Folate bioavailability - Food Standards Agency workshop report (original) (raw)
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Folate bioavailability: UK Food Standards Agency workshop report
British Journal of Nutrition, 2003
The UK Food Standards Agency convened a group of expert scientists to review current research investigating folate bioavailability. The workshop aimed to overview current research and establish priorities for future research. Discrepancies were observed in the evidence base for folate bioavailability, especially with regard to the relative bioavailability of natural folates compared with folic acid. A substantial body of evidence shows folic acid to have superior bioavailability relative to food folates; however, the exact relative bioavailability still needs to be determined, and in particular with regard to mixed diets. The bioavailability of folate in a mixed diet is probably not a weighted average of that in the various foods consumed; thus the workshop considered that assessment of folate bioavailability of whole diets should be a high priority for future research.
Journal of Agricultural and Food Chemistry, 2003
To provide a tool to study folate bioavailability under controlled conditions, a methodology was developed to produce extracts representative of natural food folates but removed from their matrix and sufficiently concentrated so as to elicit a response in biomarkers of folate status without distorting usual dietary intake patterns. Egg, spinach, and yeast were selected to represent the wide range in extent of folate conjugation found in foods (0, 60, and 100% polyglutamyl folate, respectively). The protocol, which was based on extracting food folates using only reagents safe for human consumption, was optimized in the laboratory (thermal extraction for 10 min in a 2% ascorbate solution at pH 5) and then adapted for industrial scale production in a food-processing facility. Results showed that the extracts were 2.3-12 times more concentrated in folate compared with their corresponding food sources. Neither the mono-to polyglutamate ratio nor the distribution of the main folate derivatives was altered during processing, making these extracts suitable for use in human bioavailability studies.
Importance of folate in human nutrition
British Journal of Nutrition, 2001
From a public health perspective, some of the new insights into folic acid nutrition are of significance. Folate intake recommendations vary under different conditions. Intake of 350 μg is required to maintain plasma homocysteine levels, 650 μg for those with elevated plasma homocysteine, about 400 μg for women planning to become pregnant and 4000 μg for those with history of neural tube defect affected pregnancy. This raises the question whether the folate intake is adequate for the general population, particularly in the vulnerable groups or whether there is a need for scientists to take a fresh view of the requirements, recommended dietary intakes, and consider intervention measures which will have impact on the folate nutritional status. The recommendations should provide a margin of safety to allow for decreased intake, increased requirements, individual variability and bioavailability of natural food folates. The folate intake and nutriture in relation to India and other devel...
Determining bioavailability of food folates in a controlled intervention study
The American journal of clinical nutrition, 2004
The concept of dietary folate equivalents (DFEs) in the United States recognizes the differences in bioavailability between natural food folates and the synthetic vitamin, folic acid. However, many published reports on folate bioavailability are problematic because of several confounding factors. We compared the bioavailability of food folates with that of folic acid under controlled conditions. To broadly represent the extent to which natural folates are conjugated in foods, we used 2 natural sources of folate, spinach (50% polyglutamyl folate) and yeast (100% polyglutamyl folate). Ninety-six men were randomly assigned according to their screening plasma homocysteine (tHcy) concentration to 1 of 4 treatment groups for an intervention period of 30 d. Each subject received (daily under supervision) either a folate-depleted "carrier" meal or a drink plus 1) placebo tablet, 2) 200 microg folic acid in a tablet, 3) 200 microg natural folate provided as spinach, or 4) 200 micro...
