Effect of different dosage and administration schedules of folic acid on blood folate levels in a population of Honduran women of reproductive age

BACKGROUND: Observational studies and clinical trials have shown conclusive evidence that periconceptional folic acid supplementation prevents up to 70 % of neural tube defects (NTD). The Honduran government wanted to implement a supplementation programme of folic acid but needed to assess the relative effects of two dosages of folic acid. OBJECTIVE: To determine the effect of two dosages of folic acid on blood folate levels in Honduran female factory workers aged 18 to 49 years. DESIGN: This was a randomized, double-blind control supplementation trial conducted in Choloma, Honduras. A total of 140 eligible women were randomly assigned to two dosage groups and followed up for 12 weeks. One group received a daily dosage of 1 mg folic acid and the other a once weekly dosage of 5 mg. Serum folate and red blood cell folate levels were determined by radioassay at baseline, 6 weeks and 12 weeks. RESULTS: Serum folate levels increased from 6.3 (se 0.2) to 14.9 (se 0.6) ng/ml (P < 0.0001) in women assigned to the 1 mg/d group and from 6.9 (se 0.3) to 10.1 (se 0.4) ng/ml (P < 0.0001) in those assigned to the 5 mg/week group. Red blood cell folate concentrations also increased significantly in both groups, albeit more slowly. Educational level, age and BMI were not associated with the changes in serum and red blood cell folate levels during the supplementation period. However, a differential effect on serum folate levels by dosage group and time was observed. CONCLUSIONS: Although both folate supplementation regimens increased serum and red blood cell folate levels significantly among the women studied, blood folate levels that are considered to be protective of NTD were reached faster with the daily dosage of 1 mg folic acid.     

Maternal serum vitamin B12, folate and homocysteine and the risk of neural tube defects in the offspring in a high-risk area of China

OBJECTIVE: To examine the association between the risk of neural tube defects (NTD) and maternal serum vitamin B12, folate and homocysteine in a high-risk area of China. DESIGN: A case-control study was carried out in Luliang mountain area of Shanxi Province.Subjects/settingA total of eighty-four NTD pregnancies and 110 matched controls were included in the study; their serum vitamin B12 and folate concentrations were measured by chemiluminescent immunoenzyme assay and total homocysteine concentrations by fluorescent polarisation immunoassay. RESULTS: Serum vitamin B12 and folate concentrations were lower in NTD-affected pregnant women than in controls (P < 0.01). Serum total homocysteine was higher in the NTD group than in controls at less than 21 weeks of gestation (P < 0.01). Adjusted odds ratios revealed that women with lower vitamin B12 (adjusted OR=4.96; 95 % CI 1.94, 12.67) and folate (adjusted OR=3.23; 95 % CI 1.33, 7.85) concentrations had a higher risk of NTD compared to controls. Based on dietary analysis, less consumption of meat, egg or milk, fresh vegetables and fruit intake would increase the risk of NTD. CONCLUSIONS: Lower serum concentrations of folate and vitamin B12 are related to the increased risk of NTD in high-risk populations. Both folate and vitamin B12 intake insufficiency could contribute to the increased risk of NTD. A dietary supplement, combining folate and vitamin B12, might be an effective measure to decrease the NTD incidence in these areas.     

Negative priming effect on mineralization in a soil free of vegetation for 80 years

The priming effect (PE) is a complex process corresponding to a modification of mineralization rates of soil organic matter (SOM) following inputs of fresh organic matter (FOM). The priming effect can be either positive or negative (i.e. an acceleration or retardation of SOM decomposition) and is controlled by several factors such as microbial community composition, SOM chemical structure and nutrient availability. The first objective of our experiment was to study negative or positive PE of stabilized SOM. The second was to identify the role of FOM decomposers in the PE of stabilized SOM. We incubated, for 39 days, a fallow soil free of vegetation for 80 years amended with ¹³C‐cellulose and inoculated with a FOM‐decomposing community. The soil contained stabilized SOM. The PE of the stable organic matter was always negative and tended to be more negative when the FOM‐decomposing community was added. This suggests that for this particular soil, SOM mineralization was not limited by energy. Moreover, as the inoculation of a FOM‐decomposing community led to a more negative PE, we assume that the FOM‐decomposing community facilitated the access of FOM to the indigenous bare soil community.     

