Vegetarian nutrition
Some important nutrients (amino acids, fats, vitamins A, D, K and E) are present in good quantities in meat, but with minimal attention a vegetarian diet with plenty of all of these can be designed. The American Dietetic Association states: "Plant sources of protein alone can provide adequate amounts of essential amino acids if a variety of plant foods are consumed and energy needs are met."
It is more common to find instances of scurvy and other consequences of vitamin C deficiency in people who subsist purely on a diet of fast food. However, it is important for vegetarians and vegans to be conscious of their intake of protein, B12, and other nutrients. Like any diet, one that eschews animal products needs to be balanced and include a variety of foods.
No diet is necessarily unnatural. Human beings have been omnivores since time immemorial; we have the teeth (incisors and molars) and the digestive systems of creatures who eat both meat and plants. The eating of meat enabled energy. Nearly all the other higher primates are omnivores, except the gorilla. In the past, many people ate meat infrequently, because often it wasn't available or affordable. Strict vegetarianism is something comparatively new in human history.
There is a risk that Vitamin B12 deficiency can result from veganism. While just about all animal based foods contain useful quantities of B12, no readily available plant based source does (except the not universally available Indonesian fermented soy product tempeh). However, a range of foods have the vitamin added, including breakfast cereals, soft drinks, soy milk, Marmite, Vegemite and others. B12 supplements such as vitamin pills are often prepared from abattoir waste and are thus unsuitable for vegetarians, although there are an increasing number of brands that contain no animal products. B12 is stored in the body for many months, so B12 deficiency symptoms do not appear immediately on embarking on a pure vegan diet, but can eventually be severe. However this deficiency is rarely seen in Western vegans, since the problem is well-known.
One issue raised by choosing vegetarianism to avoid the suffering of animals is that agricultural cultivation of plant foods also harms animals. Run-off from fields harms aquatic life by polluting waterways with sediments, nutrients, and chemicals. Automatic farm machines kill small animals unintentionally, while cutting down trees takes away habitat for other animals. Pesticides kill beneficial and harmful insects alike. However, it should be noted that vegetarian diets require less agricultural resources than meat based diets. Thus, in populations where most of the meat consumed does not come from grazing animals a vegetarian diet will in fact reduce the suffering caused by agriculture because less plants overall will be necessary to sustain the diet.
Vegetarians (except fructarians) also kill plants in order to survive. Even though a vegetarian might contend that plants do not have the same sensory mechanisms to feel pain, some people feel that it is a worthwhile philosophical question. Even if plants are sentient, however, a vegetarian could argue that it is acceptable to consume the plant because otherwise the vegetarian would not be able to survive. This argument is similar to the argument that it is acceptable to kill animals if it is necessary for survival (for example, barring modern importation of foods, the Inuit live in a climate where consuming fish is necessary in order to get enough calories to survive). Also, vegetarians point out that eating animals uses a lot more plants than eating plants does, as animals are very inefficient at converting plants into flesh.
Related beliefs
While vegetarianism is commonly defined strictly on the basis of dietary intake, many religiously, ethically or environmentally motivated vegetarians (in common with animal rights and Green movements) try to minimise the harm done to animals in all aspects of their lives.
Many religiously motivated vegetarians consider the avoidance of skin contact with products made from body parts (e.g., leather, tallow soap) an integral part of their definition of vegetarianism. Others consider leather made from the skin of animals who died of natural causes acceptable. While for many Hindus it is impractical, there are those who shy away completely from the use of leather articles made from cowhide. Some state and cities in India have even banned cow-slaughter in places of pilgrimage or whole regions based on the sentiments of some Hindus.
Many health-motivated vegetarians are also associated with the organic food movement and/or are concerned about the use of genetically modified organisms in food production.
See also
Vegetarian cuisine – List of notable vegetarians – Wikipedians/Vegetarians – People for the Ethical Treatment of Animals – List of diets – veganism – Macrobiotic diet – virtual water – imitation meat – in vitro meat – Animal rights – flexitarian