Naturally occurring folates in selected traditionally prepared foods in Southern India
Journal of Food Science and Technology, 2017
A wide range of Indian foods (cereals, pulses, vegetables and milk based preparations) were analysed for five folate vitamers naturally present in the foods (n = 44). A liquid chromatography-mass spectrometry (LC-MS/ MS) method using reversed phase chromatography and tandem mass spectrometry, coupled via positive mode electrospray ionization was used for the detection and quantification of the vitamers. The optimized LC-MS/MS method was capable of analysing the five most commonlyoccurring folates (folic acid, 5-methyl tetrahydrofolic acid, tetrahydrofolic acid, 10-formyl folic acid and 5-formyl tetrahydrofolic acid) in 20 min. Quantification of folates was performed using 13 C labelled internal standards. 5-methyl tetrahydrofolate was predominant in cereals, pulses and vegetable preparations. Fermented cereal preparations, beverages (coffee and tea) and green leafy vegetables were the main sources contributing to 5-formyl THF. Folic acid was identified in home-made yoghurt. All the values obtained in the present study using LC-MS/MS were compared to the total folate analysed using the microbiological assay in 2010 to generate data on the same foods. Findings suggest that the data obtained using both techniques showed agreement in the values (total folate calculated by adding the individual vitamers in the case of the LC-MS/MS values) particularly when foods were predominant in 5 methyl tetrahydrofolate. Keywords Folates Á Liquid chromatography-mass spectrometry Á Stable isotopes Á Internal standards Á Microbiological assay Abbreviations LC-MS/ MS Liquid chromatography-tandem mass spectrometry SRM Selected reaction monitoring HPLC High pressure liquid chromatography GCMS Gas chromatography mass spectrometry ESI Electrospray ionisation APCI Atmospheric pressure chemical ionisation m/z Mass to charge ratio R f Response factor SPE-SAX Solid phase extraction-strong anion exchange CID Collision induced dissociation CRM Certified reference materials & Jayashree Arcot
Folate bioavailability and health
Phytochemistry Reviews, 2002
Since its discovery in 1931 by Lucy Wills, and its first isolation in 1941 by Mitchell, Snell and Williams, our understanding of the fascinating world of folic acid and one-carbon metabolism, and its role in health and disease, has come a long way. However, there is still much to do in perfecting methods to measure folate bioavailability, and status, with a high degree of precision and accuracy. Future examination of the relationships of common gene polymorphims involved in folate bioavailability (folate polyglutamate deconjugation and carrier-mediated absorption) and one-carbon metabolism (methylation cycle, folate cycle and DNA synthesis/repair) to folate status, morbidity, mortality and longevity, need to be considered concurrently rather than as a series of individual associations, as has been the usual practice.
Scope: The objective was to perform an inventory and critical evaluation of folate data in selected European and international databases. The ultimate aim was to establish guidelines for compiling standardized folate databases for international nutritional studies. Methods and results: An ad hoc questionnaire was prepared to critically compare and evaluate folate data completeness, quantification, terminologies, and documentation of 18 European and international databases, and national fortification regulations. Selected countries participated in the European Prospective Investigation into Nutrition and Cancer project and European Food Information Resource Network (EuroFIR). Folate completeness was generally high. ''Total folate'' was the most common terminology and microbiological assay was the most frequently reported quantification method. There is a lack of comparability within and between databases due to a lack of value documentation, the use of generic or non-appropriate terminologies, folate value conversions, and/or lack of identification of synthetic folic acid. Conclusion: Full value documentation and the use of EuroFIR component identifiers and/or INFOODS tagnames for total folate (''FOL'') and synthetic folic acid (''FOLAC''), with the additional use of individual folates, will increase comparability between databases. For now, the standardized microbiological assay for total folate and HPLC for synthetic folic acid are the recommended quantification methods.
Tetrahydrofolate is the parent molecule of the folate coenzymes required for one carbon metabolism. Together with other unsubstituted folates such as dihydrofolate and folic acid, tetrahydrofolate represents the third pool of dietary folates following 5-methyltetrahydrofolate and formyl folates. Low intake of dietary folates and poor folate status are common problems in many countries. There is a critical need for reliable methods to determine folate in foods to accurately estimate folate intakes in populations. However, current values for folates in foods in databanks are often underestimated due to the high instability of several folate forms, especially tetrahydrofolate. The present review highlights the occurrence of unsubstituted folates in foods and their oxidation mechanisms and chemical behavior as well as interconversion reaction between tetrahydrofolate and 5,10-methylenetetrahydrofolate. The review shows also the important role of antioxidants in protecting folates during analysis and describes strategies to stabilize unsubstituted folates throughout all steps of the analytical procedure.