Wakefield C Brent, Yumol Jenalyn L, Sacco Sandra M, Sullivan Philip J, Comelli Elena M, Ward Wendy E
Kinesiology, Brock University, St. Catharines, Ontario, Canada.
Health Sciences, Brock University, St. Catharines, Ontario, Canada.
Bone Rep. 2018 Dec 30;10:100191. doi: 10.1016/j.bonr.2018.100191. eCollection 2019 Jun.
Calcium (Ca) and vitamin D (vit D) in the AIN-93G diet may be higher than required for healthy bone development, and mask the potential benefit of a dietary intervention.
The objective was to determine if lower levels of Ca and vit D than is present in the AIN-93G diet supports bone development in growing male CD-1 mice.
Weanling male CD-1 mice were randomized to modified AIN-93G diets containing either 100 (Trial 1) or 400 (Trial 2) IU vit D/kg diet within one of two or three Ca levels (0.35, 0.30, or 0.25% Ca diet in Trial 1 or 0.35% or 0.25% in Trial 2) or the AIN-93G diet (1000 IU/kg vit D and 0.5% Ca) from weaning to 4 months of age (n = 13-15/group). At 2 and 4 months of age, BMD and structural properties of the tibia were analyzed in vivo. Structure of lumbar vertebra 4 (L4) and mandible, and femur strength were assessed ex vivo at age 4 months.
There were no differences in tibia, L4, and mandible structure between the AIN-93G diet and the 0.35% Ca groups at either vit D level. A few structure outcomes were compromised with the 0.25 and/or 0.3% Ca diets but there were no differences in femur biomechanical strength compared to AIN-93G group in either Trial.
At 400 or 100 IU vit D/kg diet, Ca can be lowered to 0.35% without detriment to BMD or bone structure while bone strength is not altered at lower Ca (0.25%) compared to CD-1 mice fed AIN-93G diet. Because of genetic variation in CD-1 mice among different breeding facilities, results in CD-1 mice from other facilities may differ from the present study.
AIN - 93G 饮食中的钙（Ca）和维生素 D（vit D）含量可能高于健康骨骼发育所需水平，从而掩盖了饮食干预的潜在益处。
目的是确定低于 AIN - 93G 饮食中钙和维生素 D 水平是否有助于雄性 CD - 1 生长小鼠的骨骼发育。
将断奶雄性 CD - 1 小鼠随机分为改良的 AIN - 93G 饮食组，其中维生素 D 含量分别为 100（试验 1）或 400（试验 2）IU/kg 饮食，钙水平分为两个或三个水平之一（试验 1 中为 0.35%、0.30%或 0.25%钙饮食，试验 2 中为 0.35%或 0.25%），或从断奶到 4 个月龄给予 AIN - 93G 饮食（1000 IU/kg 维生素 D 和 0.5%钙）（每组 n = 13 - 15）。在 2 个月和 4 个月龄时，对胫骨的骨密度和结构特性进行体内分析。在 4 个月龄时，对第 4 腰椎（L4）、下颌骨结构以及股骨强度进行体外评估。
在两种维生素 D 水平下，AIN - 93G 饮食组与 0.35%钙组之间的胫骨、L4 和下颌骨结构均无差异。0.25%和/或 0.3%钙饮食会使一些结构指标受损，但在两个试验中，与 AIN - 93G 组相比，股骨生物力学强度均无差异。
在维生素 D 含量为 400 或 100 IU/kg 饮食时，钙含量可降至 0.35%，而不会损害骨密度或骨骼结构，并且与喂食 AIN - 93G 饮食的 CD - 1 小鼠相比，较低钙含量（0.25%）时骨骼强度未改变。由于不同繁殖设施中 CD - 1 小鼠存在遗传变异，其他设施中 CD - 1 小鼠的结果可能与本研究不同。
