Prevalence of vitamin D insufficiency in postmenopausal south Indian women

To evaluate the dietary calcium and vitamin D status in south Indian postmenopausal women.

Postmenopausal women (n = 164) were evaluated for their daily dietary calcium intake, phytate to calcium ratio, and bone mineral parameters. Their serum leutinizing hormone (LH), follicle-stimulating hormone (FSH), 25-hydroxyvitamin D (25[OH]D), and parathyroid hormone levels (PTH) were measured.

Their age and BMI were 59.5 +/- 8 years and 27 +/- 5 kg/m2, respectively. Their daily dietary intake of calcium was 323 +/- 66 mg/day; phytate to calcium ratio, 0.56+/-0.1; LH, 26 +/- 13.5 microIU/l; and FSH, 62.6 +/- 30 microIU/l. Their dietary intake of calcium was low compared with the recommended daily/dietary allowance (RDA) of the Indian Council of Medical Research (ICMR) for the Indian population. Of the 164 patients studied, based on population-based reference values, 126 (77%) had normal 25(OH)D levels (9-37.6 ng/ml), and 38 (23%) had 25(OH)D deficiency. Using functional health-based reference values, 30 (18%) patients had normal 25(OH)D levels (> 20 ng/ml), 85 (52%) had 25(OH)D insufficiency (10-20 ng/ml), and 49(30%) had 25(OH)D deficiency (< 10 ng/ml). PTH and serum alkaline phosphatase (SAP) was significantly high in patients with 25(OH)D deficiency (p < 0.05) compared with those with normal 25(OH)D levels. There was a negative correlation between 25(OH)D and PTH (r = -0.2; p < 0.007) and SAP (r = -0.2; p < 0.001). Dietary calcium correlated positively with dietary phosphates (r = 0.8; p < 0.001) and phytate to calcium ratio (r = 0.75; p < 0.001).

Population-based reference values underdiagnosed vitamin D insufficiency and overdiagnosed normal vitamin D status. The diet was insufficient in calcium and high in phytate. About 82% of the study group had varying degrees of low 25-hydroxyvitamin D levels. The quality of diet has to be improved with enrichment/supplementation of calcium and vitamin D to suppress secondary hyperparathyroidism-induced bone loss and risk of fractures.