VN: Introduction (2011)
Vegetarian Nutrition (2011) Evidence-based Practice Guideline
The focus of this guideline is on Medical Nutrition Therapy (MNT) for individuals who follow or are interested in following a vegetarian dietary pattern. Thus, the guideline is not limited to individuals who currently follow this dietary pattern.
Vegetarian dietary patterns are anything but uniform or static. This guideline aims to identify a range of factors involved in vegetarian dietary patterns. A major point of consensus among the articles analyzed is that within vegetarian diets, there are wide variations in foods eaten and complexity regarding dietary practices, beliefs and motivations. Vegetarian dietary practices vary by culture, food availability, region, age and motivation. Additionally, vegetarian diets change over time as vegetarians may become either more restrictive or lenient. All of these factors may be critically important for the health care professional serving vegetarian clients or patients. The emphasis of this guideline is on patient or client choice rather than on advocating any one particular dietary pattern. The goal is to provide resources derived from a systematic review of research, for Registered Dietitians (RD) to enable their clients to make healthful vegetarian dietary choices.
A wealth of research highlights the importance of diet in the treatment and management of a range of diseases or conditions. A well-designed diet based primarily on a variety of plant foods (see definitions below) may be used therapeutically as an alternative to an omnivorous diet in the treatment or management of these diseases or conditions. Individuals who are vegetarian, as well as those who are not but who are interested in exploring different plant-based/vegetarian dietary options to improve their medical conditions may benefit from the contents of this guideline.
Treating disease is only one reason for following a vegetarian dietary pattern. Individuals often seek to follow a vegetarian diet in order to become or stay healthy. Thus, the goal may be to maintain health by preventing, rather than treating disease. However, simply avoiding meat or animal products is not a guarantee of a healthful diet. Just as there is no single healthful “omnivorous diet, ” there is no single healthful “vegetarian diet.” Rather, “vegetarian” is a general label given to a wide range of dietary patterns that share an avoidance of animal or animal-derived foods. It must be assumed that individuals who describe themselves as vegetarian may not automatically eat in a healthful manner and so may also benefit from this guideline. This guideline is designed to provide evidence-based findings to aid in the design of healthful flesh-free and animal-free diets that meet the nutritional needs of a broad range of individuals.
Facilitating Lifestyle Choices
Further research demonstrates that there are varied and complex reasons individuals follow a vegetarian dietary pattern. For many people, avoiding animal-derived foods is not merely a dietary choice, but rather one part of their larger worldview and lifestyle choice. In addition to health and disease treatment, some motivations for choosing to follow a vegetarian diet include economics, religious beliefs, environmental concerns and support for animal rights. Thus, this guideline seeks to enable the RD to help individuals identify dietary choices that not only support their client’s moral, ethical or religious views, but promote optimal health as well.
Adapting to Changing Needs
Finally, dietary needs are not static throughout the life cycle and interest in and commitment to vegetarian dietary patterns may change throughout life. Therefore, this guideline encourages the RD to maintain flexibility and acceptance to support the lifestyle choices and dynamic intake of individuals in this population. To assist the RD, this resource provides guidance on identifying specific reasons for following a vegetarian diet as well as recognizing the needs of vegetarians, particularly within specific target groups (children, adolescents and pregnant women). This resource also encourages planning appropriate nutrition interventions and formulating a personalized plan to improve or maintain health.
Vegetarian: A dietary pattern that is exclusively or almost exclusively composed of plant foods. Some vegetarians may consume specified animal products, such as eggs, milk and milk products (lacto-ovo vegetarian), and processed foods containing small amounts of animal products (whey, casein). The two most common ways of defining vegetarian diets in research and the general population are:
Vegan diet: Diets free from all flesh foods, eggs and dairy products; May also include avoidance of honey.
Vegetarian diet: Diets free of all flesh foods, but may include egg (ovo) and dairy (lacto) products.
Ovo-vegetarian: A vegetarian dietary pattern free from all flesh and dairy foods but includes eggs.
Lacto-vegetarian: A vegetarian dietary pattern free from all flesh foods and eggs but includes dairy products.
Lacto-ovo vegetarian: A vegetarian dietary pattern free from all flesh foods but includes eggs and dairy products.
Fruitarianism: A type of vegan diet that includes consumption of fruits, nuts and seeds, but no vegetables or grains, as well as no animal products.
Vegan: A dietary pattern free from all flesh foods, eggs and dairy products; May also include avoidance of honey.
Semi-vegetarian: A plant-based dietary pattern that includes occasional meat products, but seeks to limit the type and/or amount of meat. A semi-vegetarian may seek to reduce beef and pork to once or twice a week or limit their meat intake entirely to poultry and/or fish. This dietary pattern may also be referred to as a "demi-" or "quasi-vegetarian" diet and sometimes as a flexitarian diet.
