Should most or all of the foods we eat be consumed as raw foods?
Chronic health conditions such as heart disease, cancer, stroke and diabetes are among the most frequent causes of death in America and in many other countries, including many developing countries. These health conditions are largely a result of our lifestyle, especially smoking, diet deprived of some micronutrients, phytochemicals and dietary fiber, and physical inactivity. Obesity, especially abdominal obesity is also one of the main contributing factors.
In the last several years, many new diets have been introduced in America, most if not all of which claim to be the solution to one (e.g. obesity), many, or even all of these health problems. Founders of many of these diets sometimes make outrageous claims that should raise a suspicion among potential users. For example, claims to help people lose a lot of weight in a very short period of time (e.g. “lose 10lbs in 48 hours,” or “lose 50lbs quickly, easily, with no dieting”), while still alleging that people don’t really have to make any lifestyle changes, are very prevalent. In spite of all the promises and billions of dollars spent on these diets, in America today about 70% of the people are either overweight or obese, more than 80 million of Americans have at least one type of cardiovascular disease, and close to 60 million either already have or are at risk of developing diabetes.
Although the prevalence of a raw food diet is not known, recently, there has been a growth in the number of people advocating a raw food diet. There is more than one type of raw food diets. Some people eat a vegan raw food diet while others include meats such as sushi. Regardless of the food preferences (inclusion/exclusion of specific foods) proponents of the raw food diet advocate eating somewhere between 70 to 100% of all foods as raw. The main reasons for advocating eating only raw foods include the beliefs that heating foods destroys digestive enzymes found in raw foods and that raw foods have higher nutrients content that cooked/heated foods. “Raw fooders” claim that cooked food is the cause of many diseases such as fatigue, nervousness, gastro-intestinal discomfort, recurrent infections, skin eruptions, hormonal disturbances, headaches, arthritis, sciatica, low back pain, allergies, asthma, eye, ear, nose and throat disorders, cardiac irregularities, pathological changes in the breasts, colon cancer, obesity, etc.
Among those advocating a raw food diet are many Christians, including some members of the Seventh-Day Adventist church. In some SDA churches, raw food dishes are part of their pot lucks. One reason why raw food diets, especially a raw food vegan diet may be appealing to Christians in general and Adventists in particular is the argument that in the Garden of Eden, food was not cooked or otherwise prepared with heat. While this assumption is likely correct, our world does not resemble the Garden of Eden. Furthermore, the biblical record of food and eating after the fall and after the flood does include processing with heat. Even of the “bread of heaven,” the manna, we read “now the manna was like coriander seed, and its color like the color of bdellium. The people went about and gathered it, ground it on millstones or beat it in the mortar, cooked it in pans, and made cakes of it; and its taste was like the taste of pastry prepared with oil.” (Numbers 11, 7-8) Similarly, in the writings of Ellen White, there are many statements regarding cooking including “many, many mothers need to take lessons in cooking …” (MM 270.2), “in all our schools there should be those who are fitted to educate the students, both men and women, in the art of cooking.” (MM 270.4), and “teach the principles of healthful cooking.” (WM 128.1).
Let’s examine the main assumption of the raw food diet advocates. Does heating foods destroy digestive enzymes found in foods and does the heating make nutrients less available? Raw food advocates claim that “heating food above 116 degrees F is believed to destroy enzymes in food that can assist in the digestion and absorption of food. Cooking is also thought to diminish the nutritional value and "life force" of food.” Enzymes, including digestive enzymes and enzymes found in foods are composed of amino acids; they are a specific type of protein. Heating does affect the structure of proteins. Perhaps the best example of such an impact is boiling eggs. Within just a few minutes eggs turn from a liquid to a solid state. This solidifying of eggs is a result of the changes taking place in the egg’s proteins. However, what effect does this heating have on the availability of nutrients and development of diseases? A quote from an article published in a Consumer Reports on Health may help to answer this question. “… cooking weakens the cell walls of vegetables, apparently enabling the body to extract more of the nutrients that remain after cooking. For example, studies have found that cooking triples the bioavailability of various carotenoids … and may also boost the availability of the folate in spinach.” Carrots are good examples of the effect of cooking on nutrients/compounds absorption. Carrots are rich in carotenoids a group of beneficial compounds including beta-carotene which the body uses to make vitamin A. On average, the body will absorb only about five percent of beta-carotene from raw carrots, while as much as forty percent can be absorbed from cooked carrots (as much as about ninety percent or more can be absorbed from raw carrot juice due to the destruction and removal of fiber, this fiber is weakened when carrots and other foods are cooked which enables the body to absorb more nutrients). The antioxidants activity of asparagus presented in the figure below shows that even after cooking some antioxidants activity is higher in cooked vs. raw foods.
The theory regarding the importance of food enzymes is derived from two sources: “The Status of Food Enzymes in Digestion and Metabolism” and “Enzyme Nutrition” by Edward Howell. The theory claims that enzymes found in raw foods significantly enhance digestion of foods and without them the body has to make its own digestive enzymes which over time diminishes the body’s ability to digest food. Since the body has a limited enzyme potential, the theory asserts, destroying foods’ enzymes leads to the exhaustion of body’s enzymes that ultimately is a cause of disease. The problem with this theory is that it is not based on any research and there has not been any validation of it by any credible scientist. Presenting it as scientific fact, something commonly done by the proponents of raw food diet, is incorrect and disingenuous. The burden to prove the validity of any theory should be on those who proposed it. Instead, raw food advocates often charge others to disprove it. Validation and scientific explanation of this theory is warranted because this theory defiles the logic at least for two reasons. If food enzymes are so critical for digestion, why after fruits and vegetables are picked does it take days, weeks or even months for apples, bananas, carrots, and other fruits and vegetables to digest themselves? Also, why would food digestive enzymes work efficiently in a “hostile” environment of the stomach where due to the action of a strong hydrochloric acid secreted by the stomach most proteins (enzymes) are decoiled and denaturated (and thus deactivated)?
