BACKGROUND: Few data exist on the ability of postmenopausal women to absorb calcium from diets habitually low in calcium. OBJECTIVE: The objective of this study was to evaluate fractional calcium absorption from a green leafy vegetable vs. milk in relation to vitamin D status. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.
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BACKGROUND: Few data exist on the ability of postmenopausal women to absorb calcium from diets habitually low in calcium. OBJECTIVE: The objective of this study was to evaluate fractional calcium absorption from a green leafy vegetable vs. milk in relation to vitamin D status. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.
Authors: Marlena C Kruger; Yoke Mun Chan; Lee Ting Lau; Chin Chin Lau; Yit Siew Chin; Barbara Kuhn-Sherlock; Joanne M Todd; Linda M Schollum Journal: Eur J Nutr Date: 2017-10-03 Impact factor: 5.614
Authors: Karina Bortolin Lodi; Adriana Mathias Pereira da Silva Marchini; Ana Maria do Espírito Santo; Sigmar de Mello Rode; Leonardo Marchini; Rosilene Fernandes da Rocha Journal: Int J Endocrinol Date: 2016-03-17 Impact factor: 3.257