The issue with dietary deficiencies due to eating white rice (primarily beriberi, or thiamine deficiency) actually date back centuries in Japan. White rice was a luxury food that nobles tried to get as much as they could, eating it exclusively if possible and leading to one of the few instances of a society in which the upper class were more prone to a dietary deficiency condition than the lower class. Until the 19th Century, it was believed by Japanese people to be a disease caused by living in the capital city, so when you got it you went out to the country to recover. And, since white rice was much harder to get in the country, people did recover because they were eating brown rice, beans, meat, and other things that were high in thiamine.
In the late 19th Century, a Japanese physician noticed that foreigners almost never developed the condition despite living in the same conditions as the nobles who did and began to speculate about it being caused by diet. To this end, he actually had a Japanes Navy ship equipped with the fare that Western ships carried and had it sail to New Zealand and back. Unlike most Japanese ships, which again relied almost exclusively on white rice and regularly lost a serious percentage of the crew on long voyages, this ship only lost three sailors, all of whom had refused to eat anything but white rice.
