What Makes Food Kosher?

Medically Reviewed by Jabeen Begum, MD on October 13, 2023
7 min read

Kosher food is any food or beverage that Jewish dietary laws allow a person to eat. It isn’t a style of cooking. Keeping kosher is much more complex than that. Rules are the foundation of kosher food.

Rooted in history and religion, each law is specific about what types of food you can and can't eat. The laws are also strict about the way you process, prepare, and inspect food if you're going to call it kosher.

Keeping kosher is a commitment. It governs what you eat and the way you prepare your meals, as well as the way you use your kitchen and dishes every day. But not all Jewish people keep kosher, and kosher foods aren't just for Jewish people. You probably have kosher foods in your pantry right now.

What does kosher mean?

Kosher is a Hebrew word that means "fit," and when applied to food, it shows that it's OK for someone who follows kosher laws to eat.

Scholars believe that Jewish dietary laws may be the first food laws on record. The general principles of keeping kosher are in the Torah, the first five books of the Hebrew Bible. It has commandments -- called mitzvahs -- to follow as ways to obey God. Keeping kosher is one of them.

Kashrut is the body of Jewish law dealing with kosher foods. The laws haven't changed from what the Torah commanded, but they've grown over the years to keep up with technology.

There are a lot of details, but these are the basics: 

  • You can't eat certain animals at all, including organs, eggs, and milk of the forbidden animals.
  • Birds and mammals must be killed according to Jewish law.
  • All blood must be drained from meat and poultry before it's eaten.
  • You can't eat certain parts of animals at all.
  • You must inspect fruits and vegetables for bugs before you eat them.
  • You can't eat meat and dairy together. You can eat fish, eggs, fruits, vegetables, and grains with either meat or dairy. 
  • Utensils that touch meat can't touch dairy (and vice versa). 
  • Utensils and cooking surfaces that touch hot, non-kosher food can't touch kosher food.
  • You can't eat any grape products made by anybody who isn't Jewish.

It starts out simple. Kosher foods fall into three categories: meat, dairy, and "pareve," sometimes spelled "parve." Fish and poultry are sometimes included in pareve.

Meat. The Torah says kosher meat can only come from animals that have split hooves and chew their cud, like cows, sheep, and goats. When these animals eat, partially digested food (cud) returns from the stomach for them to chew again. Pigs, for example, have split hooves, but they don’t chew their cud, so pork isn’t kosher.

Kashrut law also governs the method of slaughter and processing, and the slaughterhouse equipment. Meat isn’t kosher if the animal dies naturally. Certain parts of an animal, including types of fat, nerves, and all of the blood, are never kosher.

Dairy. All dairy products, like milk, butter, yogurt, and cheese, must come from a kosher animal. All ingredients and equipment used to produce it have to be kosher, too.

Pareve. This is the category for kosher foods that aren't meat or dairy. It covers everything from eggs and fish to fruits, vegetables, pasta, coffee, and packaged foods.

There are multiple layers of laws beneath these three. Here are just a few:

  • You can't eat milk and meat products at the same time, put them on the same dishes, or prepare or eat them with the same utensils. You also have to wait a certain amount of time to eat milk after meat and vice versa.
  • Not all cheeses are kosher. That's because many are made with an enzyme called rennet that comes from the stomachs of cows. Kosher cheese can't have animal-based rennet.

Poultry. The Torah lists 24 non-kosher bird species. Examples of kosher birds are chickens, ducks, geese, turkeys, and pigeons.

Fish and seafood. The Torah says fish is kosher if it has both fins and scales, like salmon, bass, or trout. Sea creatures that don't have fins and scales aren't kosher. This includes shellfish, crabs, shrimp, and lobster.

Plant-based kosher foods (pareve)

Bread and grains. Grains used to bake bread are kosher, but bread is only kosher if it’s certified kosher. This is to make sure the baking process didn’t add non-kosher ingredients and the equipment wasn’t greased with fats or oils from animals. 

Fruits and vegetables. Fresh produce is pareve, but you have to check it for insects before eating because they aren’t kosher. If you find any, you can wash them off. Canned or frozen produce isn’t kosher if it was processed using non-kosher equipment or ingredients. 

