Effects of High-Phosphorus Intake on Bone Mineral Density in Adult Male Rats

Abstract

  Phosphorus (P) accounts for approximately 1% of body weight in living organisms and is primarily found in hard tissues, such as bones and teeth, and it is an essential element for bone mineralization. However, due to the increasing consumption of processed foods in the modern Japanese diet, excessive P intake has become a more pressing concern than P deficiency. In a previous study, we examined the short-term effects of varying dietary P levels on bone metabolism using 7-week-old male rats. In the present study, we focused on the effects of a high-phosphorus (HP) diet (1.0% P content) over a longer period and compared its impact on bone parameters in adult rats. Eleven-week-old male Sprague-Dawley rats were divided into two groups: a control diet group (Cont.; 0.3% P content) and a high-phosphorus diet group (HP; 1.0% P content), and both groups were fed their respective diets for 28 days. At the end of the experimental period, there were no significant differences in final body weight, weight gain, or food intake between the two groups. Similarly, no significant differences were observed in serum calcium or P concentrations. In the femur, no significant differences were found between the two groups in terms of bone length, bone width, bone thickness, or dry weight. However, the bone mineral density of the whole femur (including both cortical and trabecular bone) was significantly lower in the HP group than in the Cont. group. These findings indicate that prolonged intake of a high-phosphorus diet decreases femoral bone density in adult male rats and may increase the risk of fractures.