Coronary artery disease (CAD) remains the leading cause of death in our country, with stroke, oftentimes the result of diseased blood vessels in the neck or head, only a few spots behind. Why are these ailments so prevalent? Along with cancer, which is a close second to CAD in causing mortality, these conditions are all highly influenced by our lifestyle choices.
The Standard American Diet (SAD) is loaded with saturated fats and processed foods full of sodium and sugar, and is severely lacking in fruits, vegetables, and whole grains. This has resulted in a population which is overfed but undernourished, often lacking intake of essential vitamins, minerals, fiber, and phytonutrients. Because of this, there is a high prevalence of cardiovascular risk factors such as obesity, high blood pressure, high cholesterol, diabetes, and sleep apnea, all of which contribute to the development of CAD and strokes. In fact, many states in the US have a prevalence of obesity that is more than 25%, and quite a few have a prevalence of more than one third of residents (see figure to left).
What exactly is cardiovascular disease? The inner lining of our blood vessels is called the endothelium. This is an active organ and not just a passive barrier. The cells of the endothelium produce a substance called nitric oxide which helps the blood vessels to dilate. It also has potent anti-inflammatory and blood-thinning effects. A variety of insults, including traditional cardiovascular risk factors and poor lifestyle habits, can lead to damage of the endothelium which allows LDL (bad) cholesterol to infiltrate. This process is accelerated by inflammation and blood stickiness. Most people in our country develop a lining of plaque at a young age, and this tends to cause progressive narrowing of the blood vessels over time.
When blood vessel narrowing reaches a critical threshold, oftentimes in the range of 70-80% or more, blood supply to vital organs is not enough to meet demand, particularly in the setting of physical or emotional stress. For this reason, people often first notice chest pains in these situations, as their heart does not receive enough blood, and the lack of oxygen to heart muscle cells results in discomfort. The same holds true for those with peripheral artery disease who experience pains in the legs when walking or in those with blockages in the arteries that supply blood to the brain who can experience symptoms of a stroke.
In some cases, the plaque build-up in the arteries never progresses to the point where a person has symptoms. Instead, the plaque becomes unstable due to being overfilled with cholesterol and agitated by inflammation. In this situation, the plaque can rupture suddenly and cause an immediate, complete blockage of a vessel. When this occurs in the arteries that supply blood to the heart, this leads to a heart attack. It is a surprise to most patients when they learn that heart attacks are typically result from blockages that cause less than 50% narrowing. That’s correct! The more severe blockages usually cause symptoms rather than heart attacks, while the less severe blockages tend to become more inflamed and unstable and lead to heart attacks.
When patients ask me why they had a normal stress test one day, and a heart attack a few days later, I tell them that they likely didn’t have a severe blockage when they had the stress test. That blockage occurred suddenly due to a ruptured plaque. And this is the same reason why placing stents in the coronary arteries to fix blockages generally doesn’t prevent heart attacks or save lives. Because we fix blockages that cause symptoms (stents are very effective in this situation), but not the ones prone to rupture and cause heart attacks.
This is also why strict control of risk factors which can lead to progression or instability of plaque is so vital. Medications such as the statins have been shown to be very effective at reducing heart attacks by stabilizing plaques and making them much less likely to progress or rupture. Aspirin has also been shown to save lives by reducing blood stickiness and inflammation, each of which has an important role in someone having a heart attack. Control of other risk factors such as diabetes and high blood pressure also helps to prevent further damage to endothelium, thus slowing the progression of plaque buildup.
Can diet have a similar effect in preventing or reversing buildup of cardiovascular disease? There are several small, but well conducted studies which demonstrate this to be effective.
Dr. Dean Ornish
Dr. Dean Ornish, the founder of the Preventive Medicine Research Institute, conducted a study to evaluate whether patients could make and sustain comprehensive lifestyle changes and, if so, whether these could stop progression of or reverse coronary disease without using cholesterol medications.
The study began in 1986 and followed 48 patients with moderate to severe coronary disease for 6 years. 28 patients participated in intense lifestyle change (lifestyle group) including a 10% fat, whole foods, vegetarian diet, regular aerobic exercise, stress management, and smoking cessation. The other 20 patients followed more modest, traditional heart-healthy recommendations (control group) and were encouraged to exercise.
At 5 years, approximately 75% of patients in each group remained in the study, confirming that patients could make and sustain lifestyle changes. Those in the lifestyle group experienced a 72% reduction in angina (chest discomfort associated with blockage in the heart arteries) versus a 36% reduction in the control group. To achieve even this rate of improvement, 3 patients in the traditional group required coronary angioplasty (a procedure in which a balloon is inflated inside the heart artery to lessen the severity of a blockage) to relieve symptoms while none of the intense lifestyle group did.
