In 1882-3, many Japanese sailors suffered from beriberi and some died in warships. Japanese government started a committee to prevent beriberi. A parallel controlled trial for beriberi was carried out in 1884 by Kanehiro Takagi who had studied at St Thomas Hospital in London and noticed a remarkable difference in the frequency of beriberi between Japan and London. He determined the ratio of nitrogen to carbon content of food taken by the crew of warship Rhujo which sailed from Japan to Hawaii via Chile and resulted in a miserable occurrence of beriberi. Carbon content in the food was higher during the voyage from Chile to Hawaii than that from Hawaii to Japan, the latter of which brought about beriberi much less frequently. These data prompted Dr. Takagi a trial voyage under similar conditions except partially replacing polished rice with meat in crew's diet. Dr. Takagi postulated the Emperor on importance of diet during the trial voyage. Warship Tsukuba set out on the trial voyage in February, 1884 and arrived at Hawaii without any beriberi patient. The success in preventing beriberi led to taking food without polished rice in Japanese navy, while Japanese army and professors in Tokyo Imperial University neglected these data due to an erroneous assumption that beriberi might be infectious. A mistaken trust in polished rice had prevailed in Japan until 1923 when vitamin B_1 deficiency derived from polished rice was revealed as a cause of beriberi. Thereafter, the incidence of beriberi has decreased dramatically.