Comparison of standardised dietary folate intake across ten countries participating in the European Prospective Investigation into Cancer and Nutrition

Mitigating digestive disorders: Action mechanisms of Mediterranean herbal active compounds

This study explores the effects of the Mediterranean diet, herbal remedies, and their phytochemicals on various gastrointestinal conditions and reviews the global use of medicinal plants for common digestive problems. The review highlights key plants and their mechanisms of action and summarizes the latest findings on how plant-based products influence the digestive system and how they work. We searched various sources of literature and databases, including Google Scholar, PubMed, Science Direct, and MedlinePlus. Our focus was on gathering relevant papers published between 2013 and August 2023. Certain plants exhibit potential in preventing or treating digestive diseases and cancers. Notable examples include Curcuma longa, Zingiber officinale, Aloe vera, Calendula officinalis, Lavandula angustifolia, Thymus vulgaris, Rosmarinus officinalis, Ginkgo biloba, Cynodon dactylon, and Vaccinium myrtillus. The phytochemical analysis of the plants showed that compounds such as quercetin, anthocyanins, curcumin, phenolics, isoflavones glycosides, flavonoids, and saponins constitute the main active substances within these plants. These natural remedies have the potential to enhance the digestive system and alleviate pain and discomfort in patients. However, further research is imperative to comprehensively evaluate the benefits and safety of herbal medicines to use their active ingredients for the development of natural and effective drugs.

Main sources and predictive factors of folate intake in female university students

OBJECTIVE

The study aimed to identify the main folate sources and examine socio-demographic and lifestyle determinants influencing folate intake among 1410 women aged 18 to 39.

METHODS

Data were collected using a self-administered health and lifestyle questionnaire and a 5-d dietary record method. To assess folate intake in relation to the dietary reference intakes, the probability approach was used. Folate intake determinants were identified using multivariate-adjusted logistic regression models; odds ratios (ORs) with 95% confidence intervals (95% CIs).

RESULTS

The average total folate intake among women was 311 ± 144 µg/day dietary folate equivalents. Vegetables (30.7%) and cereals (22.6%) were the most important folate sources. Foods fortified with folic acid were consumed by 20.6% of women, dietary supplements by 7.2%. More than half of the participants (55%) had a high probability of inadequate folate intake. The predictors of being in the highest tertile of folate intake (>303 versus <225 µg) were: physical activity (high versus low; OR: 2.97, 95% CI: 1.77-4.97), nutritional knowledge (high versus low; OR: 5.32, 95% CI: 2.82-10.1), following a vegetarian diet (yes versus no; OR: 6.13; 95% CI: 2.79-13.5), daily number of meals (≥5 versus ≤3; OR: 4.17, 95% CI: 2.38-7.32), excluding/including some foods (yes versus no; OR: 2.47; 95% CI: 1.41-4.31) and energy intake (3rd versus 1st tertile; OR:17.4, 95% CI: 11.1-27.4).

CONCLUSION

Identifying factors associated with a higher intake of folate may be helpful in shaping public health nutrition policy. It allows the design of effective nutrition education programs to promote increased intake of folate in subgroups at risk of deficiency.

Dietary flavonoids-microbiota crosstalk in intestinal inflammation and carcinogenesis

Colorectal cancer (CRC) is currently the third leading cancer and commonly develops from chronic intestinal inflammation. A strong association was found between gut microbiota and intestinal inflammation and carcinogenic risk. Flavonoids, which are abundant in vegetables and fruits, can inhibit inflammation, regulate gut microbiota, protect gut barrier integrity, and modulate immune cell function, thereby attenuating colitis and preventing carcinogenesis. Upon digestion, about 90% of flavonoids are transported to the colon without being absorbed in the small intestine. This phenomenon increases the abundance of beneficial bacteria and enhances the production of short-chain fatty acids. The gut microbe further metabolizes these flavonoids. Interestingly, some metabolites of flavonoids play crucial roles in anti-inflammation and anti-tumor effects. This review summarizes the modulatory effect of flavonoids on gut microbiota and their metabolism by intestinal microbe under disease conditions, including inflammatory bowel disease, colitis-associated cancer (CAC), and CRC. We focus on dietary flavonoids and microbial interactions in intestinal mucosal barriers as well as intestinal immune cells. Results provide novel insights to better understand the crosstalk between dietary flavonoids and gut microbiota and support the standpoint that dietary flavonoids prevent intestinal inflammation and carcinogenesis.

Association Between Plasma Homocysteine Level and Mortality: A Mendelian Randomization Study

BACKGROUND AND OBJECTIVES

In previous studies, high homocysteine levels were associated with high cardiovascular mortality. However, these results were inconsistent with those of randomized controlled trials. We aimed to evaluate the causal role of homocysteine on all-cause and cardiovascular mortality using Mendelian randomization (MR) analysis.

METHODS

This study included the 10,005 participants in the Namwon Study. In conventional observational analysis, age, sex, survey years, lifestyles, body mass index, comorbidities, and serum folate level were adjusted using multivariate Cox proportional regression. MR using 2-stage least squares regression was used to evaluate the association between genetically predicted plasma homocysteine levels and mortality. Age, sex, and survey years were adjusted for each stage. The methylenetetrahydrofolate reductase (MTHFR) polymorphism was used as an instrumental variable for predicting plasma homocysteine levels.

RESULTS

Observed homocysteine levels were positively associated with all-cause (hazard ratio [HR], 1.40; 95% confidence interval [CI], 1.26-1.54) and cardiovascular (HR, 1.62; 95% CI, 1.28-2.06) mortality when plasma homocysteine levels doubled. However, these associations were not significant in MR analysis. The HRs of doubling genetically predicted plasma homocysteine levels for all-cause and cardiovascular mortality were 0.99 (95% CI, 0.62-1.57) and 1.76 (95% CI, 0.54-5.77), respectively.

CONCLUSIONS

This MR analysis did not support a causal role for elevated plasma homocysteine concentrations in premature deaths.

Effect of MAOA DNA Methylation on Human in Vivo Protein Expression Measured by [11C]harmine Positron Emission Tomography

BACKGROUND

Epigenetic modifications like DNA methylation are understood as an intermediary between environmental factors and neurobiology. Cerebral monoamine oxidase A (MAO-A) levels are altered in depression, as are DNA methylation levels within the MAOA gene, particularly in the promoter/exon I/intron I region. An effect of MAOA methylation on peripheral protein expression was shown, but the extent to which methylation affects brain MAO-A levels is not fully understood.

METHODS

Here, the influence of MAOA promoter/exon I/intron I region DNA methylation on global MAO-A distribution volume (VT), an index of MAO-A density, was assessed via [11C]harmine positron emission tomography in 22 patients (14 females) suffering from seasonal affective disorder and 30 healthy controls (17 females).

RESULTS

No significant influence of MAOA DNA methylation on global MAO-A VT was found, despite correction for health status, sex, season, and MAOA variable number of tandem repeat genotype. However, season affected average methylation in women, with higher levels in spring and summer (Puncorr = .03). We thus did not find evidence for an effect of MAOA DNA methylation on brain MAO-A VT.

CONCLUSIONS

In contrast to a previous study demonstrating an effect of methylation of a MAOA promoter region located further 5' on brain MAO-A, MAOA methylation of the region assessed here appears to affect brain protein levels to a limited extent at most. The observed effect of season on methylation levels is in accordance with extensive evidence for seasonal effects within the serotonergic system.

CLINICALTRIALS.GOV IDENTIFIER

NCT02582398 (https://clinicaltrials.gov/ct2/show/NCT02582398).

