Raw Food Diet

Bircher-Benner and the Zurich sanatorium

A history published by swissinfo describes the Swiss physician Maximilian Bircher-Benner, who died on 24 January 1939, as running nutrition experiments with raw vegetables on himself, his family and selected patients between 1895 and 1900. His sanatorium, called Lebendige Kraft (Vital Force), opened in 1904 on the Zurichberg, a hill above Zurich, and was renamed the Bircher-Benner Clinic in 1939.

The same account says his approach combined raw vegetables, including an apple-based muesli, with a strict daily routine that included exercise before breakfast, and that the original muesli was built on raw apple rather than cereal. It reports that a niece ran the clinic from 1947 until 1980 and that it closed and was sold in 1995. The source does not describe how the wider medical profession received his ideas.

Ann Wigmore and living foods

The Gale Encyclopedia of Alternative Medicine entry on the Wigmore diet states that the regimen was developed in the 1960s by Ann Wigmore, born in Eastern Europe in 1909, who emigrated to the United States after World War I. It reports that she founded the Hippocrates Health Institute in Boston in 1963, that branches later opened in southern California and Florida, and that she died in a fire in 1993. The entry describes the diet as mostly vegetarian and uncooked, built around wheatgrass juice and sprouts.

An organization that carries her name gives its own account: it states that she was born in Lithuania in 1909, that she was diagnosed with colon cancer at about age 50 and credits her recovery to a raw, living-foods diet, that she founded the Hippocrates Health Institute in Boston in 1963, and that it opened a center in Puerto Rico in 1990. This is the organization's account. The sources reviewed contain no independent confirmation of the illness or recovery.

Later growth of the movement

The sources reviewed do not trace the spread of raw food eating in the 1990s and 2000s. Research papers from the Institute of Nutritional Science at the University of Giessen in Germany, published between 1999 and 2009, show that groups of long-term raw food adherents existed in Germany by the 1990s and were recruited for cross-sectional studies.

Names used in sources

Sources reviewed use several terms. Research papers speak of a raw food diet, a strict raw food diet and a raw vegetarian diet, and one describes raw food diets as predominantly plant-based diets practiced with the intention of preventing chronic disease. The Gale entry uses the terms live foods and living foods for the Wigmore regimen, and the Wigmore organization uses living-foods diet.

How raw is defined

Definitions of how much of the diet is raw differ by study. A German questionnaire survey grouped participants from 70 percent to 100 percent raw food, a later study examined adherents eating 70 to 100 percent raw food, and a dental study required more than 95 percent raw food. The Gale entry describes four food groups, living, raw, whole cooked and processed, and says followers use food-combining rules.

Because the proportion of raw food varies between studies and between people, findings from one group of adherents cannot be assumed to apply to every person who eats some raw foods. The related Machipedia pages Vegan Diet and Plant-Based Diet cover broader patterns that exclude animal products but do not require raw food.

What the diet involves in general terms

In the studies reviewed, adherents ate predominantly uncooked plant foods. One cross-sectional study of 198 strict adherents reported that on average 95 percent by weight of intake was raw, mainly fruit, and a dental study of adherents reported that fruit made up the largest share of intake, with frequent citrus consumption. Another study described intake as mainly vegetables or fruits, with the lowest consumption of animal-origin foods linked to higher homocysteine levels.

Wigmore program features

The Gale entry describes the Wigmore regimen as built around wheatgrass juice and sprouts, with filtered or distilled water, supportive habits such as light exercise and daily dry skin brushing, and a rule of avoiding medications and chemicals. It states that no special training or certification is needed to follow the diet.

Training and professional bodies

The sources reviewed identify no certification, registry or training standard specific to raw food diets. Dietetics is a regulated profession in many places, and the Machipedia page Dietetics covers how dietitians are trained. The related page Nutritional Therapy covers a separate practitioner group, and Dietary Approaches lists the wider family of diets this page belongs to.

What proponents describe

The Gale entry lists claims made for the Wigmore diet: that it detoxifies and rebuilds the body, increases vitality, strengthens the immune system, and helps arthritis, digestive problems, allergies and cancer. It states that allopathic physicians are skeptical and that it cites clinical cases and testimonials but names no controlled studies supporting the benefits.

A Giessen research paper states that raw food diets are practiced with the intention of preventing chronic diseases because of their high content of beneficial nutritive substances such as carotenoids. A history of the Zurich sanatorium describes Bircher-Benner as convinced of the healing powers of fruit and vegetables, so the aims range from general disease prevention to treatment claims.

Claims versus tested outcomes

The treatment claims above are statements by proponents. The studies reviewed on this page measured nutrient status, body weight, bone and teeth in people already following the diet, and did not test whether the diet changes the course of arthritis, allergy, cancer or other conditions.

