Aim of this review is to summarize the main features of the different FBDGs (DGLs and VFGs) usable by vegetarians of Western countries; to compare their recommendations regarding some potentially critical nutrients; to generate a list of specific recommendations, reflecting research data on the nutritional adequacy and health implications of vegetarian dietary models; eventually, to identify the most valid FBDG for vegetarians.

The selection of the FBDGs, which will be discussed in this review, was performed as follows:

The structure and content of each FBDG were carefully examined. For both categories, we summarized the main characteristics (food groups, resources for vegetarians in the DGLs, applicability to lifecycle stages) in Table 1 (for DGLs) and Table 2 (for VFGs), and compared the respective recommendations regarding some nutrients to focus on, in Table 3.

The DGLs of the countries which included in recent years recommendations for vegetarians, propose a very similar food distribution in the food groups: three plant-food groups (grains, vegetables and fruits), one group of protein foods (containing both plant and animal protein foods: legumes, nuts and seeds, soy and wheat, meat and eggs), the dairy group (including also the calcium-fortified non-dairy alternatives). This setting is used in the Canadian DGLs, edited by Health Canada41, in the Australian DGLs, edited by the National Health and Medical Research Council42, in the USA DGLs, edited by the US Department of Agriculture and Department of Health and Human Services43, and in those published by the British (UK) National Health Service44. In the latter, fruits and vegetables form one group, so that they offer only four main groups (a 5th small group is formed by food and drinks rich in fats and sugars which, in the other guides, are placed outside the diagram) (Table 1).

Canadian54,55,56,57 and Australian585960 DGLs also offer information for different ages and life stages, but the attention given to vegetarian diets simply consists in providing the respective vegetarian alternatives in the groups of protein and dairy foods, and the recommendation for VEG individuals -in the Australian DGLs- to include a vitamin B12 source⁶¹ (Table 3). On the contrary, USA and British DGLs propose some sections specifically developed for vegetarian people, at different ages and life stages.

In comparison with a 2006 national poll, reporting that 3.7% of Americans identified themselves as vegetarian (2.3%) or vegan (1.4%)62, the prevalent figures for vegetarianism in USA are rapidly raising: a new 2013 poll reports that 13% of Americans identify themselves as vegetarian (6%) or vegan (7%)39. Consequently, the 2010 Dietary Guidelines for Healthy Americans include vegetarian alternatives in the protein and dairy food groups and provide specific recommendations for vegetarians63, highlighting the favorable health outcomes resulting from prospective studies on vegetarian adults, compared to non-vegetarians (regarding obesity, cardiovascular disease and total mortality), and from intervention studies with vegetarian diets (regarding hypertension).

Information on vegetarian diets are provided in the report (pp. 45 and 52, and appendices 8 and 9) and in MyPlate website and its related resources356465.

USA DGLs state that vegetarian diets can meet all the recommendations for nutrients: the key is to consume a variety of foods in amounts adequate to satisfy the individual calorie requirements. The main sources of nutrients for vegetarians are foods available in the five main food groups of MyPlate (Table 1, Figure 1), which should all be consumed on a daily basis, varying the choices of foods belonging to the same group. Recommendations on critical nutrients for the general population (Foods and Nutrients to Increase) relate to fiber, folic acid, potassium, calcium and vitamin D, and iron, while recommendations on vitamin B12 are specific for all people over-50 years of age, and for VEGs. Since vegetarian diets are abundant in fiber, folic acid and potassium, nutrients that vegetarians may need to focus on are summarized in Table 3: unlike British DGLs and all VFGs, attention towards zinc and protein intakes is stressed for vegetarians; a recommendation for omega-3 fatty acid intake is missing.

Appendices 8 and 9 propose, respectively, LOV and VEG adaptations of the USA OMN eating patterns, providing the suggested distribution and amount of food to be consumed, for calorie requirements from 1000 to 3200 kcal. They are intended for healthy Americans aged 2 years and older. The proposed patterns from 1000 to 1400 kcal are intended for children from 2 to 8 years of age, and those from 1600 to 3200 kcal for children from 9 years through adulthood (for children aged 4-8 years requiring more energy, the patterns from 1600 kcal and above should limit the dairy group servings to the amounts of the 1400 kcal pattern). An amount of free calories, which can be optionally consumed in form of SoFAS (from “Solid Fats and Added Sugars”), is also indicated. All patterns are proposed as healthy, so both OMN and LOV are largely based on plant foods, sharing with the VEG pattern a major overlapping area composed of plant foods (about 81% by weight)66. The nutritional adequacy of the three patterns was proved67,⁶⁸,69⁷⁰, and the total environmental impact analyzed by life cycle assessment (LCA) was the lowest (35% and 22% of that of the LOV and OMN patterns, respectively) for the VEG pattern, mainly due to the absence of animal foods66.

According to a poll carried out in 2014, the prevalence of vegetarians in UK, the birthplace of vegetarianism in Western cultures, is similar to that in the USA: as high as 12%, with the figures rising to 20% among people aged 161718192021222324. Although not providing the relative figures for vegetarians and vegans, the report estimates that the UK meat-free food market is sharply increasing40.

