Effects of Polycan on calcium bioavailability in two different rat models of osteoporosis

Abstract

This study evaluated the effects of Polycan, a β-glucan produced by Aureobasidium pullulans SM-2001, on calcium (Ca) bioavailability in an ovariectomy (OVX) model and a thyroparathyroidectomy (TPTX) model of osteoporosis in the SD rat. Polycan (62.5, 125, and 250 mg/kg body weight) was administered daily with an oral gavage for 4 weeks in both the OVX group (beginning 10 weeks following OVX surgery) and the TPTX group (beginning 4 days following TPTX surgery) while a commercial food product containing 1% milk-borne Ca was available ad libitum. After 4 weeks of Polycan administration, all animals were sacrificed and changes in bone mineral density (BMD) in the femur, tibia, and lumbar vertebrae (L6) were analyzed using dual-energy X-ray absorptiometry. Ca intake was calculated based on the amount of food intake during the 24 h period prior to sacrifice and the Ca balance, absorption, and retention ratios were calculated based on Ca intake, urinary and faecal Ca content, and Ca balance. Polycan treatment resulted in a marked increase in the BMD of the femur, tibia, and L6 relative to the OVX and TPTX controls with concomitant increases in Ca bioavailability and decreases in secreted Ca. These findings indicate that Polycan may enhance the absorption and bioavailability of Ca and improve Ca balance.