Unmetabolized serum folic acid and its relation to folic acid intake from diet and supplements in a nationally representative sample of adults aged ≥60 y in the United States

Abstract

Background: Unmetabolized serum folic acid (UMFA) has been detected in adults. Previous research indicates that high folic acid intakes may be associated with risk of cancer. Objective: The objective was to examine UMFA concentrations in relation to dietary and supplemental folate and status biomarkers in the US population aged 60 y. Design: Surplus sera were analyzed with the use of data from the National Health and Nutrition Examination Survey (NHANES) 2001-2002, a cross-sectional, nationally representative survey (n = 1121). Results: UMFA was detected in 38% of the population, with a mean concentration of 4.4 6 0.6 nmol/L (median: 1.26 0.2 nmol/L). The group with UMFA (UMFA+) had a significantly higher proportion of folic acid supplement users than did the group without UMFA (60% compared with 41%). UMFA+ men and women also had higher supplemental and total (food + supplements) folic acid intakes than did their counterparts without UMFA. Forty percent of the UMFA+ group was in the highest quartile of total folic acid intake, but total folic acid intake was only moderately related to UMFA concentrations (r 2 = 0.07). Serum folate concentrations were significantly higher in the UMFA+ group and were predictive of UMFA concentrations (r 2 = 0.15). Serum 5-methyltetrahydrofolate and vitamin B-12 concentrations were higher in the UMFA+ group, whereas there was no difference between the 2 UMFA groups in red blood cell folate, serum homocysteine, or methylmalonic acid concentrations.Conclusions: Approximately 40% of older adults in the United States have UMFA that persists after a fast, and the presence of UMFA is not easily explained in NHANES by folic acid intakes alone. Given the possibility that excessive folic acid exposure may relate to cancer risk, monitoring of UMFA may be warranted. Am J Clin Nutr 2010;92:383-9.

Folate, vitamin B6 and vitamin B12 in adolescence: serum concentrations, prevalence of inadequate intakes and sources in food

“…Em contrapartida ao aparente sucesso da fortificação mandatória de alimentos com ácido fólico, a comunidade científica não é unânime à aprovação de políticas de fortificação e do uso de suplementos, havendo debates no meio científico 24 . Pesquisadores criticam a necessidade da exposição de toda a população a altas doses da vitamina e apontam que a superexposição ao micronutriente pode estar associada à ocorrência de efeitos adversos a saúde, entre eles, a elevação da incidência de câncer de cólon retal 25 * Percentil da quantidade do nutriente no alimento em relação à quantidade total do nutriente consumido pela população de estudo.…”

Interactions between plasma concentrations of folate and markers of vitamin B12status with cognitive performance in elderly people not exposed to folic acid fortification: the Hordaland Health Study

“…In line with this, cross-sectional analyses within the National Health and Nutrition Examination Survey (NHANES) study revealed that high serum folate status was generally associated with protection against cognitive impairment; however, individuals with low vitamin B 12 status combined with high folate status had an increased risk of cognitive impairment compared with those with a normal status of both vitamins (7) . It has been hypothesised that unmetabolised folic acid, which is likely to be present in individuals living in areas with mandatory folic acid fortification of food items (8,9) , may mask or exacerbate metabolic and clinical consequences of vitamin B 12 deficiency (10) . The findings from the NHANES study that high folate concentrations were associated with an increased risk of cognitive impairment in individuals with vitamin B 12 deficiency are in line with the results from the Framingham Heart Study including individuals unexposed to folic acid fortification (11) .…”

101 Increased Cancer Cell Proliferation in Prostate Cancer Patients With High Levels of Serum Folate

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