Beriberi, a name said to mean I cannot, I cannot in Sinhalese, is thiamine deficiency. With a half-life of about 17 days in the body, vitamin B1 must be constantly replaced, and without it cells cannot turn glucose into usable energy. This episode describes dry beriberi, which destroys peripheral nerves; wet beriberi, which leads to high-output heart failure; and infantile beriberi, which can paralyze a baby’s vocal cords into a silent cry. It traces the disease from Ge Hong’s third century Chinese records, which noted fermented soybeans as a cure, to Edo period Japan, where polished white rice made it a disease of samurai and urban elites while poor farmers eating brown rice, barley and beans were spared.

By the 1880s, as much as 35 percent of the Japanese Navy was sidelined. British-trained naval doctor Takaki Kanehiro sent the training ship Tsukuba on the same nine-month route on which the Ryujo had suffered more than 160 cases and 25 deaths, this time feeding the crew meat, barley, beans and fish, and it returned with almost no cases. The Army, led medically by Mori Ogai and devoted to germ theory, refused the change, and over 27,000 soldiers died of beriberi. Christiaan Eijkman’s paralyzed chickens recovered when a new cook fed them unpolished rice, paving the way for Frederick Hopkins and for Robert R. Williams, who synthesized thiamine in 1935.

• Why polishing rice for looks, texture and shelf life strips away the thiamine-rich bran
• The army’s name for a germ it never found, and Mori’s dismissal of Takaki as a fake doctor
• Prison outbreaks in Haiti, where inmates washed enriched rice, and in the Ivory Coast
• Deaths on Chinese squid fishing ships, tied to raw fish containing the enzyme thiaminase
• Wernicke-Korsakoff syndrome, and mass die-offs of Baltic birds and Atlantic salmon linked to thiamine deficiency