Consumption of a Recommended Serving of Wheat Bran Cereals Significantly Increases Human Faecal Butyrate Levels in Healthy Volunteers and Reduces Markers of Inflammation Ex Vivo

Wheat bran cereals are an important source of dietary fibre. The aim of the study was to investigate if a high intake (120 g) of fibre rich breakfast cereal (which delivers the UK Government guidelines for fibre intake in one serving but is three-fold higher than the manufacturers recommended serving) has additional potential health benefits compared to the recommended serving (40 g, containing 11 g of dietary fibre). To assess this, the study determined the short chain fatty acid (SCFA) profiles in human faecal, urine and plasma samples after consumption of two different servings of fibre-rich cereal. Inhibition of prostanoid production was measured (ex vivo) in human colonic fibroblast cells after cytokine (IL-1β) inflammation stimulation. Eight healthy volunteers, 18-55 years old; BMI (18-30 kg/m2) consumed the wheat bran-rich “ready to eat cereal”, at both the high (120 g) serving and recommended (40 g) serving. Faecal, urine and plasma samples were collected at baseline, throughout the five-hour intervention period and approximately 24 hours following consumption. Faecal butyrate showed the largest increase (p<0.05) of more than a two-fold change following the consumption of the recommended serving of wheat bran cereal (from 13.95 ± 9.17 to 31.63 ± 20.53 mM) and no significant change following the higher serving (from 21.96 ± 11.03 to 22.9 ± 12.69 mM). ANOVA analysis also found a weak serving effect (p = 0.046) of the portion size (high vs. recommended) only for butyrate in urine 24 hours after consumption of the bran cereal. The physiological nutritionally relevant concentrations of faecal SCFAs, as determined in the volunteers’ faecal samples showed significant anti-inflammatory activity or the individual faecal SCFAs; acetate (p<0.001), propionate (p<0.001) and butyrate (p<0.01), as well as in combination. Plasma folate was also increased after consumption of both wheat bran servings and was significant (p = 0.037) at the three-hour time point following consumption of the high wheat bran serving. The consumption of the recommended serving (40 g) of wheat bran cereal increased the total microbial SCFAs levels (from 96.88 to 136.96 mM) compared to the higher serving (120 g) (from 110.5 to 117.64 mM) suggesting that the intake of the higher portion size is likely to promote a faecal bulking effect and thereby decrease colonic SCFA levels. These data indicate that consumption of the recommended serving of wheat bran cereal serving would therefore be sufficient to promote microbial butyrate formation, reduce colonic inflammation and increase plasma folate levels in humans.

Ischemia-Reperfusion Injury Reduces Kidney Folate Transporter Expression and Plasma Folate Levels

Acute or chronic kidney disease can cause micronutrient deficiency. Patients with end-stage renal disease, kidney transplantation or on dialysis have reduced circulating levels of folate, an essential B vitamin. However, the molecular mechanism is not well understood. Reabsorption of folate in renal proximal tubules through folate transporters is an important process to prevent urinary loss of folate. The present study investigated the impact of acute kidney injury (AKI) on folate transporter expression and the underlying mechanism. AKI was induced in Sprague-Dawley rats that were subjected to kidney ischemia (45 min)-reperfusion (24 h). Both male and female rats displayed kidney injury and low plasma folate levels compared with sham-operated rats. The plasma folate levels were inversely correlated to plasma creatinine levels. There was a significant increase in neutrophil gelatinase-associated lipocalin (NGAL) and IL-6 mRNA expression in the kidneys of rats with ischemia-reperfusion, indicating kidney injury and increased inflammatory cytokine expression. Ischemia-reperfusion decreased mRNA and protein expression of folate transporters including folate receptor 1 (FOLR1) and reduced folate carrier (RFC); and inhibited transcription factor Sp1/DNA binding activity in the kidneys. Simulated ischemia-reperfusion through hypoxia-reoxygenation or Sp1 siRNA transfection in human proximal tubular cells inhibited folate transporter expression and reduced intracellular folate levels. These results suggest that ischemia-reperfusion injury downregulates renal folate transporter expression and decreases folate uptake by tubular cells, which may contribute to low folate status in AKI. In conclusion, ischemia-reperfusion injury can downregulate Sp1 mediated-folate transporter expression in tubular cells, which may reduce folate reabsorption and lead to low folate status.

