A lacto vegetarian (sometimes referred to as a lactarian; from the Latin root lact-, milk) diet is a diet that includes vegetables as well as dairy products such as milk, cheese, yogurt, butter, ghee, cream, and kefir, but excludes eggs. The concept and practice of lacto-vegetarianism among a significant number of people comes from ancient India.
Lacto-vegetarian diets are popular with many followers of the Eastern religious traditions such as Hinduism, Jainism , Buddhism and Sikhism. The cores of their beliefs behind a lacto-vegetarian diet is the law of ahimsa, or non-violence. According to the Vedas, (Hindu holy scriptures), all living beings are equally valued. Also, Hindus believe that one's personality is affected by the kind of food one consumes, and eating flesh is considered bad for one's spiritual/mental well-being. It takes many more vegetables or plants to produce an equal amount of meat, many more lives are destroyed, and in this way more suffering is caused when meat is consumed. In the case of Jainism, the vegetarian standards are even more strict. It allows the consumption of only fruit and leaves that can be taken from plants without causing their death. This further excludes from the diet vegetables like carrots, potatoes, onions and garlic. Although some suffering and pain is inevitably caused to other living beings to satisfy the human need for food, according to ahimsa, every effort should be made to minimize suffering. This is to avoid karmic consequences and show respect for living things. In this sense, wastage of food is considered a sin. Because all living beings are equally valued in these traditions, a vegetarian diet rooted in ahimsa is only one aspect of environmentally conscious living, relating to those beings affected by our need for food. Environmentalism and vegetarianism are often practiced together.
...
Wikipedia
