Just about any publication that explores the role of diet in disease invokes Hippocrates’ famous dictum, “Let food be thy medicine, and let medicine be thy food.” Actually, there is no record of the famous ancient Greek physician ever having said this, although it is clear from the writings of the Hippocratic authors that Greeks did believe that disease and food were linked. “Hippocratic authors” is the correct terminology because historians concur that the works attributed to Hippocrates are compilations of his own writings and those of a number of his followers.
It isn’t surprising that the Greek physicians associated food with disease because obviously without food there is no life. However, whatever dietary interventions were recommended were not based on any evidence, but rather on the belief that the body is constituted of the four humours, namely blood, phlegm, yellow bile and black bile. Illness was due to an imbalance in these humours and was to be treated with foods that would restore balance. For example, pain in the joints was described as being due to blood being contaminated and coagulated by phlegm and bile. The treatment was barley water. In terms of science this makes no sense, but undoubtedly some patients found relief through the power of the placebo.
We have come a long way from ancient Greek medicine and today our knowledge about nutrition is quite extensive especially when it comes to prevention of disease. The role of vitamins, minerals, proteins, fats and carbohydrates in the diet is well established, and we are also getting a handle on how some naturally occurring compounds in plants may contribute to the maintenance of health. However, the science of treating disease with food is much more nebulous.
I have been asked by several people to comment on a book by Dr. William Li that has the alluring title, “Eat to Beat Disease.” I first became acquainted with Dr. Li when I was looking into the work of Dr. Judah Folkman, the recognized pioneer of anti-angiogenesis research. “Angiogenesis” is the term used to describe the growth of blood vessels, and consequently “anti-angiogenesis” is the impairment of blood vessel growth. Tumours need nutrients to grow and they generate blood vessels through which these are supplied. In theory then, any factor that has anti-angiogenesis effects can rob a tumour of nutrients and cause it to shrink. Dr. Li trained under Folkman and went on to found the “Anti-Angiogenesis Society” that fosters research aimed at restricting tumour growth. He is a very sound researcher and has published widely about angiogenesis in top journals.
In 2019, Dr. Li ventured into the area of nutrition with his book, "Eat to Beat Disease." It has been a major best seller and his TED talk on the same topic has been viewed by millions. He is undoubtedly an "influencer." The question is to what extent one can benefit from his influence. Dr. Li is far from being a master of woo as some have claimed, but some of his conclusions about the relationship between diet and disease should be marked with an asterisk.
He describes, correctly, that health depends on a number of factors that include a properly functioning immune system, diversity of gut bacteria, an ability to eliminate cancer stem cells, effective repair of damaged DNA and impairment of the growth of blood vessels that feed tumors while enhancing the growth of “good” blood vessels such as the ones that feed the heart. He provides ample literature references of how nutrients in food can affect these determinants of health. These include “bioactives” in plums, apples, chicken soup and olive oil to curb inflammation. Anti-angiogenesis factors are to be found in salmon, tomatoes, onions and blueberries. Purple sweet potatoes battle cancer stem cells while compounds in oysters and turmeric are said to repair errors in DNA. Immune system activators are to be found in broccoli sprouts, peppers, garlic, liquorice root and mushrooms. Eggplant encourages the growth of “good” blood vessels. Walnuts, yogurt, sauerkraut, beans, kiwis and cocoa encourage the growth of “healthy” bacteria in the gut. The problem, though, is that the studies from which all this information is drawn come from laboratory studies using cells or animals. Extrapolating these studies to humans is not totally unreasonable, but is a touch too cavalier.
There is absolutely no doubt that along with exercise and favourable genetics, diet is a key preventative when it comes to disease. But curing disease by eating specific foods is another matter. The body is not a large test tube and humans are not giant mice. A substance that has an anti-angiogenesis effect in the laboratory cannot be assumed to have a similar effect in a cancer patient. Indeed, there is also the issue of placing an extra burden on a patient who may believe that their cancer isn’t “being beaten” by the foods they are eating because they have not properly adhered to the recommendations. That being said, there is nothing harmful about Dr. Li’s recommendations. Indeed, they are pretty well in step with what most researchers recommend, namely a diet based on fruits, vegetables, whole grains, nuts, extra-virgin olive oil and fish with limited meats and processed foods. Indeed, an analysis of nutritional studies reported in 2018 in the Journal of the American Medical Association estimated that just ten foods account for nearly half of all US deaths from heart disease, stroke and type 2 diabetes. These deaths occur due to people eating too few nuts, seeds, seafood omega-3, vegetables, fruits and grains, or eating too much sodium, processed meat, unprocessed red meat, and sugary beverages.
I think Dr. Li overplays the “Eat to Beat Disease” card, but his views about anti-angiogenesis and nutrition are sound. While his opinion about treatment of various ailments with specific foods falls into the speculative category, his dietary recommendations in terms of prevention of disease are on a firm footing. Given the rather sad state of the average “western” diet, most people would benefit from paying heed to Dr. Li’s nutritional advice. “Eat to Beat Disease” is worth reading, but “Eat to Prevent Disease” would have been a more realistic title.
