Kashrut
Among the numerous laws that form "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.
Eastern Orthodox Church
In general, fasting means abstaining from meat and meat products, dairy (eggs and cheese) and dairy products, fish, olive oil, and wine. Wine and oil—and, less frequently, fish—are allowed on certain feast days when they happen to fall on a day of fasting; but animal products and dairy are forbidden on fast days, with the exception of "Cheese Fare" week which precedes Great Lent, during which dairy products are allowed. Wine and oil are usually also allowed on Saturdays and Sundays during periods of fast. In some Orthodox traditions, caviar is permitted on Lazarus Saturday, the Saturday before Palm Sunday, although the day is otherwise a fast day. Married couples also abstain from sexual activity on fast days so that they may devote themselves fulsomely to prayer ().