I recently had a stomachache. I'd always assumed my stomach was weak because it hurt regularly when I was little. As an adult, I've rarely had abdominal pain, so I forgot about it. This last one took me back to my childhood. I was thinking about why it happened, and something came to me. I drank milk that day, which I rarely do.

I began to suspect I might be lactose intolerant, and my childhood stomachaches were caused by milk. Soon after World War II, in the 1950s, milk was included in Japanese school lunches. At the time, it was considered a sound nutritional choice for everyone, but in the 1980s, it became widely known that quite a few East Asians are lactose intolerant. Furthermore, there are alternatives to milk that are equally nourishing. Even now, milk is part of the Japanese school lunch, but I doubt it's the best for their health.