Recommending a plant-based diet

Dr. Jan Hajek (biography, no disclosures)

What I did before

As an infectious disease physician, I was concerned about the public health threats posed by animal agriculture. The emergence of antibiotic-resistant bacteria and the spread of zoonotic viral infections were of particular concern.[1] I was aware of the United Nations report “Livestock’s Long Shadow”, that identified animal agricultural as one of the most significant contributors to greenhouse gas emissions and global warming.[2] I was aware of the terrible conditions that sometimes occur on modern farms and, along with most of us, wished to minimize unnecessary suffering to animals.[3] I was aware that more and more people are making dietary choices that avoid meat and other animal products because of health, environmental, and animal welfare concerns. I saw many patients in clinic that struggled with complications of diabetes (diabetic foot infection) and recommend foot care, quitting smoking, and medication adherence. However, I did not recommend plant-based (vegan) diets to my patients.

What changed my practice

A recent essay by Dr. Kim Williams, the president of the American College of Cardiology, in which he described the potential health benefits of a plant-based diet and why he began to recommend a healthy, low-fat, plant-based diet to his patients.[4] In his essay, Dr. Williams described a patient’s anecdotal experience with a plant-based diet. He also referred to a clinical trial in which patients randomized to interventions including a plant-based diet had dramatic improvements in coronary angiography.[5] He explained that although this trial and other larger observational studies are not as rigorous as other cardiology trials, the data to support the health benefits of plant-based diets are very compelling. In fact, the data are so compelling that the U.S. Medicare system now covers a cardiac rehabilitation program that includes a plant-based diet. In 2013, Kaiser Permanente, one of the biggest HMOs in the U.S., published an article encouraging physicians to routinely recommend a plant-based diet to their patients.[6]

In evaluating the evidence, the 2015 US Government Scientific Report of Dietary Guidelines Advisory Committee concluded that: “Consistent evidence indicates that, in general, a dietary pattern that is higher in plant-based foods, such as vegetables, fruits, whole grains, legumes, nuts, and seeds, and lower in animal-based foods is more health promoting and is associated with lesser environmental impact (GHG emissions and energy, land, and water use) than is the current average U.S. diet.”[7] The newly released US Dietary Guidelines now promote a plant-based diet for both environmental and heath benefits. Although a quantitative cut-off of 300 mg per day of cholesterol is no longer included, the guidelines were clear in stating that “this change does not suggest that dietary cholesterol is no longer important to consider when building healthy eating patterns” … “individuals should eat as little dietary cholesterol as possible while consuming a healthy eating pattern.” ⁷

For diabetes in particular, observational studies suggest that persons who follow a plant-based diet have a lower risk for diabetes, and an RCT demonstrated reductions in HbA1c in patients with diabetes randomized to a vegan diet compared to the standard American Diabetes Association diet.[8]

What I do now

As well as foot care, smoking cessation, and medication adherence, I now recommend a healthy, low fat, plant-based diet to patients with complications related to diabetes.

I often start by saying that studies have shown that a plant-based, vegan diet that avoids meat, eggs and dairy products has shown health benefits, particularly in patients with diabetes. Many patients already have some experience with vegetarian and vegan diets and are happy to discuss and learn more about plant-based diets.

Although it takes planning, the guidelines for a plant-based dietary approach to improve diabetes care are generally straightforward:[9]

1. Steer clear of meat and animal products like dairy and eggs;
2. Limit high fat foods like oils and pastries;
3. Choose whole grains, vegetables, legumes, and fruits;
4. Favour low glycemic index foods; and
5. Supplement with vitamin B12 [10]

Best of all, the diet does not require calorie counting; portion sizes of pasta, grains, legumes and vegetables do not need to be restricted.

The change to a plant-based diet low in saturated fats can lead to reduced insulin requirements. Patients should let their diabetes care providers know they are switching to a plant-based diet.

