1. Introduction
Vegetarian diets, characterized by the avoidance of meat, meat products and fish and vegan diets, characterized by abstention from all animal products, have become increasingly popular in Western countries [
1]. There is also a growing body of epidemiological evidence regarding the health effects of vegetarian diets. Prospective cohort studies have reported that compared with meat-eaters, non-meat-eaters might have lower risks of obesity [
2], ischemic heart disease [
3], diverticular disease [
4], cataracts [
5] and some cancers [
6], but higher risks of some fractures [
7,
8]. Studies that have investigated the health effects of substituting red meat with vegetarian protein sources have observed lower risks of non-alcoholic fatty liver disease [
9], coronary heart disease [
10], stroke [
11] and total mortality [
12].
Comprehensive information on the food consumption patterns of non-meat-eaters is needed to better understand the differences in health outcomes between diet groups. Some previous studies have described food intakes of vegetarians and vegans [
13,
14,
15,
16,
17,
18,
19,
20,
21,
22] and reported that, compared to meat-eaters, non-meat-eaters consumed more soy and other legumes, nuts and seeds, whole grains, vegetables and fruits and less sugary drinks, refined grains, fried foods and alcohol. However, some studies were based on small numbers of vegetarians or vegans [
14,
16,
17,
18,
19,
21] and only one study investigated vegetarian diets in the UK [
15]. Therefore, there is a need for more information on this in studies with a large number of vegetarians to further characterize the food intakes of non-meat-eaters.
The European Prospective Investigation into Cancer and Nutrition (EPIC)-Oxford study collected detailed data on food intakes in a large cohort of meat-eaters and non-meat-eaters (45%) living throughout the UK. The aims of the current study are to describe and compare intakes of major protein-source foods and other food groups in regular meat-eaters, low meat-eaters, poultry-eaters, fish-eaters, vegetarians and vegans participating in the EPIC-Oxford study.
3. Results
Table 1. shows the participant characteristics by diet groups for men and women. Approximately one-third of men and one-quarter of women were vegetarian or vegan. Overall, compared with regular meat-eaters, low meat-eaters, poultry-eaters and non-meat-eaters were younger, had a higher education level, a lower socio-economic status, were less likely to smoke and consume alcohol, had higher levels of physical activity, a lower BMI, and, expressed as percentage of total energy intake, higher intakes of carbohydrates and lower intakes of protein and fat.
Mean intakes of major protein-source foods among meat-eaters and non-meat-eaters are shown in
Table 2 (men) and
Table 3 (women). The p values for differences between diet groups for all major protein-source foods were less than 0.0001, indicating that the foods consumed by the diet groups differed significantly. By definition, vegetarians and vegans did not consume red meat, processed meat, poultry or fish and, as expected, consumed more plant-based protein sources including legumes and other vegetarian protein alternatives (i.e., tofu, soya, Quorn) compared with meat-eaters. Vegetarians consumed the most cheese and vegans consumed the highest quantities of plant milk and nuts; more than 2.5 times the amount consumed by the regular meat-eaters. This pattern was similar across both the non-standardised and the 2000 kcal/day standardised intakes, showing that the differences between the diet groups for major protein sources were largely unrelated to differences in total energy intake.
Regular meat-eaters consumed nearly a third of their total energy intake from high protein-source foods (meat and fish: 15%; dairy and plant milk: 6%; and cheese, yogurt and eggs: 6%). Vegetarians consumed about a quarter of their total energy intake from high protein-source foods (legumes, nuts and vegetarian alternatives: 11%; cheese, yogurt and eggs: 8%; and dairy and plant milk: 5%). Vegans consumed approximately a fifth of their total energy intake from high protein-source foods (legumes, nuts and vegetarian alternatives: 18%; and plant milk: 5%) (
Supplementary Table S3).
Intakes of other food sources by diet group are shown in
Table 4 (men) and
Table 5 (women). Overall, low and non-meat-eaters consumed higher amounts of vegetables and whole grain foods and lower amounts of fried foods, refined grains and sugary drinks than regular meat-eaters. Low meat-eaters, poultry-eaters, fish-eaters, vegetarians and vegans each consumed significantly more brown rice and couscous (with vegans consuming approximately double), and significantly less fried or roasted potatoes and coffee than regular meat-eaters. Low meat-eaters, fish-eaters, vegetarians and vegans consumed significantly less boiled potatoes, white bread and ice cream and significantly more wholemeal bread and wholemeal pasta than regular meat-eaters (with vegans consuming approximately double). Low meat-eaters, fish-eaters and vegetarians consumed significantly less fruit squash and spirits compared with regular meat-eaters. Low meat-eaters, vegetarians and vegans consumed significantly less white rice than regular meat-eaters. Low meat-eaters consumed significantly less milk desserts than regular meat-eaters. Fish-eaters, vegetarians and vegans consumed significantly more vegetables and soy desserts than regular meat-eaters. Fish-eaters and vegetarians consumed significantly more other bread and pizza and significantly less soft drinks and diet drinks compared with regular meat-eaters. Fish-eaters consumed significantly more crisps than regular meat-eaters. Vegetarians and vegans consumed significantly less wine compared with regular meat-eaters. Vegans consumed significantly less white pasta, pizza and tea and significantly more fruit compared with regular meat-eaters. Adjusting for education and socio-economic status had minimal influence on these results. Additional sex-specific differences between the diet groups are described in
Supplementary Table S4.
