Hypervitaminosis A

Abstract

Many forms of injury are known to occur in experimental animals when they are dosed with greatly excessive amounts of oils or concentrates containing vitamin A. Takahashi, Nakamiya, Kawakami & Kitasato (1925) tested the effect of excess of their crude concentrate 'Biosterin' when given orally to rats and mice, and observed loss of hair, emaciation and paralysis of the hind legs. After periods varying from a few days to several weeks the animals died, and at autopsy fatty degeneration of the liver,

The effects of avitaminosis and hyper‐vitaminosis A upon the incisor teeth and incisal alveolar bone of rats

“…Through the kindness of Dr T. Moore, and his associates, the skulls of fourteen hypervitaminotic rats were put at the disposal of the present writer. The experimental details, diet and treatment of the animals were essentially the same as described by Moore & Wang (1945). In brief young rats were given a basal diet similar to that used by these writers, with the inclusion of halibut liver oil in a proportion calculated to provide about 40,000 i.u.…”

“…Appositional bone formation continued until inanition supervened, in strict conformity to the normal growth patterns, both as to situation and to rate, but remodelling sequences, involving concurrent resorption of bone with' bone deposition and replacement of cancellous bone by compact bone, ceased. The toxicity of vitamin A in excessive doses has been investigated by a number of workers, and the literature up to 1945 has been extensively reviewed by Moore & Wang (1945). All writers are agreed that the chief toxic effects are spontaneous fractures of the bones and a tendency to internal .haemorrhage.…”

Efeito de diferentes doses de ácido retinoico sobre a resistência óssea de ratos jovens

“…Contudo, historicamente, estudos em humanos [20][21][22] e animais [23][24][25] têm relatado que a toxicidade por essa vitamina aumenta a reabsorção e diminui a formação óssea. O presente estudo demonstrou que diferentes concentrações de ácido retinoico, pelo período de um mês, não exerceram influência sobre a resistência óssea em ratos jovens, diferentemente do descrito por Johansson et al 14 Embora não tenham sido demonstradas alterações significativas com relação às variáveis biomecânicas do osso, estudos histológicos são necessários para a complementação desta investigação.…”

Adverse Side Effects of Mega Dose of Vitamin A Administration- A need for Introspection

“…Animal studies have also reported the importance of vitamin A in the bone remodelling process (27)(28)(29). Vitamin A deficiency resulted in retarded bone growth, but the most prominent features of hypervitaminosis A was accelerated bone resorption (28), bone fragility and spontaneous fracture (29).…”