Vitamins in human nutrition

Abstract

Attempts to compare the vitamin B1 contents of white and brown breads either by (1) the rat-growth method, or (2) the cure of convulsions in rats, failed to give satisfactory results. With the rat-growth method, refection supervened, and was found to be an insuperable obstacle because (1) of its insidious onset, (2) of the asbence of criteria for its presence (the pale enlarged faeces may not be seen until it has been established for some time[long dash]and then sometimes only erratically). Refection seems to occur much more readily in some laboratories than in others. The method based on the cure of convulsions in rats was also found unsatisfactory, the principal difficulty being to get the rats when already seriously ill with convulsions to consume the relatively large amounts of bread which would be necessary to provide an adequate amount of vitamin B1 for a cure. The same difficulty is encountered with the pigeon curative test, and in addition the percentage error of the method is known to be high. The bradycardia method overcomes these several difficulties and enables an accurate assay to be carried out. As only one dose of unknown is given there is little chance of refection becoming established, and as the animal is tested before it is gravely ill and while its appetite is still good, large amounts of the unknown may be satisfactorily administered when they are relatively poor sources of the vitamin. The interesting points of the summary are: (1) A proprietary "germ bread" (prepared from a mixture of 3 parts of white flour plus 1 part of treated germ) was found to be surprisingly little superior to ordinary wholemeal bread, although about 7-8 times more potent than white bread. (2) Specimens of "without germ bread" or "bran bread" (i.e. "brown breads" containing the branny matter but with a minimum of germ) which were examined were superior to white bread in containing significant amounts of vitamin B1 and were not greatly inferior to genuine wholemeal bread or to "with germ" bread.