The most remarkable observation in the history of beri-beri, and the one which inaugurated the modern era of investigations in the field of nutrition was made in 1897 by the Dutch physician, Eijkman (4). This investigator was medical officer to a prison in Java, where beriberi was common. He noticed that the poultry which fed upon the garbage of the hospital showed symptoms of paralysis strikingly suggestive of those of his patients, and died with extensive degeneration of the peripheral nerves. Eijkman was led by this chance observation to conduct systematic experiments with chickens and pigeons. He fed some on rice in the natural condition with the husk attached to the grain; others he fed on rice from which the husk had been removed but which still retained the outer layer or "silverskin," and the embryo or germ; still others he fed on rice which had been milled and polished.

The milling of rice removes the bran or cellulose membrane, together with the aleurone layer and the germ. The coating on our polished rice is talcum powder. Eijkman's results demonstrated definitely that rice which had lost its "silverskin" would produce the condition of nerve degeneration to which he gave the name polyneuritis gallinarum, and which he rightly considered to be the analogue of beri-beri in man.

Eijkman did not correctly interpret the cause of the production of beri-beri by polished rice and its prevention by the unpolished grain. It has been shown by others that the substance which protects against beri-beri, and which is absent from polished rice, is in great measure concentrated in the germ of the seed. This portion is situated in an exposed position at the tip of the kernel, and is easily rubbed off in milling. On the grain of polished rice, there is a tiny pit in which the germ rested before its removal.

Eijkman's interpretation of the experiments was that the "silverskin" of the rice kernel contained some substance which neutralized the injurious influence of the starch-rich diet. To quote: "Aus den diesbezuglichen Versuchen zog ich den Schluss, dass in den Silberhautchen wahrscheinlich ein Stoff oder Stoffe vor-handen sind, wodurch der schadigende Einfluss der starkehaltigen Nahrung neutralisert wird" (4).

219. Climate Not A Factor In The Production Of Beri-Beri

He also studied the influence of climate as a factor in the etiology of the disease, but found it a negligible factor. In the large cities of the East Indies ( Batavia, Soeralaja), 66.7 per cent of the people suffered from beri-beri, as against 30.9 per cent among mountain dwellers. The greater number of the first group ate milled rice. Prisoners fed principally on milled rice showed an incidence of 80 per cent near the sea, as compared with 62 per cent in the mountains. In one prison 5.8 per cent of the inmates suffered from beri-beri when supplied with polished rice, but the disease disappeared when unmilled rice was substituted (5).

220. Other Foods Than Rice May Induce Beri-Beri

Eijkman tested the hypothesis that a high starch content in the diet predisposed to the disease. He produced polyneuritis in birds by restricting their diets to various Indian starches (Ambon-sago, pearl-tapioca, sago, etc.), and found that the typical symptoms were produced. These experiments were confirmed and extended by Grijns (6), Schaumann (7), and Hoist (3). They showed that in addition to polished rice, milled barley, milled wheat, and bread made from bolted flour, tapioca, etc., produced the disease in birds.

221. Schaumann's Studies On The Etiology Of Beri-Beri

Schaumann further demonstrated that dried codfish and pickled meats, heated for a time in an autoclave at 120° C. would produce polyneuritis when the energy requirements of his animals were covered by these foods. He was the first to employ mammals in studies relating to polyneuritis. Dogs, cats, rats, a goat and an ape were used in his experiments (8). He produced the characteristic symptoms of the disease in all these animals, but not in mice. The latter, however, suffered loss of weight and presented signs of malnutrition.