Raw Food Reality Hour

Raw Food Reality Hour

A few months back I addressed the issue of veganism in my blog, and provided a series of snippets and references from my book, suggesting that a long term vegan diet – especially in women and children – can be dangerous. This post generated a fair amount of reaction by vegans, but it also opened up the possibility of a more nuanced, well-reasoned approach to this issue. Today I want to continue this debate, by addressing the issue of raw foodism. The following is taken from my book, Food As Medicine, and is a compilation of my thoughts on this issue:

Today there are an increasingly large number of people claiming that raw food is the best way to eat most or all of your food, informed by the theories of early 20th century advocates such as Edward Howell, Ann Wigmore and Herbert Shelton.  Like veganism raw foodism has become a kind of underground social movement that equates social change with dietary choice.  Broadly speaking raw foodists usually lay claim to one or two camps: those that only eat raw vegetable foods such as raw vegans, fruitarians and sproutarians, and the other that also or exclusively eats raw animal products.

Historically there are very few examples of raw food cultures.  One notable example are the Inuit peoples, an aboriginal group of northern Canada called ‘Eskimo’ (‘eaters of raw meat’) by their southern Cree neighbors.  While it is true that the Inuit do eat some raw fish and meat, the idea that they traditionally ate raw food exclusively is contradicted by ethnographic reports.[i] Besides the Inuit the only other indigenous groups that regularly eat raw meat also live in circumpolar regions, where frigid temperatures prevent against microbial growth and food-borne illness.

Raw foodism maintains several arguments, central of which is the idea that raw food contains vitally important enzymes that aid in digestion, and that by cooking food we destroy them.  Taken at face value this theory seems to have a rational basis, but it doesn’t account for the fact that the body produces far more enzymes in its digestive secretions than are found in the food itself.  If it were true that these enzymes were necessary for digestion it would stand to reason that the body would not need to produce its own enzymes, when in reality the body produces up to five liters (1.3 gallons) of digestive juices on a daily basis.  Like all proteins, enzymes are denatured and digested in the gut into their constituent peptide fragments, rendering them devoid of any significant enzymatic activity.

Raw foodism suggests that raw food has a higher nutrient value than cooked food, but what this fails to take into account is the issue of bioavailability.  While cooking does reduce the nutrient content in some foods, it dramatically enhances nutrient bioavailability, offsetting any loss in nutrients by reducing the energy required for digestion and assimilation. According to anthropologists humans have been cooking food for more than a million years, and in the process have undergone both anatomical and physiological changes that reflect our reliance upon it.[ii] Compared to our primate cousins, humans have a much smaller gut and yet characteristically larger brains (i.e. a higher encephalization quotient).  Research suggests that cooking enhanced the efficiency of nutrient absorption, allowing for the evolution of a much smaller absorptive surface and hence smaller digestive tract, while at the same time boosting the energy intake required for the characteristically larger and more complex human brain.[iii]

Some raw foodists also believe that cooking destroys naturally occurring microbes such as Lactobacilli that support gut health and prevent disease.  Unless the raw food has been fermented to allow these “friendly” bacteria to out-compete other microbes however, raw food may also contain pathogenic bacteria such as Campylobacter, Clostridium, Salmonella and Escherichia coli. Other potential pathogens in raw food include pathogenic viruses (e.g. norovirus, enterovirus, hepatitis A virus), pathogenic fungi (Aspergillus, Fusarium) and parasites (Giardia lamblia, Entamoeba histolytica) that can cause both acute and chronic illness.  In contradistinction to the claim that raw food is healthy, there are an estimated 76 million food-borne illnesses each year in the United States, accounting for 325,000 hospitalizations and 5,000 deaths, all from eating raw or improperly cooked food.[iv] This is not to suggest that raw food is necessarily unhealthy, but that there are certain risks that need to be taken into consideration.

The last of the major arguments put forward by raw foodists is that cooking food results in the formation of toxins including glycotoxins, heterocyclic amines, transfats and nitrosamines.  Here the argument for raw food finds its most strength, but much of this concern relates to specific cooking methods rather than cooking itself.  In some instances raw food does have apparent benefits over cooked food, but these theoretical issues need to be weighed against empiricism and traditional practices.  Although often couched in simplistic terms, the issue of raw versus cooked food isn’t as black and white as many believe.

From a traditional medical perspective raw food can be eaten as part of a healthy diet but always with an eye to the nature of the food and the capacity of digestion.  According to Ayurveda people that have strong digestion (pitta) can usually tolerate raw food on a regular basis, but consuming raw food all the time aggravates the quality of coldness in the body (vata, kapha), diminishing digestive activity and vital energy – a notion supported by anthropological evidence.[v]Although support for a raw food diet is weak in traditional systems such as Ayurveda and Chinese medicine, raw food has special therapeutic application in the treatment of disease and in particular to promote detoxification (p. 216).


