Figure 1

Tuna bone calcium supplementation resulted in higher fractional calcium absorption and bone formation rate than calcium carbonate supplementation. (A) Experimental design, all rats were challenged with low calcium diet (0.15% w/w) for 2 weeks, then diet was switch to calcium-replete diet (0.55% w/w) and fed for another 4 weeks. Extra calcium (0.4% w/w) came from tuna bone (S2) or CaCO₃ (S1). (B) Intestinal fractional calcium absorption and 3-day urinary calcium excretion, (C) bone microstructure analyzed by bone histomorphometry (bone volume fraction, BV/TV, trabecular thickness, Tb.Th, trabecular separation, Tb.Sp, trabecular number, Tb.N, osteoclast surface normalized with bone surface, Oc.S/BS and osteoblast surface normalized with bone surface, Ob.S/BS), (D) dynamic parameters (doubled labeling surface normalized with bone surface, mineral apposition rate, MAR, bone formation rate normalized with bone surface, BFR/BS), and (E) bone turnover markers analyzed by commercial ELISA (bone formation marker, P1NP and bone resorption marker, CTX-1). S1, calcium supplementation in diet from CaCO₃, S2, calcium supplementation in diet from tuna bone. Results are expressed as means ± SE. The different between two sets of data was determined by two-tailed unpaired Student’s t test. *P < 0.05, **P < 0.01, and ***P < 0.001 compared with CaCO₃ (S1).