Folate status of elderly women following moderate folate depletion responds only to a higher folate intake
Dietary Reference Intakes (DRI) for folate for elderly women have been based primarily on data extrapolated from studies in younger women. This study was conducted to provide the first age-specific data in elderly women (60-85 y) from a controlled metabolic study on which to base folate intake recommendations. Subjects (n = 33) consumed a moderately folate-deplete (118 microg/d) diet for 7 wk, followed by repletion diets providing either 200 or 415 microg folate/d as diet plus folic acid (FA) or a combination of FA and orange juice (OJ) for 7 wk (n = 30). Comparisons among and within groups were made for serum folate (SF), RBC folate and plasma total homocysteine (tHcy) concentrations. SF concentrations decreased significantly (P < 0.001) during depletion (65 +/- 15%). Postrepletion, the adjusted SF concentration for subjects consuming 415 microg folate/d was significantly greater (P = 0.003) than for subjects consuming 200 microg folate/d. RBC folate concentrations decreased (P < 0.001) during depletion (21 +/- 10%) and further (P < 0.001) during repletion (5 +/- 14%). During depletion, plasma tHcy concentrations increased significantly (P < 0.001) and an inverse relationship between SF and plasma tHcy concentrations was observed in 94% of subjects (P < 0.001). Reversal of this inverse relationship was significant only for subjects consuming 415 microg folate/d (P < 0.001). Postrepletion, subjects consuming 200 microg folate/d had a significantly higher (P = 0.009) adjusted plasma tHcy concentration than subjects consuming 415 microg folate/d. These data in elderly women indicate that 415 microg/d folate, provided as a combination of diet, FA and OJ, or diet and FA, normalizes folate status more effectively than does 200 microg/d, thus providing age-specific data for future folate intake recommendations.