Last week we published Part 1 of a three-part series for our new wellbeing research programme. Here in Part 2, Researcher Network member, Laura Grimes, continues her review of the literature on mental health and veganism and considers how a variety of different lifestyle factors contribute to positive mental wellbeing. However, she asks, where does a vegan diet fit into this?
Last week, I reported on research into the positive impacts of vegetarian and vegan diets on mental health. While these research findings made encouraging reading for Vegan Society members, it’s important to highlight that this evidence isn’t conclusive and that some studies have reported the opposite effect. The conflicting findings have been the subject of many publicised discussions (Borg, 2017). Here in Part 2 of this series, I’m reporting on some of those studies and what the implications of some of these may mean for individuals following a plant-based diet.
Vegetarians and vegans are often perceived to be more health-conscious and healthier in their consumption of fruits and vegetables. Indeed, Baines et al. (2007) carried out a cross-sectional data analysis of the Australian Longitudinal Study on Women’s Health in 2000 – the prevalence of vegetarians and vegans in the study was reported to be 10% and 3% respectively. Both groups had a lower body mass index (BMI) 23.0 (22.7–23.3) kg/m2 and 22.2 (21.7–22.7) kg/m2 compared to their non-vegetarian peers (23.7 (23.6–23.8) kg/m2); the vegetarian and vegan groups were also found to exercise more. However, where physical health parameters appeared to benefit from these lifestyles, mental health did not, with vegetarians and vegans being found to suffer from poorer mental health. In fact 21–22% reported depression compared to only 15% of non-vegetarians. Low iron levels and dysfunctional menstrual symptoms were also commonly reported in the vegetarian and vegan groups.
In another study, taken from the Austrian Health Interview Survey (AT-HIS 2006/07), examining the differences between different dietary habit groups and health-based variables, it was found that a vegetarian diet is linked with a lower BMI and reduced alcohol consumption. Positive findings so far – however, it also showed that a vegetarian diet is associated with poorer health otherwise, including higher incidences of mental health disorders and poorer quality of life. This research concluded that there needs to be a public health focus on reducing health risks to individuals consuming a vegetarian diet (Burkert et al. 2014).
Another study examined the one-month, twelve-month and lifetime prevalence rates of mental disorders in vegan, vegetarian and non-vegetarian groups and matched samples (Michalak et al. 2012). The twelve-month and lifetime prevalence of depressive illness in vegans was nearly 15% higher compared to the non-vegetarian group. Furthermore, the vegan and vegetarian groups demonstrated a statistically significant increase in the rates of anxiety disorders across all three timespans examined. Interestingly, this study also examined the prevalence of somatoform disorders – these are defined as any mental disorder manifesting as physical symptoms suggestive of illness or injury, but which cannot be explained fully by a general medical condition or by the direct effect of a substance and are not attributable to another mental disorder. They include hypochondriasis, conversion disorder, pain disorder and body dysmorphic disorder. Again, the one month, twelve month and lifetime prevalence rates were statistically significantly increased in the vegan and vegetarian groups compared to the non-vegetarians – the rates between vegans and vegetarians were similar; however, they were found to be between 5–10% higher than in the non-vegetarians.
So what could the reasons for these differences be? We know that vegans and vegetarians often consume more fruits and vegetables overall, which would in theory contribute to better nutritional status, so it’s unlikely to be linked to this. However, this is only one dietary factor. Looking at factors outside of nutritional status, it’s important to consider that vegetarians and vegans differ compared to their non-vegetarian counterparts in a number of psychological and socio-demographic characteristics that may impact on their risk of adverse mental health outcomes. The majority of vegetarians and vegans are female (Larsson et al. 2002) and they are more likely to live in urban areas and also be single (Baines et al. 2007) – all of which are factors that are associated with the prevalence of mental illness (Jacobi et al. 2004). Furthermore, vegans and vegetarians often define themselves more negatively by emphasising what they ‘do not do’ and consequently they place a focus on how they are dissimilar compared to their peers within the general population (Back et al. 1981). Many vegans and vegetarians emphasise the fact that ethical decision-making motivates their lifestyle, specifically in terms of animal welfare (Fox et al. 2008). Could this finding open a new avenue of research about self-perception and its effect on our psychological functioning as a whole? It’s important to take into consideration that some of these psychological and socio-demographic aspects of individuals consuming vegan and vegetarian diets may be responsible for the findings on mental health. It may be that vegan and vegetarian diets themselves don’t result in worse mental health but that the individuals opting for these lifestyles may benefit from public health interventions as a whole to improve their mental health.
You can read Part 1 of Laura's articles here. Part 3 will be published later this month.
Back KW. Glasgow M: Social networks and psychological conditions in diet preferences: Gourmets and vegetarians. BASP. 1981, 2: 1–9.
Baines, S. Powers, J. and Brown, WJ. How does the health and well-being of young Australian vegetarian and semi-vegetarian women compare with non-vegetarians? Public Health Nutrition 2007, 10(5), pp.436–442.
Borg, C. Why are mental health disorders higher in the vegetarian/vegan (veg*n) population? Australian Journal of Herbal Medicine 2017, 29(1), pp.4–6.
Burkert NT. Muckenhuber J. Großschädl F. Rásky É and Freidl W. (2014) Nutrition and Health–The Association between Eating Behavior and Various Health Parameters: A Matched Sample Study. PLoS ONE 9 (2): e88278. doi: 10.1371/journal. pone. 0088278
Fox NJ. Ward KJ: What are health identities and how may we study them? Sociol Health Illn. 2008, 30: 1007–1021. 10.1111/j.1467-9566.2008.01093.x.
Jacobi F. Wittchen H-U. Hölting C. Höfler M. Müller N. Pfister H and Lieb R: Prevalence, comorbidity and correlates of mental disorders in the general population: Results from the German Health Interview and Examination Survey (GHS). Psychol Med. 2004, 34: 597–611. 10.1017/S0033291703001399.
Larsson CL. Klock KS. Nordrehaug Astrom A. Haugejorden O and Johansson G: Lifestyle-related characteristics of young low-meat consumers and omnivores in Sweden and Norway. J Adolesc Health, 2002, 31: 190–198. 10.1016/S1054-139X(02)00344-0.
Michalak, J. Zhang, XC. and Jacobi, F. Vegetarian diet and mental disorders: results from a representative community survey. International Journal of Behavioral Nutrition and Physical Activity 2012, 9(1), p.67.
The views expressed by our Research News contributors are not necessarily the views of The Vegan Society.