Overall, the rate of heart attack was 2.74 times greater, angioplasty was 2.4 times greater, coronary artery bypass surgery (CABG) was 3.4 times greater, and cardiac hospitalizations were 2.6 times greater in the control group.
Coronary angiography (an x-ray picture taken of the heart arteries after injecting dye) showed 7.9% reduction in coronary blockage in the lifestyle group while there was a 27.7% increase in the control group over a 5-year period (see figure to right).
Other remarkable findings included a drop in LDL (bad) cholesterol of 37.2% in the lifestyle group versus a 6% increase in the control group after 1 year. At 5 years, 60% of those in the control group required statins (medications to lower cholesterol) while no one required these in the control group.
Finally, those patients in the lifestyle group experienced an average weight loss of 12.8 pounds which was maintained over 5 years.
Dr. Caldwell Esselstyn, Prevent and Reverse Heart Disease
One of my the most remarkable groups of patients studied was a cohort managed by Dr. Caldwell Esselstyn. Dr. Esselstyn is one of the major figures recognized in promoting a plant-based diet, and is featured in the documentary Forks Over Knives. He was a former Olympic rower and was a general surgeon at the Cleveland Clinic. Despite having grown up on a farm where he mostly consumed dairy and meat, he had an epiphany later in life and began to follow a rigid, oil-free, vegan diet. He saw that traditional medicine was failing many patients and realized the impact dietary change could have on improving health. He approached cardiovascular physicians at the Cleveland Clinic and offered to recruit cardiac patients into his diet and lifestyle program. After being initially rejected for his unconventional approach, he ultimately enrolled 23 patients with refractory chest pain from coronary artery disease or leg pain from peripheral artery disease. These patients had exhausted all other therapeutic options including optimization of medications and procedures to open blood vessels.
Once they were part of his study, these 23 patients were required to follow a strict plant-based diet with no added oils or fats, even from plant sources. They received regular individual and group counseling, and were followed for more than a decade. The results were astonishing.
To begin with, the average total cholesterol dropped from 266 mg/dL to 132 mg/dL (remember that a level of less than 150mg/dL is ideal and is associated with an absence of development or progression of coronary disease). In the 8 years leading up to the study, these patients experienced a total of 49 cardiovascular events including unstable angina, heart attacks, and strokes. Over the next 11 years, there was only a single event in a patient that stopped the diet for 2 years.
11 patients had coronary angiography which again demonstrated a 7% diameter reduction in coronary narrowing (similar to what was seen in patients enrolled in Dr. Ornish’s sudy). Some patients showed nearly complete resolution of blockage.
Additionally, even within a matter of weeks of starting the lifestyle change, patients were noted to have improvement in blood flow patterns on nuclear stress test images (see figure to right). While it is unlikely that there was significant improvement in artery blockage in this short period of time, dietary change likely affected the health of the blood vessels, allowing them to dilate appropriately with stress.
Dr. Caldwell Esselstyn, A Way to Reverse CAD?
Dr. Esselstyn went on to perform a larger, randomized study to once again evaluate the effects of lifestyle on cardiovascular disease. This time he enrolled 198 patients with cardiovascular disease in a similar plant-based eating program free from oils and fats.
With close follow-up, he found that 89% were able to stick with the diet over the next 3-4 years, demonstrating again that motivated patients can make and sustain lifestyle changes.
The results were once again remarkable. In adherent patients, not only was there an average weight loss of nearly 19 pounds, but there was only one cardiovascular event (heart attack, stroke, etc.) out of 177 participants. 104 of 112 (93%) had fewer symptoms of angina, and reversal of coronary artery blockage was noted in 39 patients by coronary angiography or stress testing.
In the 21 patients who were not able to follow the dietary changes, 64% (13 of 21) had an event, again demonstrating the profound influence diet can have in managing cardiovascular disease.
In summary, these small, but well-conducted studies clearly demonstrate that motivated patients can make and sustain lifestyle changes. These changes can favorably influence multiple risk factors for cardiovascular disease, and ultimately reverse coronary artery plaquing and reduce cardiovascular events such as heart attacks and strokes.
Ornish, Dean, MD, et. al. “Intensive Lifestyle Changes for Reversal of Coronary Heart Disease.” JAMA, December 16, 1998. Vol 280, No 23.
Esselstyn, Caldwell, MD, et. al. “A way to reverse CAD?” The Journal of Family Practice, July 2014. Vol 63, No 7.
Hu, Frank. “Plant-based foods and prevention of cardiovascular disease: an overview.” Am J Clin Nutr 2003;78(suppl):544S-51S.
Campbell, T Colin, PhD. The China Study. Dallas. BenBella Books, 2005.
Esselstyn, Caldwell, MD. Prevent and Reverse Heart Disease. New York. Penguin Group, 2008.