Dr. Joel Fuhrman, M.D. is a family physician and internationally recognized expert on nutrition and natural health and healing. Dr. Fuhrman believes eating an all-raw diet is "disadvantageous" although he does say eating plenty of raw vegetables is a good anti-cancer practice. Caloric needs cannot be met on only raw vegetables. He says a vegan diet causes health problems such as muscular wasting.
The common belief is that important nutrients are lost in the cooking process. This is only the case with certain types of cooking methods. Overcooking and cooking with high temperatures (baking) can destroy some nutrients. Frying and barbecuing can also destroy nutrients. Dr. Fuhrman says,
"When we heat, soften and moisturize the vegetables and beans we dramatically increase the potential digestibility and absorption of many beneficial and nutritious compounds. In many cases, cooking actually destroys some of the harmful anti-nutrients that bind minerals in the gut and interfere with the utilization of nutrients."
He recommends steaming and boiling because it is done at a lower temperature, food does not brown which is what causes toxic compounds, and most importantly, we eat the liquid portion when food is prepared this way.
A raw food diet study published in the British Journal of Nutrition (2013) found that people eating only raw foods had normal levels of vitamin A, high levels of antioxodant beta-carotene and high levels of antioxidant lycopene, an anti-cancer agent. Lycopene also prevents heart disease and is more potent than vitamin C.
Lycopene can be found in tomatoes, watermelons and red bell peppers among others. Rui Hai Liu, professor of food at Cornell University, notes that cooking tomatoes boost lycopene by breaking down the cell wall. Liu recommends boiling carrots, spinach, mushrooms, cabbage and peppers. Some vitamin C is lost but vitamin C is consumed more readily in other foods whereas lycopene is not.
Broccoli, that has been shown to reduce the risk of stomach cancer, is more nutritious raw. However, broccoli, cabbage and cauliflower create an organic compound called indole when cooked. Indole kills precancerous cells before the become cancerous.
Kale is also an antioxidant. Vitamin C and beta-carotene levels become lower when kale is cooked.
Once a month raw food enthusiast meet in Lorena, Texas at a gathering called the Lorena Raw Food and Drum Circle. Their next meeting is August 2, 2014.
Sikora. Composition and antioxidant activity of kale raw and cooked. (2012) Acta Polornarum Technologia Alimentaria.