Issues in assessing the validity of nutrient data obtained from a food-frequency questionnaire: folate and vitamin B12 examples

OBJECTIVE: To compare methods used to assess the validity of nutrient intake data obtained from a food-frequency questionnaire (FFQ), using folate and vitamin B12 as nutrient examples. DESIGN: Cross-sectional sample from a population cohort. SETTING: Two postcode areas west of Sydney, Australia. SUBJECTS: In total, 2895 people aged 49 years and older provided dietary data using a semi-quantitative FFQ (79% of 3654 subjects examined). The validity of the FFQ was assessed against three 4-day weighed food records (WFRs) completed by 78 people (mean age 70 years). RESULTS: Folate and vitamin B12 validity data were assessed using different methods. The Spearman ranked correlations (energy-adjusted) were 0.66 for folate and 0.38 for vitamin B12. Using the Bland-Altman method, following loge transformation, no linear trend existed between the differences and means for folate and vitamin B12. Large differences existed between the FFQ and WFR in individual cases, particularly for vitamin B12. Finally, data were divided into quintile categories for the test and reference method: 79% classified folate within one quintile, 65% classified vitamin B12 within one quintile; there was no gross misclassification for folate and only 3% misclassification for vitamin B12. CONCLUSIONS: Different methods of analysis provided different information about the validity of the FFQ. Correlation coefficients should not be used alone to assess the validity of nutrient data, but should be used in conjunction with Bland-Altman analyses. Depending on the use of the data, additional assessment of classification categories is recommended. This worked example demonstrates that absolute intakes of folate and vitamin B12 should be used with caution.     

Synchronous fluorescence as a rapid method for the simultaneous determination of folic acid and riboflavin in nutritional beverages

A rapid synchronous spectrofluorimetric method was first developed for the simultaneous determination of folic acid and riboflavin in nutrimental beverages. Folic acid could be detected by using H(2)O(2) plus Cu(II) as oxidation system to produce pterine-6-carboxylic acid, which had strong fluorescence in aqueous solution, and riboflavin itself was obviously fluorescent. Various operational parameters were thoroughly discussed in terms of their effects on the fluorescence signals, including instrumental parameters, concentration of the oxidation system, and pH. Under optimum conditions, the calibration curves were linear in the ranges of 100-250 μg/L for folic acid and 1-250 μg/L for riboflavin, and the detection limits were 2.0 and 0.014 μg/L, respectively. In addition, this method was applied to the determination of folic acid and riboflavin in nutrimental beverages with satisfactory results.     

Effects of preparation and cooking of folic acid-fortified foods on the availability of folic acid in a folate depletion/repletion rat model

The practice of food fortification with folic acid offers the potential to increase the folate intake of the general population. To fully exploit the potential of fortification for raising folate nutriture, appropriate food vehicles need to be selected. Selection should involve determination of the availability of folic acid as affected by characteristics of the carrier food, food matrix, food preparation, and cooking. The present study investigated the effects of preparation and cooking of a range of folic acid-fortified foods on the folate status of folate-deficient rats. Fifty-six weanling male rats (Wistar strain) were fed a folate-deficient diet containing 1% succinyl sulfathiazole for 28 days. Following depletion, six rats were randomly assigned to each of eight repletion diets containing cooked or uncooked meringue mix, quick bread mix, brownie mix, or pizza base mix. The test foods were fortified with 1400 microg of folic acid/kg of food and incorporated as 19% of the repletion diets. Each of the first four groups was pair-fed a diet containing a cooked fortified food with another group fed the corresponding uncooked fortified food. After a further 28 days, plasma, liver, and kidney folate concentrations were determined by microbiological assay. Mean plasma and liver folate concentrations of rats fed diets containing cooked fortified foods were similar to those of rats fed uncooked fortified foods. Preparation and cooking did not affect the availability of folic acid from the selected cereal-based convenience foods in this rat model system, suggesting that these foods are appropriate vehicles for fortification with folic acid.     

Change in SOC content in a small karst basin for the past 35 years and its influencing factors

ABSTRACT

To research soil organic carbon (SOC) in a typical small karst basin of western Guizhou in southwest China, data from the second national soil resource survey (1980) and data analysed in the laboratory in 2015 were used. This paper examines the changes in soil organic carbon density (SOCD) and soil organic carbon stock (SOCS) in the topsoil (0–20 cm) over the past 35 years based on soil types, and the primary influencing factors are also discussed. The SOCD and SOCS slightly increased over this period. The SOCD increased from 4.91 kg m^?2 to 5.13 kg m^?2, and the SOCS increased from 368.27 × 10³ t to 385.09 × 10³ t. The basin sequestered a low level of carbon during this time. Paddy fields were the key contributor to the increases, and the SOCD and SOCS of paddy fields increased by 1.61 kg m^?2 and 32.39 × 10³ t, respectively. Generally, the SOCD and SOCS in the soils from the southern part of Houzhai Basin increased considerably, and those from the northern part of the basin decreased significantly. The spatial variation of SOCD in the Houzhai Basin was mainly due to natural factors. However, the temporal change of SOC was primary caused by human activities.     

Lactic and succinic acid levels and refractive indices in the determinations of the age of eggs.

