Participants in this study were similar to others who use CAM in that the majority were female, educated, and of higher socioeconomic status, and many had a history of cancer.(20
) At 12 weeks after their baseline measurements, subjects who had stayed at the raw vegan institute reported improved QOL, specifically mental QOL, anxiety, and stress. Staying there was also associated with the belief that participants were taking better care of themselves, particularly those who were newly adhering to the diet at 12 weeks. CRP did not change significantly over the 12 weeks, but some subgroups of lymphocytes did decrease slightly.
A strength of our study is that it addresses the health effects of an increasingly popular diet, the raw vegan diet, about which little is known. In addition, the study was longitudinal and included many subjects who were new to the diet. A limitation is that the subjects were a self-selected group of people, unrepresentative of the general population, and the sample size was small, particularly for those adhering to the diet and for those whose blood was analyzed. There were a number of participants who did not provide follow-up data, however, their baseline characteristics were similar to those with complete follow-up data, and analyses that assumed no change from baseline for the dropouts showed similar results. Although not formally assessed, subjects frequently stated that they were too busy to complete the survey and blood tests. Finally, our method of assessment of adherence to the raw vegan diet has not been validated; our findings should therefore be considered an estimate of adherence.
Diet’s effect on QOL is most frequently considered in studies of gastrointestinal diseases. We included it in our study because we wanted to capture the effects of diet on well-being among people with a broad spectrum of diseases and without a specific disease diagnosis. In addition, complementary therapies (CAM) are commonly used to improve QOL.(21
) We observed little change in participants’ physical QOL, but significant improvement in their mental QOL. These changes may be due to the change in diet, perceived improvement in self-care, the stay at HHI, or other lifestyle changes. A study of prostate cancer patients showed that CAM users experienced less psychological distress, over time, than non-users.(22
) Improved QOL may also have occurred because the participants in our study had a very high internal locus of control at baseline (results not shown). If they felt they were doing something to control their health by going to HHI, those who were ill might have more confidence that they would be cured (5
), and therefore, experience less stress. In some respects, a stay at HHI is more like a vacation than a health care intervention. So some of the improvement in QOL may reflect the self-renewal that vacations are intended to provide. However, that improvement was reported 2 months after subjects departed from HHI. Finally, although the raw vegan diet is a focus of the program, there are a number of other elements to the HHI program, such as exercise and supplements, which could account for these changes.
Contrary to our expectations, dietary QOL did not diminish, though the raw vegan diet is very restrictive and different from the standard American diet. Even those subjects who reported that they were adhering to the diet did not rate their diet’s taste, cost, and convenience on follow-up lower than at baseline. These results may reflect the selection factors for choosing to stay at HHI. However, a vegan diet that included cooked food also had high acceptability in a study of overweight, post-menopausal women.(23
) Future studies with longer follow-up are needed to assess duration of both adherence to and satisfaction with the raw vegan diet.
Mean hsCRP rose slightly. This finding contradicts those of a cross-sectional study comparing adherents of the raw vegan diet with omnivores.(13
) However, it is consistent with a study of the diet in rheumatoid arthritis patients, in which CRP increased non-significantly over the 2–3 month intervention, while participants’ symptoms improved.(24
) It may be that among subjects who initiate a raw vegan diet, CRP increases in the short term, but decreases in the long term. The effect of the diet on CRP also may depend on baseline health status. The subjects of the above-mentioned cross-sectional study were without chronic disease, unlike the participants in the rheumatoid arthritis study. In our study, mean CRP levels decreased slightly among those with a comorbidity score of zero, while it increased slightly among those with higher comorbidity scores.
The decrease in the different types of lymphocytes was consistent with results from one raw vegan study(11
) and one vegan study(12
), each of which showed a decrease in white blood cell count. Although there was a decrease in the absolute number of natural killer cells, which are thought to fight diseases such as cancer(25
), their activity may not have changed, as was found in a study of vegans.(12
) Psychosocial interventions have also been found not to increase the number of natural killer cells.(26
) It remains to be determined whether the change in number of certain subgroups of lymphocytes is clinically meaningful.
This exploratory study indicates that a stay at a raw vegan institute is associated with improvement in mental and emotional quality of life 12 weeks later, and has minimal adverse effects for most people. Since this was not a randomized intervention study, it is impossible to be sure if this positive outcome is a result of the raw vegan diet, a different aspect of a stay at HHI, or some other factor. Nevertheless, these results may be reassuring for clinicians whose patients follow this extreme diet. Of note, a cross-sectional study deemed the raw vegan diet unsafe based on the prevalence of underweight and amenorrheic adherents.(12
) Thus, particular attention to these outcomes is warranted in future studies and in clinical practice. The negative experiences reported by the 2 elderly women and the man with advanced cancer also suggest that extra caution is needed when studying vulnerable populations.
Results of this study should help guide future studies of this diet by providing information about the short-term safety and acceptability of the diet and showing that it may also be beneficial. Although, for the most part, we did not find the raw vegan diet to be associated with significant changes in selected immune or inflammatory markers, other studies have shown it to be associated with elevated and lower CRP levels, possibly related to baseline health status or other unknown factors.(13
) Aside from this study, little information is available regarding the raw vegan diet’s effect on adherence, quality of life, and other immune markers. Information from this study may help to inform power calculations for interventional studies that evaluate the diet, first in a population of healthy people and subsequently in those with disease. Such studies would help clarify the diet’s effects on quality of life and the immune system as well as the course of specific diseases.