A new study from the UK suggests that intake of oral vitamin D at 5,000 IU daily for three months has a superior effect than 2,000 IU daily in treating mild to moderate vitamin D deficiency.
In the study, 30 vitamin D deficient patients with blood levels less than 20 ng/ml were given 5,000 IU /day or 2,000 IU /day of a vitamin D supplement (1). After three months, changes in vitamin D levels and muscle strength were measured. The study results showed that after three months of receiving 2,000 IU /day vitamin D levels averaged 30 ng/ml (75 nmol/L), meaning about half the patients were still vitamin D deficient. In the 5,000- IU /day group the average vitamin D level was 45 ng/ml (114 nmol/L), which is considered to be within the normal range. In addition, 93% of the patients had levels which measured greater than the average 30 ng/ml. Among the 2,000- IU /day group, however, only 45% had levels above 30 ng/ml. In both groups, grip strength improved significantly compared to baseline, while the improvements in timed tests of sitting to standing and the 6-meter walk test also improved, but not significantly. The improvements in muscle strength did not vary with dosage: the 2,000- IU /day group showed the same improvements in grip strength as the 5,000- IU /day group did.
The researchers commented that these findings demonstrate that the administration of oral vitamin D at 5,000 IU daily for three months is superior to 2,000 IU daily in treating mild to moderate vitamin D deficiency. Muscle strength improvements, it was noted, were the most dramatic at changes in lower ranges of vitamin D levels. Although the UK Food and Nutrition Board recommends a vitamin D intake of 4,000 IU /day as the upper limit, quite a few people would still have inadequate levels at this dose, the scientists added.