A fine structural demonstration that some benzopyrones act as vitamin P in the rat.

In rats fed a diet lacking flavonoids (but which had supplementary vitamin C) definite fine structural alterations were found in blood capillaries and tissues. These fine structural alterations were quite different from those reported in C-avitaminosis and imply a different deficiency. They were largely prevented by feeding the benzopyrones, coumarin or coumarin plus troxerutin, thus pointing to the specificity of the lesions. This implies that, for the rat, benzopyrones are vitamins and that vitamin C and "vitamin P"-deficiency states are qute distinct. In "P-avitaminosis" the basic lesion is the opening of some blood capillary endothelial intercellular junctions. Unlike in C-avitaminosis, the endothelial cells are intact, without pale, grossly swollen cytoplasms.