Inverse Association of Serum Folate Level with Metabolic Syndrome and Its Components in Korean Premenopausal Women: Findings of the 2016–2018 Korean National Health Nutrition Examination Survey

Research on the association of serum folate levels with metabolic syndrome (MetS) in premenopausal women is lacking. This study was aimed to investigate this association in 1730 premenopausal women using the 2016 to 2018 Korean National Health and Nutrition Examination Survey data. Participants’ mean age and BMI were 35.9 years and 22.7 kg/m2, respectively. Participants were divided into three groups according to serum folate tertiles. Odds ratios (OR) and 95% confidence intervals (CIs) for abdominal obesity, elevated blood pressure (BP), high fasting plasma glucose (FPG), high triglycerides (TG), low high-density lipoprotein cholesterol (HDL-C), and MetS were calculated in multiple logistic regression models adjusted for possible confounders, by serum folate level tertiles. Prevalence of MetS (14.9, 11.0, and 8.6%); abdominal obesity (17.8, 16.0, and 11.4%); high TG (17.5, 14.0, and 11.1%); and low HDL-C (50.3, 44.6, and 42.5%) decreased with increasing folate level tertile. Prevalence of elevated BP (14.3, 12.0, and 11.7%) and high FPG (11.9, 15.8, and 13.0%) showed no significant differences according to serum folate level tertiles. The multivariate-adjusted ORs (95% CIs) for MetS, abdominal obesity, elevated BP, high TG, and low HDL-C in the highest folate level tertile were 2.17 (1.46–3.22), 1.80 (1.25–2.60), 1.77 (1.16–2.70), 1.90 (1.35–2.67), and 1.49 (1.14–1.94), respectively. The ORs for high FPG did not show significant differences according to serum folate level tertiles. In conclusion, serum folate levels were inversely associated with an increased risk of MetS in Korean premenopausal women. These results suggest that MetS can be prevented and managed by improving the serum folate levels in premenopausal women.

Adequate intake and supplementation of B vitamins, in particular folic acid, can play a protective role in bone health

In vitro and animal model studies have shown that B vitamins (VB) deficiency have negative consequences on bone, as a result of direct or mediated activity of hyperhomocysteinemia. However, there are still no precise indications regarding a possible VB role in order to maintain bone health. So, the aim of this narrative review was to consider the state of the art on correlation between VB dietary intake, blood levels and supplementation and bone health (bone mineral density (BMD), bone turnover markers and fractures risk) in humans. This review included 29 eligible studies. Considering VB blood levels, the 14 studies considered have shown that low serum folate can be a factor risk for reduced BMD and fractures in elderly, particularly women; no independent association was found for other VB. Studies that evaluate relationship between VB dietary intake and BMD are only 2; one, conducted on 1869 women, demonstrated a positive effect of folate intake on BMD, another demonstrated a dose-dependent inverse relationship between vitamin B6 dietary intake and risk of hip fracture, but only for 35298 female participants. Regarding the relationship between BV supplementation and bone health (9 studies with only VB and 4 with other nutrients), all studies that considered patients with hyperhomocysteinemia or with low folate blood levels, are in agreement in demonstrating that folate supplementation (500mcg-5mg) is useful in improving BMD. In conclusion, a request for folate and homocysteine blood levels in elderly patients with osteopenia/osteoporosis is mandatory. For patients with hyperhomocysteinemia or with low folate blood levels, folate supplementation (500mcg-5mg) is crucial.

Age and seasonal variation and establishment of reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry

OBJECTIVES

We aimed to establish reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry to improve the diagnosis of vitamin deficiency and outcomes of associated conditions.

METHODS

In this retrospective analysis of 24 810 specimens, we aimed to examine sex-, age-, and season-related variations in vitamin levels in different groups, set reference-value intervals for vitamin levels, and evaluate these reference values against those recommended by manufacturers.

RESULTS

Levels of vitamins B₃, B₅, B₆, B₇, and B₁₂ were higher, and those of vitamins B₂, B₉, and C were lower, in men than in women. There were seasonal variations in levels of vitamins B₁, B₃, B₅, B₆, B₉, B₁₂, and C. Levels of vitamins B₁, B₂, B₃, B₅, B₆, B₇, B₉, and C differed across age groups; vitamin B₁ displayed significant differences between ages 0 to 14 years and adults compared with reference change values. The lower limits of vitamins B₁ (ages 15-100 y), B₂, B₃, B₇, and C were lower, and that of vitamin B₅ was higher, than the recommended reference values. Finally, the upper limits of vitamins B₁, B₃, B₅, B₆, and B₇ were lower than the recommended values.

CONCLUSIONS

For values obtained using liquid chromatography tandem mass spectrometry, the lower limits of reference intervals for vitamins B₁ (ages 15-100 y), B₂, B₃, B₇, and C should be lowered, that of vitamin B₅ should be raised, and the upper limits of reference intervals for vitamins B₁, B₃, B₅, B₆, and B₇ should be lowered.

Associations of one-carbon metabolism-related gene polymorphisms with breast cancer risk are modulated by diet, being higher when adherence to the Mediterranean dietary pattern is low

PURPOSE

Breast cancer is more likely attributed to a combination of genetic variations and lifestyle factors. Both one-carbon metabolism and diet-related factors could interfere with the carcinogenesis of breast cancer (BC), but whether diet consumed underlie a specific metabolism pathway could influence the impact of genetic variants on breast cancer risk remains equivocal.

METHODS

A case-control study of the Chinese female population (818 cases, 935 controls). 13 SNPs in eight one-carbon metabolism-related genes (MTHFD1, TYMS, MTRR, MAT2B, CDO1, FOLR1, UNG2, ADA) were performed. Diet was assessed by a validated food-frequency questionnaire. We examined the associations of the adherence to the Mediterranean dietary pattern (MDP) and single-nucleotide polymorphisms (SNPs) of one-carbon metabolism with breast cancer risk. We constructed an aggregate polygenic risk score (PRS) to test the additive effects of genetic variants and analyzed the gene-diet interactions.

RESULTS

High adherence (highest quartile) to the MDP decreased the risk of breast cancer among post- but not premenopausal women, respectively (OR = 0.54, 95% CI = 0.38 to 0.78 and 0.90, 0.53 to 1.53). Neither of the polymorphisms or haplotypes was associated with breast cancer risk, irrespective of menopause. However, a high PRS (highest quartile) was associated with more than a doubling risk in both post- and premenopausal women, respectively (OR = 1.95, 95% CI = 1.32 to 2.87 and 2.09, 1.54 to 2.85). We found a gene-diet interaction with adherence to the MDP for aggregate PRS (P-interaction = 0.000) among postmenopausal women. When adherence to the MDP was low (< median), carries with high PRS (highest quartile) had higher BC risk (OR = 2.80, 95% CI = 1.55 to 5.07) than low PRS (lowest quartile), while adherence to the MDP was high (≥ median), the association disappeared (OR = 1.57, 95% CI = 0.92 to 2.66).

CONCLUSION

High adherence to the MDP may counteract the genetic predisposition associated with one-carbon metabolism on breast cancer risk in postmenopausal women.

