Identifying healthy and unhealthy dietary patterns among Swiss vegan adults

Currently, a diet quality score for vegans does not exist in Switzerland and neither internationally, but such a tool is urgently needed for research purposes and clinical practice.



Veganism has recently gained popularity in Switzerland and elsewhere. Health, climate change, animal welfare and religion are among the most common reasons for adopting a vegan lifestyle. The EAT-Lancet Commission proposed a global shift toward a sustainable and healthy diet based on the decrease in meat consumption and an increase in vegetables. While all reductions in meat deliver climate benefits, vegan diets are the most environmentally sustainable diets as they have the lowest greenhouse gas emissions. Vegans have a high intake of plant-based foods, such as fruits, vegetables, grains, legumes, nuts, vegetable oils but they abstain from all animal products including honey and animal-derived ingredients used in food production, such as gelatin. However, they may also have a higher risk of nutrient deficiencies. Previous studies on vegans have not considered diet quality but rather analyzed vegans as one homogenous group, comparing their nutrition and health status with those of vegetarians and omnivores. Recent large-scale prospective cohort studies suggest that not all plant-based diets are equal, and they distinguish between healthy and unhealthy plant-based diets. The major limitation of these large cohort studies is that they have not studied vegans but instead looked at plant-based food intake as a continuum among mostly omnivores; thus, it is unclear to what extent this applies to vegans.

Course of action

Our primary aim is to examine the heterogeneity of vegan diets in Switzerland by identifying dietary patterns that explain the variation in key nutrients and nutritional status among vegans. It is intended to reach this overall aim by means of the following four specific aims: a) we will develop an a priori-defined diet quality score for vegans (DQS-V) with special attention to potentially critical nutrients among vegans b) we will employ reduced rank regression (RRR) to identify combinations of food groups that explain as much variation as possible in nutrient intakes and blood biomarkers c) we will analyze whether the motivation (e.g. health, climate, animal welfare) for following a vegan or vegetarian diet is associated with nutrient and food intake as well as with biomarkers of nutritional status (e.g. BMI, ferritin) d) we will describe the intake of ultra-processed foods (UPFs) in Swiss vegan and vegetarians and compare them to the intake of UPFs in omnivores For this study, we will draw upon a dataset that has already been collected by the Human Nutrition Laboratory, ETH Zurich and closely collaborate with Dr Herter-Aeberli, Isabelle. The dataset includes 206 healthy adult female and male subjects between the age of 18 and 50 years, who have been following either a vegan (n=53), ovo-lacto vegetarian (n=53) or omnivorous (n=100) diet for at least 1 year prior to the study.