Endocrine Abstracts

Introduction: Use of supplements (VDS) and vitamin-D measurements have been rising in the recent past globally. Despite increasing intake, our observations reveal that a large percentage of the population remains deficient (VDD). We designed the present real-world study, to address this controversy.

Methods: We collected data from patients attending our clinics between March 2014 and December 2022. We recorded our subjects’ gender, age, history of VDS use, duration and dose, and vitamin-D measurements, when available. We estimated the ratio of patients with vitamin-D adequacy (>30ng/ml) (VDA) by year and month of measurement, stratified by the dose of VDS intake: low-dose (≤ 1200IU/day)(LD), medium-dose (1201-3000IU/day)(MD), high-dose (>3000IU/day)(HD), duration of intake: short-term-use(<12months), long-term-use (≥12months)(LT), and use at present: current-users(CU), past-users(discontinued for ≥2months)(FU), non-users(NU).

Results: Out of 10,292patients, data on VDS intake were available in n=8605 patients(83.6%): NU, n=7212(71.4%), FU, n=566(5.6%) and CU, n=827 (8.2%). Vitamin-D measurements were available in n=6912 patients (67.2%); NU n=5644 (81.7%), FU n=507 (7.3%), CU n=761 (11.0%). Vitamin-D measurement was available in 42.1% of patients in 2014 rising gradually to 86.8% in 2022, P<0.001. The cohort’s mean vitamin-D was 23.1±9.1ng/ml. VDD was found in n=5401 (78.1%). VDD was identified in 55.2% of CU, 76.8% of FU and 84.5% of NU (P<0.001). The rate of VDD went down with the dose of VDS used both in FU(LD 83.9%, MD 78.8%, HD 73.0%, P<0.05) and CU (LD 60.1%, MD 53.2%, HD 51.9%, P<0.05). The rate of VDD reached its nadir in August(62.1%) and September(61.2%), but rose to >70% in October and >80% during the remaining months, P<0.001. Intake of VDS at any time went up from 2.9% in 2014 to 35.2% in 2022(P<0.001), and the VDD rate went down from 85.2% in 2014, to 74.5% in 2022. The serum vitamin-D increased from 21.7±9.0ng/ml in 2014 to 25.0±10.3ng/ml in 2022, P<0.001. Longer duration of VDS intake lowered the risk of VDD (LT vs ST use OR 0.51, 95%CI 0.38-0.69, P<0.0001). LT use of VDS in HD yielded the lowest risk (30.2%), while ST and LT use of VDS in LD yielded the highest risk of VDD (81.6% and 83.3% respectively).

Conclusions: Despite a gradual increase in vitamin-D measurements, and VDS intake, most patients attending our clinics remain VDD. A modestly effective strategy in controlling that epidemic is the long-term intake of higher doses of VDS, but efficacy goes down shortly after stopping treatment. Studies are urgently in need to solve this major global health issue.