The relative mean consumption of food groups for low and non-meat-eaters compared to regular meat-eaters, after adjustment for age, is shown in
Figure 1 for men and
Figure 2 for women. Compared with regular meat-eaters, fish-eaters, vegetarians and vegans consumed more than double the amounts of legumes, vegetarian alternatives and nuts. Among men, vegetarians and vegans consumed 1.5 times as much the sum of brown rice, wholemeal pasta, brown and wholemeal bread than regular meat-eaters, whereas only vegans consumed this amount among women.
4. Discussion
This study assessed intakes of major protein-source foods and other foods in different groups of meat-eaters and non-meat-eaters living in the UK. Our results indicate that there are large differences in dietary intakes between meat-eaters and non-meat-eaters; non-meat-eaters consumed higher amounts of soy, legumes, pulses, nuts and seeds, whole grains, vegetables and fruits, and lower amounts of refined grains, fried foods, alcohol and sugar-sweetened beverages (SSBs). These results were similar when we standardised intakes to a 2000 kcal daily diet, indicating that our findings were largely independent of energy intakes.
Our finding of a higher consumption of a wide variety of plant-based foods in low and non-meat-eaters is consistent with findings from previous studies. The Adventist Health Study-2 and the UK Biobank both observed higher intakes of legumes, vegetarian protein alternatives (e.g., soy, tofu), nuts, whole grains, vegetables and fruits among low and non-meat-eaters [
15,
20]. Likewise, the NutriNet-Santé study in France and the Netherlands cohort study both reported a higher consumption of soy, cereals or grains, legumes or pulses, nuts, vegetables and fruits among non-meat-eaters [
13,
18]. Similar findings were reported by smaller studies [
14,
16,
17,
19,
21,
22].
It might be expected that vegetarians and vegans would replace meat with higher intakes of animal-sourced protein alternatives (including dairy and eggs) and non-animal protein alternatives (including legumes and nuts), respectively. However, our findings suggest that vegetarians and vegans did not completely replace meat consumption with non-meat protein sources and high-protein plant-sources but increased their consumption of a large variety of plant-based foods and consumed lower amounts of high protein-sourced foods compared with meat-eaters (proportion of total energy from high protein-sourced foods was one-third in regular meat-eaters, one-quarter in vegetarians; and one-fifth in vegans). Relatively low protein intakes have been previously observed in vegetarians and vegans in this cohort [
27]. For vegans, we noted a higher consumption of plant milk and nuts, but also the highest consumption of brown rice, wholemeal pasta, couscous and wholemeal bread. This has also been observed in previous studies [
15,
20]. For vegetarians, we found lower intakes of total dairy and egg consumption compared with meat-eaters. However, cheese consumption was the highest in vegetarians. This pattern of dairy consumption has been reported previously [
15,
18,
19,
22]. Cheese can be high in energy, so it is possible that, to achieve energy requirements in their diet, vegetarians might preferentially replace meat with cheese over other lower calorie dairy products. The findings for egg consumption are less consistent in the literature [
13,
15,
18,
20,
21,
22] and we found that egg consumption was low in all diet groups. It is possible that in this ‘health conscious’ cohort [
27], low egg consumption is due to the perceived healthfulness of plant-based foods, and thus high-protein vegetarian alternatives (including legumes, soy and nuts) and other plant-based foods (e.g., whole grains) are the preferred food substitutes for meat among vegetarians and vegans.
We observed a lower consumption of refined carbohydrates, fried foods, alcohol and foods high in free sugars (e.g., ice cream and SSBs) among low and non-meat-eaters. Similar findings were reported by the largest previous studies that also found lower consumption of fried potatoes [
15,
20], refined grains, sweet and fatty foods, sugary drinks and alcoholic beverages [
13,
15,
20] among non-meat-eaters. These findings suggest that non-meat-eaters might be consuming an overall “healthier” diet than meat-eaters.
Well-planned vegetarian and vegan diets can comply with national dietary recommendations [
28] and our study, together with estimates of nutrient intakes in previous studies [
27,
29], supports this. Compared to meat-eaters, the non-meat-eaters in this study consumed a diet that was consistent with most of the UK’s food recommendations, i.e., high in a wide variety of plant-based foods, vegetables and fruits and low in red and processed meat, refined grains, sugary foods and alcohol [
30].
Important strengths of this study include the large sample size including a large proportion of vegetarians and vegans. Furthermore, the questionnaire was designed to identify dietary groups [
2]. Additionally, previous work with this cohort suggests that participants had a high adherence to diet group over time [
31]. However, some limitations should be considered when interpreting our findings. Dietary intake was self-reported and could be subject to misreporting, especially regarding unhealthy food items such as SSBs [
32]. The generalizability of our results might be limited by the ‘health-conscious’ make up of our cohort and our cohort structure, which is predominantly of white, European descent. It is also possible that some vegetarian and vegan products that are commonly consumed were not captured in our FFQ. However, care was taken to include additional plant-based protein foods in the 2010 FFQ.