British DGLs44 include a very detailed section for vegetarians71, basically in accordance with the more specific VFGs, and provide links to other resources edited by the UK Vegetarian and Vegan Societies7273. The Eatwell Plate is composed of four main slices (33% starchy foods, 33% vegetables and fruits, 12% protein foods, 15% dairy products and their non-dairy alternatives) and includes a small slice of fatty and sugary foods (corresponding to the USA DGLs SoFAS calories)74. Recommendations for vegetarians are distinct for VEGs75 and LOVs76, and include specific information for the different lifecycle stages (pregnancy, lactation77 and childhood78)(Table 1). Information to meet the requirements of critical nutrients for LOVs and VEGs is included (Table 3). These recommendations reflect the content of USA and Canadian VFGs48,49.

Far back in 1988, the American Dietetic Association (ADA, actually renamed the Academy of Nutrition and Dietetics) released its first position statement on vegetarian diets79. Since then, this statement is periodically reconfirmed on the basis of the updates available from research on vegetarian nutrition. The most recent ADA’s Position Paper on Vegetarian Diets, delivered in 2009, states that appropriately planned vegetarian diets (including total vegetarian or vegan diets), are “healthful, nutritionally adequate, may provide health benefits in the prevention and treatment of certain diseases”, and that they are “appropriate for individuals during all stages of the lifecycle”23.

Since only in recent times DGLs of some countries have included sections for vegetarians, about 20 years ago some prominent scientists in the field of vegetarian nutrition agreed upon developing a food guide for vegetarians; later, some scientific societies and organizations developed other VFGs.

Foods consumed by vegetarians are placed in food groups that can be different in the various VFGs, as shown in Table 2. However, all VFGs were developed by professionals with long-standing expertise in vegetarian nutrition: for this reason, their recommendations may be more reliable than those provided by the DGLs discussed in the previous section.

This was the first VFG in the world. In 1995, an international group of researchers in the field of vegetarian nutrition began to develop this VFG454647. The process was completed in 1997, when this VFG was presented at the 3rd International Congress on Vegetarian Nutrition, organized by the University of Loma Linda, California (major research center in the field of vegetarian nutrition). Based on a few main principles, resulting from consensus among researchers and summarized in Table 4, this first VFG was “designed to reflect healthy patterns of dietary intake that are not only adequate but promote optimal health"47.

Translated into a pyramid-shaped diagram, these recommendations can be adopted both by LOVs and VEGs, as they propose five groups of plant foods at the bottom of the pyramid, representing the core of any healthy vegetarian diet, and four groups at the top of the pyramid, considered optional, unnecessary for the nutritional adequacy of the diet (Figure 2 and Table 2). This VFG recommends also the attention toward potentially critical nutrients, as listed in Table 3, regular physical activity and the abundant consumption of water and fluids. The process leading to the development of this first VFG has been accurately described45.46. Its updated version, released in 2008, is shown in Figure 380.

The Adventist cohort, recruited in North America for the studies on the Adventist’s Mortality and Health, largely adopts this VFG, and its favorable health outcomes were recently reported in a cumulative analysis81. The environmental impact of the diet was also addressed: the average greenhouse gases emissions per year, assessed in a large sample of participants of the Adventist Health Study 2, were 29% lower for vegetarians, compared to non-vegetarians82.

In 2003, American Dietetic Association (ADA) in collaboration with Dietitians of Canada (DoC), updated its position statement on vegetarian diets83. A complementary New Food Guide for North American Vegetarians4849 was edited by a team of nutritionists with expertise in vegetarian nutrition: it contains practical information and recommendations to plan vegetarian diets for adults, pregnant and lactating women, children over 4 years and adolescents. Formulated in the shape of a pyramid (USA, Figure 4) and a rainbow (Canada), it distributes food in 5 major groups (Table 2). A key peculiarity of this VFG is the creation of a 6th transverse group, collecting all calcium-rich foods from the other food groups. Therefore, the consumption of at least 8 servings of foods belonging to this group can allow meet calcium requirements, without focusing on dairy and non-dairy analogues. The Special Considerations emphasize the importance of consuming reliable sources of some critical nutrients (Table 3). It is stated that the requirements of protein, iron and other nutrients not included in the Special Considerations section, can be met by the varied consumption of foods belonging to all the food groups.

The Japanese VFG, released in 200951, was developed on the basis of ADA recommendations23,48 and the Japanese Food Guide Spinning Top84 for OMNs. Inspired by an asymmetric double-pointed pyramid, this VFG is composed of 6 food groups (Table 2). Conceived for adult Japanese LOVs, it includes typical Asian dishes in the protein group, but does not consider non-dairy alternatives, even if it proposes, for lactose intolerance, foods from other groups such as calcium sources (nuts and seeds, seaweeds and green leafy vegetables), in accordance with ADA/DoC VFG4849. No recommendation on critical nutrients is included (Table 3).

