"The results of our study could implicate that the elderly should be sure to get adequate vitamin D to reduce their risk of falling," lead research Dr. Marieke Snijder from the Vrije Universiteit Amsterdam told NutraIngredients.com."Possibilities to prevent falls by raising vitamin D levels (through supplementation, increase of sun exposure, or diet) must be explored in the general elderly population."
Falls among the elderly individuals occur frequently and lead to substantial morbidity and mortality, but although research has already shown use of vitamin D supplements to reduce the risk, not all trials confirm these benefits.
These interventions, said Snijder, have been small (looking at the risk of falling), and have focused predominantly on institutionalized persons (mainly women).
The new prospective cohort study, published in the August issue of The Journal of Clinical Endocrinology & Metabolism (Vol. 91, pp. 2980-2985), followed 1231 men and women older than 65. Serum levels of 25-hydroxyvitamin D (the non-active 'storage' form) - 25(OH)D - were measured at the start of the study.
During the course of the following year, falls were prospectively recorded by self-reporting of the participants.
Snijder and colleagues report that levels of 25(OH)D lower than 10 nanograms per millilitre of serum were linked to a 78 per cent increased risk of falling at least twice, after adjusting the results for age, sex, education level, region, season, physical activity, smoking, and alcohol intake.
About 12 per cent of people with serum 25(OH)D levels of less than 10 nanograms per millilitre fell at least three times during the year, while only 4.4 per cent of people with serum 25(OH)D levels of more than 30 nanograms per millilitre had the same number of falls.
The researchers reported a statistically significant effect of age, with younger subjects (younger than 75) with low 25(OH)D levels over four times more likely to fall at least twice than people over 75.
"The present study shows that low serum 25(OH)D levels (less than 10 nanograms per millilitre) are independently associated with a higher risk of recurrent falling in the elderly," wrote Snijder.
Dr. Snijder said however that such a link should be investigated further in intervention studies.
"For future research it would be relevant to explore the possibilities for prevention of recurrent falling by raising serum 25(OH)D levels in the general elderly population, but also to investigate the underlying mechanism that explains the association between serum 25(OH)D levels and risk of recurrent falling," Snijder told NutraIngredients.com.
While studies need to look at the underlying mechanism, the researchers do note that previous research has shown that low serum levels of the vitamin are independently associated with lower neuromuscular performance, which may affect gait, postural balance, and muscle strength.
"Because the population attributable fraction was even higher in persons aged between 65 and 75 years as compared with the participants older than 75, vitamin D supplementation could be particularly effective in the younger elderly," they said.
Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former is produced in the skin on exposure to UVB radiation (290 to 320 nm) and can also be consumed from oily fish. The latter is derived from plants and only enters the body via the diet.
Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D, the non-active 'storage' form, and 1,25-dihydroxyvitamin D, the biologically active form that is tightly controlled by the body.