High Folate Status Research Articles

Folate-Related Nutrients, Genetic Polymorphisms, and Colorectal Cancer Risk: the Fukuoka Colorectal Cancer Study

One-carbon metabolism plays an important role in colorectal carcinogenesis. Meta-analyses have suggested protective associations of folate and vitamin B6 intakes with colorectal cancer primarily based on studies in Caucasians, and genetic polymorphisms pertaining to the folate metabolism have been a matter of interest. Less investigated are the roles of methionine synthase (MTR) and thymidylate synthetase (TS) polymorphisms in colorectal carcinogenesis. In a study of 816 cases and 815 community controls in Japan, we investigated associations of dietary intakes of folate, methionine, vitamin B2, vitamin B6, and vitamin B12 with colorectal cancer risk. The associations with MTR 2756A>G, MTRR 66A>G, and TSER repeat polymorphism were examined in 685 cases and 778 controls. Methionine and vitamin B12 intakes were inversely associated with colorectal cancer risk, but the associations were totally confounded by dietary calcium and n-3 fatty acids. The other nutrients showed no association with the risk even without adjustment for calcium and n-3 fatty acids. The TSER 2R allele was dose-dependently associated with an increased risk. The MTR and MTRR polymorphisms were unrelated to colorectal cancer risk. There was no measurable gene-gene or gene-nutrient interaction, but increased risk associated with the TSER 2R allele seemed to be confined to individuals with high folate status. This study does not support protective associations for folate and vitamin B6. The TSER 2R allele may confer an increased risk of colorectal cancer. The role of the TSER polymorphism in colorectal carcinogenesis may differ by ethnicity.

Low folate status enhances pregnancy changes in plasma betaine and dimethylglycine concentrations and the association between betaine and homocysteine

Folate, choline, and betaine participate in homocysteine metabolism. It is not known whether they interact during pregnancy. The objective was to investigate how folate status affects choline, betaine, and dimethylglycine during pregnancy. Fasting plasma folate, cobalamin, free choline, betaine, dimethylglycine, and total homocysteine (tHcy) were measured longitudinally at <12, 15, 24-27, and 34 gestational weeks (GW); at labor (nonfasting); and in the cord in participants (n = 522) from the Reus-Tarragona Birth Cohort (NUTrició i Creixement Intrauterí Retardat phase). Timing, dose, and duration of folic acid supplement use were recorded. Folate status was classified as below (low) or above (high) median plasma folate at baseline (27.6 nmol/L) and at 24-27 GW (11.4 nmol/L). Associations between folate or betaine with tHcy were investigated by using multiple linear regression analysis. Plasma betaine decreased by 34.8% (1.0%) throughout pregnancy, and dimethylglycine increased by 39.7% (2.7%) between 24-27 GW and labor (all P < 0.001). Compared with high folate status, low status was associated with a higher dimethylglycine/betaine ratio from 15 GW and with lower plasma betaine and higher dimethylglycine from 24 to 27 GW, for the rest of pregnancy. Regression analysis showed that by 24-27 GW, both plasma folate and betaine were inversely associated with tHcy when folate status was low and that the association between betaine and tHcy depended on folate status at 24-27 and 34 GW (interaction terms: P < 0.001 and P < 0.01). Betaine was inversely associated with tHcy at labor regardless of folate status. Low folate status enhances the reduction in betaine and the increase in dimethylglycine during pregnancy and strengthens the association between betaine and tHcy. This trial was registered at clinicaltrials.gov as NCT01778205.

