Keeping kosher—adhering to Jewish dietary laws—is not as simple as you might think. Follow along to learn all about this ancient practice and how to keep kosher in the modern world.
What Is Kosher? Here Are the Rules of Kosher Cooking
Updated on Feb. 28, 2025
Kosher food is food that follows a complex set of ancient Jewish dietary laws. The rules of keeping kosher—known as kashrut—involve what you eat, how you eat it, how it was prepared, how the food was grown and how the animals were raised.
Truly following kosher guidelines requires rigorous adherence and, in the case of restaurants and commercial kitchens, the careful watch of a religious supervisor to make sure all rules and spiritual laws are followed. We’ll talk about what is kosher, what makes food kosher and what it means to keep a kosher kitchen.
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What does kosher mean?
The word kosher means “fit,” as in “fit to eat,” and it refers to the set of Jewish dietary laws regarding cooking, eating and preparing food. Adhering to these laws is known as keeping kosher, meaning you follow a strict set of rules about what you eat, and where and how the food is prepared.
Some of the major rules of kashrut are well known, like not mixing milk and meat. But when it comes to other rules, especially about meat, they can get very intricate. It isn’t just about which animals are kosher, but how they’re prepared. From the slaughterhouse to the kitchen, strict rules of preparation must be followed to ensure food remains kosher. And since meat and dairy products must never be combined or even touched by the same utensil, there are many different rules to adhere to to keep a kosher kitchen.
Like any religious laws, people’s adherence to keeping kosher can vary greatly. Some Jewish people keep kosher only inside their home, but will eat out at restaurants that are not kosher, and some people don’t keep kosher at all. Other sects of Judaism adhere as strictly as possible to kosher law and would never eat at a restaurant without a kosher certification, or even in a home kitchen that isn’t completely kosher.
What foods are kosher?
When it comes to what makes food kosher, the answer can be quite long. The easiest rule of kosher law is that all vegetables are kosher—as long as they’re washed properly so there are no bugs in them. Meat is much more complicated since some animals are off limits entirely, whereas others have parts that are kosher so long as the animals are raised and butchered a certain way.
Animals with split hooves—cows, sheep and goats—are kosher if they’re prepared and raised in the proper way. With beef, the forequarters of the cow are kosher, which includes cuts of beef like chuck, rib, brisket and plate. Kosher cuts of lamb include the rack, shoulder, shank and chops. Chicken, duck, goose and turkey are other popular kosher options. For fish, stick to fish with fins and scales if you want to adhere to kosher rules.
Nearly any cuisine can be made kosher. Kosher foods don’t have to be Jewish, just like Jewish food—like matzo ball soup, brisket, bagels and lox—doesn’t have to be kosher. Pretty much any style or type of cuisine can be made kosher with the proper ingredients and kitchen setup.
There’s another level of kashrut that’s known as kosher-style cooking, which you can think of as “kosher-ish.” Kosher-style cooking can include any dish that celebrates Jewish culture or that you might associate with Jewish cuisine, but which may not follow traditional kosher rules.
What foods are not kosher?
Some foods are never kosher, like pork, rabbit, shellfish or fish without both fins and scales, as well as birds of prey. There are also food combinations that aren’t kosher, like meat and dairy, which can never be served together. Kosher law also includes any ingredients derived from animals that aren’t considered kosher, such as gelatin. That’s right, no Jell-O unless it’s specifically kosher and made without gelatin.
Kosher Food Symbols
When buying kosher snacks or other prepared foods, look for a kosher symbol on the label. There are several kosher symbols, but “K” and “OU” are the two main symbols that people tend to look for, as well as Star-K which is a star with a “K” inside. Markings will also indicate if a food is pareve, which means it does not contain meat or dairy. These symbols, known as hechshers, are given out by kosher certifying rabbis.
Other hechshers include (but aren’t limited to) “M” or “Glatt” for products containing meat; “F” for products containing fish; “D” or “DE” for products containing dairy or made in a dairy area; and “P” for food suitable to consume during Passover. Sometimes you’ll see “kosher for Passover” spelled out on a package.
How do you keep a kosher kitchen?
A lot of keeping a kosher kitchen has to do with how the kitchen is organized, assuring that meat and dairy don’t come into contact and that the dishes, utensils and cookware are kept separate as well.
Everything must be stored in separate designated cabinets, and it’s helpful to label your cookware or use designated color themes to help separate the two. Preparation of meat and dairy dishes should happen on different countertop spaces, and open containers of meat and dairy products should be stored on separate shelves in the fridge or freezer. When cleaning dishes, people will have separate sinks for meat and dairy kitchenware, and won’t load meat and dairy dishes in the dishwasher at the same time. They’ll even use separate tablecloths, napkins and place settings for meat and dairy meals.
Since adherence to kosher law varies by branches of Judaism, as well as by individuals’ personal observances, there’s a wide range in how strictly people follow the many rules.
Who keeps kosher?
As with every religion, there are those who follow the text literally, those who loosely follow it and those who don’t follow it at all.
Orthodox Jews are more strictly observant, while Conservative and Reform Jews interpret the laws in different ways and have different levels of observance.
Is kosher for Passover different?
During the holiday of Passover, an additional set of kosher rules apply, which are primarily to avoid any leavened foods. Matzo is eaten during Passover because it’s unleavened bread.
Additionally, to be kosher for Passover, store-bought food must be certified as “kosher for Passover,” and food that is not kosher for Passover must be kept separate from food that is.
There’s a lot to keep in mind if you’re keeping kosher for Passover or hosting a Passover Seder, from understanding the rules and rituals to making the best Passover recipes and stocking up on Kosher wines.
