Perspective: Which Diet is Good for Your Heart?

Chris Guerin, MD
healthy foods

Why is it so hard to reach a consensus on this topic? In the 1980s and 1990s, the American Heart Association (AHA) recommended a low-fat diet. Over the years, the AHA recommendations have changed and gradually increased the amount of fat in the diet, but only mono- and poly- unsaturated fats; saturated fats and trans fats are still not recommended. Fortunately, trans fats are now rarely used in this country due to government regulation. The incidence of heart disease in this country is decreasing, but is it because we are changing our diet habits, or do we have better methods to detect and/or treat heart disease?

Some cardiologists promote an extremely low-fat, cholesterol-restricted, plant-based diet, as some data suggest that it works! Particularly, the LIFESTYLE Heart trial looked at treating patients with comprehensive lifestyle changes without using medications. It was found that 82% of patients had regression of atherosclerosis, as opposed to the control group, in which 53% had progression of atherosclerosis. Some people have attributed these results to the non-diet aspects of the program, such as meditation and exercise.

Another very well-known diet, the Mediterranean diet, has been touted as the best diet for cardiovascular disease (CV) prevention. It is certainly well proven to be better than the Standard American Diet (SAD - notice the irony of this acronym!) and sustainable. It has been assumed that the benefit comes from replacing most fats, such as butter and cream, with extra virgin olive oil and canola oil margarine. People who advocate for the Mediterranean diet still recommend cheese and allow occasional red meat. In one recent study, there was a 25% decrease in cardiovascular events in those following the Mediterranean diet.

Another study, that I found personally encouraging, included nearly 200 patients who were advised to follow a whole food, plant-based, very low-fat diet. Over a course of 3.7 years, 0.6% of those who were adherent to this regimen had cardiovascular events compared to 66% who did not follow the diet. Even our most powerful lipid lowering medicines cannot come close to replicating these types of results!

In the popular press, there are cardiologists and cardiac surgeons who claim they have the answers. One popular program suggests that lectins and beans are undesirable, and they have a proprietary formula for sale. Lectins are proteins that bind to sugars and can decrease nutrient absorption. Multiple other books demonize grains. Time magazine claimed, “Butter is Back!” on its cover in one of its issues. There are many other examples, but how can we have so many people and authorities with such diverse solutions? No wonder everyone is still confused.

Part of the problem is that it’s hard, and/or unethical, to do long-term studies and compare diet interventions on groups of people. For one thing, we can’t have patients in locked rooms for decades while we manipulate and observe what they consume! Another issue is that certain populations are genetically more likely to get heart disease, diabetes, cancer, obesity, etc. Lastly, it is possible that a “one size fits all” approach may not be the answer. There are other factors that play a role such as food allergies, celiac disease, etc., that one must consider when recommending a certain diet.

Here is my own personal story, and how it has evolved over the last 15 years. Being an endocrinologist, I was devastated to diagnose myself with type 2 diabetes mellitus at age 50! On top of that, I had a coronary artery calcium score (EBCT) that indicated atherosclerosis. My BMI was 26, which put me in the overweight category, despite exercising vigorously and eating what I thought was a healthy diet. Many of my family members died prematurely of strokes and heart attacks from their late 40’s to early 60’s. (My dad developed his diabetes at age 38 and was dead from a stroke at age 51). I was aware that I had all the markers of insulin resistance, with elevated triglycerides, low HDL (good cholesterol), and excess small, dense LDL (bad cholesterol.) I was disheartened that it looked like I would follow the same path as my family members. Around that time, one of my patients gave me the book, The China Study. This book brought to the forefront many of the problems of the Western diet, and showed from an epidemiologic standpoint what happens to heart disease, diabetes, cancer, and obesity as our diet becomes more processed (spoiler alert-it’s not good!). Since I grew up in the Midwest and consumed a lot of meat and dairy, I wasn’t sure I could really implement what would be a drastic lifestyle change for me. However, I had two young children, so I decided to give it a try for three weeks. Surprisingly, I began to appreciate vegetables and fruits that I wouldn’t have tried previously, and I was always full! I lost over 20 lbs of weight the first year, and I have kept it off for 15 years. Initially, I didn’t even tell people about my new diet as I was afraid that I might have developed cancer or some other disease, which caused the weight loss.

I have to be honest. From 2004-2013, I mostly followed a whole food, plant-based diet 98% of the time. I would occasionally have a bite of salmon, or a slice of pizza with cheese, but otherwise stayed the course. What happened in 2013? I attended a lecture and read articles by Stanley Hazen from the Cleveland Clinic, who brought to the forefront his work on trimethylamine N-oxide (TMAO). TMAO is formed in the gut from meat and dairy and leads to atherosclerosis. It has always bothered me that 2/3 of patients who are on cholesterol-lowering medications such as statins will still get strokes and heart attacks. This persistent danger is known as “residual risk.” Too many people (doctors included) think they can eat whatever they want if they are on a statin, and they are surprised when I bring up the topic of residual risk. In the case of TMAO, it is really the type of bacteria in our colon that promotes health or disease. We have ten times the number of bacteria in our body than the number of human cells. Probiotics are advertised to change the gut microbiome, but I think this is wishful thinking. It is what we eat day in and day out that make a difference.

Despite being older at age 65, I think I am much healthier now than 15 years ago. My hemoglobin A1c (HbA1C), which denotes the average blood sugar for the past 3 months, decreased from 6.7% (within diabetes range) to 5.3% (within non-diabetes range) and my lipid panel is markedly improved. I take vitamin B12, vitamin D3, metformin 1000 mg, and rosuvastatin 5 mg daily. I kept my weight stable and my BMI is now 23 instead of 26. I have also become much more aware of the environmental and ethical aspects of not eating meat and dairy. I don’t proselytize, but I do share my experiences with my friends, family, and patients when they ask me about why I am a “vegan.” First of all, I let them know I don’t like that terminology; you can be a junk food vegan, and still have cookies, sodas, and fries! I prefer the designation plant-based, whole food. If people want more information, I encourage them to watch “Forks Over Knives” or go to Dr. Greger’s website as a good place to start to learn about this and get motivated.

So, in summary, I think a whole food, plant-based diet is a diet to consider. It has been shown to be helpful in preventing and mitigating heart disease, diabetes, cancer and obesity. I personally know it works, and encourage you to give it a try!