Serum folate and prostate-specific antigen in the United States

Increased evidence suggests that folate may play a significant role in cancer development. This study investigates the association between levels of serum folate and prostate-specific antigen (PSA), a biomarker for prostate cancer detection. Using data from the 2007 to 2010 National Health and Nutrition Examination Survey, a total of 3,293 men aged 40 years and older with serum PSA and folate measures were studied. Total PSA level (tPSA) and percent free/total PSA ratio (%fPSA) were major outcomes. The alternative cutpoints were used to categorize these measures as higher risks of prostate cancer (tPSA: ≥10, ≥4, and ≥2.5ng/ml; %fPSA: ≤15 and ≤5%). Serum folate level was analyzed as continuous and as quintiles. Association between serum folate and PSA levels were evaluated by multivariate linear and logistic regressions. Higher serum folate levels were associated with decreased log10-transformed tPSA (β=-001, p=0.061) and increased %fPSA (β=0.064, p=0.012). Adjusting for age, race/ethnicity, socioeconomic status, use of non-steroidal anti-inflammatory drugs, body mass index, and smoking status, higher serum folate (fifth quintile) was associated with lower odds of having higher tPSA (≥10ng/ml) and lower %fPSA (≤25%): (tPSA: odds ratio, OR associated with fifth to first quintile of folate level=0.42; 95% confidence interval, CI=0.21, 0.83; p for trend=0.022 and %fPSA: OR=0.71; 95% CI=0.52, 0.95; p for trend=0.044). Results of this study suggest that higher folate status may be protective against elevated PSA levels among men without diagnosed prostate cancer. Additional epidemiologic studies are necessary to confirm our findings and to investigate potential mechanisms.

Mutation at the folate receptor 4 locus modulates gene expression profiles in the mouse uterus in response to periconceptional folate supplementation

Periconceptional supplementation of folic acid to the diet of women is considered a great success for a public health intervention. Higher folate status, either by supplementation, or via the mandatory fortification of grain products in the United States, has led to significant reduction in the incidence of neural tube defects. Besides birth defects, folate deficiency has been linked to a variety of morbidities, most notably to increased risk for cancer. However, recent evidence suggests that excess folate may be detrimental — for birth defect incidence or in the progression of cancer. How folate mediates beneficial or detrimental effects is not well understood. It is also unknown what molecular responses are elicited in women taking folate supplements, and thus experience a bolus of folate on top of the status achieved by fortification. To characterize the response to a periconceptional regimen of supplementation with folinic acid, we performed gene expression profiling experiments on uterus tissue of pregnant mice with either wildtype alleles or targeted disruption at the folate receptor 4 locus. We observed that, depending on the genetic background, folinic acid supplementation affects expression of genes that contribute to lipid metabolism, protein synthesis, mitochondrial function, cell cycle, and cell activation. The extent of the response is strongly modulated by the genetic background. Finally, we provide evidence that folinic acid supplementation in the mutant paradigm affects histone methylation status, a potential mechanism of gene regulation in this model.

Genetic C677T polymorphisms of methylenetetrahydrofolate reductase and one‐carbon metabolites as prognostic predictors for survival outcome of patients with hepatocellular carcinoma.

The aims of this study were to investigate the association between methylene‐ tetrahydrofolate reductase(MTHFR) C677T polymorphism, two thymidylate synthase(TS) polymorphylisms (a tandem‐repeat of 5′UTR and 6‐bp ins/del polymophylism on the 3′UTR), one carbon‐status and survival rates of patients with hepatocellular carcinoma (HCC). The cohort study included 232 HCC patients. MTHFR C677T and TS polymorphisms were analyzed by real‐time PCR. Survival outcome of HCC patients was analyzed by Kaplan–Meier method and Cox proportional hazard model. The results showed that Cox elevated serum AFP (&gt;;200 vs. &lt;20, HR=3.61, CI=1.99–6.55), vitB12(&gt;;1500 vs. &lt;699, HR=2.69, CI =1.24–5.84), RBC folate (&gt;;818 vs. &lt;566, HR=2.05, CI=1.11–3.78), overweight (&gt;;24 vs. &lt;18.5, HR=4.86, CI=1.11–21.17) and increase tumor size (5~10 vs. &lt;5, HR=1.97; CI=1.18–3.27) will elevate the hazard ratio of HCC death. MTHFR 677 CT or TT genotypes were associated with reduced hazard ratio of HCC death (CT/TT vs. CC, HR=0.48; CI=0.30–0.79). CC genotype in combination with high folate status (566–818 ng/mL) or with elevated vitamin B12 levels (699–1500 ng/ mL) were associated with increased HR (HR=2.02, 95%CI=1.00–4.11) for RBC; (HR=2.04, 95% CI=1.11–3.77) for vitamin B12. Taken together, folate, B12 and MTHFR C677T polymorphism serve as the potential predictors for survival outcome of HCC patients.