Folate Transporters Are Found Throughout the Colon of Humans and Their mRNA Expression Appears to Be Unaffected by Low Dose Folic Acid Supplementation

Objectives A large depot of folate resides in the colon and can exceed dietary intake. Little is known about the capacity of the colon to absorb folate. We aimed to determine the expression of key folate transporters, reduced folate carrier (RFC) and proton-coupled folate transporter (PCFT), throughout the colon of healthy adults and the impact of low dose folic acid (FA) supplementation. Methods In this 16 wk open-labelled randomized control trial, healthy adults (n = 25) from a colonoscopy waiting list were randomized to receive daily a multivitamin plus a 400 μg FA (400FA, n = 12) or no FA supplement (0FA, n = 13). Subjects were provided with low FA bread and pasta and instructions how to follow a low FA containing diet. Six 24-hr diet recalls were administered throughout the study and blood samples were collected at baseline, 8 and 16 wk. At colonoscopy (16 wk), 4 tissue biopsies were collected from the terminal ileum, cecum, ascending and descending colon. Blood folates were determined by microbial assay; mRNA levels of folate transporters were assessed using qPCR. Results One subject was removed from analysis due to missing data (0FA). No group differences in age, sex, BMI, dietary intake, vitamin B12, red blood cell (RBC) and plasma folate levels at baseline were observed. Mean ± SD FA supplement adherence was 92 ± 12% and 96 ± 9% at 8 and 16 wk, respectively. Subjects in the 400FA group had higher total folate intake (P &lt; 0.05) and higher RBC and plasma folate levels (P &lt; 0.01) at 8 and 16 wk compared to 0FA subjects. RBC values at 16 wk were 1764 ± 636 and 865 ± 190 nmol/L in the 400FA and 0FA group, respectively. RFC and PCFT were detected in terminal ileum and colon biopsies (n = 96) and their mRNA levels in each section did not differ between groups. However, expression of RFC was markedly higher than PCFT across all biopsy sections (P &lt; 0.05) and highest in the terminal ileum, compared to the cecum, ascending and descending colon in both groups (P &lt; 0.05). Conclusions We demonstrated expression of folate transporters, RFC and PCFT, throughout the human colon suggesting their potential contribution to overall folate absorption. mRNA expressions were not affected by a low dose FA supplement. A deeper understanding of how FA and folate status affect colonic transporter regulation may inform future revisions of folate intake recommendations. Funding Sources Natural Sciences and Engineering Research Council.

Comparative Carcinogenic Effects of Folic Acid vs. 5-Methyltetrahydrofolate Supplementation on Colon Cancer Progression in a Rodent Model

Objectives High folic acid (FA) intake may be associated with adverse health outcomes, including colon cancer promotion. 5-methyltetrahydrofolate (5MTHF) has been proposed as a safer alternative form of folate supplementation. We compared the effects of FA and 5MTHF supplementation on the progression of aberrant crypt foci (ACF; earliest colon cancer precursor). Methods Male Sprague Dawley rats (n = 120) received a control diet (1mg FA or equimolar 5MTHF) at weaning and ACF were induced by azoxymethane. Six weeks post-induction, rats were randomized to the control or supplemental (10mg FA or equimolar 5MTHF) diets for 18 weeks. Plasma folate concentrations were assessed using microbiological assay and compared. Colorectal tumor incidence, multiplicity and burden (sum of tumor diameters) were determined and compared. Results 5MTHF resulted in higher plasma folate concentration compared to FA (p &lt; 0.05). Tumor incidence (adenoma, p = 0.5; adenocarcinoma, p = 0.60) did not differ between the folate forms. Both FA and 5MTHF supplementation resulted in a higher number of adenocarcinomas compared to respective controls. 5MTHF groups had higher tumor burden compared to the corresponding levels of FA (p &lt; 0.05). Conclusions 5MTHF resulted in higher tumor burden than FA and was at least as effective as FA in increasing the number of adenocarcinomas in predisposed rats harboring ACF. 5MTHF does not confer a safer alternative to FA supplementation with regards to colon cancer promotion and may in fact have a higher colon tumor promoting effect than FA supplementation. Notwithstanding the inherent limitations associated with animal models, our study suggests that future studies are warranted to compare biochemical and biologic effects and safety of FA and 5MTHF supplementation. Funding Sources Canadian Institutes of Health Research.

