Raw Foods Diets

It is well established that vegetarian lifestyles are associated with health advantages. The American Dietetic Association states that "… appropriately planned vegetarian diets are healthful, are nutritionally adequate, and provide health benefits in the treatment and prevention of certain diseases." (16)

Much of what is known about vegetarian diets and related health effects is based on research on lacto ovo vegetarian diets. Relatively little information is available about the health and nutrition aspects of vegan diets, however, as well as variants such as raw foods or living foods diets. A review of the literature was conducted to determine the extent to which there is scientific documentation of the health and nutrition aspects of raw foods diets as a first step toward further study of this dietary practice.

Worldwide, little research data is available on the subject of raw foods diets. The majority of published research has been conducted in Finland at the University of Kuopio. Of the 24 papers included in this review, 15 originated in Finland. The remainder of the research was conducted in the U.S., the Netherlands, and Germany.

Raw foods diets are variously described as uncooked vegan diets, uncooked vegetable diets, and "living foods" diets. In one case, a raw foods diet included raw liver (8). All other studies reviewed here referred to vegetarian diets, most of which excluded all animal products and derived the majority of calories from uncooked plant matter. In one study, up to 95 percent of food was consumed in raw form (7). One study group derived 55 percent of calories from uncooked fruits, carrot juice, salads and raw vegetables, and grain products, though 58 percent of subjects also consumed some animal product during the recorded week of food intake (4). In other studies, a "living foods" diet was defined as an uncooked vegan diet that included germinated seeds, sprouts, cereals, vegetables, fruits, berries, and nuts (9, 11).

The scientific literature contains relatively little information about the rationale for a raw foods or living foods diet. One paper by Kenton (1985) provides philosophical discussion examining food energy and its role in sustaining optimal health. Other papers focus on specific health effects on adult subjects following a raw foods or living foods diet for a period of time ranging from as little as one week (10) to as long as 3.7 years (14). Study groups ranged in size from as small as 13 subjects (2) to as many as 513 subjects (14). Findings include dietary effects on weight, serum lipid levels, symptoms of rheumatoid arthritis and fibromyalgia, rates of dental erosion, fecal microflora, cancer treatment, vitamin B₁₂ status, and antioxidant and other nutrient intakes.

Four studies found uncooked vegan ("living foods") diets to be associated with substantial loss of weight (5, 12, 14, 20). In one case, weight loss was associated with reduction of diastolic blood pressure (5), in one case reduction of fibromyalgia symptoms (12), and with amenorrhea in another case (14). Other studies found subjective improvement of fibromyalgia and rheumatoid arthritis symptoms with adoption of an uncooked vegan diet (9, 11, 17).

An uncooked vegan diet was associated with decreased serum total and LDL-cholesterol levels (2). Another study found that long term uncooked vegan diets resulted in decreased levels of n-3 fatty acids due to high intakes of linoleic and oleic acids (1). Two studies found significant reductions of serum vitamin B₁₂ concentrations in subjects following a raw foods ("living foods") diet, suggesting that long-term adherents to a raw vegan diet should include a reliable source of vitamin B₁₂ in their diets (3, 22).

Other studies focused on favorable effects of an uncooked vegan diet on fecal microflora and other potential chemopreventive factors for cancer risk (6, 15, 18, 25). One study found overall favorable changes in biochemical and metabolic health indicators including serum protein, urea, and total cholesterol in subjects eating a raw foods diet for one week but concluded observation over a longer period was needed (10). One study found increased risk of dental erosion in subjects following an uncooked vegan diet (7). Another study examined coumarin 7-hydroxylation in subjects consuming a raw foods vegan diet matched with omnivorous controls and concluded that plant substances had little effect on coumarin hydroxylase activity in subjects consuming a raw foods diet (23).

Finally, one study of 141 American long-term (mean time 28 months) adherents to a raw foods diet found self-reported improvements in health and quality of life after adoption of the diet (4). Measurement was based on survey results of subjects’ current health and retrospectively for health prior to dietary changes. The study found that salads, fruits, carrot juice, and cooked grain products provided 60-88 percent of most of the nutrients found in the diet. Dehydrated barley grass juice, nuts and seeds, potatoes and squash provided the remaining 12-40% of nutrients in the diet. The diet provided a mean calorie intake of 1460 kcal/day for women and 1830 kcal/day for men. Fat provided 24% of calories, and mean protein intake was 0.66g/kg body weight. Mean calcium intakes were 580 mg/day for women and 690 mg/day for men. As compared to mean nutrient intakes of people in the United States, as reported in the National Health and Nutrition Examination Survey (NHANES III), intakes of several nutrients were significantly higher in subjects eating a raw foods diet, and intakes of several nutrients were lower. Intakes of fiber, vitamins A, B6, C, and E, folate, copper, and potassium were significantly higher in subjects eating a raw foods diet as compared with those reported in NHANES III, and intakes of protein, total and saturated fat, cholesterol, vitamin B₁₂, phosphorus, sodium, and zinc were significantly lower.

Overall, the body of scientific literature describing health and nutrition aspects of raw foods or living foods diets is limited. Only one survey of American individuals consuming a raw foods diet has been reported. Little or no information is available describing the rationale for a raw foods diet, nor has the range of practices among individuals consuming raw or living foods diets been documented. The majority of available research findings related to raw foods diet is confined to studies of European populations.