Differences in vitamin D3 dosing regimens in a geriatric community-dwelling population.

OBJECTIVE: The adequate dose of vitamin D supplementation for community-dwelling elderly people has not been thoroughly investigated. This study aims to determine the efficacy of a low-dose and a higher dose of vitamin D3 in maintaining 25-hydroxyvitamin D [25(OH)D] levels at or above 30 ng/mL.

METHODS: This was a single site, double-blind, randomized exploratory clinical trial that enrolled adults 65 years of age and older. Within strata of baseline 25(OH)D levels (<30 versus ≥ 30 ng/mL) subjects were randomized in a 1:2 ratio to receive either 400 or 2,000 IU vitamin D3 daily for 6 months. The main outcome measures were changes in serum 25(OH)D levels according to baseline 25(OH)D levels and dose of vitamin D3.

RESULTS: At baseline, 41 of 105 participants (39%) had low 25(OH)D levels (<30 ng/mL). After 6 months of vitamin D3 supplementation, 21 of 32 participants (66%) receiving 400 IU and 14 of 59 participants (24%) receiving 2,000 IU of vitamin D3 still had low 25(OH)D levels. The largest increases in serum 25(OH)D levels were observed in subjects with baseline levels <30 ng/mL who received 2,000 IU of vitamin D daily.

CONCLUSION: Regardless of baseline 25(OH)D level, in persons 65 years of age and older, 6-month vitamin D3 supplementation with 400 IU daily resulted in low 25(OH)D in most individuals, while 2,000 IU daily maintained 25(OH)D levels within an acceptable range in most people on this regimen.