Dietary copper intake influences skin lysyl oxidase in young men

The effect of low dietary copper on copper status and the copper-containing enzyme lysyl oxidase was studied in young men. The study was divided into three dietary periods. During the first period, subjects were fed 0.66 mg/day Cu for 24 days (marginal copper). The level of copper was dropped to 0.38 mg/day for the next 42 days (low copper) and they were repleted with 2.49 mg/day Cu for next 24 days. Skin biopsies were taken at the beginning of the study and at the end of each dietary period and lysyl oxidase was measured enzymatically. There was a 24% drop in activity when the dietary copper level was reduced from 0.66 to 0.38 mg/day. When the subjects were repleted with copper, there was a significant increase in the activity of lysyl oxidase. The activity reached the level observed before the subjects were fed the restricted copper diet. These data show that, in humans, lysyl oxidase activity declines when dietary copper intake is inadequate and suggests that the cross-linking of collagen may be modulated by dietary copper. Lysyl oxidase in healthy young men can serve as a useful indicator of copper status.