Despite the strong body of evidence supporting plant-based diets, many of us do not recommend a healthy plant-based diet and avoiding consumption of meat, dairy and eggs as a treatment option for diabetes or health promotion. This could be because of a lack of awareness of these diets or perhaps because our own personal eating habits affect our decisions about foods and how we counsel patients.

We should all consider recommending a healthy, low-fat, plant-based diet to our patients, particularly those with diabetes.

Handouts for Patients

There are many useful online resources, starter kits, and educational pamphlets available such as those from the Kaiser Permanente group [11] or the Physicians Committee for Responsible Medicine (PCRM). [12]

I found the PCRM website particularly useful. The website includes handouts and a 21-day vegan kickstart to support anyone interested in trying a 21-day trial of a low-fat plant based diet and also has information specific to patients with diabetes.

Additional reading

The nutritional update published by Kaiser Permanente provides an excellent overview of the evidence supporting plant-based diets and recommendations for how to discuss the dietary changes with patients.⁶

An article in the American Diabetes Association Spectrum journal has a very useful article on preparing to prescribe plant-based diets to patients for diabetes prevention and treatment.⁹

Finally a detailed, practical, evidence-based review of how nutritional requirements are met by following a plant-based diet – addressing concerns about protein, iron, calcium, and omega-3 fatty acid intake – has been recently published. [13]

References

1. Liu, Y-Y, Wang, Y, Walsh, TR et al. Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China: a microbiological and molecular biological study. Lancet Infect Dis. 2016;16: 161–168. (View with CPSBC or UBC)  DOI: 10.1016/S1473-3099(15)00424-7
2. Livestock’s Long Shadow: Environmental Issues and Options. United Nations Report (2006). View
3. Hutchinson, B. Canada’s largest dairy farm crippled by abuse allegations from undercover animal rights worker on his first mission. June 10, 2014. National post. Retrieved July 29, 2016. <http://news.nationalpost.com/news/canada/canadas-largest-dairy-farm-crippled-by-abuse-allegations-from-undercover-animal-rights-worker-on-his-first-mission>
4. Williams, KA. Cardio Buzz: Vegan Diet, Healthy Heart? July 21, 2014. Cardiobuzz. Retrieved 29 July, 2016. <http://www.medpagetoday.com/Blogs/CardioBuzz/46860>
5. Ornish D, Brown SE, Scherwitz LW  et al.  Can lifestyle changes reverse coronary heart disease? Lifestyle Heart Trial. Lancet 1990; 336:129-133. (Request with CPSBC or view UBC)  DOI: 1016/0140-6736(90)91656-U
6. Tuso PJ, Ismail MH, Ha BP et al. Nutritional update for physicians: plant-based diets. Perm J. 2013 Spring; 17(2):61-6. View
7. Dietary guidelines. 2016. US Office of Disease Prevention and Health Promotion. Retrieved 29 July, 2016. <http://health.gov/dietaryguidelines>
8. Barnard ND, Cohen J, Jenkins DJ, et al. A low-fat vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes. Diabetes Care 2006;29: 1777–1783. View
9. Trapp C, Levin S. Preparing to prescribe plant-based diets for diabetes prevention and treatment. Diabetes Spectrum 2012;25:38–44. View
10. What you need to know about vitamin B12. EatRight Onatrio. Retrieved 29 July, 2016. <http://www.eatrightontario.ca/en/Articles/Nutrients-(vitamins-and-minerals)/What-you-need-to-know-about-vitamin-B12.aspx#.V6DKQfmAOkp> From the article:  Health Canada recommends that all adults 50 and older, regardless of dietary meat, egg and dairy consumption, take vitamin B12 supplements or include foods fortified with vitamin B12 in their daily food choices.
11. The Plant-Based Diet. 2015. Kaiser Permanente. View
12. The Physicians Committee for Responsible Medicine. <http://www.pcrm.org/health/diets/kickstart>
13. Is a Vegetarian Diet Adequate? Medical Journal of Australia 2012; 1 Supplement 2. View