Influence of Mediterranean Diet on Human Gut Microbiota

Gut microbiota changes correlate with health status. Literature data on gut microbiota show that all dietary changes can induce the alteration of gut microbiota composition. Mediterranean diet (MD) is associated with a reduction of all-cause mortality and in this review, we analyzed its interactions with human microbiota. In particular, we explored the modulation of the human microbiota, in response to MD adherence, focusing the attention on polyphenols, polyunsaturated fatty acids (PUFA) ω-3 and fiber. Evidences suggest that MD is able to modulate the gut microbiota, increasing its diversity. In fact, a Mediterranean-type dietary pattern is associated with specific gut microbiota characteristics. The available evidence, suggests that gut microbiota of subjects that follow a MD is significantly different from subjects that follow a Western diet model. In fact, the latter show an increased gut permeability, which is responsible for metabolic endotoxemia. For this reason, we can speculate that the gut microbiota of the subjects following a MD is able to prevent the onset of chronic non-communicable degenerative diseases, such as cardiovascular diseases and some types of cancer. However, in order to understand these correlations with dietary patterns, controlled intervention studies on the gut microbiota composition and activity are needed.

Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS

Quantification of the specific folate vitamers to estimate total folate in foods is not standardized. A collaborative study, including eight European laboratories, was conducted in order to determine the repeatability and reproducibility of the method for folate quantification in foods using the plant-origin γ-glutamyl hydrolase as part of the extraction procedure. The seven food samples analyzed represent the food groups; fruits, vegetables, dairy products, legumes, offal, fish, and fortified infant formula. The homogenization step was included, and six folate vitamers were analyzed using LC-MS/MS. Total folate content, expressed as folic acid equivalent, was 17-490 μg/100 g in all samples. Horwitz ratio values were within the acceptable range (0.60-1.94), except for fish. The results for fortified infant formula, a certified reference material (NIST 1869), confirmed the trueness of the method. The collaborative study is part of a standardization project within the Nordic Committee on Food Analysis (NMKL).

Prevalence of inadequate intake of folate after mandatory fortification: results from the first National Dietary Survey in Brazil

PURPOSE

Our aim was to estimate the prevalence of folate inadequacy (POFI) according to life stage, socio-economic status, and geographical regions after the mandatory fortification of wheat and maize flour in Brazil.

METHODS

This was a population-based study. Data from two non-consecutive food records from the National Dietary Survey/Household Budget Survey 2008-2009 were used to estimate the usual dietary folate intake in µg dietary folate equivalents (DFEs). The National Cancer Institute method was used to account for within-person variance and the Estimated Average Requirement (EAR) cut-point method was used to calculate the POFI. The survey included 32,749 individuals, 15,700 males and 17,049 females, over 10 years old. Pregnant women, lactating women, and individuals with unreliable energy intake data were excluded.

RESULTS

Overall POFI was 31.5% and mean dietary folate intake was 411.1 µg DFE. The lowest POFI occurred in the youngest age group of 10-13 years in both sexes, while the highest POFI was observed in the group ≥ 71 years. In women of childbearing age, POFI was around 32%. The lowest income strata had the highest POFI. The most developed regions (South and Southeast) had the lowest POFI compared to less developed regions.

CONCLUSIONS

Our data show that folate inadequacy is still prevalent in Brazil mainly in low-income groups and less developed regions. Actions need to be taken to ensure that women of childbearing age, who presented a high prevalence of inadequate folate intake, achieve the recommended daily intake of 400 µg DFEs.

Health Effects of Phenolic Compounds Found in Extra-Virgin Olive Oil, By-Products, and Leaf of Olea europaea L

Olea europaea L. fruit is a peculiar vegetal matrix containing high levels of fatty acids (98–99% of the total weight of extra-virgin olive oil, EVOO) and low quantities (1–2%) of phenolics, phytosterols, tocopherols, and squalene. Among these minor components, phenolics are relevant molecules for human health. This review is focused on their beneficial activity, in particular of hydroxytyrosol (HT), oleuropein (OLE), oleocanthal (OLC), and lignans found in EVOO, olive oil by-products and leaves. Specifically, the cardioprotective properties of the Mediterranean diet (MD) related to olive oil consumption, and the biological activities of polyphenols recovered from olive oil by-products and leaves were described. Recent European projects such as EPIC (European Prospective Investigation into Cancer and Nutrition) and EPICOR (long-term follow-up of antithrombotic management patterns in acute coronary syndrome patients) have demonstrated the functional and preventive activities of EVOO showing the relation both between cancer and nutrition and between consumption of EVOO, vegetables, and fruit and the incidence of coronary heart disease. The data reported in this review demonstrate that EVOO, one of the pillars of the MD, is the main product of Olea europaea L. fruits; leaves and by-products are secondary but precious products from which bioactive compounds can be recovered by green technologies and reused for food, agronomic, nutraceutical, and biomedical applications according to the circular economy strategy.

The Vitamine Source, Usual Food Intake at Students

Introduction:

Inadequate vitamin B 12, folate status and B6 are associated with an increased risk for chronic diseases that may have a negative impact on the health.

Aim:

The aim of our study was to investigate dietary intake of vitamin B12, B6 and folates from various foods among the university students.

Methods:

Dietary intake of foods having vitamins B12, B6 and folate was assessed among the students of University of Sarajevo, 19-22 years old, from 2017 to 2018. The participants were interviewed to collect information regarding age, socioeconomic status, B12, folate, B6 vitamin, and usual food intake during one week.

Results:

The main sources of vitamin B12 and B6 in the students’ diet were chicken white meat (51.8-53.7 %), beef (45-63 %), cream (62.2 -72.1 %), sardines in oil (47.9-52.2 %), tuna (55.2 -60.4 %), cheese edamer (80.1%) and cheese feta (67.4%-73%). The foods with a high source of vitamin B12 and B6 but rarely consumed were fish, shellfish, salmon, roasted trout and mackerel. Sufficient folate intake was mainly achieved through dietary intake of beans (48.5-57.2%) and oatmeal (46.3-48.2%), while folate-insufficient diet resulted from intake of spinach (30.9-35 %), turkey (26.2-33.4 %), lentils (16.9-19.7 %) and soy (9.4-15.5%).

Conclusion:

Our results show that there is an important percentage of the students in Canton Sarajevo that do not meet the recommended intakes for vitamin B12 and B6 and folate. Additional research is needed to establish the best cost-effective public health approach to achieve sufficient intake of these vitamins.

Dietary folate intake and pancreatic cancer risk: Results from the European prospective investigation into cancer and nutrition

Pancreatic cancer (PC) has an exceptionally low survival rate and primary prevention strategies are limited. Folate plays an important role in one-carbon metabolism and has been associated with the risk of several cancers, but not consistently with PC risk. We aimed to investigate the association between dietary folate intake and PC risk, using the standardised folate database across 10 European countries. A total of 477,206 participants were followed up for 11 years, during which 865 incident primary PC cases were recorded. Folate intake was energy-adjusted using the residual method. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. In multivariable analyses stratified by age, sex, study centre and adjusted for energy intake, smoking status, BMI, educational level, diabetes status, supplement use and dietary fibre intake, we found no significant association between folate intake and PC risk: the HR of PC risk for those in the highest quartile of folate intake (≥353 μg/day) compared to the lowest (<241 μg/day) was 0.81 (95% CI: 0.51, 1.31; ptrend = 0.38). In current smokers, a positive trend was observed in PC risk across folate quartiles [HR = 4.42 (95% CI: 1.05, 18.62) for ≥353 μg/day vs. <241 μg/day, ptrend = 0.01]. Nonetheless, there was no significant interaction between smoking and dietary folate intake (pinteraction = 0.99). We found no association between dietary folate intake and PC risk in this large European study.

