Alopecia induced in young mice by exposure to excess dietary zinc

In the 1986 study, young mice were divided into two groups: Group I received a normal zinc diet (50 ppm) and Group II received an excess zinc diet (2000 ppm) from gestation until they were 8 weeks old. The results showed that the mice in Group II had lower plasma copper levels, body weight, and hematocrit values compared to Group I. Furthermore, Group II mice exhibited delayed and abnormal hair growth, with their second coat of hair appearing late and lighter in color. The most severe alopecia was observed at 5 weeks of age, with hair regrowth starting around 6 weeks but the color remained lighter. The study concluded that the alopecia and achromotrichia (loss of hair pigment) in the mice were likely due to a copper deficiency caused by the excess dietary zinc, as copper is crucial for pigmentation and hair growth. This suggests that high levels of dietary zinc can disrupt hair growth cycles by affecting copper absorption and utilization.