A number of religions have dietary guidelines which might be observed more or less closely. Different denominations within the same religion may have slight differences in food guidelines.
Meats should be slaughtered under Halal guidance; pork is not allowed. Generally, foods that are kosher are also accepted under Halal. The major exception is alcohol, which is banned under Halal. For strict observers, this may mean not eating foods cooked with vanilla extract. There are numerous guidelines for fasting, particularly during Ramadan.
This extremely complex set of guidelines includes restrictions on how meat is slaughtered, which animals/birds/seafood may be eaten (most famously pork and shellfish are not allowed), the part of the animal that can be eaten, who makes certain foods, combinations of foods, avoiding contamination, what can be eaten on religious holidays, and more. Many non-Jewish people prefer foods labeled kosher because they believe them to be cleaner / more strictly prepared.
A lactovegetarian diet is followed by many Hindus – no meat, poultry or fish, no eggs, but milk products are allowed and encouraged. Beef is prohibited, as the cow is considered sacred. Brahmins may have restrictions on who prepares their food and how it is stored. There are many fasting days and periods in the calendar, with restrictions such as eating only plant foods.
There are no set prescriptions for food restrictions in Buddhism. Under the concept of ahisma / doing no harm, a lacto-vegetarian diet is followed by many Buddhists. Buddhist monks have additional restrictions such as fasting and not eating solid foods after noon.
Devout Catholics fast on holy days and periods.
Practicing orthodox Christians follow a number of fasts. Weekly fasts include abstention from meat, fish, eggs, dairy, and sometimes other foods such as olive oil and alcohol as well. Other fasts are longer and exclude some or all of the foods avoided in the weekly fasts.
Seventh-Day Adventists are lacto-ovo-vegetarian – they avoid meat, poultry and fish but eat eggs and milk products. Alcohol is also prohibited.
Jainism prescribes to ahisma, or nonviolence, following scrupulous rules for the protection of all life forms. Strict Jains don’t eat meat, poultry, fish, or eggs, and sometimes milk; they may avoid eating root vegetables as the whole plant is killed when the root is dug up. There are a number of religious practices involving fasting, particularly for women.