Hypovitaminosis D: Which oral supplement therapy?

Abstract

Objectives

the possible therapeutic role of vitamin D in different kind of diseases explains the growing interest in this vitamin due to its pleiotropic effects. This short report shows preliminary results of prevalence of hypovitaminosis D in a group of patients and proposes a oral supplement therapy effective in correcting hypovitaminosis in a short time, without side effects.

Methods

243 patients (aged 26–93; 67 males) were enrolled at this study. We evaluated plasma levels of 25-hydroxyvitamin D [25(OH)D] with the following cut-off values: < 10ng/ml or <0–25 nmol/L (deficient), 10–30 ng/ml or 25–75nmol/L 30–50 (insufficient) and > 30 ng/ml or > 50 nmol/L (normal). The first 73 patients with hypovitaminosis D received at baseline 25,000 IU (Cholecalciferol) per os twice a month (Tp.A). The next patients (Tp.B) at baseline received a loading dose of 50,000 IU once a week for 8 weeks, followed by a maintenance dose of 25,000 IU twice a month.

Results

hypovitaminosis D is a widespread condition (i.e. 82.3%) not only in elderly (75.6% of 75 patients aged <65 yrs and 86.5% of 168 subjects aged >65 yrs). Preliminary results at 6 months show that Tp.B is more effective in correcting hypovitaminosis D (baseline 14.4 ± 5.3 ng/ml; 24 wk 43.3 ± 14.7 ng/ml; p<0.0001).

Conclusion

hypovitaminosis D is an important public health problem. We believe it is important to quickly achieve normal Vit. D plasma values in order to produce pleiotropic effects.

In recent times further vitamin D (vit.D) pleiotropic effects have been observed (1). Several studies have found that Vitamin D (Vit. D) has both skeletal and extra-skeletal benefits (2, 3, 4). Our Department is currently performing a study in order to investigate the effects of Vit. D supplement therapy on cardio-vascular risk and on cognitive function. We are going to illustrate some interesting preliminary results at baseline (T0) and after 6 months of follow up (T1). From May 2011 we enrolled 243 patients (aged 26-93; 67 males). We excluded subjects who were already on Vit. D supplement therapy and those who had osteoporosis. By assessing plasma levels of 25-hydroxyvitamin D [25(OH)D], we found that 200 patients (i.e. 82.3%) of our study population had 25(OH)D <30 ng/ml. Of these, almost 1 out of every 4 patients had 25(OH)D <10 ng/ml. These results clearly show that hypovitaminosis D has a high prevalence even in a city such as Rome that is the second sunniest city in Europe (1687 hours of sunshine/year). Moreover we observed that Vit. D deficiency seems to affect both older and younger subjects (75.6% of 75 patients aged <65 yrs and 86.5% of 168 subjects aged >65 yrs). A sedentary lifestyle and poor dietary habits could be the main determinants of Vit. D deficiency.

The importance of keeping sufficient plasma levels of vitamin D is a matter of fact, also in order to implement primary prevention of falls and fractures (5, 6, 7, 8). However there is no consensus on the way to achieve this goal. Cholecalciferol (vitamin D3) is widely used in Europe. The minimum recommended dose in the elderly is 800 IU/day although doses of 1,500-2,000 IU/day are usually tolerated. Higher daily doses could be more likely to generate pleiotropic effects. A recent report emphasizes that Vitamin D doses of more than 4,000 IU/day could cause side effects and that more than 10,000 IU/day may lead to renal failure (8). In a recent investigation the authors recommended to keep plasma Vit. D >30 ng/ml through the administration of small daily or weekly or monthly doses of Vit. D, in order to minimize the likelihood of side effects (9). In our sample, 73 patients with hypovitaminosis D received at T0 25,000 IU (Cholecalciferol) per os twice a month (Tp.A), but we did not achieve satisfactory results: after 6 months (T1), only 40% of the subjects achieved plasma Vit. D > 30 ng/ml (baseline 21.2 ± 10.2 ng/ml; 24 wk 40.2 ± 9.2 ng/ml; p<0.0001 at Student's paired t-test). For this reason, we decided to administer to all remaining patients (Tp.B) at T0 a loading dose of 50,000 IU once a week for 8 weeks, followed by a maintenance dose of 25,000 IU twice a month. Preliminary results at 6 months (T1) in 81 treated patients show that almost 75% of patients achieved plasma Vit. D >30 ng/ml (baseline 14.4 ± 5.3 ng/ml; 24 wk 43.3 ± 14.7 ng/ml; p<0.0001 at Student's paired t-test), without side effects. At the end of the study we propose to investigate the non- responders to supplement therapy.

The preliminary results allow us to state that:

• 1)hypovitaminosis D is a widespread condition not only in elderly or postmenopausal women, but even in the young/adults of both sexes;
• 2)a loading dose is needed to achieve an adequate level of Vit. D;
• 3)the preliminary results of our study show that Tp.B is effective in correcting hypovitaminosis D in a short time, without side effects.

All in all, there is still no consensus on the dose to supplement in order to produce pleiotropic effects, but we believe it is important to quickly achieve normal Vit. D plasma values.

Conflict of interest statement: The authors have no competing interests to report.