The use of a plant enzyme for rapid and sensitive analysis of naturally-occurring folates in food by liquid chromatography-tandem mass spectrometry

A rapid, sensitive and reproducible method for analysis of naturally-occurring folates and folic acid in food has been developed and validated. A single-enzyme extraction step, in which a pure recombinant enzyme of plant origin (Arabidopsis thaliana) was used, enabled fast and reproducible deglutamylation during folate extraction within the incubation time of 1 h. Six commonly occurring folate forms (tetrahydrofolate, 5,10-methenyltetrahydrofolate, 10-formylfolic acid, 5-formyltetrahydrofolate, folic acid and 5-methyltetrahydrofolate) were detected and quantified in 9 min using liquid chromatography-tandem mass spectrometry (LC-MS/MS). ¹³C₅-labeled 5-formyltetrahydrofolate, ¹³C₅-labeled folic acid and ¹³C₅-labeled 5-methyltetrahydrofolate were used as internal standards for the quantification. The method is described by a calibration curve (R²>0.99 and trueness 85-115%), a limit of quantification at 0.1 μg/100 g, trueness at 80-120% in spiked samples and certified reference materials, and a precision <10%. However, the precision in quantification of tetrahydrofolate was not within the acceptable limits due to the lack of use of the corresponding internal standard. An interconversion study of unstable formyl forms was performed which showed that 50% of 5,10-methenyltetrahydrofolate is converted to 5-formyltetrahydrofolate during the analysis. The developed LC-MS/MS method is a candidate for a future standard method for folate analysis in food.

One-Carbon Metabolism: Linking Nutritional Biochemistry to Epigenetic Programming of Long-Term Development

One-carbon (1C) metabolism comprises a series of interlinking metabolic pathways that include the methionine and folate cycles that are central to cellular function, providing 1C units (methyl groups) for the synthesis of DNA, polyamines, amino acids, creatine, and phospholipids. S-adenosylmethionine is a potent aminopropyl and methyl donor within these cycles and serves as the principal substrate for methylation of DNA, associated proteins, and RNA. We propose that 1C metabolism functions as a key biochemical conduit between parental environment and epigenetic regulation of early development and that interindividual and ethnic variability in epigenetic-gene regulation arises because of genetic variants within 1C genes, associated epigenetic regulators, and differentially methylated target DNA sequences. We present evidence to support these propositions, drawing upon studies undertaken in humans and animals. We conclude that future studies should assess the epigenetic effects of cumulative (multigenerational) dietary imbalances contemporaneously in both parents, as this better represents the human experience.

Systematic Review of Observational Studies with Dose-Response Meta-Analysis between Folate Intake and Status Biomarkers in Adults and the Elderly

BACKGROUND

Dietary reference values for folate intake vary widely across Europe.

METHODS

MEDLINE and Embase through November 2016 were searched for data on the association between folate intake and biomarkers (serum/plasma folate, red blood cell [RBC] folate, plasma homocysteine) from observational studies in healthy adults and elderly. The regression coefficient of biomarkers on intake (β) was extracted from each study, and the overall and stratified pooled β and SE (β) were obtained by random effects meta-analysis on a double log scale. These dose-response estimates may be used to derive folate intake reference values.

RESULTS

For every doubling in folate intake, the changes in serum/plasma folate, RBC folate and plasma homocysteine were +22, +21, and -16% respectively. The overall pooled regression coefficients were β = 0.29 (95% CI 0.21-0.37) for serum/plasma folate (26 estimates from 17 studies), β = 0.28 (95% CI 0.21-0.36) for RBC (13 estimates from 11 studies), and β = -0.21 (95% CI -0.31 to -0.11) for plasma homocysteine (10 estimates from 6 studies).

CONCLUSION

These estimates along with those from randomized controlled trials can be used for underpinning dietary recommendations for folate in adults and elderly.

Thyroid Dysfunction and Anemia: A Prospective Cohort Study and a Systematic Review

BACKGROUND

Even though the association between thyroid dysfunction and anemia is commonly described, it is not known whether it is clinically relevant. This study set out to quantify the association of thyroid dysfunction on hemoglobin (Hb) concentration and risk of anemia. A systematic review (MEDLINE and EMBASE, from inception until May 15, 2017) was conducted to interpret the findings in context.

METHODS

Participants from the EPIC-Norfolk cohort with available baseline thyrotropin (TSH), free thyroxine (fT4), and Hb were included. Euthyroidism was defined as TSH 0.45-4.49 mIU/L (reference category), hypothyroidism as TSH ≥4.50 mIU/L (subclinical [SHypo] with normal fT4 or overt [OHypo] with low fT4), and hyperthyroidism as TSH ≤0.44 mIU/L (subclinical [SHyper] with normal fT4 or overt [OHyper] with elevated fT4). Anemia was defined as Hb <12 g/dL in women and Hb <13 g/dL in men. In the cross-sectional analyses, multiple linear regression was used to compare Hb across TSH categories. In the prospective analysis, participants with OHypo/OHyper at baseline were excluded, as it was assumed that they were treated for overt thyroid disease. A covariance model was used to determine change in Hb concentration from baseline to last follow-up, and multivariable Cox regression was used to analyze anemia risk.

RESULTS

In the cross-sectional population (n = 12,337), the adjusted Hb was 0.22 g/dL lower [confidence interval (CI) 0.07-0.38] in OHypo compared to euthyroids, and 0.08 g/dL lower [CI -0.23 to 0.38] in OHyper. In the prospective analysis, 460/7031 participants developed anemia over a median follow-up of 4.7 years. The adjusted mean Hb change over time was -0.04 g/dL in SHypo [CI -0.14 to 0.06] and 0.05 g/dL in SHyper [CI -0.10 to 0.20]. The adjusted hazard ratio for anemia was 0.99 [CI 0.67-1.48] in SHypo, and 0.52 [CI 0.23-1.16] in SHyper. The systematic review returned no other prospective studies on this association, but cross-sectional and case-control studies showed comparable results.

CONCLUSION

In this first prospective population-based cohort, subclinical thyroid dysfunction was not associated with a change in Hb concentration during follow-up and was not an independent risk factor for developing anemia; variations in Hb concentration in patients with overt thyroid dysfunction were not clinically relevant.

Development and Validation of the Brief Folate-Specific Food Frequency Questionnaire for Young Women's Diet Assessment

The tools enabling brief assessment of folate intake may be of great value for public health purposes. The aim of the presented study was to design a brief folate-specific food frequency questionnaire for Central and Eastern European population of women, as well as to assess the validity and reproducibility of the designed Folate-Intake Calculation-Food Frequency Questionnaire (Fol-IC-FFQ) on a group of Polish women aged 20-30 years. Participants collected 3-day dietary records and completed the Fol-IC-FFQ twice (FFQ1: directly after the dietary record; and FFQ2: six weeks later). The analysis included an assessment of validity (comparison of the results of FFQ1 and 3-day dietary record) and of reproducibility (comparison of the results of FFQ1 and FFQ2). In assessment of validity, a Bland-Altman index of 5.3% was observed. In assessment of reproducibility, a Bland-Altman index of 2.7% was observed, the share of individuals classified into the same intake adequacy category was over 85%, the share of individuals classified into the same tertile was almost 75%, the weighted κ statistic indicated substantial agreement (0.67) and correlation was significant (p = 0.0000; R = 0.7995). Assessment of the Fol-IC-FFQ revealed a satisfactory level of validity and very good level of reproducibility in the population of young Polish women. The Fol-IC-FFQ may be considered a valid tool for the assessment of folate intake in young Polish women and a promising tool for the assessment of folate intake in young women in Central and Eastern Europe.

