V. Experience and Experimentation

There are many, interconnected reasons why I am here in India. The “official, proximal” reason is to study the role of diet in causing cancer. Good enough, let me start there. This business about diet and cancer is something that has interested me for a long time. All told, I have published several hundred peer-reviewed scientific papers on diet, dietary assessment, cancer, or some combination of these.

Any decent epidemiologist will tell you that the evidence supporting the role of diet in cancer is inconsistent. I have spent a good part of my career trying to explain why the results of studies conducted in the West should be expected to be inconsistent with results that we have obtained in our cross national comparisons. Those studies, published over about a 20-year period, have revealed associations between death rates for a number of different cancers (esophagus, oral cavity, lung, breast, prostate, bladder) and per capita consumption of meat and fat (positive correlations) and dietary fiber and other plant-based components (negative correlations). Laboratory animal studies that simulate the wide distributions of fat and other nutrients observed internationally also show significant associations between diet and many of these cancers. This, in turn, is consistent with a protective effect of primarily vegetarian diets and certain traditional foodways (e.g., East Asian, South Asian, Mediterranean, African cuisines) that are associated with lower rates of many cancers. So, much of the argument that I made to obtain this Fulbright Fellowship, and which also underpins the Mumbai Cohort Study, is based on these observations.

Many people in India are vegetarians, and even ones who aren’t tend to eat a diet that is primarily grain and plant-based. The traditional vegetarian Indian diet is loaded with flavorful and colorful things that are anti-inflammatory. It is now becoming more widely accepted that inflammation is important in causing a number of chronic conditions, including many cancers and heart disease, along with every “itis” under the sun (arthritis, diverticulitis, colitis, etc.). Acute inflammatory responses are necessary for wound healing; however, chronic inflammation is not good for you.

Plant foods are a rich source of bioactive phytochemicals; the biologic properties of which make them prime candidates to aid in cancer prevention. Phytochemicals provide protection and modify carcinogenesis by modulating several important biological pathways. They induce or inhibit Phase 1 (cytochrome P450 detoxification/activation) enzymes; modify carcinogen detoxification through Phase 2 (conjugation) pathways (to increase excretion of potentially harmful compounds); scavenge DNA reactive agents; suppress the abnormal proliferation of early, preneoplastic lesions; and inhibit certain properties of the cancer cell that are essential to their immortality and ability to spread beyond the host tissue or organ. So, there is increasing recognition of diet-induced modulation of inflammatory responses as being central to the processes of human carcinogenesis. The argument for this stems from the observations that pro-inflammatory and pro-oxidant states are closely linked to tumor promotion.

Now, I have always been a bit of a scientist. One of my earliest memories (at around 3-4 years of age) is of sitting on the bathroom floor with our heating fan disassembled. Ummm…. How does this work? When my mother discovered me and the fan she was distraught. When my father got home from work, I recall him being quite delighted (once he was certain that I had unplugged the thing). Apparently, I inherited a penchant for taking things apart. Also, I inherited a tendency towards arthritis. Well, I've been having these chronic joint pains for about the past year (especially my right ankle, for no apparent reason). On one of my long walks a couple days back I noticed (and mentioned this to Dr. Sarin) that after eating Indian vegetarian food for two weeks the joint pains are gone! Ummm …. How does this work?