Both the patient, a young woman who had recently become an adult, and her mother breathed a sigh of relief. The girl’s symptoms, which initially appeared to be heart-related, had other explanations. As they were getting ready to leave, the mother told me, “My daughter hasn’t had her period for some time, and we can’t find the cause of this problem.” I turned to the young patient and asked, “Are you on a raw food diet?” I could see the surprise on her face. “Yes! How did you know?” “Secondary amenorrhoea is a common consequence of a raw vegan diet,” I replied.
Myth: raw foods are more nutritious.
A raw vegan diet largely or exclusively consists of uncooked and unprocessed foods such as fruits, vegetables, nuts, seeds, and sprouted legumes. Some adherents also consume unpasteurised dairy products, or even raw meat and fish (Craig, Mangels & American Dietetic Association, 2009), while others consume some cooked foods and are considered raw foodists if more than 70% of their diet is raw (Koebnick, Strassner et al., 1999). In fact, some foods considered “raw” are cooked, but at temperatures below 48°C (Raba, Iancu et al., 2019).
Proponents of raw food offer numerous arguments for their choice, the main one being that cooking destroys a considerable proportion of the nutrients in food. In reality, even though certain nutrients, such as vitamin C and some B vitamins, may be significantly reduced during cooking, it seems that the remaining nutrients are sufficient for the body’s needs (Wanjek, 2013). At the same time, cooking can facilitate the release of certain nutrients by breaking down fibres and cell walls. Furthermore, some cooking methods can increase the bioavailability of nutrients (i.e. how well they are absorbed and used by the body) and the physicochemical qualities of food (Raba, Iancu et al., 2019).
The benefits and risks of a raw vegan diet
Although there are studies indicating the benefits of a raw food diet, they are limited in terms of number, duration, and participants (most are conducted over a period of less than a year, with some lasting only one to three months). The main benefit is weight loss, leading to lower blood sugar and blood pressure. There have also been reports of lower blood lipids and reduced inflammatory markers, as with any vegetarian diet (Pahlavani and Azizi-Soleiman, 2023; Raba, Iancu et al., 2019). Some patients reported an improvement in quality of life and those with fibromyalgia experienced an improvement in joint symptoms (Raba, Iancu et al., 2019). However, it is not known whether these positive effects persist in the long term, as very few people can maintain such a diet long-term.
What happens when the duration of a raw food diet exceeds one year? A study of 515 subjects (216 men and 297 women) over an average period of 3.7 years highlighted two concerning effects (Koebnick, Strassner et al., 1999). Over a third of women under 45 reported amenorrhoea (the absence of menstruation for at least three months). The exact cause of amenorrhoea in the context of a raw vegan diet is unknown, but it is clear that these women’s bodies are experiencing disturbances. A second issue identified in the study was significant weight loss: men lost an average of 9.9 kg and women up to 12 kg. Thus, the body mass index (BMI) of those studied fell below the standard considered healthy: 14.7% of men and 25% of women had a BMI below 18.5 kg/m². While weight loss is often seen as an achievement, it becomes problematic when it crosses the line of health. The data suggests that the people studied did not eat in a balanced or sufficient manner.
As with the results on the benefits of a raw food diet, the results of this study should be approached with caution, as they do not provide certainty. Nevertheless, the relevance of this observational study (with a relatively small number of participants) is amplified by the method used to assess the percentage of raw food consumed. The observations indicated that the aforementioned problems were directly correlated with the amount of raw food ingested, suggesting a possible causal relationship. Other negative effects observed in various studies include a decrease in good cholesterol (HDL), an increase in homocysteine, and a decrease in lycopene levels (Koebnick, Garcia et al. 2005), decreased bone mass (Fontana, Shew et al. 2005), and tooth erosion (Ganss, Schlechtriemen, and Klimek 1999).
Raw foods are healthy, but cooked foods also have their benefits. Besides being delicious, cooked food can help us to better absorb certain nutrients. It is important to remember that our perception of health and well-being is intrinsically linked to our food experience. Thus, a balanced diet that includes both categories can be considered ideal, incorporating fresh salads as well as hot soups. If you are considering trying a raw vegan diet, I would not recommend doing so for more than a month.
Bibliography
- Craig, W. J., Mangels, A. R., and American Dietetic Association (2009), “Position of the American Dietetic Association: Vegetarian diets,” in Journal of the American Dietetic Association, vol. 109, no. 7, pp. 1266–1282.
- Fontana, L., Shew, J. L., et al. (2005), “Low bone mass in subjects on a long-term raw vegetarian diet,” in Archives of Internal Medicine, vol. 165, no. 6, pp. 684–689.
- Ganss, C., Schlechtriemen, M., and Klimek, J. (1999), “Dental erosions in subjects living on a raw food diet,” in Caries Research, vol. 33, no. 1, pp. 74–80.
- Koebnick, C., Garcia, A. L., et al. (2005), “Long-term consumption of a raw food diet is associated with favorable serum LDL cholesterol and triglycerides but also with elevated plasma homocysteine and low serum HDL cholesterol in humans,” in The Journal of Nutrition, vol. 135, no. 10, pp. 2372–2378.
- Koebnick, C., Strassner, C., et al. (1999), “Consequences of a long-term raw food diet on body weight and menstruation: Results of a questionnaire survey,” in Annals of Nutrition and Metabolism, vol. 43, no. 2, pp. 69–79.
- Pahlavani, N., and Azizi-Soleiman, F. (2023), “The effects of a raw vegetarian diet from a clinical perspective; review of the available evidence,” in Clinical Nutrition Open Science, vol. 49, pp. 107–112.
- Raba, D. N., Iancu, T., et al. (2019), “Pros and cons of raw vegan diet,” in Advanced Research in Life Sciences, vol. 3, no. 1, pp. 46–51.
- Wanjek, C. (2013), “Reality check: 5 risks of raw vegan diet,” in Live Science (online), January 15, 2013, available at https://www.livescience.com/26278-risks-raw-vegan-diet.html [accessed October 29, 2023].
