It says a lot about the Nobel Prize in Medicine that Ernst Wynder, co-discoverer that smoking causes cancer, never got one. Wynder was also one of the founders of modern epidemiology. Here’s what he believed about the Nurses’ Health Study:
He had a strong skepticism about methods of dietary assessment, and always felt that the failure of analytic studies such as the Nurses’ Health Study to report associations between cancer and diet were due to a combination of random misclassification related to the imprecision of food frequency questionnaires and the narrow range of nutrient intake within a given population. I feel certain that he would have criticized the recent negative findings from the Women’s Health Study on dietary fat and breast and colon cancer on similar grounds. This was one area where he felt that international comparisons at the ecological [country-by-country] level provided better etiologic support than [more] analytic studies, and he published many studies over a period of decades to make just that point.
He developed a friendship with Kunio Aoki at the Aichi Cancer Research Institute in Nagoya, Japan, which resulted in our study which found that Japanese men with smoking habits similar to American men had considerably lower lung cancer risks.
I didn’t know that. It suggests that either Americans eat something that promotes cancer or the Japanese eat something that protects against it. I suspect it’s the latter — specifically, the big consumption of fermented food in Japan and not in America. I’m sure the food-frequency questionnaires Wynder criticizes, written by Americans, are tone-deaf to fermented food. I doubt they ask about kimchi or kefir or miso consumption, or distinguish between pickles aged for a day and pickles aged for a year. In Japan, people eat fermented food in many forms: vinegar drinks, yogurt, other fermented milk drinks, and alcoholic beverages. Above all, they eat miso and long-fermented pickles daily. They also have the longest life expectancy in the world.