What is Kashrut (Dietary Laws)?
Kashrut (also kashruth or kashrus, כַּשְׁרוּת) is a set of Jewish religious dietary laws. Food that may be consumed according to halakha (Jewish law) is deemed kosher (/ˈkoʊʃər/ in English, Yiddish: כּשר), from the Ashkenazi pronunciation of the Hebrew term kashér (כָּשֵׁר), meaning "fit" (in this context, fit for consumption).
Among the numerous laws of kashrut are prohibitions on the consumption of certain animals (such as pork and shellfish), mixtures of meat and milk, and the commandment to slaughter mammals and birds according to a process known as shechita. There are also laws regarding agricultural produce that might impact the suitability of food 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 for man's obedience, while others have suggested philosophical, practical and hygienic reasons.
Over the past century, many rabbinical organizations have started to certify products, manufacturers, and restaurants as kosher, usually using a symbol (called a hechsher) to indicate their support. Currently, about a sixth of American Jews or 0.3% of the American population fully keep kosher, and there are many more who do not strictly follow all the rules but still abstain from some prohibited foods (especially pork).
The laws of kashrut can be classified according to the origin of the prohibition (Biblical or rabbinical) and whether the prohibition concerns the food itself or a mixture of foods.
Although the details of kashrut (Dietary Laws) are extensive, the laws all derive from a few fairly simple, straightforward rules:
- Certain animals may not be eaten at all. This restriction includes the flesh, organs, eggs and milk of the forbidden animals.
- Of the animals that may be eaten, the birds and mammals must be killed in accordance with Jewish law.
- All blood must be drained from meat and poultry or broiled out of it before it is eaten.
- Certain parts of permitted animals may not be eaten.
- Fruits and vegetables are permitted, but must be inspected for bugs (which cannot be eaten)
- Meat (the flesh of birds and mammals) cannot be eaten with dairy. Fish, eggs, fruits, vegetables and grains can be eaten with either meat or dairy. (According to some views, fish may not be eaten with meat).
- Utensils (including pots and pans and other cooking surfaces) that have come into contact with meat may not be used with dairy, and vice versa. Utensils that have come into contact with non-kosher food may not be used with kosher food. This applies only where the contact occurred while the food was hot.
- Grape products made by non-Jews may not be eaten.
- There are a few other rules that are not universal.
Which animals are kosher?
- Mammals: A mammal is kosher if it has split hooves and chews its cud. It must have both kosher signs. Examples: cows, sheep, goats and deer are kosher; pigs, rabbits, squirrels, bears, dogs, cats, camels and horses are not.
- Fowl: The Torah lists 24 non-kosher bird species—mostly predatory and scavenger birds. Examples of kosher birds are the domestic species of chickens, ducks, geese, turkeys and pigeons.
- Reptiles, amphibians, worms and insects: With the exception of four types of locust, these are not kosher.
- Fish & Seafood: A water creature is kosher only if it has fins and scales. Examples: salmon, tuna, pike, flounder, carp and herring are kosher; catfish, sturgeon, swordfish, lobster, shellfish, crabs and all water mammals are not.
The Slaughter and Butchering of Kosher Meat
- Kosher mammals and birds are slaughtered by a special procedure called shechitah, in which the animal’s throat is quickly, precisely and painlessly cut with a sharp, perfectly smooth knife (called a chalaf) by a shochet—a highly trained, Torah-observant and G‑d-fearing individual.
- After the slaughtering, the internal organs of cattle are examined for potentially fatal diseases or injuries, such as adhesions (sirchot) in the lungs or holes in the stomach. The occurrence of any one of dozens of specified tereifot, as these defects are called, renders the entire animal not kosher.
- Nikur (“deveining”) involves removing certain forbidden veins and fats from cattle. They are extremely prevalent in the hindquarters, and due to the complexity involved in their removal, this part of the animal is generally not sold as kosher.
- The blood of mammals and fowl is utterly forbidden for consumption according to the Torah. Within 72 hours of slaughter, all extractable blood is drained from the meat by a special soaking and salting process. (Today, most kosher meat is sold with the blood already removed.)
- The liver, which has an especially high blood content, needs to undergo a special broiling process before it can be eaten.
