We investigated the effects of mineral water fortified with folic acid, vitamins B(6), B(12), D and calcium on folate concentrations in serum and erythrocytes, serum vitamin B(12) and plasma homocysteine concentrations in free-living subjects. In addition, we investigated the bioavailability of calcium added to mineral water by measuring urinary calcium excretion and serum alkaline phosphatase activity.
Randomized, controlled, double-blinded, parallel design.
Outpatient dietary intervention with free-living subjects in Eastern Finland.
Altogether, 66 subjects were recruited for the study. In all, 60 subjects completed the study.
The study began with a 2-week run-in period followed by an 8-week intervention period. During the intervention study, subjects consumed mineral water fortified with folic acid (563 microg/day), vitamins B(6) (1 mg/day), B(12) (7.5 microg/day), cholecalciferol (0.6 microg/day) and calcium (563 mg/day) or placebo mineral water.
The fortified mineral water increased serum and erythrocyte folate concentrations by 16.1+/-5.6 nmol/l (P<0.001) and 199+/-76 nmol/l (P<0.001), respectively, and decreased plasma homocysteine concentration by 1.6 micromol/l (P<0.001). Urinary calcium excretion and serum alkaline phosphatase activity for 24 h increased significantly (P<0.001 and P=0.01 respectively) in the intervention group.
Mineral water fortified with folic acid, vitamins B(6), B(12) and D and calcium enhanced folate status and reduced plasma homocysteine concentration in normohomocysteinemic subjects without folate deficiency. Indirect measures of calcium and bone metabolism indicated that the calcium used in the fortification of the mineral water was bioavailable.