Influence of physical activity on serum vitamin D levels in people with multiple sclerosis

Short-Term Risk Factors for Bone Loss in Multiple Sclerosis: A Prospective Study and Literature Review

BACKGROUND

Reduced bone mass and increased osteoporosis risk are common in people with multiple sclerosis (pwMS). The aim of the study was to identify risk factors for short-term bone loss in MS.

METHODS

This prospective study included 139 pwMS (ages 18-65). Baseline data included demographics, body-mass index, physical activity, smoking, menopause status, 25-hydroxy vitamin D levels, and history of glucocorticoid use. Bone mineral density (BMD) was measured at baseline and after 2 years using dual-energy X-ray absorptiometry (DXA) for the lumbar spine and hip. Disability worsening was assessed by the Expanded Disability Status Scale (EDSS). Additionally, a literature review was conducted on longitudinal data regarding BMD in MS.

RESULTS

Over the 2-year follow-up period, significant BMD loss was observed in the hip (baseline g/cm2: median 0.898; IQR 0.808-1.014; 2-year follow-up: 0.882; 0.784-1.01; p < 0.001), but not in the lumbar spine. Overall, 101 (73.1%) experienced hip BMD loss, with a median decrease of 3.5%. Patients with disability worsening had an approximately 7-times higher risk of bone loss compared to those without disability worsening (p = 0.013). PwMS with fractures during the follow-up period had significantly lower hip BMD (0.760, 0.546-0.890 vs. 0.909, 0.828-1.015; p = 0.024), a higher EDSS score (4.4, 2.8-5.8 vs. 2.0, 1.0-4.0 vs. p = 0.026), and were older (59, 46-62 vs. 47, 37-54; p = 0.030) compared to those without fractures.

CONCLUSION

Disability worsening was identified as a risk factor for BMD loss. These findings underscore the need for active monitoring of pwMS with disability worsening to prevent bone loss and, thus, to reduce fracture risk.

The effect of physical activity on vitamin D: A systematic review and meta-analysis of intervention studies in humans

Objectives

Cross-sectional studies demonstrate a positive association between higher physical activity and serum 25-hydroxyvitamin D (25(OH)D) concentration. However, whether this association is causal is unclear. We conducted a systematic review to identify intervention studies that examined the effect of physical activity on serum 25(OH)D concentration in humans.

Study design

Systematic review and meta-analysis.

Methods

We searched PubMed, Scopus and Web of Science to identify full-text peer-reviewed articles published in English from inception until January 2023. Eligible studies were randomised controlled trials or quasi-experimental studies. We used random effects meta-analysis to calculate the weighted mean difference (WMD) in the change in 25(OH)D concentration between physical activity and control groups. We used the revised Cochrane risk-of-bias tool for randomized trials (RoB 2) to assess the methodological quality of included studies.

Results

We included 32 articles in the systematic review and 24 in the meta-analysis. The intervention varied from resistance and weight-bearing exercises (n = 13) to aerobic exercises (n = 10), moderate and moderate-to-vigorous exercises (n = 5), aquatic exercise (n = 2), and multicomponent traditional exercises (n = 2) (Tai Chi and Yijinjing). The WMD in 25(OH)D in the physical activity and control groups was 9.51 and 4.87, respectively (between-group mean difference 4.64, p = 0.002). However, the difference was only evident in studies that implemented the intervention outdoors (n = 3; between-group mean difference 17.33, p < 0.0001); when the intervention was indoors there was no significant effect of physical activity on 25(OH)D (n = 16; between-group mean difference 1.80, p = 0.113).

Conclusions

This meta-analysis of physical activity interventions in humans showed that physical activity does not lead to increased 25(OH)D independently of time outdoors. However, most studies were under-powered, in many the exercise was low intensity, and vitamin D was not the primary outcome.