[Stability and effect of ingestion on the levels of folate in plasma].

The physiological demand of folates increases during adolescence, pregnancy and lactation due to the rapid growth and anabolic activity during these stages of life. The periconceptional deficiency of folates is a risk for the presence of neural tube defects. We studied the stability of folates concentration in plasma and the effect of ingestion of a breakfast rich in folates on the postprandial levels of this micronutrient, up to two hours after food intake. For the stability assay the samples were stored protected from light at -70 degrees C and analysed at time intervals of 1, 8, 30, 90 and 120 days. The mean folates concentration in plasma was higher in postprandial stage (8.9 ng/dl) that in fasting (7.9 ng/dl), which represents a statistically significant (p < 0.01) increase of 11%. This study confirms that fasting is important in folates determination for diagnosis and research purposes to establish deficiency prevalence of this micronutrient in a population. Concerning the stability of folates concentration, we did not find a significant difference between the several time analysis (p > 0.1); this suggests that folates concentrations in plasma remain stable under the experimental conditions described.