Effects of rice protein hydrolysate on bone fracture properties in ovariectomized rats

Osteoporosis is a global health concern, particularly in developed countries with aging populations, where the incidence of postmenopausal osteoporosis is increasing. Various nutrients have been studied as potential interventions, and components derived from regionally familiar foods may enhance acceptability and adherence. In this study, we focused on rice, a staple food in Asia and Africa. Recent studies have suggested that rice-derived peptides may help prevent bone fragility. Therefore, we examined the effects of rice protein hydrolysate (RPH) on bone health in ovariectomized rats.

In Study 1, which was designed to prevent osteoporosis, 5-week-old female Sprague-Dawley rats were acclimated for one week and then underwent ovariectomy (OVX). They were divided into three groups: a control group fed a normal diet and two experimental groups fed diets containing 0.01% or 0.1% RPH for eight weeks. In Study 2, which aimed at promoting recovery from osteoporosis, the setup was similar; however, after OVX, rats were fed a low-calcium diet for four weeks to induce osteoporosis, followed by the same diet groups as in Study 1 for an additional four weeks.

Study 1 showed that RPH significantly increased bone-breaking force (0.01% RPH, p < 0.01; 0.1% RPH, p < 0.05). In Study 2, RPH intake reduced serum tartrate-resistant acid phosphatase (TRAP) levels, a marker of bone resorption (both p < 0.05). However, a significant effect on bone mineral density was observed only in the 0.01% RPH group in Study 1 (p < 0.05).

These findings suggested that RPH may help treat postmenopausal osteoporosis.