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.
Shellfish Association of Great Britain
Shellfish are excellent sources of protein; a 100 gram serving of shellfish provides about 10-25 grams of protein, roughly a third to half of the average UK recommended protein intake. The protein in shellfish is of high quality, containing many essential amino acids and, because of a lack of connective tissue, very digestible for people of all ages. Shellfish are also generally lower in fat, less than 5%, and accordingly contain fewer calories than beef, poultry or pork. For example, a 100g portion of prawns (a typical prawn cocktail amount) contains only 0.2g of saturated fat and 76 calories, whilst 100g of beef mince contains 6.9g and 225 calories.