A chronically deficient calcium intake causes defluxion of calcium from osseous tissue, while at the same time increasing the calcium concentration within cells that results in various disorders to cell functions or calcification of soft tissue. It has also been hypothesized that a deficient calcium intake promotes the migration of calcium into the nails. This study was conducted on 24 female university students to assess the effect of an increased calcium intake on the calcium concentration in the nails. Each subject was instructed to consume one pack per day of a calciumenriched food for 2 months. The calcium concentration in the fingernails and the osteo sono-assessment index (OSI) were measured before starting consumption of the calcium-enriched food (baseline) and after 2, 3 and 4 months. OSI was significantly higher after 3 and 4 months, while the fingernail calcium concentration was significantly lower after 4 months (baseline, 1.294±0.234mg/g; after 4 months, 1.089±0.197mg/g (P<0.01)). These results clearly demonstrate that the fingernail calcium concentration can be decreased by improving the calcium nutritional status, and it is suggested that measuring the fingernail calcium concentration would be useful as an indicator of the calcium nutritional status.