[i] Stefansson V. 1913. My life with the Eskimo. New York: MacMillan p. 176-8.  Available online: http://openlibrary.org/books/OL6562100M/My_life_with_the_Eskimo

[ii] Wrangham R, Conklin-Brittain N. 2003. Cooking as a biological trait. Comp Biochem Physiol A Mol Integr Physiol. 136(1):35-46.

[iii] Carmody RN, Wrangham RW. 2009. The energetic significance of cooking. J Hum Evol. 57(4):379-91

[iv] Mead PS, Slutsker L, Dietz V, McCaig LF, Bresee JS, Shapiro C, Griffin PM, Tauxe RV. 1999. Food-related illness and death in the United States. Emerg Infect Dis. 5(5):607-25

[v] Boback SM, Cox CL, Ott BD, Carmody R, Wrangham RW, Secor SM. 2007. Cooking and grinding reduces the cost of meat digestion. Comp Biochem Physiol A Mol Integr Physiol. 148(3):651-6

Busting some myths about raw-food veganism…

Busting some myths about raw-food veganism…

In 15 years of clinical practice I have seen dietary trends rise and fall, but one trend that I have seen steadily increase is raw-food veganism. Too often I see folks like this in my practice, who based on an ethical choice informed more by aesthetics, dogma and inference, have ended up doing real harm to their bodies. So in the interest of public health I am out to bust some myths around raw food veganism, in favor of an awareness that is more informed and nuanced. Quotes and research pulled from my new book, Food As Medicine.

Humans evolved eating raw food.

“Compared to our primate cousins, humans have a much smaller gut and yet characteristically larger brains (i.e. a higher encephalization quotient). Research suggests that cooking enhanced the efficiency of nutrient absorption, allowing for the evolution of a much smaller absorptive surface and hence smaller digestive tract, while at the same time boosting the energy intake required for the characteristically larger and more complex human brain.” p. 108

Carmody RN, Wrangham RW. 2009. The energetic significance of cooking. J Hum Evol. 57(4):379-91

Humans evolved as vegetarians.

“Researchers at the University of Colorado suggest that whenever possible our early ancestors preferred animal foods as their primary source of nutrition, comprising between 45-65% of their total energy intake, supplementing the remaining percentage with plant foods.” p. 93

Cordain L, Miller JB, Eaton SB, Mann N, Holt SHA, Speth JD. 2000. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Am J Clin Nutr. 71:682–92

Raw foods contains enzymes necessary for digestion.

“If it were true that these enzymes were necessary for digestion it would stand to reason that the body would not need to produce its own enzymes, when in reality the body produces up to five liters (1.3 gallons) of digestive juices on a daily basis. Like all proteins, enzymes are denatured and digested in the gut into their constituent peptide fragments, rendering them devoid of any significant enzymatic activity.” p 107

Raw food has a higher nutrient content than cooked food.

“While cooking does reduce the nutrient content in some foods, it dramatically enhances nutrient bioavailability, offsetting any loss in nutrients by reducing the energy required for digestion and assimilation. According to anthropologists humans have been cooking food for more than a million years, and in the process have undergone both anatomical and physiological changes that reflect our reliance upon it.” p. 108

Wrangham R, Conklin-Brittain N. 2003. Cooking as a biological trait. Comp Biochem Physiol A Mol Integr Physiol. 136(1):35-46.

Cooking destroys the healthy bacteria such as Lactobacilli.

“Unless the raw food has been fermented to allow these ‘friendly’ bacteria to out-compete other microbes however, raw food may also contain pathogenic bacteria such as Campylobacter, Clostridium, Salmonella and Escherichia coli. Other potential pathogens in raw food include pathogenic viruses (e.g. norovirus, enterovirus, hepatitis A virus), pathogenic fungi (Aspergillus, Fusarium) and parasites (Giardia lamblia, Entamoeba histolytica) that can cause both acute and chronic illness. In contradistinction to the claim that raw food is healthy, there are an estimated 76 million food-borne illnesses each year in the United States, accounting for 325,000 hospitalizations and 5,000 deaths, all from eating raw or improperly cooked food.” p. 108

Mead PS, Slutsker L, Dietz V, McCaig LF, Bresee JS, Shapiro C, Griffin PM, Tauxe RV. 1999. Food-related illness and death in the United States. Emerg Infect Dis. 5(5):607-25

The vegan diet is higher in nutrients than non-vegetarian foods.