Red blood cell folate concentrations and coronary heart disease prevalence: A cross-sectional study based on 1999-2012 National Health and Nutrition Examination Survey

BACKGROUND AND AIM

Folate is involved in a number of metabolic pathways. Red blood cell (RBC) folate is a well-established indicator of folate intake. However, studies focused on the association between RBC folate and coronary heart disease (CHD) are limited. The aim of the current study was to investigate the effect of RBC folate concentrations on the presence of CHD in a nationally representative sample of American adults.

METHODS AND RESULTS

In the 1999-2012 National Health and Nutrition Examination Survey (NHANES), 22,499 subjects aged 30-74 years with RBC folate concentrations, CHD status and responses to co-variates questions were included; 822 (3.65%) participants were identified as having CHD. Bio-Rad Quanta Phase II radioassay and microbiological assay were used to measure RBC folate concentrations. Firstly, we treated RBC folate as a categorical variable, based on RBC folate tertiles, and used logistic regression analysis to display the RBC folate and CHD relationship. Secondly, we explored associations using a combination of restricted cubic spline and logistic regression models, stratified by sex. After adjusting for several well-established traditional CHD risk factors, RBC folate was positively related to CHD presence in the total population and the association was more pronounced among males than females. A J-shaped pattern was observed in RBC folate concentrations for females.

CONCLUSION

Elevated RBC folate concentrations were associated with higher CHD risk. Further investigation is needed to test the association in large-scale follow-up studies.

Folate intake in a Swedish adult population: Food sources and predictive factors

Introduction: Folate plays an important role in cell metabolism, but international studies show that intake is currently below recommendations, especially among women. The study objective was to identify folate food sources by food group, gender, and age group, and to identify factors influencing folate intake, based on food consumption data for Swedish adults in the 2010–11 Riksmaten study.

Methods: The sample included a representative Swedish population aged 18–80 years (n = 1657; 56.3% female). Food and nutrient intakes were estimated from self-reported food records during 4 consecutive days. Food consumption was categorized into 26 food groups. Stepwise regression was used to analyze food groups as folate sources for participants. Factors predicting the highest folate intake (third tertile) were determined by logistic regression analysis.

Results: Vegetables and pulses represented the most important folate source for all age groups and both genders, especially in women aged 45–64 years (49.7% of total folate intake). The next folate source in importance was dairy products for the youngest group (18–30 years), bread for men, and fruit and berries for women. The likelihood of being in the highest tertile of folate intake (odds ratio = 1.69, 95% confidence interval 1.354–2.104) was higher for men. Influencing factors for folate intake in the highest tertile were low body mass index and high educational level in the men, and high educational level, vegetarian diet, organic product consumption, non-smoking, and alcohol consumption within recommendations in the women.

Conclusion: This study describes the folate intake per food group of Swedish adults according to the 2010–11 Riksmaten survey, identifying vegetables and pulses as the most important source. Data obtained on factors related to folate consumption may be useful for the development of specific nutrition education programs to increase the intake of this vitamin in high-risk groups.

Untangling the role of one-carbon metabolism in colorectal cancer risk: a comprehensive Bayesian network analysis

The role of one-carbon metabolism (1CM), particularly folate, in colorectal cancer (CRC) development has been extensively studied, but with inconclusive results. Given the complexity of 1CM, the conventional approach, investigating components individually, may be insufficient. We used a machine learning-based Bayesian network approach to study, simultaneously, 14 circulating one-carbon metabolites, 17 related single nucleotide polymorphisms (SNPs), and several environmental factors in relation to CRC risk in 613 cases and 1190 controls from the prospective Northern Sweden Health and Disease Study. The estimated networks corresponded largely to known biochemical relationships. Plasma concentrations of folate (direct), vitamin B6 (pyridoxal 5-phosphate) (inverse), and vitamin B2 (riboflavin) (inverse) had the strongest independent associations with CRC risk. Our study demonstrates the importance of incorporating B-vitamins in future studies of 1CM and CRC development, and the usefulness of Bayesian network learning for investigating complex biological systems in relation to disease.

Validity of the Food Frequency Questionnaire Assessing the Folate Intake in Women of Reproductive Age Living in a Country without Food Fortification: Application of the Method of Triads

The study aimed to examine the external validity of the Folate Food Frequency Questionnaire (F-FFQ) designed for assessing the folate intake in Serbian women of reproductive age. The F-FFQ was tested against repeated 24 h dietary recalls and correspondent nutritional biomarkers (red blood cells (RBC) and serum folate concentrations) using the method of triads. In a cross sectional study, 503 women aged 18-49 years completed dietary questionnaires and representative validation subsample (n = 50) provided fasting blood samples for biomarker analyses. Correlation coefficients were calculated between each of the dietary methods and three pair-wise correlations were applied for the calculation of validity coefficients. Correlation coefficients observed between F-FFQ and three 24 h recalls were r = 0.56 (p < 0.001) and r = 0.57 (p < 0.001) for total sample and validation group, respectively. Bland-Altman plot and cross-classification analyses indicated good agreement between methods. High validity coefficients were determined between the true intake (I) and dietary assessment methods, F-FFQ (Q) and 24 h dietary recalls (R) (ρQIrbc = 0.871 and ρQIser = 0.814; ρRIrbc = 0.652 and ρRIser = 0.698), and moderate ones for biomarkers (B) (ρBIrbc = 0.428 and ρBIser = 0.421). The F-FFQ is valid instrument for the assessment of dietary folate intake in women living in Serbia, a country without mandatory folic acid food fortification.

Circulating Folate and Vitamin B12 and Risk of Prostate Cancer: A Collaborative Analysis of Individual Participant Data from Six Cohorts Including 6875 Cases and 8104 Controls

BACKGROUND

Folate and vitamin B12 are essential for maintaining DNA integrity and may influence prostate cancer (PCa) risk, but the association with clinically relevant, advanced stage, and high-grade disease is unclear.

OBJECTIVE

To investigate the associations between circulating folate and vitamin B12 concentrations and risk of PCa overall and by disease stage and grade.

DESIGN, SETTING, AND PARTICIPANTS

A study was performed with a nested case-control design based on individual participant data from six cohort studies including 6875 cases and 8104 controls; blood collection from 1981 to 2008, and an average follow-up of 8.9 yr (standard deviation 7.3). Odds ratios (ORs) of incident PCa by study-specific fifths of circulating folate and vitamin B12 were calculated using multivariable adjusted conditional logistic regression.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Incident PCa and subtype by stage and grade.

RESULTS AND LIMITATIONS

Higher folate and vitamin B12 concentrations were associated with a small increase in risk of PCa (ORs for the top vs bottom fifths were 1.13 [95% confidence interval (CI), 1.02-1.26], ptrend=0.018, for folate and 1.12 [95% CI, 1.01-1.25], ptrend=0.017, for vitamin B12), with no evidence of heterogeneity between studies. The association with folate varied by tumour grade (pheterogeneity<0.001); higher folate concentration was associated with an elevated risk of high-grade disease (OR for the top vs bottom fifth: 2.30 [95% CI, 1.28-4.12]; ptrend=0.001), with no association for low-grade disease. There was no evidence of heterogeneity in the association of folate with risk by stage or of vitamin B12 with risk by stage or grade of disease (pheterogeneity>0.05). Use of single blood-sample measurements of folate and B12 concentrations is a limitation.

CONCLUSIONS

The association between higher folate concentration and risk of high-grade disease, not evident for low-grade disease, suggests a possible role for folate in the progression of clinically relevant PCa and warrants further investigation.

PATIENT SUMMARY

Folate, a vitamin obtained from foods and supplements, is important for maintaining cell health. In this study, however, men with higher blood folate levels were at greater risk of high-grade (more aggressive) prostate cancer compared with men with lower folate levels. Further research is needed to investigate the possible role of folate in the progression of this disease.