Correlations between Coffee Consumption and Metabolic Phenotypes, Plasma Folate, and Vitamin B12: NHANES 2003 to 2006

Metabolic syndrome (MetS) is prevalent not only among the overweight and obese but also normal weight individuals, and the phenotype is referred to as a metabolically unhealthy phenotype (MUHP). Besides normal weight individuals, overweight/obese individuals are also protected from MetS, and the phenotype is known as a metabolically healthy phenotype (MHP). Epidemiological studies indicate that coffee and micronutrients such as plasma folate or vitamin B12 (vit. B12) are inversely associated with MetS. However, correlations among coffee consumption metabolic phenotypes, plasma folate, and vit. B12 remain unknown. Our objective was to investigate the correlation between coffee consumption, metabolic phenotypes, plasma folate, and vit. B12 as well as to understand associations between plasma folate, vit. B12, and metabolic phenotypes. Associations among coffee consumption metabolic phenotypes, plasma folate, and vit. B12 were assessed in a cross-sectional study of 2201 participants, 18 years or older, from 2003–2004 and 2005–2006 National Health and Nutrition Examination Surveys (NHANES). MUHP was classified as having > three metabolic abnormalities. Coffee consumption was not associated with metabolic phenotypes, but negatively correlated with several metabolic variables, including BMI (p < 0.001). Plasma folate was positively associated with MUHP (p < 0.004), while vit. B12 was inversely associated with MUHP (p < 0.035). Our results suggest the potential protective impact of coffee on individual components of MetS and indicate a positive correlation between coffee consumption and MUHP among overweight individuals. Identifying possible dietary factors may provide practical and low-cost dietary intervention targets, specifically for early intervention. Larger and randomized intervention studies and prospective longitudinal studies are required to further evaluate these associations.

Associations of Early Pregnancy and Neonatal Circulating Folate, Vitamin B-12, and Homocysteine Concentrations with Cardiometabolic Risk Factors in Children at 10 y of Age

ABSTRACT Background Higher circulating folate and vitamin B-12 concentrations and lower circulating homocysteine concentrations during pregnancy seem to be associated with fetal development. These micronutrients may also be associated with cardiometabolic health. Objective We examined the associations of circulating folate, vitamin B-12, and homocysteine concentrations during pregnancy and in neonates with childhood cardiometabolic outcomes. Methods This study was embedded in the Generation R Study, a population-based prospective cohort study from early pregnancy onward. We sampled blood in early pregnancy and cord blood. We measured cardiometabolic outcomes in the children at school age. Among 4449 children aged 10 y (median: 9.7; 95% range: 9.3, 10.7), we examined associations of plasma folate, serum vitamin B-12, and plasma homocysteine concentrations in early pregnancy and at birth with BMI, body fat distribution, heart rate, blood pressure, and insulin, glucose, and lipid concentrations, using linear regression models. Using logistic models, we examined the associations of these micronutrients with risks of overweight/obesity and clustering of cardiovascular risk factors. Results One standard deviation score (SDS) higher maternal plasma folate concentration was associated with lower BMI (−0.04 SDS; 95% CI: −0.08, −0.01), android-to-gynoid fat ratio (−0.04 SDS; 95% CI: −0.07, −0.01), systolic blood pressure (−0.06 SDS; 95% CI: −0.10, −0.03), risk of overweight (OR: 0.87; 95% CI: 0.78, 0.96), and clustering of cardiovascular risk factors (OR: 0.79; 95% CI: 0.68, 0.91). One SDS higher maternal serum total B-12 concentration was associated with lower glucose (−0.06 SDS; 95% CI: −0.10, −0.02) and higher HDL cholesterol concentrations (0.04 SDS; 95% CI: 0.00, 0.08). Cord blood folate, vitamin B-12, and homocysteine concentrations were not consistently associated with cardiometabolic outcomes. Conclusions Subtle differences in circulating folate and vitamin B-12 concentrations in early pregnancy may be associated with child cardiometabolic health at age 10 y. The causality and mechanisms underlying these associations need further study.