Do raw foods have higher nutrients content that cooked/heated foods? The evidence shows that this issue is not as simple as the raw food proponents make it to be. Some nutrients, namely water-soluble vitamins are dissolved in water and may be destroyed by heat. As a result, the amount of these nutrients may be lower in cooked vs. raw foods (although this may not always be the case as one quote below will show), although this will largely depend on the temperature and time of cooking. The same isn’t necessarily the case with other nutrients such as fat-soluble vitamins, many phytochemicals and dietary fiber. A comparison between nutrient content of raw vs. cooked foods included in the table below clearly shows that cooked food have the same or higher mineral content than the same raw foods. The following statement includes additional examples and gives partial explanation of the matter. “… cooking concentrates food into denser, more nutrient-rich servings. A standard half-cup serving of cooked spinach, for example, weighs three times as much as a standard one-cup serving of raw spinach. Even after boiling, the cooked serving contains slightly more vitamin C; two to two and a half times as much fiber, potassium, and folate; and roughly three times as much calcium, iron, magnesium, and vitamin A.”
Like most other diets, raw food diet advocates assert the healing power of this diet from many diseases. They often bring up anecdotal stories as a proof of its effectiveness. It shouldn’t be surprising to see some benefits among people who for years consumed a diet based on a lot of refined foods, one that is micronutrients- and fiber-deprived, while being rich in calories, protein and fat, especially of animal origin. Most people who introduce more raw foods in their diet will likely increase intake of dietary fiber (on average Americans consume less than fifty percent of the recommended amount of dietary fiber) and several micronutrients such as potassium, folate, and vitamin C, while in the same time reducing intake of saturated fat and protein of animal origin. Thus, introducing more raw produce should result in beneficial changes such as reducing serum cholesterol, better blood glucose control, decrease weight, and more regular bowel movement. However, reliable and controlled research studies are needed in order to evaluate the healthfulness of any diet and its effectiveness in prevention and/or treatment of any health conditions.
There are a few studies that evaluated the adequacy and health effect of the raw food diets. These studies showed some health benefits of eating some raw foods (e.g. fruits and vegetables) but also pointed out several problems, mainly a result of inadequate intake of some nutrients and rapid weight loss. For example, one review of medical literature from 1994 to 2003 of the impact of eating raw and cooked vegetables showed that intake of raw vegetables reduced the risk of some cancers such as oral, pharyngeal, laryngeal, esophageal, lung, gastric, and colorectal cancers. Please note, that this review did not actually assessed the impact of any specific raw food diet but rather the impact of eating raw and/or cooked vegetables. The same analyses showed that cooked vegetables had a similar preventive effect (which seems to contradict the assertion that cooked foods are the cause of cancer).
Studies on people consuming a raw food diet showed that both the severity and the length of adherence are associated with some detrimental health conditions. In a study published by the Annals of Nutrition and Metabolism, Keobnick and colleagues showed that adherence to such a diet is associated with severe weight loss among both men and women and either irregular period or amenorrhea (lack of menstruation). In fact, 25% of females and almost 15% of males included in this study had below normal body mass index. The rate of amenorrhea depended on the amount of foods consumed as raw. “Odds of having amenorrhea were 7 times higher for strict raw food dieters (100% raw food) than for moderate raw food dieters (80% raw food).” Based on their findings the researchers concluded that “since many raw food dieters exhibited underweight and amenorrhea, a very strict raw food diet cannot be recommended on a long-term basis.” Like many other vegetarians and vegans, those consuming mostly raw vegan diet are at risk for vitamin B12 deficiency. In one study thirty-eight percent of 201 people who consumed “an extremely high dietary intake of raw vegetables and fruits (70–100% raw food)” had B12 deficiency, which resulted in an increase in total homocysteine level (tHcy). Elevated tHcy is a risk factor for several serious health conditions such as cardiovascular disease, dementia or neural tube defects. Other studies showed an association between consumption of a raw food diet with dental erosion and low bone mineral density.
Moderate amounts of raw foods, especially produce (e.g. salads, fruits, berries), as a part of a plant-based diet will likely contribute to the overall balance diet and may help in reducing many very prevalent diet-related health conditions. However, eating 70 to as much as 100 percent of foods as raw foods may be associated with inadequate intake of some nutrients and may increase risk for some health conditions, especially weight loss and amenorrhea. While many professional organizations, including branches of the government (e.g. Department of Health and Human Services) periodically issue dietary guidelines (e.g. Dietary Guidelines for Americans), to the best of my knowledge, no professional organization ever issued recommendations in terms of percentage of foods that should be consumed raw. A healthy diet should include a variety of foods from different food groups (e.g. grains, fruits, vegetables) that are either raw or cooked (or otherwise processed with heat). Cooking not only will help to increase the variety of foods consumed, it will enhance their palatability. Thus, Adventists who follow raw food diet should consider advice given by Ellen White: “many are debilitated from disease, and need nourishing, well-cooked food.”
*Roman Pawlak, Ph.D RD
Associate Professor of Nutrition
Department of Nutrition and Dietetics,
East Carolina University
Dr. Pawlak authored a book titled „I Am the Lord who heals you”, and he co-authored a book titled „Matka wegetarianka i jej dziecko” (Vegetarian mother and her baby). He teaches undergraduate and graduate nutrition classes including Nutrition and Wellness, Vegetarian Nutrition, Nutrition Science, and Lifecycle Nutrition.