The increase in the concentration of lactic and succinic acid during storage was measured in an attempt to determine the age of eggs. The increase in succinic acid alone is not sufficient to indicate egg age. Although lactic acid concentrations increase more rapidly, the levels are still very low, the increase is not linear, and concentrations in fresh eggs vary widely. On the other hand, refractive indices showed a nearly linear correlation with age and very little variation between eggs. These measurements are reproducible and easy to perform and, with further study, should provide an alternative to the AOAC method.     

Spinach cultigen variation for tissue carotenoid concentrations influences human serum carotenoid levels and macular pigment optical density following a 12-week dietary intervention

Increasing intakes of carotenoid-rich plant foods can increase serum carotenoid concentrations and macular pigment optical density (MPOD) in most, but not all, individuals. Research objectives for this study were to (1) characterize tissue lutein (L) and beta-carotene (BC) concentrations in carotenoid-rich spinach (Spinacia oleracea L.) cultigens and (2) determine serum carotenoid and MPOD responses in human subjects consuming spinach cultigens differing in tissue L and BC concentrations. Thirteen spinach cultigens were evaluated for carotenoid accumulations over two consecutive growing seasons. "Springer" (8.4 and 6.5 mg/100 g of fresh mass for L and BC, respectively) and "Spinner" (12.1 and 9.2 mg/100 g of fresh mass for L and BC, respectively) spinach cultigens were selected for a dietary intervention study and represented low- and high-L concentrations. The high-L ("Spinner") and low-L ("Springer" ) spinach treatment groups consisted of 10 subject volunteers ingesting five 50-g spinach servings/week during a 12-week intervention. Average serum L concentrations increased by 22% (P = 0.07) from baseline (0.233 micromol/L) to 12 weeks (0.297 micromol/L) for subjects consuming low-L spinach. Subjects consuming high-L spinach showed increases of 33% (P = 0.04) in serum L from baseline (0.202 micromol/L) to 12 weeks (0.300 micromol/L). Average MPOD did not change for the low-L treatment group; however, subjects in the high-L group demonstrated increases (P = 0.02) in MPOD at the 30' eccentricity between baseline (0.343) and 12 weeks (0.374). This study demonstrates that serum carotenoid and MPOD are determined by L concentrations present in the spinach matrix. Results emphasize the role of cultigen selection among vegetable crops in determining phytochemical effects on human health.     

Quantitation of N2-[1-(1-carboxy)ethyl]folic acid, a nonenzymatic glycation product of folic acid, in fortified foods and model cookies by a Stable isotope dilution assay

A stable isotope dilution assay (SIDA) for the quantitation of N(2)-[1-(carboxy)ethyl]folic acid (CEF) has been developed by using [(2)H(4)]CEF as the internal standard. After sample cleanup by anion exchange chromatography, the three-dimensional specifity of liquid chromatography-tandem mass spectrometry enabled unequivocal determination of the nonenzymatic glycation product of folic acid (FA). When CEF was added to cornstarch, the detection limit for CEF was found to be 0.4 microg/100 g, and a recovery of 98.5% was determined. In analyses of cookies, the intra-assay coefficient of variation was 8.0% (n = 5). Application of the SIDA to commercial cookies produced from wheat flour fortified with FA revealed CEF contents of up to 7.1 microg/100 g, which accounted for approximately 10-20% of the cookies' FA content. In baby foods, multivitamin juices, and multivitamin sweets, however, CEF was not detectable. Further studies on CEF formation during baking of cookies made from fortified flour and different carbohydrates revealed that fructose was most effective in generating CEF followed by glucose, lactose, and sucrose with 12.5, 3.9, 2.5, and 2.5 microg/100 g of dry mass, respectively. During baking, approximately 50% of FA was retained for both monosaccharides fructose and glucose, and 77% as well as 85% of its initial content was retained for the disaccharides lactose and sucrose, respectively. Of the degraded amount of FA, CEF comprised 28% for fructose as well as 18, 12, and 8% for sucrose, lactose, and glucose, respectively. Therefore, CEF can be considered an important degradation product of FA in baked foods made from fructose. To retain a maximum amount of FA, products should rather be baked with sucrose than with reducing carbohydrates.     

Technique for rapid, small-scale analysis of vitamin C levels in fruit and application to a tomato mutant collection

We present a technique for easy, rapid analysis of both total and reduced forms of vitamin C in fruits using microplates and a plate reader. This technique has been compared with a spectrofluorometric technique classically used for assaying vitamin C in fresh tomato. We have applied these methods to a population of 118 tomato mutant lines and controls in search of variability for this trait. Six lines, identified as having high vitamin C levels, and four lines having low vitamin C levels have been chosen for further study. The vitamin C levels have been compared with sugar concentration, dry matter content, fruit weight, titratable acidity, and firmness. The correlations that often exist in tomato varieties between sugar and vitamin C content (positive correlation) or fruit weight and vitamin C content (negative correlation) can be uncoupled in the lines selected for further analysis.