Thyroid dysfunction and anaemia in a large population-based study

OBJECTIVE AND BACKGROUND

Anaemia and thyroid dysfunction are common and often co-occur. Current guidelines recommend the assessment of thyroid function in the work-up of anaemia, although evidence on this association is scarce.

PATIENTS AND METHODS

In the 'European Prospective Investigation of Cancer' (EPIC)-Norfolk population-based cohort, we aimed to examine the prevalence and type of anaemia (defined as haemoglobin <13 g/dl for men and <12 g/dl for women) according to different thyroid function groups.

RESULTS

The mean age of the 8791 participants was 59·4 (SD 9·1) years and 55·2% were women. Thyroid dysfunction was present in 437 (5·0%) and anaemia in 517 (5·9%) participants. After excluding 121 participants with three most common causes of anaemia (chronic kidney disease, inflammation, iron deficiency), anaemia was found in 4·7% of euthyroid participants. Compared with the euthyroid group, the prevalence of anaemia was significantly higher in overt hyperthyroidism (14·6%, P < 0·01), higher with borderline significance in overt hypothyroidism (7·7%, P = 0·05) and not increased in subclinical thyroid dysfunction (5·0% in subclinical hypothyroidism, 3·3% in subclinical hyperthyroidism). Anaemia associated with thyroid dysfunction was mainly normocytic (94·0%), and rarely macrocytic (6·0%).

CONCLUSION

The prevalence of anaemia was higher in overt hyperthyroidism, but not increased in subclinical thyroid dysfunction. Systematic measurement of thyroid-stimulating hormone in anaemic patients is likely to be useful only after excluding common causes of anaemia.

Compilation of a standardised international folate database for EPIC

This paper describes the methodology applied for compiling an "international end-user" folate database. This work benefits from the unique dataset offered by the European Prospective Investigation into Cancer and Nutrition (EPIC) (N=520,000 subjects in 23 centres). Compilation was done in four steps: (1) identify folate-free foods then find folate values for (2) folate-rich foods common across EPIC countries, (3) the remaining "common" foods, and (4) "country-specific" foods. Compiled folate values were concurrently standardised in terms of unit, mode of expression and chemical analysis, using information in national food composition tables (FCT). 43-70% total folate values were documented as measured by microbiological assay. Foods reported in EPIC were either matched directly to FCT foods, treated as recipes or weighted averages. This work has produced the first standardised folate dataset in Europe, which was used to calculate folate intakes in EPIC; a prerequisite to study the relation between folate intake and diseases.

Why do women invest in pre-pregnancy health and care? A qualitative investigation with women attending maternity services

BACKGROUND

Despite the importance attributed to good pre-pregnancy care and its potential to improve pregnancy and child health outcomes, relatively little is known about why women invest in pre-pregnancy health and care. We sought to gain insight into why women invested in pre-pregnancy health and care.

METHODS

We carried out 20 qualitative in-depth interviews with pregnant or recently pregnant women who were drawn from a survey of antenatal clinic attendees in London, UK. Interviewees were purposively sampled to include high and low investors in pre-pregnancy health and care, with variation in age, partnership status, ethnicity and pre-existing medical conditions. Data analysis was conducted using the Framework method.

RESULTS

We identified three groups in relation to pre-pregnancy health and care: 1) The "prepared" group, who had high levels of pregnancy planning and mostly positive attitudes to micronutrient supplementation outside of pregnancy, carried out pre-pregnancy activities such as taking folic acid and making changes to diet and lifestyle. 2) The "poor knowledge" group, who also had high levels of pregnancy planning, did not carry out pre-pregnancy activities and described themselves as having poor knowledge. Elsewhere in their interviews they expressed a strong dislike of micronutrient supplementation. 3) The "absent pre-pregnancy period" group, had the lowest levels of pregnancy planning and also expressed anti-supplement views. Even discussing the pre-pregnancy period with this group was difficult as responses to questions quickly shifted to focus on pregnancy itself. Knowledge of folic acid was poor in all groups.

CONCLUSION

Different pre-pregnancy care approaches are likely to be needed for each of the groups. Among the "prepared" group, who were proactive and receptive to health messages, greater availability of information and better response from health professionals could improve the range of pre-pregnancy activities carried out. Among the "poor knowledge" group, better response from health professionals might yield greater uptake of pre-pregnancy information. A different, general health strategy might be more appropriate for the "absent pre-pregnancy period" group. The fact that general attitudes to micronutrient supplementation were closely related to whether or not women invested in pre-pregnancy health and care was an unanticipated finding and warrants further investigation.

Association between serum folate and vitamin B-12 and outcomes of assisted reproductive technologies

BACKGROUND

Preconceptional folate and vitamin B-12 have been linked to beneficial reproductive outcomes in both natural pregnancies and those after assisted reproductive technology (ART) treatment.

OBJECTIVE

The objective of the study was to evaluate the associations of serum folate and vitamin B-12 with ART outcomes.

DESIGN

This analysis included a random sample of 100 women (154 ART cycles) participating in a prospective cohort study [Environment and Reproductive Health (EARTH)] at the Massachusetts General Hospital Fertility Center (2007-2013). Serum folate and vitamin B-12 were measured in blood samples collected between days 3 and 9 of treatment. Generalized estimating equations with adjustment for age, BMI, and race were used to evaluate the association of serum folate and vitamin B-12 with ART outcomes.

RESULTS

Women in the highest quartile of serum folate (>26.3 ng/mL) had 1.62 (95% CI: 0.99, 2.65) times the probability of live birth compared with women in the lowest quartile (<16.6 ng/mL). Women in the highest quartile of serum vitamin B-12 (>701 pg/mL) had 2.04 (95% CI: 1.14, 3.62) times the probability of live birth compared with women in the lowest quartile (<439 pg/mL). Suggestive evidence of an interaction was observed; women with serum folate and vitamin B-12 concentrations greater than the median had 1.92 (95% CI: 1.12, 3.29) times the probability of live birth compared with women with folate and vitamin B-12 concentrations less than or equal to the median. This translated into an adjusted difference in live birth rates of 26% (95% CI: 10%, 48%; P = 0.02).

CONCLUSION

Higher serum concentrations of folate and vitamin B-12 before ART treatment were associated with higher live birth rates among a population exposed to folic acid fortification. This trial was registered at clinicaltrials.gov as NCT00011713.

Intake of dietary folate and folic acid in Germany based on different scenarios for food fortification with folic acid

PURPOSE

Besides the adverse health effects of a low folate intake, the risks of high intakes of folic acid have moved into the focus. The aim of this study was to investigate the potential range of folate and folic acid intake of the German population under consideration of different fortification scenarios.

METHODS

Food consumption data of 13,926 participants of the German National Nutrition Survey II (NVS II), collected with two 24-h recalls, were used to calculate the nutrient intake. The nutrient data are based on the German Nutrient Database (BLS), information from a market survey and analyses of multivitamin juices. The scenarios were modelled without, as well as with low and high fortification levels of folic acid.

RESULTS

The median intake of dietary folate equivalents ranged from 191 µg/d (men) and 168 µg/d (women) without fortification to 425 µg/d (men) and 334 µg/d (women) in the highest fortification scenario. Thus, 12.4-68.2% (men) and 5.9-56.1% (women) met the 300 µg/d recommended by the nutrition societies of Germany, Austria and Switzerland. In the highest fortification scenario, 1.9% (men) and 0.8% (women) exceeded the tolerable upper intake level (UL) of 1,000 µg/d folic acid given by the European Food Safety Authority. For supplement users, this proportion was 5.2 and 5.4%.

