Role of a Whole Food, Plant-Based Diet in Preventing Disease, Part One

By Paul E. Lemanski, MD, MS, FACP

Medicines are a mainstay of American life and the healthcare system not only because they are perceived to work by the individuals taking them, but also because their benefit may be shown by the objective assessment of scientific study. Clinical research trials have shown that some of the medicines of Western science may reduce the risk of heart attacks, strokes and cardiovascular death, while others may reduce certain types of cancer.

In the first 80 installments of the Non-Medicated Life, informed diet and lifestyle have been shown to accomplish naturally for the majority of individuals most of the benefits of medications in the prevention and treatment of chronic medical conditions – such as hypertension, high cholesterol, diabetes and heart disease. With respect to diet, increasingly, nutritional research supports a predominately whole food, plant-based diet as optimal.

What constitutes such a diet and what is the evidence for its use is addressed below, in Part One. How you most easily may incorporate this approach into your daily way of eating will be addressed in the next installment of the Non-Medicated Life, as Part Two (April 2018 issue).

Quite simply, a plant-based diet means the majority of your caloric intake comes from plants: the leaves and stems of plants, the roots of plants, and the seeds of plants, including the seed bearing structure or what is commonly referred to as fruit. Further qualifying this by specifying the use of whole food emphasizes minimal, if any, processing. For example, minimally processing a wheat plant would include retaining the wheat germ by stone grinding whole wheat.

The evidence for the healthful benefits of this approach continues to accumulate and includes in vitro studies (test tube), in vivo studies including animal studies, and human population-based studies, observational studies, meta-analyses (a type of statistical comparison of similar studies), and randomized, controlled clinical trials.

For example, population-based studies, such as the Seven Countries Study, established lower rates of chronic disease in Mediterranean countries, with some of the lowest rates observed in Crete. While it was suspected that a predominantly plant-based diet played a major role in this observation, causation had to be established with a randomized clinical trial in which individuals were randomly assigned to eat a specified diet or a control diet, and were followed over time.

The Lyon Diet Heart Study established that a predominantly plant-based, so called “Mediterranean diet” as eaten in Crete, with higher amounts of omega-3 fats, reduced fatal and non-fatal heart attack by 70% – as compared to the prudent Western control diet. There were also lower rates of certain cancers noted during the five years of the study.

Over 20 years ago, the Lifestyle Heart Trial showed that in individuals with established coronary artery disease a whole food, plant-based diet, along with modest exercise and stress reduction could actually shrink cholesterol plaques in the walls of the heart arteries. Thus, plant-based eating not only can prevent disease, but it can also be instrumental in the treatment and, indeed, reversal of disease.

Population-based studies also have established extreme long, disease-free life in Okinawa, Japan; Sardinia, Italy; and Loma Linda California – examples of so called blue zones. Common to these diverse locations and genetically dissimilar inhabitants is a predominantly plant-based diet.

You may speculate why plant-based eating lead to lower rates of chronic disease as well as longer life. Certainly, humans evolved under circumstances of continual scarcity of food. On the basis of the structure of human teeth and our inability to synthesize vitamin B-12, humans are obligate omnivores rather than carnivores or herbivores. That said, it certainly is easier to find, kill, and eat a plant than to try to hunt down, kill, and then eat an animal. As a consequence, human biochemistry became adapted primarily to metabolizing plants.

Animal protein consumption as the predominant calorie source may be a relatively recent phenomena for the majority of humans. Admittedly, some humans who eat meat predominantly may have genetically adapted to animal protein over thousands of years. Inuit people from Arctic regions come to mind as healthy, predominantly meat eaters, who may have evolved a distinctly different biochemistry in order to cope with large amounts of animal protein. While a determination of whether any given individual may safely eat large amounts of animal protein is difficult to make, without perhaps genomic testing, the safe bet is that plant-based appears to be safer for most.

Recent studies such as the China Study suggest that as the amount of animal protein consumed increases, so does the cardiovascular mortality. Significant increases in animal protein consumption, especially with increases in saturated fat, have resulted in increases in serum LDL or “bad” cholesterol, the accelerated development of cholesterol plaque, and increases in the rates of premature coronary artery disease and stroke.

Plants are generally very low in saturated fat, and have relatively low calories for the volume consumed. Eating predominantly plants minimizes saturated fat intake. The larger volume consumed per calorie activates stretch receptors in the wall of the stomach, contributing to a feeling of fullness, and achieving satiety at lower total caloric intake. When we avoid consuming excess calories in this way, we also are more likely to avoid increases in body weight that contribute to co-morbid conditions such as diabetes, hypertension and sleep apnea – each of which may also increase cardiovascular risk.

The China Study also suggests that rates of cancer rise with increased consumption of animal protein. The precise mechanism for this increase is not clear, but it has been known for over 30 years that high temperature cooking – baking, broiling, grilling and frying of fish, chicken and red meat – produces carcinogens called heterocyclic aromatic amines (HCA) shown to cause cancer in laboratory animals.

Moreover, in humans, cancer rates are known to be higher in those who cook their meat, chicken and fish to well done, thereby maximizing exposure to HCAs. High temperature cooking of plants does not produce HCAs.

While diet alone cannot cure cancer, cancer patients consuming a predominantly whole food, plant-based diet can slow cancer progression and improve the quality of their life. In a recent study of men with less aggressive prostate cancer opting for “watchful waiting” (through serial biopsies of their prostates), those on a whole food, plant-based diet showed decreased progression to more aggressive cancer, with fewer requiring early aggressive treatment with surgery or radiation.

In summary, a predominantly whole food, plant-based diet requires that the majority of calories consumed come from a variety of plants and include, as appropriate, leaves, stems, roots, seeds and fruit. It requires, where possible the use of the whole plant minimally processed or, when not possible, to minimally process those parts which are used.

A predominantly whole food, plant-based diet may help to effectively prevent and treat both cardiovascular disease and cancer, and as such provide a firm foundation upon which to live a Non-Medicated Life. To find out how to easily incorporate this approach into your daily way of eating, stay tuned for Part Two.

Paul E. Lemanski, MD, MS, FACP (plemanski@capcare.com) is a board certified internist at the Center for Preventive Medicine, CapitalCare Medical Group in Albany. He is medical director of the Department of Community Medicine and Population Health at CapitalCare Medical Group. Paul has a master’s degree in human nutrition. He is an assistant clinical professor of medicine at Albany Medical College, and a fellow of the American College of Physicians.