Milk, Eggs and Honey
- A rule of thumb cited by the Talmud is: What comes from a kosher animal is kosher; what comes from a non-kosher animal is not kosher.
- Thus, milk and eggs are kosher only when they come from kosher animals. In addition, all eggs should be carefully examined before use to ensure that they are free of blood spots.
- Honey is not considered an animal product, so honey is kosher though bees are not.
Separating Milk and Meat
Meat and milk are never combined. Separate utensils are used for each, and a waiting period is observed between eating them.
Kosher foods are thus divided into three categories:
- Meat includes the meat or bones of mammals and fowl, soups or gravies made with them, and any food containing even a small quantity of the above.
- Dairy includes the milk of any kosher animal, all milk products made with it (cream, butter, cheese, etc.), and any food containing even a small quantity of the above.
- Pareve foods are neither “meat” nor “dairy.” Eggs are pareve, as are all fruits, vegetables and grains. Pareve foods can be mixed with and eaten together with either meat or dairy (fish are parve, but not eaten with meat due to health concerns outlined in the Talmud).
- Fruits, vegetables and grains are basically always kosher, but they must be insect-free.
- Produce grown in the Land of Israel has special kashrut Tithes must be separated from produce before it can be eaten, and special care must be taken since fruit from the first three years following a tree’s planting (orlah) is unfit for consumption, and special laws govern the produce of shemittah, the sabbatical year.
- Therefore, produce from Israel should be purchased only if it comes with a reliable kosher certificate. Other produce is fine, with some needing bug checking. This can vary by locale and by season, depending on the level of infestation of various crops.
- Many vegetables, fruits, nuts, and grains must be checked before cooking or eating for the presence of small insects. Packages of pasta are also occasionally infested. Some particularly severe problem vegetables are artichokes, asparagus, Brussel sprouts, cauliflower, and leafy vegetables.
- The method of checking depends on the vegetables. Leafy vegetables such as cabbage and lettuce should be checked leaf by leaf. Washing under running water or soaking in salt water is helpful, but the vegetables must also be inspected under a bright light, either daylight or artificial light. Certain vegetables, such as celery and zucchini may be used after they are washed under running water and scrubbed with a vegetable brush.
Even a small trace of a non-kosher substance—as little as 1/60th (1.66 percent) of the food’s volume, and in certain cases, even less than that—will render an otherwise kosher food not kosher. By the same token, utensils that come in contact with hot food will absorb its “taste” and subsequently impart it to other food.
For example, a loaf of bread baked in a pan smeared with shortening that contains a small percentage of lard, fruit juice pasteurized in the same machinery as non-kosher milk, or a vegetarian dish prepared in a restaurant kitchen with the same utensils in which a non-kosher dish was cooked earlier—these would all be regarded as non-kosher if the proportion of the non-kosher substance is greater than the permissible percentage.
It is for this reason that separate utensils are used for meat and milk, and that a reliable kosher certification is needed for foods processed or prepared outside the home.
Even the slightest residue or “taste” of a non-kosher substance will render a food not kosher. So it’s not enough to buy only kosher food. The kitchen, too, must be “kosher,” meaning that all cooking utensils and food preparation surfaces are used exclusively for kosher food, and that separate stoves, pots, cutlery, dishes, counter surfaces and table coverings are used for meat and dairy.
A general rule of thumb is that any time hot food comes in contact with another food or a utensil, the food or utensil will absorb its “taste.” Also cold foods and utensils will, under certain circumstances (such as when the food is spicy or salty, is cut with a knife, or it sits in the utensil for an extended period of time), transmit their “taste.” So, food prepared in a kitchen or plant in which non-kosher food is also prepared will invariably become non-kosher as well (unless the embedded taste is first extracted from the utensils in a special koshering process).
The intricacies of modern-day food technology make it virtually impossible for anyone but an expert in the field to know whether a processed food is free of any trace of non-kosher ingredients. So all processed foods and eating establishments require certification by a reliable rabbi or kashrut supervision agency.
Check the labels of packaged foods and the kashrut certificates of restaurants and hotels for a copyrighted kashrut symbol.
You can find more information about kashrut at the websites of major kosher certification organizations.
