Bone marrow adiposity as an early marker of maternal recovery after preconception protein deficiency in rats with Spirulina supplementation: An experimental study

Preconception protein deficiency can impair maternal physiological adaptation during pregnancy and lactation; however, recovery during nutritional repletion remains poorly understood. Despite this limited understanding, few studies have assessed integrated maternal responses, particularly bone marrow adiposity alongside hepatic and mammary adaptation. Therefore, this study aimed to evaluate whether Spirulina-assisted protein recovery can restore maternal metabolic adaptation, using bone marrow adiposity as a skeletal marker of nutritional stress and a novel indicator of maternal recovery. Female rats were subjected to a protein-deficient diet for 5 weeks before mating and allocated to five groups (n = 5/group), followed by protein repletion with or without Spirulina supplementation from gestational day 1 to postpartum day 7. Maternal body weight, serum protein levels, liver indices, milk production, and bone histology were assessed after parturition. The results showed that protein deficiency significantly reduced gestational weight gain (33.8 ± 16.4 g vs. 74.6 ± 14.0 g in controls, p < 0.001), decreased serum protein levels (5.74 ± 0.74 g/dL vs. 7.20 ± 0.40 g/dL, p < 0.05), and increased liver weight (4.19 ± 0.43% vs. 3.26 ± 0.46%, p < 0.05). These changes were accompanied by a marked increase in bone marrow adiposity (7.14 ± 7.87% vs. 0.30 ± 0.25% in controls, p < 0.05), while trabecular bone remained preserved. Protein repletion improved most parameters, and Spirulina supplementation was associated with more consistent recovery across maternal systems. In conclusion, bone marrow adiposity may serve as a responsive marker of maternal metabolic adaptation following preconception protein deficiency in a rat model. Spirulina-assisted recovery supports coordinated restoration across maternal compartments; however, further validation in humans is needed.