Vitamin D Status in Israeli Subjects before the Initiation and after the Cessation of Vitamin D Supplements

Vitamin D supplements are often recommended to restore sufficiency, although the adherence to treatment is low. This study assessed vitamin D status at different time intervals following the cessation of treatment. The database of Clalit-Health-Services (CHS), a not-for-profit HMO covering more than half of the Israeli population, was retrospectively searched for all members with available serum 25OHD test results in 2009 (245,493). We then identified those who filled any cholecalciferol prescription in 2008–2009 (121,817). Subjects were included in the final analysis only if they started treatment in 2009, had serum 25OHD < 50 nmol/l before the first prescription in 2009, and had at least one additional test result after the last dated prescription in 2009 (5,461). Serum 25OHD increased from 32 ± 11 nmol/l at baseline to 58.6 ± 22.3 nmol/l after treatment (P < 0.001). The proportion of subjects with sufficient vitamin D after treatment increased with increasing cholecalciferol daily dose and treatment duration (P < 0.001) and decreased with increasing time from cessation of treatment (P < 0.001). The effect of time from treatment cessation persisted after controlling for baseline serum 25OHD, daily cholecalciferol dose, treatment duration, seasonality, gender, age, ethnicity, and BMI; the ORs for sufficient vitamin D were 2.02 (95% CI 1.66–2.45), 1.67 (1.39–2.01), and 1.23 (1.04–1.47) for >30–60, 61–99, and 100–155 days compared to >155 days, respectively. Long-term vitamin D treatment is needed to maintain sufficient levels in those with baseline serum 25OHD below 50 nmol/l.