B vitamin blood concentrations and one-carbon metabolism polymorphisms in a sample of Italian women and men attending a unit of transfusion medicine: a cross-sectional study

Purpose To define blood status of folate, vitamin B12, vitamin B6, homocysteine, and major one-carbon metabolism-related polymorphisms in healthy, males and females blood donors, aged 18–65 years were evaluated. General characteristics and lifestyle factors were also investigated. Methods An explorative cross-sectional study design was used to evaluate a sample of blood donors attending the Unit of Transfusion Medicine of the Verona University Hospital, Italy. From April 2016 to May 2018, 499 subjects were enrolled (255 men, 244 women of whom 155 of childbearing age). Major clinical characteristics including lifestyle and dietary habits, B vitamins and homocysteine were analyzed. The MTHFR 677 C>T, cSHMT 1420 C>T, DHFR 19 bp ins/del, RFC1 80 G>A polymorphisms were also determined. Results Mean plasma concentrations of folate, vitamin B12, vitamin B6 and homocysteine were 14.2 nmol/L (95% CI 13.7–14.8), 271.9 pmol/L (95% CI 262.6–281.5), 51.0 nmol/L (95% CI 48.7–53.4) and 13.5 µmol/L (95% CI 13.1–14.0), respectively. Plasma folate, was adequate (> 15 nmol/L) in 44.7% of all subjects, 39.0% of males and 42.5% of women < 45 years. Similarly, vitamin B12 was adequate (> 350 pmol/L) in 25.1% of all subjects and in 20.3% of men ≥ 45 years. The rare allele frequencies were 0.21 for MTHFR 677TT, 0.11 for cSHMT 1420TT, 0.18 for DHFR 19 bp del/del, 0.20 for RFC1 80AA, and a gene–nutrient interaction was confirmed for folate concentrations according to MTHFR 677C>T and DHFR 19 bp del/del. Conclusion An Italian sample of healthy blood donors shows that an adequate concentration of plasma folate and vitamin B12 is reached only in a limited percentage of subjects, thus encouraging consideration for specific public health strategies.

Association between tea drinking and plasma folate concentration among women aged 18–30 years in China

Objective: Association was found between tea and neural tube defects. However, few studies investigated the relationship between tea consumption and blood folate levels. We aimed to investigate the association between tea consumption and plasma folate concentrations among women aged 18–30 years in different ethnicities of China. Design: Data were obtained from a national cross-sectional study conducted from 2005 to 2006 of women aged 18–30 years in China. Socio-demographic characteristics and lifestyle were obtained from a questionnaire. Dietary folate intake was determined by 24-h dietary recall. Plasma folate concentrations were measured by a microbiological assay. Multiple linear regression model was used to calculate partial regression coefficients after adjusting for confounding factors. Setting: Nine provinces or autonomous regions in China. Participants: A total of 2932 women aged 18–30 years in China. Results: After stratifying by ethnicity and tea type, tea consumption was significantly positively associated with plasma folate levels in Han women who drank unfermented tea weekly (β = 0·067, and P = 0·037) or daily (β = 0·119, and P = 0·031) and in Uighur women who drank fermented tea weekly (β = 0·325, and P = 0·028). For women who drank unfermented tea in Han ethnicity, weekly and daily tea drinkers had 6·77 % (95 % CI: 6·36 %, 7·21 %) and 7·13 % (95 % CI: 6·40 %, 7·96 %) increase in plasma folate concentration compared with no tea drinkers. Conclusions: There is a suggestion of possible positive association between unfermented tea drinking in Han ethnicity and plasma folate concentrations, for Chinese women aged 18–30 years. The relationship between tea drinking in other ethnic groups and plasma folate still needs to be further explored.