons.[2][3][4]

Over the past century, many kashrut certification agencies have started to certify products, manufacturers and restaurants as kosher, usually authorizing the use of a proprietary symbol called a hechsher on products, or issuing a certificate, also called a hechsher, to be displayed by the food establishment, to indicate their approval that they are in compliance with the kosher laws.



Jewish philosophy divides the 613 commandments (or mitzvot) into three groups—laws that have a rational explanation and would probably be enacted by most orderly societies (mishpatim), laws that are understood after being explained but would not be legislated without the Torah's command (eidot), and laws that do not have a rational explanation (chukim). Some Jewish scholars say that kashrut should be categorized as laws for which there is no particular explanation since the human mind is not always capable of understanding divine intentions. In this line of thinking, the dietary laws were given as a demonstration of God's authority, and man must obey without asking why.[5] However, Maimonides believed that Jews were permitted to seek out reasons for the laws of the Torah.[6]

Some theologians have said that the laws of kashrut are symbolic in character: Kosher animals represent virtues, while non-kosher animals represent vices. The 1st-century BCE Letter of Aristeas argues that the laws "have been given ... to awake pious thoughts and to form the character".[7] This view reappears in the work of the 19th century Rabbi Samson Raphael Hirsch.[8]

The Torah prohibits "seething the kid (goat, sheep, calf) in its mother's milk". While the Bible does not provide a reason, it has been suggested that the practice was perceived as cruel and insensitive.[9][10]

Hasidic Judaism believes that everyday life is imbued with channels connecting with Divinity, the activation of which it sees as helping the Divine Presence to be drawn into the physical world;[11] Hasidism argues that the food laws are related to the way such channels, termed sparks of holiness, interact with various animals. These sparks of Holiness are released whenever a Jew manipulates any object for a holy reason (which includes eating);[12] however, not all animal products are capable of releasing their sparks of holiness.[13] The Hasidic argument is that animals are imbued with signs that reveal the release of these sparks, and the signs are expressed in the biblical categorization of ritually clean and ritually unclean.[14]

According to Christian theologian Gordon J. Wenham, the purpose of kashrut was to help Jews maintain a distinct and separate existence from other peoples; he says that the effect of the laws was to prevent socialization and intermarriage with non-Jews, preventing Jewish identity from being diluted.[15] Wenham argued that since the impact of the food laws was a public affair, this would have enhanced Jewish attachment to them as a reminder of their distinct status as Jews.[15]


There have been attempts to provide empirical support for the view that Jewish food laws have an overarching health benefit or purpose. One of the earliest is that of Maimonides in The Guide for the Perplexed. In 1953, David Macht, an Orthodox Jew and proponent of the theory of biblical scientific foresight, conducted toxicity experiments on many kinds of animals and fish.[16] His experiment involved lupin seedlings being supplied with extracts from the meat of various animals; Macht reported that in 100% of cases, extracts from ritually unclean meat inhibited the seedling's growth more than that from ritually clean meats.[17] At the same time, these explanations are controversial. Scholar Lester L. Grabbe, writing in the Oxford Bible Commentary on Leviticus, says "[a]n explanation now almost universally rejected is that the laws in this section [18] have hygiene as their basis. Although some of the laws of ritual purity roughly correspond to modern ideas of physical cleanliness, many of them have little to do with hygiene. For example, there is no evidence that the 'unclean' animals are intrinsically bad to eat or to be avoided in a Mediterranean climate, as is sometimes asserted."[19]