Low Protein Intake Magnifies Detrimental Effects of Ovariectomy and Vitamin D on Bone

• Published in: Calcified tissue international Vol. 93; no. 2; pp. 184 - 192
• Main Authors: Marotte, Clarisa, Gonzales Chaves, Macarena M. S., Pellegrini, Gretel G., Friedman, Silvia M., Lifshitz, Fima, Mandalunis, Patricia, Zeni, Susana N.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.08.2013; Springer Nature B.V
• Subjects: Animal Feed; Animals; Biochemistry; Biomedical and Life Sciences; Body Weight; Bone and Bones - pathology; Bone Density; Calcium - blood; Calcium - metabolism; Calcium, Dietary - pharmacology; Cell Biology; Diet, Protein-Restricted - adverse effects; Endocrinology; Feeding Behavior; Female; Homeostasis; Life Sciences; Original Research; Orthopedics; Osteoblasts - drug effects; Osteocalcin - chemistry; Osteocalcin - metabolism; Ovarian cancer; Ovariectomy; Proteins; Rats; Rats, Wistar; Vitamin D; Vitamin D - administration & dosage; Rats; Bisphosphonate; Low protein intake; Bone; Vitamin D insufficiency
• ISSN: 0171-967X; 1432-0827
• DOI: 10.1007/s00223-013-9740-8

Protein-induced changes in bone and calcium homeostasis could potentially be greater in the elderly and in women at risk for osteoporosis. We hypothesize that a low protein intake would magnify the negative changes in bone metabolism seen in vitamin D (vitD) insufficiency and/or estrogen deficiency. The present study was undertaken to better understand how a low protein diet along with vitD insufficiency could affect bone metabolism using a rodent ovariectomized (OVX) model. Rats ( n  = 60) underwent ovariectomy (OVX) or sham operation. The first 15 days after surgery, all rats were fed a standard rodent diet. Thereafter, rats ( n  = 10/group) were fed a low protein diet (LP; 2.5 %) or a control diet (NP; 12.5 %) with 100 IU% vitD (+D; cholecalciferol) or without vitD (−D) for 45 days. The groups were as follows: SHAM + NP + D (control); SHAM + LP + D; SHAM + LP − D; OVX + NP + D; OVX + LP + D; OVX + LP − D. Body weight (BW) of control and OVX + NP + D groups increased while those feeding the LP diet, independently of vitD feedings, decreased ( p  < 0.05). The OVX + LP − D group presented the lowest serum Ca, phosphorus and osteocalcin levels and the highest CTX levels ( p  < 0.05). At the end of the study, total skeleton bone mineral content, proximal tibia bone mineral density, bone volume and trabecular number levels decreased as follows: SHAM + NP + D (controls) > SHAM + LP + D > OVX + NP + D > SHAM + LP − D > OVX + LP + D > OVX + LP − D ( p  < 0.05). A low protein diet negatively affected bone mass and magnified the detrimental effects of vitD and/or estrogen deficiencies.