Endocrine Abstracts

Background: Vitamin D deficiency is common in elderly nursing home residents. It has been associated with low bone mineral density, muscle weakness, increased body sway and falls. Evidence indicates that supplementation of vitamin D in these individuals helps to improve locomotor function and general health.

Patients and methods: We evaluated, in a 12 months interval, the effects of vitamin D supplementation on grip strength in 45 nursing home residents (28 women and 17 men, aged 58–89 years) who consumed daily one bun fortified with 125 μg vitamin D₃ (25(OH)D) and 320 mg elemental calcium, in order to achieve optimal blood levels of 25(OH)D >75 nmol/l. Grip strength was measured at baseline and 12 months after vitamin D supplementation, using a specific dynamometer (Baseline Squeeze Bulb Dynamometer, USA). For each hand, the highest of three attempts was noted as maximal grip strength. The average of maximum values for the left and right hands was considered as the measure of the participant’s muscle strength.

Results: Muscle strength positive correlated with locomotion functions score (P=0.034) and levels of vitamin D (P=0.046), but significant improvement of grip strength could not be proven although optimal levels of vitamin D were maintained for long term. Although optimal levels of 25(OH)D were associated with an amelioration of locomotor function, grip strength improvement was not statistically significant (P=0.570).

Conclusions: Vitamin D deficiency is only one of the conditions that affect muscle function in elderly people. Our results showed a good correlation between muscle strength and 24(OH)D₃ levels, but sustained normalisation of vitamin D levels is not sufficient for significant improvement of muscle function. Further control randomized studies may be necessary for a better understanding of the effects of long term vitamin D supplementation on the health outcomes in the elderly.