CONCLUSIONS

Only a high fortification of several foods leads to a marked increase of the proportion of population reaching the recommendation. Simultaneously, with a high fortification a higher proportion exceeds the UL, especially in combination with supplements.

Single-nucleotide polymorphisms in one-carbon metabolism genes, Mediterranean diet and breast cancer risk: a case-control study in the Greek-Cypriot female population

Single-nucleotide polymorphisms (SNPs) within genes of the one-carbon metabolism pathway have been shown to interact with dietary folate intake to modify breast cancer (BC) risk. Our group has previously demonstrated that the Mediterranean dietary pattern, rich in beneficial one-carbon metabolism micronutrients, protects against BC in Greek-Cypriot women. We aimed to investigate whether SNPs in the MTHFR (rs1801133 and rs1801131) and MTR (rs1805087) genes modify the effect of the Mediterranean dietary pattern on BC risk. Dietary intake data were obtained using a 32-item food-frequency questionnaire. A dietary pattern specific to the Greek-Cypriot population, which closely resembles the Mediterranean diet, was derived using principal component analysis (PCA) and used as our dietary variable. Genotyping was performed on subjects from the MASTOS study, a case-control study of BC in Cyprus, using TaqMan assays. Adjusted odds ratios (ORs) were estimated using logistic regression analyses. High adherence to the PCA-derived Mediterranean dietary pattern further reduced BC risk with increasing number of variant MTHFR 677T alleles (ORQ4vs.Q1 for 677TT = 0.37, 95 % CI 0.20-0.69, for 677 CT = 0.60, 95 % CI 0.42-0.86). Additionally, high adherence to the Mediterranean dietary pattern decreased BC risk in subjects with at least one MTR 2756A allele (ORQ4vs.Q1 for 2756AA = 0.59, 95 % CI 0.43-0.81, for 2756AG = 0.59, 95 % CI 0.39-0.91) and in subjects with the MTHFR 1298CC genotype (ORQ4vs.Q1 0.44, 95 % CI 0.30-0.65). Overall P-interaction values, however, were not statistically significant. Our study suggests that these MTHFR and MTR SNPs may act as effect modifiers, highlighting their biological significance in the association between Mediterranean diet, the one-carbon metabolism pathway and BC.

Dietary folate intake and breast cancer risk: European prospective investigation into cancer and nutrition

BACKGROUND

There is limited evidence on the association between dietary folate intake and the risk of breast cancer (BC) by hormone receptor expression in the tumors. We investigated the relationship between dietary folate and BC risk using data from the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

A total of 367993 women age 35 to 70 years were recruited in 10 European countries. During a median follow-up of 11.5 years, 11575 women with BC were identified. Dietary folate intake was estimated from country-specific dietary questionnaires. Cox proportional hazards regression models were used to quantify the association between dietary variables and BC risk. BC tumors were classified by receptor status. Subgroup analyses were performed by menopausal status and alcohol intake. Intake of other B vitamins was considered. All statistical tests were two-sided.

RESULTS

A borderline inverse association was observed between dietary folate and BC risk (hazard ratio comparing top vs bottom quintile [HRQ5-Q1] = 0.92, 95% CI = 0.83 to 1.01, P trend = .037). In premenopausal women, we observed a statistically significant trend towards lower risk in estrogen receptor-negative BC (HRQ5-Q1 = 0.66, 95% CI = 0.45 to 0.96, P trend = .042) and progesterone receptor-negative BC (HRQ5-Q1 = 0.70, 95% CI = 0.51 to 0.97, P trend = .021). No associations were found in postmenopausal women. A 14% reduction in BC risk was observed when comparing the highest with the lowest dietary folate tertiles in women having a high (>12 alcoholic drinks/week) alcohol intake (HRT3-T1 = 0.86, 95% CI = 0.75 to 0.98, P interaction = .035).

CONCLUSIONS

Higher dietary folate intake may be associated with a lower risk of sex hormone receptor-negative BC in premenopausal women.

Dietary folate and reproductive success among women undergoing assisted reproduction

OBJECTIVE

To prospectively evaluate the associations of folate with assisted reproductive technology outcomes within a population in the United States.

METHODS

This analysis included women (n=232) in a prospective cohort study at the Massachusetts General Hospital Fertility Center. Diet was assessed before assisted reproductive technology treatment using a validated food frequency questionnaire. Intermediate and clinical endpoints of assisted reproductive technology were abstracted from medical records. Generalized linear mixed models with random intercepts to account for multiple cycles per woman were used to evaluate the association of folate intake with assisted reproductive technology outcomes adjusting for calorie intake, age, body mass index, race, smoking status, infertility diagnosis, and protocol type.

RESULTS

Among the 232 women (median age 35.2 years, median folate intake 1,778 micrograms/day), higher folate intake was associated with higher rates of implantation, clinical pregnancy, and live birth. The adjusted percentage (95% confidence interval [CI]) of initiated assisted reproductive technology cycles resulting in a live birth for women in increasing quartiles of folate intake were 30% (95% CI 21-42%), 47% (95% CI 35-59%), 42% (95% CI 30-35%) and 56% (95% CI 43-67%) (P for trend=0.01). Live birth rates were 20% (95% CI 8-31%) higher among women in the highest quartile of supplemental folate intake (more than 800 micrograms/day) than among women in the lowest quartile (less than 400 micrograms/day). Higher supplemental folate intake was associated with higher fertilization rates and lower cycle failure rates before embryo transfer (P for trend=0.03 and 0.02).

CONCLUSION

Higher intake of supplemental folate was associated with higher live birth rates after assisted reproductive technology treatment.

LEVEL OF EVIDENCE

: II.

Seasonality modifies methylation profiles in healthy people

DNA methylation is a well-characterized epigenetic modification that plays an important role in the regulation of gene expression. There is growing evidence on the involvement of epigenetic mechanisms in disease onset, including cancer. Environmental factors seem to induce changes in DNA methylation affecting human health. However, little is known about basal methylation levels in healthy people and about the correlation between environmental factors and different methylation profiles. We investigated the effect of seasonality on basal methylation by testing methylation levels in the long interspersed nucleotide element-1 (LINE-1) and in two cancer-related genes (RASSF1A and MGMT) of 88 healthy male heavy smokers involved in an Italian randomized study; at enrolment the subjects donated a blood sample collected in different months. Methylation analyses were performed by pyrosequencing. Mean methylation percentage was higher in spring and summer for the LINE1, RASSF1A and MGMT genes (68.26%, 2.35%, and 9.52% respectively) compared with autumn and winter (67.43%, 2.17%, and 8.60% respectively). In particular, LINE-1 was significantly hypomethylated (p = 0.04 or 0.05 depending on the CpG island involved) in autumn and winter compared with spring and summer. Seasonality seems to be a modifier of methylation levels and this observation should be taken into account in future analyses.

