Whole plant-based diet is a lifestyle for managing type 2 diabetes.
Primary: Canadian Endocrinologists
Secondary: Registered dietitians, certified diabetes educators in Canada
Type 2 diabetes (T2D) is a serious health concern in Canada. In 2022, more than 4 million Canadians were diagnosed with diabetes.1 That's about 10% of our country's entire population. This percentage rises to 14% when factoring in cases of type 1 diabetes and undiagnosed type 2 diabetes.1 Individuals living with diabetes experience a twofold higher risk of all-cause mortality than those without diabetes.2 It's time to act now to end diabetes!
Incorporating nutrition therapy alongside other diabetes care components can yield significant clinical and metabolic benefits, including a reduction in glycated hemoglobin (A1C) by 1.0% to 2.0%.3 But what type of nutrition therapy is most effective?
Observational studies have shown that adopting a whole plant-based diet (WPBD), which prioritizes whole grains, legumes, vegetables, fruits, nuts, and seeds, reduced the prevalence of type 2 diabetes.4 Intervention studies have also shown that WPBD enhanced multiple diabetes risk factors such as body weight, cardiovascular disease, insulin sensitivity, glycated hemoglobin levels, oxidative stress, and renovascular markers.4 Furthermore, patients who adopted a low-fat whole plant diet could put diabetes in remission by reversing insulin resistance and reducing the need for diabetes medications.4
Nevertheless, previous analyses of national data showed that Canadians' vegetable and fruit intakes are consistently low, and the majority of Canadians do not meet national recommendations.(5'6) Thus, there seems to be a disconnect between what clinicians offer patients as a nutrition guideline and what patients believe they should do. Moreover, The concept of a whole plant-based diet is elusive. Patients and clinicians face challenges in defining the WPBD precisely due to its overlapping nature with other plant-predominant dietary approaches, such as the vegan, Mediterranean, and vegetarian diets. This needs assessment addresses the barriers to adopting WPBD as a lifestyle.
Type 2 diabetes is a concerning growing disease in Canada, with an average of 549 Canadians diagnosed with diabetes every day; that is approximately 201,000 new cases per year.2 The financial cost of this disease burdens the Canadian healthcare system. Diabetes Dialogue, the official publication of Diabetes Canada, remarked in November 2019:
"Diabetes can be expensive — treating the disease will cost our healthcare system nearly $30 billion this year." Laura Tennant 7
Although diabetes supplies are typically covered by provincial insurance for most Canadians, many individuals still face high out-of-pocket costs due to inadequate coverage. Canadians with diabetes incur expenses exceeding 3% of their income or surpassing $1,500 per year for prescribed medications, devices, and supplies.7 Kimberley Hanson, Diabetes Canada's executive director of federal affairs, raised her concerns to Diabetes Dialogue:
"We know that the vast majority of Canadians with diabetes struggle with what is considered “catastrophic costs.” Many medications and supplies people require are not covered unless the individual has an extended medical plan." 7
Healthcare providers, including endocrinologists, registered dietitians and certified diabetes educators, should look for cost-effective interventions and communication strategies to become more involved in helping their patients adopt healthier lifestyles. One way to accomplish this is by guiding patients to diets that reverse insulin resistance, the root cause of type 2 diabetes.
The whole plant-based diet is a dietary pattern that emphasizes consuming unprocessed plant-based foods and discouraging the intake of meats, dairy products, eggs, and refined/processed foods while maintaining a calorie-balanced approach to nutrition. This dietary pattern has received increasing interest in the past few years because of its effectiveness in managing various chronic diseases, including cancer, cardiovascular disease, obesity, hypertension and type 2 diabetes. 8,9
The American Dietetic Association (ADC) and Dietitians of Canada (DC) have acknowledged vegetarian and vegan diets as suitable options for medical nutrition therapy in individuals with type 2 diabetes.10 Dietitians in Canada have stated that vegetarian and vegan diets are nutritionally complete and can conform to the guidelines for managing type 2 diabetes as long as patients plan and follow them appropriately.11 However, are these dietary patterns the same as WPBD?
Despite the knowledge of health benefits associated with plant-based diets, randomized controlled trials (RCTs) have not been thoroughly investigated to define the term “plant-based accurately.” Therefore, clinical practice guidelines (CPGs) have not provided in-depth quantitative data describing the effectiveness and application of this diet outside experimental settings. Furthermore, the current research has not fully examined how the perceptions of both patients and clinicians could act as a barrier to recommending and adopting this dietary pattern in clinical and community settings. For knowledge translation, Plant-Based Canada is collaborating with many stakeholders to address these gaps and improve outcomes for the alarming level of diabetes in Canada.
The objective of Plant-Based Canada12 is to provide education to the public and healthcare professionals regarding the scientifically supported advantages of plant-based whole-food nutrition.
