Many claims have been made for the benefits of the raw food diet. It has been touted as a means of increasing health and longevity, of getting more nutrients from food, even of "increasing the radiance of your vital life force". Cooking, according to raw food advocates, "not only destroys nutrition and enzymes, but chemically changes foods from the substances needed for health into free-radicals and poisons that destroy our health!"
The implications of cooking are apparently so terrifying that it's a wonder the human race has survived for thousands of years of adulterating perfectly good food with fire. According to biological anthropologist Richarg Wrangham, cooking was in fact a crucial factor in our evolution as homo sapiens. In addition to the use of tools, the discovery of fire has long been believed to be the evolutionary starting gun that led to humans becoming the dominant species on Earth.
In his book Catching Fire: How Cooking Make Us Human, Wrangham explains that the application of heat rendered previously indigestible roots and vegetables edible. Time spent masticating was also drastically reduced. While other primates such as chimpanzees spend six hours a day chewing, cooking allowed evolving humans to devote time to other activities. Eating cooked foods changed the shape of the jaw, shrunk the digestive tract and allowed for the development of the brain.
Furthermore, cooking has become an integral part of the human psyche. The idea of transformation implied by cooking has compelled human beings for millenia. In his seminal work The Raw and the Cooked, legendary anthropologist Claude Lévi-Strauss suggested that cooking is inextricably linked with culture. In the mythologies of places as diverse as Ireland and Latin America, cooking is a metaphor for the transition from wilderness to society. In the Old Irish tale Táin Bó Cuailgne, liminal hero Cú Chulainn is sent into a seething frenzy by the sight of naked women. He is plunged into a series of vats, causing the water to boil over. He is symbolically 'cooked' in order to render him fit for society.
In addition to its metaphorical implications, Wrangham contends that cooking is essential to long-term survival. Accounts of people isolated from society, such as castaways and people lost in the wilderness show how essential fire is to health. Virtually every example of people forced to eat a solely raw food diet died, whereas those who managed to make fire had a much greater survival rate. The answer to this riddle comes from caloric intake. Among those who eat a cooked diet, there is no difference between the energy absorbed by vegetarians and meat-eaters.
However, studies have found that an exclusively raw food diet does not provide adequate amounts of vitamins B12 and D, zinc, and calcium. The Giessen Raw Food study, conducted between 1993 and 1994 found that over a quarter of the participants were underweight and women often found that menstruation became infrequent or stopped altogether. Studies also found that people who were overweight or had high blood pressure or elevated cholesterol achieved good results from a raw food diet. Such studies suggest that raw foodism can be a short-term way of achieving balance in one's health. However, the long-term affects of a strict raw food diet can be detrimental to human health.
Proponants of raw food diets have responded to such challenges to their claims. Dr. Douglas N. Graham suggests increasing the number of bites taken per meal in order to increase the elasticity of the stomach and "to gently encourage your digestive system to regain its flexibility". To those of us who don't want to spend the day masticating furiously, this might prove something of a challenge.