Folate deficiency is not associated with increased mitochondrial genomic instability: results from dietary intake and lymphocytic mtDNA 4977-bp deletion in healthy young women in Italy

The mitochondrial DNA (mtDNA) 4977-bp deletion is a biomarker of mitochondrial genomic instability. It is frequently detected in a number of sporadic diseases, and it accumulates in many tissues during aging. Folic acid plays an important role in the maintenance of genomic stability in mammals. The aim of the present cross-sectional study was to characterise the levels of the mtDNA deletion in the lymphocytes of healthy young women, taking into account folate intake, red blood cell (RBC) folate levels and the distribution of the methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism. Folate intake was estimated by a food frequency questionnaire. Determination of the MTHFR C677T polymorphism and of the mtDNA deletion was performed by real-time polymerase chain reaction analysis. A total of 476 women were enrolled. Low levels of deletion were found (mean ΔCt = 1.24). After multivariate analysis, results did not show any significant relationship between age, smoking habits, pregnancy status, nutritional status, inadequate folate intake, folate deficiency, use of folic acid supplements, MTHFR C677T polymorphism and mtDNA 4977-bp deletions. The lack of association between inadequate folate intake, folate deficiency and mitochondrial genomic instability was confirmed also considering reference values of folate based on DNA damage prevention. Our results indicate that mtDNA 4977-bp deletions are maintained at low levels in lymphocytes of young healthy women despite the wide range of variation of folate intakes and folate status. Future studies, carefully designed to address limits and methodological issues related to variation of this biomarker as an effect of different dietary patterns and of folate status, could provide further insight on the specific mechanisms that are acting in lymphocytes of healthy subjects under observed folate intake.

Folate intake and folate serum levels in men and women from two European populations: The IMMIDIET project

OBJECTIVE

Folate status has been associated with neural tube defects and cerebrovascular disease. The aim of this study was to evaluate possible differences in folate status in two European Union countries and to assess their possible association with dietary patterns and/or other lifestyles.

METHODS

In the framework of the European Union-funded IMMIDIET Project, 1068 individuals (534 male-female pairs), ages 26 to 64 y, were enrolled in Italy and the United Kingdom. One-year-recall food frequency questionnaire was used to evaluate dietary intake. Reduced rank regression analysis was used to derive a dietary pattern better describing high dietary folate intake.

RESULTS

Of the total participants, 11.3% of the Italians and 45.1% of the British exceeded the optimal dietary folate intake of 400 μg/d (Recommended Dietary Allowance). Of the women, 66.7% and 22.1% of Italian and British women, respectively, all at childbearing age, had folate serum levels <6.62 ng/mL (P = 0.01). The percentage of total variance of dietary folate intake explained by food group consumption was 14.2% and 16.3% in Italy and the United Kingdom, respectively. Reduced rank regression analysis indicated a healthy pattern that was positively associated with folate serum levels in both countries (for all β-coefficients >0; P < 0.001): 100 μg/d increase in dietary folate intake was associated with 13.8% and 10.5% increase in folate serum levels in the Italian and British population, respectively (for 100 μg/d increase e(β-coef) = 1.138 and 1.105; P < 0.001). Smoking habit was negatively but physical activity positively associated with folate serum levels (P < 0.05).

CONCLUSIONS

An inadequate dietary folate intake and subsequent serum levels were observed in the Italian participants. High consumption of food sources of folate was positively associated with folate serum levels, explaining a good proportion of its variability.

Intake and blood concentrations of folate and their association with health-related behaviors in Korean college students

The purpose of this study is to assess folate intake, and serum and red blood cell (RBC) folate concentrations, and investigate the association between folate status and health-related behaviors among Korean college students. A total of 169 students, aged between 18 and 27 years, participated in this study. Dietary intake data were collected by trained interviewers using a 24-hour recall method for three non-consecutive days in 2009. Information on health-related behaviors was obtained by a self-administered questionnaire. Serum and RBC folate concentrations were measured by microbiological assay. The average intakes of folate were 456 µgDFE and 347 µgDFE in male and female students, respectively. While the average serum folate concentration was significantly lower in male students (8.9 ng/mL) compared to female students (12.5 ng/mL), RBC concentrations were not significantly different between male (398.6 ng/mL) and female students (405.3 ng/mL). In male students, low serum folate concentrations were associated with total folate intake less than the Estimated Average Requirement, non-use of folic acid supplements, smoking, alcohol drinking at least once a week and low physical activity. In female students, low serum folate concentrations were associated with smoking and alcohol drinking at least two drinks at a time and BMI ≥ 25. Alcohol drinking and low physical activity were also associated with low RBC folate concentrations in both male and female students. In order to improve folate nutritional status of college students, the practice of desirable health-related behaviors, such as non-smoking, moderate alcohol drinking, regular physical activity, and maintenance of healthy BMI should be encouraged along with consumption of folate-rich foods and supplements.

North–south gradients in plasma concentrations of B-vitamins and other components of one-carbon metabolism in Western Europe: results from the European Prospective Investigation into Cancer and Nutrition (EPIC) Study

Different lifestyle patterns across Europe may influence plasma concentrations of B-vitamins and one-carbon metabolites and their relation to chronic disease. Comparison of published data on one-carbon metabolites in Western European regions is difficult due to differences in sampling procedures and analytical methods between studies. The present study aimed, to compare plasma concentrations of one-carbon metabolites in Western European regions with one laboratory performing all biochemical analyses. We performed the present study in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort among 5446 presumptively healthy individuals. Quantile regression was used to compare sex-specific median concentrations between Northern (Denmark and Sweden), Central (France, Germany, The Netherlands and United Kingdom) and Southern (Greece, Spain and Italy) European regions. The lowest folate concentrations were observed in Northern Europe (men, 10·4 nmol/l; women, 10·7 nmol/l) and highest concentrations in Central Europe. Cobalamin concentrations were slightly higher in Northern Europe (men, 330 pmol/l; women, 352 pmol/l) compared with Central and Southern Europe, but did not show a clear north–south gradient. Vitamin B2 concentrations were highest in Northern Europe (men, 22·2 nmol/l; women, 26·0 nmol/l) and decreased towards Southern Europe (Ptrend< 0·001). Vitamin B6 concentrations were highest in Central Europe in men (77·3 nmol/l) and highest in the North among women (70·4 nmol/l), with decreasing concentrations towards Southern Europe in women (Ptrend< 0·001). In men, concentrations of serine, glycine and sarcosine increased from the north to south. In women, sarcosine increased from Northern to Southern Europe. These findings may provide relevant information for the study of regional differences of chronic disease incidence in association with lifestyle.

Evaluation of a diet quality index based on the probability of adequate nutrient intake (PANDiet) using national French and US dietary surveys

BACKGROUND

Existing diet quality indices often show theoretical and methodological limitations, especially with regard to validation.

OBJECTIVE

To develop a diet quality index based on the probability of adequate nutrient intake (PANDiet) and evaluate its validity using data from French and US populations.

MATERIAL AND METHODS

The PANDiet is composed of adequacy probabilities for 24 nutrients grouped into two sub-scores. The relationship between the PANDiet score and energy intake were investigated. We evaluated the construct validity of the index by comparing scores for population sub-groups with 'a priori' differences in diet quality, according to smoking status, energy density, food intakes, plasma folate and carotenoid concentrations. French and US implementations of the PANDiet were developed and evaluated using national nutritional recommendations and dietary surveys.

RESULTS

The PANDiet was not correlated with energy for the French implementation (r = -0.02, P>0.05) and correlated at a low level for the US implementation (r = -0.11, P<0.0001). In both implementations, a higher PANDiet score (i.e. a better diet quality) was associated with not smoking, having a lower-energy-dense diet, consuming higher amounts of fruits, vegetables, fish, milk and other dairy products and lower amounts of cheese, pizza, eggs, meat and processed meat, and having higher plasma folate and carotenoid concentrations after controlling for appropriate factors (all P<0.05, carotenoid data for US not available).

CONCLUSIONS

The PANDiet provides a single score that measures the adequacy of nutrient intake and reflects diet quality. This index is adaptable for use in different countries and relevant at the individual and population levels.