Nuts, seeds, and oils. Nuts and seeds are kosher in their natural form. But if they’ve been processed, they have to be certified kosher. Oils have to come from ingredients that were kosher in the first place, then be certified kosher to ensure they didn’t come in contact with non-kosher ingredients when they were processed.

Wine. In order to be kosher, wine must be prepared under strict rules and certified by an Orthodox rabbi.

Forbidden foods

Extra restrictions apply during the Jewish holiday of Passover. Besides all the other kosher guidelines, you aren't allowed to eat anything with grain that has risen or fermented. These forbidden foods are called "chametz."

  • Foods that aren’t kosher for Passover include breads, pastas, beers, liquors, and more.
  • The only grain product that may be kosher for Passover is matzah, and it must be certified.
  • Processed foods, including matzah, must have a label saying they are kosher for Passover. Look for a "P" next to the seal that certifies it’s kosher.
  • Kosher meat, fish, and chicken and fresh produce are kosher for Passover as long as they didn’t come into contact with chametz.
  • Observant Jewish people scour their kitchens, dishes, pots, pans, and utensils to make sure they have no trace of chametz. 

For meat to be considered kosher, it has to be prepared according to the Jewish standards known as shechita. The animal has to be slaughtered in a way that's painless, by someone's who's been specially trained and certified by a rabbi. All blood must be removed.

To keep a kosher kitchen, you also have to make your food according to Jewish dietary laws. Some of those laws include:

  • You have to keep and store meat and dairy separately.
  • You have to use only kosher ingredients.
  • You must clean any evidence of non-kosher ingredients from your kitchen surfaces and utensils before you can use them.

Any product considered kosher will have one of several kosher certifications on the packaging:

  • A "K" means kosher certified. If the "K" is in a circle, it means the company OK Kosher Certification approved the product as kosher.
  • When there's a "D" after the "K," it means the product has dairy, or that processing equipment that handles this food also handles dairy. The rules for dairy products apply when you eat that item. For example, you can't eat it with meat.
  • The word "pareve" or "parve" after the kosher symbol means it's neutral -- not dairy or meat, but still kosher. A "U" in a circle means the same thing.
  • A "P" means the product is kosher for the Jewish holiday Passover, which has its own dietary laws.

Most Jewish people who keep kosher do so because the Torah says to, not for health reasons. But kosher symbols on products mean that each ingredient, even food additives, meets strict regulations. Keeping kosher is especially helpful if you have allergies to certain foods like dairy products.

You might also appreciate kosher food labels if you are vegetarian or vegan. Kosher food packaging must note when the food shared equipment with meat or dairy.

There are challenges to keeping kosher, too, though. You might not always find kosher food everywhere, like on a long road trip. 

Keeping kosher also can be costly. You can expect to pay higher prices for kosher meat and poultry than you would for other meats because of things like the strict processing requirements.

There's a kosher version of almost every food and drink in the world. Almost half of all foods you find in a package are kosher. 

Many supermarkets have kosher food sections, and some major cities have stores that sell kosher products exclusively.

Salt is a mineral, so pure salt (not iodized) is always kosher. Look for the kosher symbol on the package to be sure.

The term "kosher salt" comes from the process of preparing meat according to Jewish law. An animal's blood isn't kosher, so any that remains after the slaughtering process is removed by soaking and salting the meat. It's known as koshering meat, or melichah ("salting") and is typically done today by a qualified butcher. Coarse-grained salt works best, and came to be known as kosher salt. 

Kosher food is any food or drink that someone following Jewish dietary laws can have. Keeping kosher is not a style of cooking. The strict laws come from the Torah and spell out what foods you can and can't eat, how they have to be prepared, and how animals have to be slaughtered to be considered kosher.

Why can't Jews mix meat and dairy?

In three passages, the Torah says not to "boil a kid in its mother's milk" -- kid being a baby goat. That's been interpreted as a rule against eating meat and dairy together.

Are kosher foods only for Jewish people? 

No. Anybody can eat kosher foods, and a lot of foods fit that category naturally. But only a Jewish person following dietary laws in the Torah can be considered to be "keeping kosher."