The Orthodox Union, which is responsible for "OU" certification, has some excellent information on its website, including a kosher primer, an explanation of their kosher policy, a philosophical discussion about "thinking kosher" and a questions and answers section. (Please note: the "Judaism 101" listed on some of their pages is not this website and has no connection with this website).
The Star-K Kosher Certification organization also has an excellent website. The wonderful thing about Star-K is, they give you an incredible amount of detail about the research that they put into determining whether a product is kosher. They tell you what products may be used without kosher certification, and they explain why such products can or cannot be used without kosher certification, giving complete detail about the research that went into making their determination. It also has articles about kashering appliances, and other useful information.
KosherQuest has a searchable database of kosher products as well as an extensive list of reliable kosher symbols and other interesting things.
Typical Food Consumed During Different Holidays
Each week, the Sabbath is an opportunity for us to pause our too-busy lives, rest, re-focus and re-connect with family and friends – whether observing the Sabbath strictly with prohibitions on work and other areas of our lives or simply enjoying a meal with dear ones, whether at home or in a restaurant. Friday night blessings over candles, wine and challah can quickly immerse us in the spirit of Shabbat shalom (peace) by involving all of our senses while special traditional foods often get modern twists – gluten-free challah, vegetarian or vegan main dishes instead of chicken or brisket and the addition of exciting flavors from around the world.
The traditional Sabbath eve meal often consists of chicken soup with kreplach (meat filled dough), chopped liver or gefilte fish, chicken or fish prepared in any number of ways, a kugel (noodle or potato pudding), and vegetables. The traditional dish for Shabbat afternoon in Eastern Europe was cholent (meaning “hot”). Potatoes, kasha(groats), and the little meat available were placed into a pot and cooked for twenty-four hours in the community oven before being carried home by a child for the noon meal. In this country, a typical cholent includes brisket, onions, lima beans, and barley or potatoes. It is a perfect dish for crock pot cooking. Sephardic dishes for Shabbat would include various vegetables, such as carrots, zucchini, or eggplants stuffed with ground meat, or delicious rice-based dishes.
Often called “the Birthday of the World,” Rosh Hashanah is a time of discovery, introspection and new beginnings. Wishes for a sweet new year are expressed in foods such as crispy autumn apples dipped in honey, tzimmes (sweet stew usually of meat, carrots, sweet potatoes and prunes), rich honey cake and Sephardic tispishti (a walnut cake with sweet syrup).
The challah is baked in a round shape (reminding us of eternity) instead of a braid and is enriched with extra eggs, sugar, and raisins to signify the promise for a sweet and rich year. Gefilte fish, chicken soup with three-cornered kreplach (said to symbolize the three patriarchs), carrot or prune tzimmes, and meat or fowl would complete the meal.
Other foods, such as carrots cut into rounds like coins and black-eyed peas are eaten for prosperity while round challahs symbolize long life and eternity. On the holiday eve, Sephardic Jews sit down to a special “seder” to welcome the New Year with seven symbolic foods and blessings.
A holiday known more for its lack of food, Yom Kippur – the Day of Atonement – is a time to reconcile with each other and with God. Prayer and fasting force us to suspend our daily existence; physical abstinence deepens us spiritually with greater appreciation for our everyday life. The evening break-fast is often a light meal of dairy foods such as sweet noodle kugel, cheesy blintzes, eggs, salads, bagels and fish such as herring, whitefish and lox. For Turkish Jews, the traditional first break-fast taste is delicious homemade preserves of quince and other fruits served with a rehydrating glass of water.
On the eve of Yom Kippur, it is important to serve a filling meal without provoking thirst. The meal is similar to that of Rosh Hashanah less some of the sweets. The meal is eaten before the onset of Yom Kippur. It is called seudah mafseket, the concluding meal before a fast. There is no kiddush, and the festival candles are lit after the meal and before going to the synagogue. A light dairy dinner is often eaten after the fast, consisting of assorted fish, eggs, and salads.
