Factors influencing the intake and plasma levels of calcium, phosphorus and magnesium in southern Spain.

OBJECTIVE

The aim of the study was to assess factors influencing the intake and plasma levels of calcium (Ca), phosphorus (P) and magnesium (Mg) in an adult population from southern Spain, in order to identify patterns of intake and groups at risk for deficiency.

METHODS

A cross-sectional survey was carried out in Andalusia, a western Mediterranean region in southern Spain. Nutrient intakes were studied in a random sample of 3,421 subjects (1,747 men, 1,674 women) between 25 and 60 years of age. Blood samples were obtained for biochemical assays in a random subsample of 354 subjects (170 men, 184 women). Food consumption was assessed by a 48-h recall. Concentrations of Ca, P and Mg were measured in plasma. Information about level of education, smoking habit, alcohol consumption and physical exercise was collected with a structured questionnaire.

RESULTS

Intakes were below two-thirds of the RDA in 39.52% of the sample for Ca, and in 32.31% for Mg. Gender, age, educational level, obesity, smoking, alcohol use and physical activity were associated with differences in nutrient intakes. Plasma concentrations were below the reference value in 14.81% of the sample for Ca, and in 8.82% for Mg. Obese persons [body mass index (BMI) >/= 30 kg/m(2)] consumed less Ca, P and Mg, and had lower plasma Ca concentrations (P < 0.05) than non-obese persons. BMI showed an inverse correlation with plasma concentrations of Ca (r = -0.21, P < 0.05).

CONCLUSION

Our results provide an estimate of the intake of Ca, P and Mg in the adult population of southern Spain. Of the factors that affected the intake of these nutrients, logistic regression analysis showed that only female gender and older age were associated with the risk of low plasma Ca concentrations.