Pesco-vegetarian: While not a vegetarian dietary pattern, this self-defined term used by some to define a semi-vegetarian plant-based eating pattern is free from red meat (beef, pork, lamb, etc.) and poultry, but includes fish and other seafood, and may include eggs and dairy products. May also be called pescetarian.
Macrobiotic: A macrobiotic diet (or macrobiotic) is a strict whole-foods vegetarian or pesco-vegetarian (a diet that includes fish, but no meat or poultry) diet. The foundation of a typical macrobiotic dietary regimen includes brown rice and whole grains (50% to 60%), supplemented with other foodstuffs such as local vegetables and seaweed (25% to 30%), beans and bean soups (5% to 10%), fish, nuts, seeds, certain fruits and miso soup (5% to 20%).
Macrobiotic principles also govern food preparation and the manner in which food is eaten. For example, the principles recommend avoiding use of the microwave, chewing food completely, eating in an orderly and relaxed manner using good posture, and avoiding overeating.
Omnivore: A dietary pattern that includes both plant and animal products, including flesh foods.
The recommendations in the guideline were based on a systematic review of the literature. It should be noted here that the research reviewed revealed ambiguity in definitions of vegetarian diets that are prevalent in the general population at large.
- Types and Diversity of Vegetarian Diets
- Vegetarian Nutrition and Nutrients
- Vegetarian Nutrition and Vitamin B-12
- Vegetarian Nutrition and Lipids
- Vegetarian Nutrition in the Lifecycle
- Vegetarian Nutrition in Adolescence
- Vegetarian Nutrition in Pregnancy
- Vegetarian Nutrition and Chronic Diseases
- Vegetarian Nutrition and Cardiovascular Disease
- Vegetarian Nutrition and Obesity
- Vegetarian Nutrition and Type 2 Diabetes
- Therapeutic Diets and Attrition
The recommendations are based on the work performed by the project team. The number of supporting documents for these topics is below:
- Recommendations: Seventeen (17)
- Conclusion Statements: Thirty-nine (39)
- Evidence Summaries: Twenty-one (21)
- Article Worksheets: Ninety-five (95)
Application of the Guideline
This guideline will be accompanied by a set of companion documents (i.e., a toolkit) to assist the practitioner in applying the guideline. The toolkit will contain materials such as the MNT protocol, documentation forms, outcomes management tools, client education resources and case studies. It is currently under development and will undergo pilot testing through the ADA's Dietetic Practice-Based Research Network prior to publication.
The literature search will be repeated for each guideline topic on an annual basis to identify new research that has been published since the previous search was completed. Based on the quantity and quality of new research, a determination will be made about whether the new information could change the published recommendation or rating.
If a revision is unwarranted, then the search is recorded, dated and saved until the next review and no further action is taken. If it is determined that there could be a change in the recommendation or rating, then the supporting evidence analysis question(s) will be re-analyzed following the standard ADA Evidence Analysis Process (see ADA Evidence Analysis Manual).
When the analysis is completed, the expert workgroup will approve and re-grade the conclusion statements and recommendations. The guideline will undergo a complete revision every three to five years.
Medical Nutrition Therapy and Vegetarian Nutrition
The RD plays an integral role on the interdisciplinary care team by determining the optimal nutrition prescription and developing the nutrition care plan for vegetarian individuals. An RD knowledgeable or experienced in vegetarian diet counseling is preferred.
As part of the nutrition care process, the RD applies knowledge, skills and training to first conduct a comprehensive nutrition assessment in order to determine an accurate nutrition diagnosis(es) for the patient or client.
The RD then considers the patient's or client's lifestyle preferences and other health conditions to develop the nutrition prescription, according to the Vegetarian Nutrition Guideline. The RD may also consult other relevant, evidence-based nutrition practice guidelines, such as adult weight management, disorders of lipid metabolism, hypertension and Type 2 diabetes or other guidelines that will further influence the optimal treatment. The RD skillfully blends the macronutrient and micronutrient mix to achieve the appropriate diet prescription without compromising individual health needs and therapeutic goals.
During MNT intervention, the RD and the patient or client plan the course of action and the RD educates or counsels the patient or client on the appropriate diet, behavior and lifestyle changes in a manner and sequence that best meet the patient's or client's needs. Use of motivational interviewing or other proven strategies can further enhance adherence. Following the initial intervention, the RD monitors and evaluates progress over subsequent visits to determine whether the goals are being met and provides ongoing support and adjusts the nutrition prescription as needed.
Populations to Whom This Guideline May Apply
This guideline applies to people who follow or are interested in following a vegetarian dietary pattern.
Other Guideline Overview Material
For more details on the guideline components, click an item below:
Scope of Guideline
Statement of Intent
Implementation of the Guideline
Benefits and Harms of Implementing the Recommendations.
Clinical judgment is crucial in the application of these guidelines. Careful consideration should be given to the application of these guidelines for patients with significant medical problems.