Vitamin status in different groups of the Spanish population: a meta-analysis of national studies performed between 1990 and 1999

Objective: Studies performed on the nutritional status of the Spanish population have been very heterogeneous with respect to methodology, sample size, geographical location, socio-economic level and health status of the subjects involved. in order to gain an overall view of the state of knowledge in this area, a meta-analysis was performed on the results of all such studies undertaken in Spain between 1990 and 1999. Results: The dietetic data reviewed showed mean intakes similar to those recommended. The results obtained for the biochemical parameters analysed were within normal limits. However, results for some vitamins were very close to the lower established limits for the reference intervals (recommended intakes or blood levels), meaning that a variable percentage of subjects show values lower than those recommended. The percentage of subjects with intakes below those recommended for niacin, vitamin B-12 and C was small. The percentage of inadequate intakes of thiamine and riboflavin was small as well. However, for all other vitamins, especially D and E, the number of people with intakes below recommended was rather high, particularly so in some studies. At blood level, deficiencies of vitamins B-12, A and E were infrequent. However, for all other vitamins, prevalence of deficiency varied within a wide range. With respect to vitamins D, B-1, B-2 and B-6, over 50% of the population showed inadequate levels. Conclusions: The methodologies used in the studies included in this review were very varied and the knowledge gained is still incomplete. Despite the average Spanish diet often being regarded as satisfactory, this review and other studies show the situation can be improved.