Beginning just four days after Yom Kippur, Sukkot coincides with the harvest when workers in Biblical times would live in temporary huts in the fields. It also commemorates the 40 years the Israelites lived in temporary shelters while wandering in the desert. Sukkot is a joyous eight-day celebration when we build and eat (and sleep!) in temporary outdoor structures, decorated with fresh fruit, gourds and other decorations hung from roofs of branches open to the stars. Fall foods such as pumpkin and squash are served along with cabbage, grape leaves, peppers and other stuffed vegetables symbolic of a “full” harvest. The Sukkot table is laden with the fruits and vegetables of the fall harvest. Stuffed foods of all kinds are served to symbolize the richness of the harvest. Cabbage filled with ground beef in a sweet and sour sauce, holishkes (or gefilte krult), are popular among Ashkenazic Jews. Israelis stuff eggplants (chatsilim) and green peppers (pilpel memula). Strudel stuffed with apples, peaches, or other fruits is served for dessert.
Falling the day after Sukkot, Simchat Torah – Rejoicing with the Torah – celebrates with humor, joy and song the completion and immediate beginning again of the yearly cycle of reading the Torah, Jewish written law. Children are given honey so they “taste” the sweetness of the Torah. An Ashkenazic tradition is eating kreplach (aka Jewish wonton), dough stuffed with meat filling then boiled and served in chicken soup or fried and served as a side dish.
The first recorded holiday celebrating religious freedom, Hanukkah commemorates the rededication of the temple in Jerusalem, wrecked by idol worshippers and recaptured by the Maccabees and their followers around 165 BCE. Only one day’s worth of sacramental oil for the Eternal Light was found, but miraculously it lasted the eight days needed to prepare more. Thus, Hanukkah is known as the Festival of Lights – with one more candle on the nine-branched menorah lit each night – and also the festival of fried foods! It’s a good excuse for parties and eating potato latkes and foods fried in oil. Sephardim enjoy bimuelos, fried doughnuts sprinkled in cinnamon and sugar or coated in honey. Israelis popularized sufganiot, gooey jelly doughnuts, to Hanukkah festivities.
Hanukkah is celebrated by eating foods cooked in oil, such as potato latkes(potato pancakes) and sufganyot (jelly doughnuts) to symbolize the miracle of the oil. It is also customary to eat dairy dishes in remembrance of the story of Judith in the Apocrypha.
Around the time the sap begins to flow and fruit of trees begin to form, this New Year of the Trees is an early recognition of environmental awareness. Today it’s a kind of Arbor Day when people plant trees or donate money to environmental causes. A special “seder” focuses on three symbolic groupings of fruits and nuts as well as four cups of wine! The groups include those with pits (cherries, apricots, olives, dates, and plums), those with outside shells that must be discarded (pomegranates, almonds and other nuts) and those that are totally edible (figs, grapes, apples, pears, berries).
Costumes, carnivals, plays, parodies and the consumption of liquor make Purim quite popular! In the synagogue, the Megillah is read, re-telling the story of how wicked Haman’s plot to kill all the Jews of ancient Persia was thwarted by the lovely Esther and her wise uncle Mordecai. There is the holiday custom of giving gifts of fruit and sweets, mishloah manot, to friends as well as the mitzvah (commandment to do good deeds) of donations to the poor. Hamantashen, Purim’s popular tri-cornered cookies filled with poppy seeds or preserved fruit, are said to represent Haman’s triangular-shaped hat.
Hamantaschen, a three-cornered pastry filled with prunes, poppy seeds (muhn), apricots, or other fruits, is the most popular of Purim foods. It is three-cornered, tradition says, to look like Haman’s ears or like the purse he wanted to fill with the Jews’ gold. Haman’s ears are a favorite Purim dessert. They are a fritter-like pastry, deep-fried, and sprinkled with sugar or honey. They are known as Hamansooren in Holland, Orechie de Aman in Italy, Oznei Haman in Israel, and Honuelos de Haman in Spanish-speaking countries.
A springtime holiday, Passover (Pesach) celebrates the exodus of the Israelites from Egypt with themes of liberation and rebirth that are at the heart of the re-telling of the Biblical story during the ritual holiday meal, the seder. The seder table is full of symbolic foods including charoset, which has nearly as many varieties as there are Jews, with the Eastern European apples-walnut-wine version perhaps most popular in the US. The many symbolic foods as well as the prohibition on eating hametz (leavening) – a reminder of the hasty departure from Egypt when the bread dough had no time to rise – make food intrinsic to this holiday perhaps more than any other time. Matzah and its by-products plus fresh vegetables and fruits (especially spring’s bounty of asparagus, leeks and strawberries) take their place at holiday tables along with favorites like matzah ball soup, brisket and mina, Sephardic pies of matzah with vegetable or meat filling.