The nutritional composition of this VFG, developed with the contribution of some Japanese Adventist Hospitals and Loma Linda University, is reported as adequate51.

The Italian VFG, proposed for adult vegetarians, was first delivered in 2005 and later further revised508586. Its principles are set out in a pyramid-shaped diagram, VegPyramid (Figure 5), whose components are (Table 2): a)the main food groups, which form the 5 bands of different colours and width of the main pyramid; b)the transverse group of calcium-rich foods, represented by the smaller pyramid inside the main one; c)the discretionary calories (corresponding to the USA DGLs SoFAS calories and the Eatwell Plate 5th slice), represented by the grey strip at the basis of the pyramid. Information for optimizing the intakes of potentially critical nutrients are provided as Particular Recommendations, which are compliant with ADA/DoC VFG48,49 (Table 3). Its nutritional composition in macro- and micronutrients, for the calorie range 1600-3000 kcal, is reported as adequate50.

PCRM research group authored pioneering intervention studies with low-fat vegan diets in the management of diabetes mellitus, hypercholesterolemia, and obesity-overweight. Its VFG proposal, Power Plate53(Figure 6), excludes any form of added fat, as well as animal food, representing a model of low-fat vegan diet, which can be applicable also as therapeutic regimen. It includes only 4 groups of plant foods, recommends the consumption of a small amount of nuts and seeds (about 30g/d) (Table 2), and of a reliable source of vitamin B12 (Table 3).

Unlike other VFGs, Power Plate does not include information on the amount of foods to consume for each of the four groups, thus representing an extremely simple food guide. It states that any scientific basis for emphasizing one or more groups is lacking, and that the key message is to consume a variety of plant foods rather than focusing on specific food groups87.

The nutritional composition of this VFG, promoting ad libitum consumption of plant foods without any added fats, was checked in clinical trials: it can meet or exceed the Dietary Reference Intakes, and provide a beneficial ratio of health protective-detrimental nutrients88899091. Its acceptability was also assessed and resulted similar to that of other therapeutic regimens929394.

Attention toward vegetarian citizens has been shown in modern times by some Western governments, with the inclusion of specific sections and recommendations for vegetarians in their DGLs. However, since 1997, some VFGs are available. Their advantage is not to simply represent an "adaptation" of recommendations for OMNs: VFGs are devoted to vegetarians, including only foods they consume. In addition to being easy to use, VFGs offer qualified advice to carry out well-planned vegetarian diets. This paragraph intends to propose a list of five items specific for vegetarians, summarized in Table 5: we believe that, taken all together, they may allow to plan vegetarian diets respecting the most modern standards of adequacy and safety. Any item, to be included in the list, was considered valuable if present in at least two VFGs. We did not consider an item as valuable, if present in DGLs but not in VFGs (as shown in Table 3). Two further items, reflecting other healthy lifestyle habits for everyone, complete the list.

almost all the FBDGs state that a vegetarian diet can be nutritionally adequate if it meets the calorie requirements from a varied selection of nutrient-dense foods, belonging to all the vegetarian food groups. This means that some types of restrictive diets, i.e., fruitarian one, can not provide adequate amounts of nutrients. Since many nutrient-dense foods are unprocessed, they should be emphasized in the diet, making it easier to meet nutrient requirements, including protein, iron and zinc.

the inclusion of these foods is not considered necessary to guarantee the nutritional adequacy of a vegetarian diet, since the nutrients they provide (calcium, protein, and vitamin B12) can also be obtained from other sources. They can be consumed in small amounts, if desired. Thus, the same FBDG can be used both by LOV and VEG people.

the current recommendations on fat intakes state that the percentage of calories from fat should not exceed 35% of total calories. Complying with this limit means to prioritise foods with higher nutritional density, and limit excess calories. Vegetable fats should also be carefully chosen, avoiding trans fats and tropical oils (rich in saturated fats), limiting omega-6 fats, and emphasizing the consumption of monounsaturated oils and omega-3 fatty acids.The intake of omega-3 fatty acids from plant sources contributes to the adequacy of the diet, as research has shown that it can vary among vegetarians. This means to regularly consume small amounts of flaxseeds, flaxseed oil and walnuts.

these are fundamental principles of any healthy diet. Research has shown that the intake of calcium can be low in vegan subjects; so, good calcium sources should be emphasized in the diet, by increasing the intakes of calcium-rich foods from plant sources. Conversely, as no kind of diet can provide adequate amounts of vitamin D, the recommendations for vitamin D are the same as for the general population.

the intake of reliable sources of vitamin B12, not only for VEGs but also for LOVs, is fundamental for a well-planned vegetarian diet, as vitamin B12 status can be compromised, over time, in vegetarian subjects who do not supplement it.

in every kind of diet, the intake of adequate amounts of fluids is obviously important. While vegetable beverages with added calcium, which may increase calcium dietary content, can be useful, empty-calorie fluids may be consumed using the amount of calories provided for this purpose.

this recognizes the importance of other lifestyle habits, primarily physical activity, but also the correction of risk behaviors such as smoking and the indiscriminate consumption of unnecessary substances.