Can vitamin D arrest daily physical activity decline in low-functioning adults at risk for falls?

USA: Vitamin D3 supplementation at doses of 1000 IU/day or higher did not have a significant impact compared to the control group receiving 200 IU/day on daily physical activity, a recent study has revealed. The findings are intriguing as the supplementation was thought to be helpful to counteract the decline in physical activity. 

"Vitamin D3 supplementation at doses of 1000 IU/day or higher did not appear to mitigate the decline in physical activity in low-functioning older adults with serum 25(OH)D levels between 10 and 29 ng/mL," the researchers reported. 

The research is a secondary data analysis of the STURDY (Study to Understand Fall Reduction and Vitamin D in You) clinical trial involving 571 participants aged 70 years and older. These participants exhibited baseline serum 25(OH)D levels ranging from 10 to 29 ng/mL and had an elevated risk of falls.

The study published in the Journal Of The American Geriatrics Society was conducted by Jennifer A. and colleagues on the potential benefits of vitamin D3 supplementation on daily physical activity in low-functioning adults at risk of falls. 

Throughout the study, participants were equipped with wrist accelerometers, allowing researchers to monitor their daily physical activity. They were randomly assigned to one of four groups: a control group receiving 200 IU/day of vitamin D3, and three supplementation groups receiving 1000, 2000, or 4000 IU/day of vitamin D3.

The study's findings revealed some critical insights. Over time, there was a decline in physical activity levels among the participants, which was statistically significant. Additionally, this decrease in physical activity was accompanied by increased fragmentation, indicating that physical activity became more "broken up" over time.

However, the most intriguing finding was related to vitamin D3 supplementation. Despite the hope that supplementation might help counteract the decline in physical activity, the study found that vitamin D3 supplementation at doses of 1000 IU/day or higher did not have a significant impact compared to the control group receiving 200 IU/day.

Interestingly, the study identified a subgroup of participants with baseline serum 25(OH)D levels below 20 ng/mL. Among this subgroup, the decline in physical activity was more rapid compared to those with baseline 25(OH)D levels in the range of 20–29 ng/mL. This suggests that baseline vitamin D levels may play a role in how individuals respond to supplementation.

In conclusion, for low-functioning older adults with serum 25(OH)D levels between 10 and 29 ng/mL, vitamin D3 supplementation at doses of 1000 IU/day or higher did not appear to mitigate the decline in physical activity. These findings emphasise the need for alternative interventions to address the reduction in physical activity in older adults with low serum 25(OH)D levels. This research underscores the complexity of the relationship between vitamin D and physical activity, prompting further exploration into effective strategies to maintain or improve mobility in older populations.

Reference:

Schrack JA, Cai Y, Urbanek JK, Wanigatunga AA, Mitchell CM, Miller ER 3rd, Guralnik JM, Juraschek SP, Michos ED, Roth DL, Appel LJ. The association of vitamin D supplementation and serum vitamin D levels with physical activity in older adults: Results from a randomized trial. J Am Geriatr Soc. 2023 Jul;71(7):2208-2218. doi: 10.1111/jgs.18290. Epub 2023 Feb 23. PMID: 36821761; PMCID: PMC10363216.