Body weight, menstruation and vitamin B12

A cross-sectional questionnaire survey of 216 men and 297 women eating long-term raw food diets (average 3.7 years) found an average weight loss since starting of 9.9 kg in men and 12 kg in women. Body mass index was below 18.5 in 14.7 percent of men and 25.0 percent of women, and about 30 percent of women under 45 had partial to complete amenorrhea, more often among those eating more than 90 percent raw. The authors concluded that a very strict raw food diet cannot be recommended on a long-term basis.

A cross-sectional study of 201 adherents found that 38 percent were vitamin B12 deficient, with plasma homocysteine inversely correlated with B12. Serum LDL cholesterol and triglycerides were favorable, but 46 percent had low HDL cholesterol. The authors attribute the raised homocysteine to B12 deficiency.

Bone and teeth

In a cross-sectional study of 18 people following a raw vegetarian diet for a mean of 3.6 years, lumbar spine and hip bone mineral content and density were lower than in an age- and sex-matched group eating typical American diets. Bone turnover markers were similar between groups, and 25-hydroxyvitamin D was higher in the raw group. The study is small and cannot show causation.

A German dental study compared 130 people eating more than 95 percent raw food with 76 clinic controls. Only 2.3 percent of the raw group had no erosive defects, and 60.5 percent had at least one tooth with severe erosion, against 31.6 percent of controls. A dental review lists raw food diets among special diets that can raise the risk of dental erosion.

Trials and reviews

The searches run for this page (PubMed searches on raw food diet with systematic review, randomized trial, B12, bone and dental erosion) found no systematic review or meta-analysis of raw food diets as a whole, and no Cochrane review. A 2020 systematic review of randomized trials of diet and supplements in rheumatoid arthritis included 27 articles, three of them whole-diet studies (Mediterranean, raw food and anti-inflammatory diets), and reported moderate-strength evidence for a Mediterranean diet and some other interventions, with other diets or supplements showing no effect or low to very low strength of evidence.

Fertility and long-term outcomes such as cardiovascular events were not found in the sources reviewed beyond the amenorrhea, lipid and weight data above. Most evidence comes from cross-sectional studies of self-selected adherents, which cannot separate the effect of the diet from other differences between groups.

Laboratory findings on cooked and raw vegetables

Advocates hold that cooking reduces the value of food. Laboratory studies show a mixed picture that depends on the food, nutrient and method. An in vitro digestion study of zucchini, red pepper and tomato found that beta-carotene levels in the digested material fell after boiling, grilling, microwaving or steaming, yet all cooking methods increased beta-carotene transfer to micelles, and carotenoid micellarisation ranged from 1.7 to 100 percent depending on food, carotenoid and method.

An in vitro study of seven tomato products reported that paste processing and drying raised bioaccessible lycopene 2.2-fold and 3.8-fold compared with fresh tomatoes. These are laboratory findings and do not show an effect on human health outcomes. The sources reviewed do not address vitamin C loss on cooking.

Carotenoid status in raw food adherents

Among 198 strict adherents, 63 percent had plasma beta-carotene at levels associated with chronic disease prevention and vitamin A status was normal in 82 percent, but 77 percent had lycopene below the reference value for healthy populations. A comparison of women found that for comparable dietary beta-carotene intake, plasma levels were lower in the raw food group than in women following a wholesome diet. The authors note that plasma beta-carotene may not reflect intake.

What dietetic bodies state

The Academy of Nutrition and Dietetics position paper states that appropriately planned vegetarian, including vegan, diets are healthful, nutritionally adequate and appropriate for all stages of life, including pregnancy, lactation, infancy, childhood and adolescence, and that vegans need reliable sources of vitamin B12 such as fortified foods or supplements. The paper concerns vegetarian and vegan diets in general, and the sources reviewed do not show a position statement on strict raw-only eating, so its conclusions should not be carried over to it.

Foodborne illness and raw sprouts

Archived CDC consumer advice from 2016 states that sprouts are a known source of foodborne illness and that children, older adults, pregnant women and people with weakened immune systems should avoid eating raw sprouts of any kind. A European Food Safety Authority review reports that a 2011 outbreak of Escherichia coli O104:H4 infection linked to sprouted seeds caused hundreds of cases of hemolytic uremic syndrome and several deaths. The sources reviewed do not address unpasteurized dairy products in raw diets.

Pregnancy, children, eating disorders and care boundaries

No source reviewed studies raw-only eating in pregnancy, childhood or eating disorders. The weight, amenorrhea and low bone mass findings above are relevant to those groups because they involve underweight and loss of weight, and a dental review lists eating disorders and raw food diets as separate risk groups for erosion. Anyone considering the diet, particularly in these situations, can discuss it with a physician or dietitian. The diet is not a substitute for treatment, and necessary medical care should not be delayed.