“While it is very true that a vegan diet is abundant in healthy foods such as vegetables and fruits, without rigorous supplementation it is also deficient in key nutrients including protein, omega-3 fats, cholesterol, iron, calcium, iodine, vitamin D3 and vitamin B-12. Among proteins, the vegan diet is deficient in important amino acids such as carnosine, a dipeptide found in muscle tissue that has been shown to suppress many of the biochemical changes that accompany aging, diabetes and neurodegenerative disorders.” p. 106

Li D. 2011. Chemistry behind Vegetarianism. J Agric Food Chem. [Epub ahead of print]
Craig WJ. 2009. Health effects of vegan diets. Am J Clin Nutr. 89(5):1627S-1633S.
Hipkiss AR. 2006. Would carnosine or a carnivorous diet help suppress aging and associated pathologies? Ann N Y Acad Sci. 1067:369-74

Science has proven that the raw vegan diet is healthier.

“Research backs up the assertion that a long-term vegan diet impairs health, promoting weight loss, premenstrual syndrome and infertility, impaired bone density, bone fracture, dental problems, and immunodeficiency. A vegan diet is especially problematic and even dangerous in pregnant or lactating mothers as well as young children, increasing the risk of anemia, neurological disorders and developmental delay.” p. 106

Koebnick C, Strassner C, Hoffmann I, Leitzmann C. 1999. Consequences of a Long-Term Raw Food Diet on Body Weight and Menstruation: Results of a Questionnaire Survey. Annals of Nutrition & Metabolism. 43:69-79
Ambroszkiewicz J, Klemarczyk W, Gajewska J, Chelchowska M, Franek E, Laskowska-Klita T. 2010. The influence of vegan diet on bone mineral density and biochemical bone turnover markers. Pediatr Endocrinol Diabetes Metab. 16(3):201-204
Krivosíková Z, Krajcovicová-Kudlácková M, Spustová V, Stefíková K, Valachovicová M, Blazícek P, Nemcová T. 2010. The association between high plasma homocysteine levels and lower bone mineral density in Slovak women: the impact of vegetarian diet. Eur J Nutr. 49(3):147-53
Appleby P, Roddam A, Allen N, Key T. 2007. Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. Eur J Clin Nutr. 61(12):1400-6
Laffranchi L, Zotti F, Bonetti S, Dalessandri D, Fontana P. 2010. Oral implications of the vegan diet: observational study. Minerva Stomatol. 59(11-12):583-91
Labay y Matías MV, Matamoros Florí N, Aguiló Regla A, Tomás Cardús L, Galiana Ferré C, Gómez Rivas B, Reynes Muntaner J. 1984. Strict vegetarian diet, malnutrition, immunodeficiency and infection. An Esp Pediatr. 20(1):69-71
Baatenburg de Jong R, Bekhof J, Roorda R, Zwart P. 2005. Severe nutritional vitamin deficiency in a breast-fed infant of a vegan mother. Eur J Pediatr. 164(4):259-60
Mariani A, Chalies S, Jeziorski E, Ludwig C, Lalande M, Rodière M. 2009. Consequences of exclusive breast-feeding in vegan mother newborn: case report Arch Pediatr. 16(11):1461-3

Still want to be a vegetarian?

Learn from the Indians, who have been doing it for thousands of years. While my recommendations with regard to diet are purely pragmatic, I understand why some people still want to be a vegetarian. “Although vegetarianism has become increasingly mainstream in the West I am consistently surprised how few have researched the components of an Indian vegetarian diet, which would otherwise seem to be a pre-requisite. Apart from a diet necessarily rich in grains, pulses, nuts and seeds to supply the proteins and fats that are otherwise missing from a meat-free diet, the hallmark of Indian vegetarianism is the regular consumption milk and milk products. The importance of consuming dairy is clearly seen in the Hindu’s veneration of the cow, which serves not only as an allegory of spiritual love, but provides a source of nutrients that are otherwise difficult to get in a vegetable based diet. Employing a variety of dairy-based foods including boiled milk (p. 173), yogurt (p. 174), panir and ghee (p. 194) not only provides for a density of fats and proteins unmatched by any vegetable-based food, it also provides vital nutrients such as essential fatty acids, calcium, potassium, magnesium and cholesterol that are difficult to get from a strict vegetable-based diet. Beyond the ubiquitous presence of dairy the other feature commonly found in Indian cuisine is the diverse abundance of herbs and spices that not only enhance digestion to increase nutrient bioavailability, but contributes essential minerals and antioxidants that support health. My recommendation for all who want to become vegetarian is to learn to cook Indian food, and the different ways to prepare dairy products, legumes and grains, and how to use herbs and spices. It doesn’t mean that Indian food needs to be eaten exclusively, but that the strategies used to prepare and enhance the food are employed in a similar manner.” p. 104

Weaver CM. 2009. Should dairy be recommended as part of a healthy vegetarian diet? Point. Am J Clin Nutr. 89(5):1634S-1637S Tapsell LC, Hemphill I, Cobiac L, Patch CS, Sullivan DR, Fenech M, Roodenrys S, Keogh JB, Clifton PM, Williams PG, Fazio VA, Inge KE. 2006. Health benefits of herbs and spices: the past, the present, the future. Med J Aust. 185(4 Suppl):S4-24.

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