Gap 1: The lack of comprehensive randomized controlled trial investigations led to an elusive definition of WPBD and vague recommendations.
Sufficient pieces of evidence support using a plant-based dietary approach in nutrition therapy for individuals with type 2 diabetes. Systematic reviews and meta-analysis of the available randomized controlled trials have shown that the plant-based dietary patterns resulted in clinically meaningful improvements in HbA1C, lipid panel and fasting blood glucose in people with type 1 and type 2 diabetes.(12,13) However, the definition of this diet remains challenging. According to a survey study published in the American Journal of lifestyle medicine, which included 200 medical students and family medicine residents, 85% of respondents claimed to be familiar with the health benefits of a whole food, plant-based diet; however, 69% expressed a desire for additional information or evidence before recommending it to patients.14 Furthermore, responders believed there was a lack of evidence supporting the effectiveness of WFPB.14 This perception contradicts the existing body of robust data that strongly supports using plant-predominant and plant-exclusive diets, including the WFPB diet, for preventing and managing chronic diseases. This discrepancy emphasizes the urgent need for incorporating evidence-based nutrition education into medical training, which begins by defining the term "plant-based" and "whole food."
What is a WPBD?
The whole-foods, plant-based diet is a low-fat diet emphasizing plant-based foods while minimizing animal products and avoiding processed foods. The extent of including animal products can significantly influence the composition of a whole plant-based diet. Nevertheless, the fundamental principles of a whole-food, plant-based diet are as follows:
Emphasizing whole food.
Avoiding processed foods.
Limiting or avoiding animal products.
Focusing on plants, including vegetables, fruits, whole grains, legumes, seeds, and nuts.
Excluding refined foods, like added sugars, white flour, and processed oils.
It should be noted that followers of WPBD also pay attention to food quality, with many advocates promoting locally sourced, organic food whenever possible.8 Also, this dietary pattern is low in fat — daily calorie intake from fat should be between 15 - 25%. (15,16) A 2023 review paper published in the European Journal of Nutrition defined plant-based as "a dietary pattern in which foods of animal origin are totally or mostly excluded.17
A low-fat plant-based diet for optimal health: scientific evidence
While extensive research substantiates the myriad health advantages of a low-fat plant-based diet, we focus on two large randomized clinical trials with type 2 diabetes subjects. The first study conducted by Branard ND et al. was a randomized, controlled 74-week clinical trial involving 99 participants with type 2 diabetes. This trial compared the effects of a low-fat plant-based diet (10% of energy from fat) to a conventional diabetes diet as a potential treatment for type 2 diabetes.15 While both diets improved glycemic control, the low-fat plant-based diet was associated with more reductions in cholesterol levels, body weight, and medication use compared to the conventional diabetes diet.15
The second study by Kahleova et al. compared WPBD to conventional diets regarding insulin resistance and oxidative stress markers in individuals with type 2 diabetes.16 This was a 24-week, randomized, open, parallel design with 74 patients with type 2 diabetes. The results indicated that a plant-based diet, defined as 25% of energy from fat, improved insulin resistance and oxidative stress markers more effectively than the conventional diet.16 In a subsequent study, the same authors also measured participant-reported quality of life, mood, and eating behaviours at baseline, 12 weeks, and 24 weeks.18 The results indicated significant improvement in all three areas for six months. Participants reported better quality of life, increased positive mood, reduced emotional eating and less reliance on external cues. These findings suggest that this dietary pattern may have benefits beyond glycemic control in individuals with type 2 diabetes and could be sustainable in the long term.18
The need for a better definition
Because of sufficient evidence, Diabetes Canada recommended a plant-based diet among the dietary patterns for managing type 2 diabetes.19 However, the absence of precise macronutrient distribution and food sources guidance for this diet makes it harder to follow. Moreover, the terms vegetarian, vegan, and whole plant-based diets are used interchangeably in medical literature and can be misleading and confusing (20,4). A review analyzing the term "plant-based" diet in the medical literature found that 50% of clinical trials use the term interchangeably with vegan, meaning that the interventional diet did not include foods of animal origin. 30% of studies had dairy products, and 20% of the interventions focused on a semi-vegetarian eating pattern.21
Education needed: Doctors need education on the safety and efficacy of a WPBD by reviewing the current literature and scientific evidence. Insights that can be gained through education include:
(1) Relating the WPBD and the prevalence of type 2 diabetes.
(2) Defining WPBD and related terminology.
(3) Analyzing and comparing the WPBD with other dietary patterns.
(4) Understanding the mechanism of insulin resistance reversal by following WPBD.
(5) Assessing the quality and strength of WPBD for diabetes management and beyond.
