medwireNews: Researchers have found no evidence for a link between low vitamin D levels and impaired physical performance in people aged 80 years or older.
The findings contrast with previous studies that do show such an association in younger populations of older adults, they say.
"The very old (aged >80 years) tend to be under-represented… in the studies investigating the relationship between vitamin D and physical performance," note Catharina Matheï (University of Leuven, Belgium) and colleagues. "Yet, the relevance of this association for the oldest old in particular is obvious, since the decline of physical performance is a major problem in this population."
In an analysis of baseline data available for 367 individuals (aged a mean of 84.7 years) who participated in a prospective, population-based cohort study, the researchers found that levels of 25-hydroxyvitamin D (25[OH]D) were deficient (20-29 ng/mL) in 21.5%, insufficient (10-19 ng/mL) in 32.9%, and severely insufficient (<10 ng/mL) in 32.7%.
A sufficient 25(OH)D level (30 ng/mL or more) was only found in 12.8% of the population.
"Among the oldest old in Belgium low 25-OHD serum levels are rather the rule than the exception," says the team.
As reported in Age and Ageing, univariate analysis showed no association between 25-OHD levels and balance, grip strength, or gait speed, as assessed by the Lipid Research Clinics Physical Activity Study Amsterdam Lipids Physical Activity Questionnaire.
Neither were any such associations observed after adjustment for age, level of education, gender, comorbidities, body mass index, smoking habits, serum calcium level, serum parathyroid hormone level, season of blood-sampling, vitamin D supplementation, and diuretic use.
A significant association was observed between gait speed score in the lowest quartile and higher age and lower serum calcium level. And a higher number of comorbidities and higher age were predictive of grip strength score in the lowest quartile.
The team says the lack of association between 25-OHD and the measures of balance, grip strength, and gait speed might be at least partly the consequence of an age-related down-regulation of the vitamin D receptor in muscle tissue.
"Further research is needed to investigate whether vitamin D supplementation can improve physical performance in the oldest old," concludes the team.
By Sally Robertson, medwireNews Reporter