Campbell’s initial experimental research was designed to understand a most unusual and provocative observation in what appeared to be a higher risk for liver cancer in young children in the Philippines among the few families consuming the most dietary protein. This observation was only anecdotal and would have gone unnoticed were it not supported by experimental animal findings published by a research group in India whose authors who did not make this interpretation. These preliminary findings were sufficient to support a request for generous research funding from NIH, particularly a research project that was to continue for the next 27 years.

The main purpose of Campbell’s research was twofold: to validate this highly provocative observation which seemed to link increased liver cancer with dietary protein consumption, and, assuming its validity, to investigate the cellular mechanisms responsible for the effect. Both objectives were met over the next two decades, with a pivotal discovery by Dr. Campbell made in 1983.

Although preceded by suggestive experiments and followed by additional experiments on explanations and consequences, Dr. Campbell discovered, in a rodent study, that cancer development is controlled by nutrition.1 Subsequent experiments refined this observation in important ways, including the showing that cancer development by nutrition is reversible, forward and backward, short-term and long-term,2-4 thus challenging the common belief of cancer researchers and clinicians that cancer is a genetic, irreversible disease5 which has prompted cancer treatment protocols based on the killing of cancer cells.6 This finding on nutrition primacy was shown by alternating the amount7 and kind (animal vs. plant)8 of dietary protein, which responsiveness occurs within a dietary range of 10 to 20% of diet calories that lies above the amount of dietary protein recommended for optimum health (8 – 10%).

This finding, of unusual effect size and replicated in varied ways, was unequivocal, eventually leading to a large number of mechanistic studies to further refine and extend the initial observation (recently reviewed6), finally leading to a more expansive human study in rural China beginning in the early 1980s to seek confirmation.9 The New York Times described this as the “most comprehensive large study ever undertaken of the relationship between diet and the risk of developing disease”, calling it the “Grand Prix of epidemiology.”10 Dr. Campbell and his team gathered data on 367 diet, lifestyle and disease mortality characteristics among 130 villages that yielded more than 8,000 statistically significant associations between diet, lifestyle and disease. The results of this historic study supported and complemented 9,11 the initial laboratory studies to confirm that a whole food plant-based diet is optimal for human health. Most importantly, Dr. Campbell’s research has led to substantially different algorithms for understanding nutrition12 and cancer6, both of which are based on a wholistic rather than a reductionist perspective that describes, in reality, how nutrition functions and diseases like cancer occur.13

Importantly, this discovery that a whole foods plant-based diet is optimal for human health has now been confirmed in hundreds, and likely, thousands of human case studies, by medical practitioners who have used a plant-based diet to not only reduce disease risk in their patients, but to treat a wide range of chronic conditions, including serious conditions like cancer, heart disease and type 2 diabetes.

In addition to Dr. Campbell’s primary discovery, his research elucidated new principles of nutrition, including: 1) the ability of nutrition to control the expression of gene-dependent diseases, thus emphasizing responsibility and control of health by individuals, 2) the presence of countless, simultaneously acting mechanisms for each nutrient, among countless nutrients and nutrient -like substances, to produce outcomes, 3) the ability of nutrition not only to prevent future disease outcomes but also to reverse (i.e., treat) existing, diagnosed diseases, and 4) the likelihood that nutrients acting in isolation (as in nutrient supplements) will not have the same property as when acting in the context of whole food. Together with additional evidence, the recommended level of dietary protein—which often motivates food choice and for animal-based food—can be readily provided by a whole food plant-based lifestyle. Most importantly, these findings provided an understanding of nutrition that is wholistic (‘w’ intended), which enables our understanding of the basis for serious diseases like heart disease, cancer and diabetes.