Gap 2: Doctors don't receive a nutrition curriculum in medical school: limited knowledge about the concept of WPBD for chronic disease management, and a gap in practical clinical settings
Nutrition has been mostly absent from preclerkship medical training in Canada and other countries for decades.(22-24) Many schools dedicate less than 25 hours to the subject over five or six years.25 Studies have highlighted that many healthcare professionals, including doctors, perceive themselves as having insufficient knowledge and skills in nutrition counselling.(26,27) This is reflected in many ways during their practice. For example, they feel less confident in addressing complex dietary issues or find it hard to keep up with the latest research in the field. This lack of emphasis on nutrition can make healthcare professionals ill-equipped to provide detailed dietary guidance.
A 2022 survey-based study published by the American Journal of Lifestyle Medicine evaluated medical students' and family residents' general perceptions of their current level of nutrition and regarding a whole-foods, plant-based diet.14 According to the study, many respondents felt they lacked adequate nutrition training during their medical education and expressed a strong desire for curriculum reform that would address the importance of dietary counselling for managing chronic diseases. Trainees recognized the complexity of applying nutritional guidelines in patient care and the perceived gap between what they learned and the practical application of these concepts in clinical settings.
"We need more instruction on what works for patients and how to help real people, not just the ideal 70-kg man or a hypothetical patient in a question stem."14
Additionally, students acknowledged WPBD as a healthy diet that should be taught alongside other healthy dietary patterns rather than being presented as the exclusive or sole approach to eating.14
Providing additional nutrition training to healthcare professionals, including WPBD guidance, is necessary. This could be facilitated by developing educational workshops and standardized, user-friendly practice guidelines. These strategies would serve as a valuable tool to support healthcare professionals in educating their patients about the benefits and implementation of WPBD for chronic disease management.
Education needed: Clinicians will benefit from WPBD nutrition workshops and training by:
(1) Applying WPBD nutrition training to clinical practice.
(2) Creating a WPBD user guide, which will facilitate communication with patients.
Gap 3: Despite some level of awareness, doctors and diabetes educational centers don't recommend WPBD due to low acceptability and the absence of practical guidelines.
Regional Diabetes Education Centre in Ontario conducted a pilot study to explore the level of awareness and perceptions of plant-based diets among 98 patients attending the Diabetes Education Centre and 25 healthcare providers.28 Participants were given a questionnaire to assess their knowledge and perceptions of plant-based diets and their potential to improve diabetes management. The questionnaire also included questions about dietary habits, medication use, and other health-related information.28
According to the survey, patients' awareness and interest in the benefits of a plant-based diet for diabetes management were below optimal levels, and the perceptions of diabetes educators and clinicians may influence this. Also, 72% of the providers at a diabetes clinic were aware of the benefits of a WFPB diet in managing and treating type 2 diabetes, yet only 32% recommended this diet to their patients due to low perceived acceptability. According to doctors, one of the primary reasons for hesitating to advocate a plant-based diet is that it is perceived as challenging to adhere to, and patients may resist it.28 Moreover, healthcare staff reported a lack of clear clinical practice guidelines and scientific evidence as another factor contributing to their hesitation in recommending the diet.28 A vague food and practical guidelines challenge nutrition counselling with inconsistent understanding and recommendations.
To address patients' and clinicians’ perceptions, nutrition professionals need to establish WPBD-specific education programs in community-based diabetes centers. These programs can be developed in collaboration with local nutrition services providers, such as community kitchens, grocery stores, and the local food network. This partnership would facilitate the exchange of teaching experiences, provide new perspectives among educators, and enable the sharing of teaching resources to clinicians.
Education needed: Doctors, registered dietitians, and patients will benefit from creating effective communication strategies through diabetes education centers by:
(1) Addressing taste preferences, social factors, and cost when promoting plant-based diets as a diabetes management strategy.
(2) Delivering education in a small group or one-on-one setting.
(3) Incorporating adult education principles such as hands-on activities, cooking lessons, and group discussions.
(4) Conducting motivational interviews to identify challenges and promote behavioural change.
Plant-based diets can enhance insulin sensitivity and glycemic control, improving the management and potential reversal of type 2 diabetes, which can lessen the burden on the Canadian healthcare system. It is evident that education plays a crucial role in enhancing the understanding and confidence of clinicians and patients regarding the whole food plant-based diet lifestyle. Investing in comprehensive educational initiatives and resources can empower healthcare professionals and individuals to embrace and effectively implement this health-promoting approach. Clinicians and patients need an accurate definition of WBPD and a comprehensive rationale for incorporating this dietary pattern within the Canadian clinical practice guidelines for individuals diagnosed with type 2 diabetes.
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28. Lee V, McKay T, Ardern CI. Awareness and perception of plant-based diets for the treatment and management of type 2 diabetes in a community education clinic: a pilot study. J Nutr Metab. 2015;2015:236234. doi:10.1155/2015/236234