Using Evidence Mapping to Examine Motivations for Following Plant-Based Diets

Abstract

Motivations to adopt plant-based diets are of great public health interest. We used evidence mapping to identify methods that capture motivations to follow plant-based diets and summarize demographic trends in dietary motivations. We identified 56 publications that described 90 samples of plant-based diet followers and their dietary motivations. We categorized the samples by type of plant-based diet: vegan (19%), vegetarian (33%), semivegetarian (24%), and other, unspecified plant-based diet followers (23%). Of 90 studies examined, 31% administered multiple-choice questions to capture motivations, followed by rate items (23%), Food Choice Questionnaire (17%), free response (9%), and rank choices (10%). Commonly reported motivations were health, sensory/taste/disgust, animal welfare, environmental concern, and weight loss. The methodological variation highlights the importance of using a structured questionnaire to investigate dietary motivations in epidemiological studies. Motivations among plant-based diet followers appear distinct, but evidence on the association between age and motivations appears limited.

Keywords: Food Choice Questionnaire; evidence mapping; flexitarian; motivations; plant-based diets; vegan; vegetarian.

FIGURE 1

Flow diagram of literature search and screening results.

FIGURE 2

Weighted scatter plot of method of capturing dietary motivation vs. publication year. Each bubble represents a single sample of plant-based diet followers, and its size corresponds to the sample size. The sample bubbles (n = 90) are colored by plant-based dietary pattern (vegan, vegetarian, semivegetarian, and plant-based diet followers), and they are separated by the reported method of capturing data on dietary motivation.

FIGURE 3

Measured motivations by percentage of samples. Studies captured data on various combinations of motivations. This graph shows the breakdown of studies that measured broad motivations (health, ethical, and other) and specific motivations (weight, animal welfare, environmental concern, etc.) of plant-based diet followers.

FIGURE 4

Weighted scatter plot of most prevalent motivation vs. age. Each bubble represents a single sample of plant-based diet followers, and its size corresponds to the sample size. The sample bubbles (n  = 81) are colored by plant-based dietary pattern (vegan, vegetarian, semivegetarian, and plant-based dietary followers), and they are separated by the most prevalent motivation. “Other” motivations included sensory appeal, taste, and preference for eating a variety of foods. The mean age is displayed for 93% (n = 75) of the samples, and the median is displayed for 4% (n = 3) of the samples. The median estimated from the reported age range is displayed for 4% (n = 3) of the samples. Demographic data on plant-based diet followers were extracted for 57% (n = 46) of the samples. For studies that did not report demographic data on plant-based diet followers, the combined data on plant-based diet followers and omnivores were extracted (43%, n = 35).