The seder is a celebration and learning experience shared by all present. The special foods served enhance the beauty and the meaning of the night. Passover foods vary in Sephardic and Ashkenazic communities. Ashkenazim exclude rice while Sephardim serve rice. Ashkenazim also exclude millet, corn, and legumes (beans and nuts). The Rabbis thought that the seed inside the bean would “rise” like leavening. Since no leaven (chamets) may be used, matzah is the main ingredient of Passover cooking. There is a rich variety of foods made from matzah and matzah meal. Ashkenazic favorites are kneidlach (matzahmeal dumplings), matzah brei (fried matzahwith egg and onion), and kremslach (matzah meal fritters), which recall the meal cakes offered as sacrifices in Biblical times. Matzahmeal or potato flour is used instead of flour.
Sephardic dishes are pahthut, a Yemenite soup stew made with matzah meal, and Turkish minas and mahmuras, layers of matzah filled with vegetables, cheese, or meat.
Seven weeks after the second night of Passover, Shavuot connects the Israelites rebirth during the exodus to the redemption of receiving the Torah from God at Mt. Sinai during their wanderings. The 49-day period leading up to the holiday is also the time of the spring growing season and harvest in Israel. Along with staying up all night to study and show our eagerness to learn Torah, the custom is to eat grains, fresh fruit and dairy foods during Shavuot, making it a feast of blintzes and cheesecake.
Dairy foods are served on Shavuot. According to legend, after our ancestors received the Torah on Mt. Sinai, they returned to their tents too hungry to wait for meat to be cooked so they ate previously prepared dairy dishes. Milk, cheese, and honey are the favorite foods of this festival. The sweet dishes made from cheese and honey symbolize the sweetness and richness of the Torah. Popular dishes are blintzes stuffed with cheese, cheese-filled Strudel, beet Borsht served with sour cream, kugel(noodle pudding), and cheese cake. Sephardic Jews serve dishes like shpongous (a cheese-spinach bake), sometimes using salted ewe’s milk.
Few days in history associate such disasters with one people – beginning with the devastating destruction of the first and second Temples in Jerusalem in and exile of the people, to the association with Spain’s edict of expulsion in 1492 and beyond into modern times. A day of fasting and lamentation, it also represents the need for tikkun, repair of our incomplete world. In preparation, some maintain a simple, all-dairy diet for the week preceding the Tisha b’Av.
Goody CM and Drago L (editors) Cultural Food Practices. American Dietetic Association 2010 pages 170 – 184
Shalit N, Shalit R and Sheiner E. The effect of a 25-hr fast during the Day of Atonement on preterm delivery. The J Maternal Fetal Neonatal Med. 2015 Aug ;28(12); 1410-1413
Grajower MM, Zangen D. Expert opinion and clinical experience regarding patients with type 1 diabetes mellitus fasting on Yom Kippur. Pediatric Diabetes 2011;12:473-477
Becker M, Karpatti T, Heymann A. The impact pf the Yom Kippur fast on emergency room visits among people with diabetes. Diabetes Research and Clinical Practice 2013; 99(1): e12-e13
Katz Y, Zangen D, Leibowitz G, Szalatt A. Diabetic patients in the Yom Kippur fast – who can fast and how to treat the fasting patient. Harefuah, 2009 Sep;148(9)586-91, 659, 658 (abstract in Hebrew)
Venegas-Borsellino C, Sonikpreet, Martindale RG. From Religion to Secularism: the Benefits of Fasting. Current Nutrition Reports 2018; 7(3); 131-138 https://doi.org/10.1007/s13668-018-0233-2
Forst, Binyomin (1994). The laws of kashrus: a comprehensive exposition of their underlying concepts and applications. Brooklyn, N.Y: Mesorah Publications. pp. 32–49. ISBN 0-89906-103-6.