Clark S A, Boass A, Toverud S U
Department of Pharmacology and Dental Research Center, University of North Carolina, Chapel Hill 27514.
Bone Miner. 1989 Mar;5(3):291-302. doi: 10.1016/0169-6009(89)90007-x.
We tested the hypothesis that dietary calcium would lead to greater impairment of body weight gain and calcium homeostasis if rats are fed a diet with a high glucose content compared with our standard diet in which the carbohydrate is supplied by whole wheat flour. Groups of female rats at 21 days of age were given either of two equivalent calcium-deficient diets with carbohydrate supplied either by glucose (LCaG) or by wheat flour (LCaW). Control rats were fed the wheat-flour diet containing 0.4% calcium. Since previous studies indicated divergent effects of glucose-based and flour-based diets on body weight in vitamin D-deficient rats, we designed a parallel study with vitamin D-deprived rats. Compared with rats fed the LCaW diet, the rats fed the LCaG diet had inferior body weight gain and more severe hypocalcemia (1-2 mg/ml lower) over a 40-day period, and no significant elevation of the plasma 1,25(OH)2D3 level at 61 days of age. Rats fed the LCaW diet maintained a 3-fold elevation of plasma 1,25(OH)2D3 relative to the level of control rats fed the 0.4% calcium diet. The dry weight and percent ash of tibias were similarly reduced in the two calcium-restricted groups compared to the control group. Among the vitamin D-deprived rats, those fed the glucose diet had poorer weight gain than those fed the wheat flour diet. However, both groups had similarly depressed serum calcium level, tibia ash content and 1,25(OH)2D3 level. Thus, a glucose diet combined with calcium restriction or vitamin D deprivation appears to accentuate the impairment of body weight gain and, when combined with calcium restriction, it also accentuates the impairment of calcium homeostasis and interferes with the adaptive increase in plasma 1,25(OH)2D3.
与以全麦面粉提供碳水化合物的标准饮食相比，如果给大鼠喂食高糖饮食，膳食钙会导致体重增加和钙稳态受到更严重的损害。将21日龄的雌性大鼠分成几组，分别给予两种等量的缺钙饮食，碳水化合物分别由葡萄糖（LCaG）或小麦粉（LCaW）提供。对照大鼠喂食含0.4%钙的小麦粉饮食。由于先前的研究表明，基于葡萄糖的饮食和基于面粉的饮食对维生素D缺乏大鼠的体重有不同影响，我们设计了一项针对维生素D缺乏大鼠的平行研究。与喂食LCaW饮食的大鼠相比，喂食LCaG饮食的大鼠在40天内体重增加较差，低钙血症更严重（低1 - 2毫克/毫升），并且在61日龄时血浆1,25(OH)2D3水平没有显著升高。喂食LCaW饮食的大鼠血浆1,25(OH)2D3水平相对于喂食0.4%钙饮食的对照大鼠升高了3倍。与对照组相比，两个钙限制组的胫骨干重和灰分百分比同样降低。在维生素D缺乏的大鼠中，喂食葡萄糖饮食的大鼠体重增加比喂食小麦粉饮食的大鼠差。然而，两组的血清钙水平、胫骨灰分含量和1,25(OH)2D3水平同样降低。因此，高糖饮食与钙限制或维生素D缺乏相结合似乎会加重体重增加的损害，并且当与钙限制相结合时，还会加重钙稳态的损害，并干扰血浆1,25(OH)D3的适应性升高。