Abstract 5420: The effect of folate deficiency on chemosensitivity of colon cancer cells to 5-Fluorouracil

Abstract Background: Folate is an essential cofactor in one-carbon transfer reactions including nucleotide biosynthesis, thereby playing an important role in DNA replication and repair. In cancer cells, folate depletion interrupts DNA synthesis, thereby causing cancer cell death. This has been the basis for chemotherapy using antifolates and 5-Fluorouracil (5FU). We determined the effect of folate deficiency on the sensitivity of colon cancer cells to 5FU in a well established in vitro model of folate deficiency. Methods: Three human colon cancer cell lines (HCT116, Caco-2, HT29) were grown in RPMI1640 medium containing 0 (deficient) and 2.3 μM (replete) of folic acid. Proliferation was measured with growth curves every 3 days for 12 days and intracellular folate concentrations were determined at day 0, 6 and 12. Functional folate depletion was determined by the deoxyuridine suppression test. In vitro chemosensitivity of these colon cancer cell lines to 5FU with leucovorin (LV; 5 μM) was determined using a modified SRB protein assay. In HCT116 and Caco-2, thymidylate synthase (TS) activity was measured and TS, p53 and p21 protein expression was determined by immunoblotting. Results: All three colon cancer cell lines grown in the folate-deficient medium exhibited significantly slower growth rates than the corresponding cell lines grown in the folate-replete medium (p&amp;lt;0.05). Intracellular folate concentrations were significantly lower in all three cell lines grown in the folate-deficient medium than those grown in the folate-replete medium (p&amp;lt;0.05). Intracellular folate depletion induced in these cells was functionally significant as indicated by the deoxyuridine suppression test (p&amp;lt;0.05). All cells grown in the folate-deficient medium showed progressively lower intracellular folate concentrations over time (p&amp;lt;0.05). All three cell lines grown in the folate-deficient medium exhibited significantly higher chemosensitivity to 5FU+LV, albeit to a different degree, compared with those grown in the folate-replete medium (p&amp;lt;0.05). Caco-2, but not HCT116, cells grown in the folate-deficient medium showed significantly lower TS activity (p&amp;lt;0.05). Caco-2 cells grown in the folate-deficient medium had significantly lower protein expression of p53 and p21 but not TS. No differences in protein expression of TS, p53, and p21 were observed in HCT116 cells. Conclusion: Our data suggest that folate deficiency significantly enhances the sensitivity of colon cancer cells to 5FU based chemotherapy. Dietary or other strategies to deplete intracellular folate concentrations in colon cancer cells to enhance chemosensitivity to 5FU are worthy of further investigation. Given the dramatically increased dietary intake and blood levels of folate in North America resulting from folic acid fortification and supplementation, whether or not high folate status would affect chemotherapy for colon cancer also warrants future studies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5420. doi:1538-7445.AM2012-5420

Vitamin B-12 and homocysteine status in a folate-replete population: results from the Canadian Health Measures Survey

