Efficacy of a 28-day oral cyanocobalamin supplementation on vitamin B status in Spanish institutionalized elderly.

Background: Cobalamin deficiency is a common problem in the elderly. There is no consensus about adequate doses for supplementation.
Subjects/methods: We performed an intervention study in order to establish the efficacy of a supplement providing 500 µg cyanocobalamin for four weeks in sixty-four institutionalized elderly residents, over 60 years of age, in Madrid (Spain). Before and after treatment, concentrations of serum cobalamin, serum holotranscobalamin, serum total homocysteine, and serum and red blood cell folate were analyzed. Clusters were built according to the initial cobalamin status and differences in the effect of supplementation were checked using a general linear model for repeated measures.
Results: Cobalamin and holotranscobalamin increased highly significantly from 308 to 558 pmol/L and from 54 to 96 pmol/L (p < 0.001) in the whole study group as well as in each subgroup (clustered by initial cobalamin levels, all p < 0.01), with the highest relative change in the subgroup with the lowest initial cobalamin values. Total homocysteine decreased from 15 to 13 µmol/l, p < 0.001). Only the change of cobalamin (F = 4.61, p < 0.01), but not of holotranscobalamin nor total homocysteine, depended on the initial serum cobalamin status.
Conclusions: A supplementation with an oral supplement solution of 500 µg cyanocobalamin daily for only four weeks, a shorter period than that found in former studies, may be considered suitable in institutionalized elderly.