Sirichakwal Prapaisri P, Kamchansuppasin Achiraya, Akoh Christine C, Kriengsinyos Wantanee, Charoenkiatkul Somsri, O'Brien Kimberly O
Institute of Nutrition, Mahidol University, Nakhon Pathom, Thailand; and.
Division of Nutritional Sciences, Cornell University, Ithaca, NY.
J Nutr. 2015 May;145(5):990-5. doi: 10.3945/jn.114.207290. Epub 2015 Mar 25.
Few data exist on the ability of postmenopausal women to absorb calcium from diets habitually low in calcium.
The objective of this study was to evaluate fractional calcium absorption from a green leafy vegetable vs. milk in relation to vitamin D status.
We measured fractional calcium absorption from both a dairy- and plant-based source in 19 postmenopausal Thai women (aged 52-63 y) with low calcium consumption (350 ± 207 mg/d) in relation to serum parathyroid hormone (PTH) and serum 25-hydroxyvitamin D [25(OH)D]. Fractional calcium absorption was measured using a triple stable calcium isotope method based on isotope recovery in a 28-h urine collection. Two extrinsically labeled test meals were ingested in random order: a green leafy vegetable (cassia) ingested along with ⁴³Ca or a glass of milk containing ⁴⁴Ca. Women received intravenous ⁴²Ca with the first test meal.
In 19 postmenopausal women studied (mean age, 56.9 ± 3.4 y), ~95% were 25(OH)D sufficient (≥20 μg/L). Serum 25(OH)D status was positively correlated with fractional absorption from both cassia (P = 0.05, R² = 0.21) and milk (P = 0.03, R² = 0.26). Fractional calcium absorption from cassia was significantly lower than that measured from milk (42.6% ± 12.3% vs. 47.8% ± 12.8%, P = 0.03), but true calcium absorption did not significantly differ (120 ± 35 mg/d vs. 135 ± 36 mg/d). Serum PTH was significantly inversely associated with serum 25(OH)D (P = 0.006, R² = 0.37) even though PTH was not elevated (>65 pg/mL).
These findings suggest that vitamin D status is an important determinant of calcium absorption among Thai women with low calcium intakes, and cassia may be a readily available source of calcium in this population. Furthermore, these data indicate that serum 25(OH)D concentrations may affect PTH elevation in postmenopausal women with low calcium intakes.
关于绝经后女性从习惯性低钙饮食中吸收钙的能力的数据很少。
本研究的目的是评估绿叶蔬菜与牛奶中钙的分数吸收与维生素D状态的关系。
我们测量了19名绝经后泰国女性（年龄52 - 63岁）从乳制品和植物性来源中吸收钙的分数，这些女性钙摄入量低（350±207毫克/天），并与血清甲状旁腺激素（PTH）和血清25-羟基维生素D [25(OH)D]相关。使用基于28小时尿液收集同位素回收率的三重稳定钙同位素方法测量钙的分数吸收。随机摄入两种外源性标记的测试餐：与⁴³Ca一起摄入的绿叶蔬菜（决明子）或含有⁴⁴Ca的一杯牛奶。女性在第一次测试餐时接受静脉注射⁴²Ca。
在研究的19名绝经后女性（平均年龄56.9±3.4岁）中，约95%的人25(OH)D充足（≥20μg/L）。血清25(OH)D状态与决明子（P = 0.05，R² = 0.21）和牛奶（P = 0.03，R² = 0.26）的分数吸收呈正相关。决明子的钙分数吸收显著低于牛奶（42.6%±12.3%对47.8%±12.8%，P = 0.03），但实际钙吸收没有显著差异（120±35毫克/天对135±36毫克/天）。血清PTH与血清25(OH)D显著负相关（P = 0.006，R² = 0.37），即使PTH未升高（>65 pg/mL）。
这些发现表明，维生素D状态是低钙摄入量泰国女性钙吸收的重要决定因素，决明子可能是该人群中易于获得的钙源。此外，这些数据表明血清25(OH)D浓度可能影响低钙摄入量绝经后女性的PTH升高。