Vitamin B-12 is an important cofactor required for nucleotide and amino acid metabolism. Vitamin B-12 deficiency causes anemia and neurologic abnormalities-a cause for concern for the elderly, who are at increased risk of vitamin B-12 malabsorption. Vitamin B-12 deficiency is also associated with an increased risk of neural tube defects and hyperhomocysteinemia. The metabolism of vitamin B-12 and folate is interdependent, which makes it of public health interest to monitor biomarkers of vitamin B-12, folate, and homocysteine in a folic acid-fortified population. The objective was to determine the vitamin B-12, folate, and homocysteine status of the Canadian population in the period after folic acid fortification was initiated. Blood was collected from a nationally representative sample of ∼5600 participants aged 6-79 y in the Canadian Health Measures Survey during 2007-2009 and was analyzed for serum vitamin B-12, red blood cell folate, and plasma total homocysteine (tHcy). A total of 4.6% of Canadians were vitamin B-12 deficient (<148 pmol/L). Folate deficiency (<320 nmol/L) was essentially nonexistent. Obese individuals were less likely to be vitamin B-12 adequate than were individuals with a normal BMI. A total of 94.9% of Canadians had a normal tHcy status (≤13 μmol/L), and individuals with normal tHcy were more likely to be vitamin B-12 adequate and to have high folate status (>1090 nmol/L). Approximately 5% of Canadians are vitamin B-12 deficient. One percent of adult Canadians have metabolic vitamin B-12 deficiency, as evidenced by combined vitamin B-12 deficiency and high tHcy status. In a folate-replete population, vitamin B-12 is a major determinant of tHcy.

Low folate status and indoor pollution are risk factors for endemic optic neuropathy in Tanzania

AimsBilateral optic neuropathy in Dar-es-Salaam, Tanzania was first reported as an epidemic in 1988. Now argued to be endemic in 2010, the aetiology remains unclear. The authors investigated the hypothesis...

The oldest old: red blood cell and plasma folate in African American and white octogenarians and centenarians in Georgia.

To determine the overall folate status of a population-based multi-ethnic sample of octogenarians and centenarians and the specific dietary, demographic and physiological factors associated with observed abnormalities. Population-based multiethnic sample of adults aged 80 to 89 and 98 and above. Northern Georgia, USA. Men and women aged 80 to 89 (octogenarians, n = 77) and 98 and older (centenarians, n = 199). Wilcoxon rank sum tests, and Chi square and logistic regression analyses were used to examine associations of low and high folate status with hematological indicators and other variables of interest. The prevalence of low red blood cell (RBC) folate was low overall, but tended to be higher in centenarians than in octogenarians (6.5% vs. 1.3%, p = 0.058; defined as RBC folate < 317 nmol/L). The risk of having lower RBC folate (< 25th vs. > 25th percentile for RBC folate for 60yr+ in NHANES 1999-2000) was greater in association with vitamin B12 deficiency (OR = 5.36; 95%CI: 2.87-10.01), African American race (OR = 4.29; 95%CI: 2.08-8.83), and residence in a skilled nursing facility (OR = 3.25; 95%CI: 1.56-6.78) but was not influenced by age, gender, B-vitamin supplement use, high/low food score or presence of atrophic gastritis. Combined high plasma folate and low vitamin B12 status was present in some individuals (n=11), but was not associated with increased prevalence of anemia or cognitive impairment in this study. Low RBC folate status (< 317 nmol/L) was rare in this post folic acid fortification sample of octogenarians and centenarians. RBC folate status (< 25th percentile) was strongly associated with 1) vitamin B12 deficiency, which has strong implications for vitamin treatment, and 2) with being African American, suggesting racial disparities exist even in the oldest old.

Abstract LB-460: Effects of folic acid supplementation on mammary tumor progression

Abstract Background: The role of folate in breast cancer is highly controversial. Although some epidemiologic studies have suggested a protective effect of high folate status on breast cancer risk, recent studies have suggested that high folate intake, largely from folic acid (the synthetic form of folate), and high plasma folate levels may increase breast cancer risk. In animal studies, folic acid supplementation was shown to promote the progression of established preneoplastic lesions of colon cancer. Folic acid intake in North America has drastically increased over the past decade due to folic acid fortification and widespread supplemental use. Almost 70% of breast cancer patients consume folic acid containing vitamin supplements after diagnosis. The benefits of folic acid supplementation in patients with breast cancer are unknown and there is a concern that folic acid supplementation may in fact adversely affect breast cancer progression. We therefore investigated the effects of folic acid supplementation on the progression of established mammary tumors in the DMBA rat model. Methods: Female Sprague Dawley rats were placed on a control diet containing 2 mg folic acid/kg diet and mammary tumors were initiated with DMBA at 7 weeks of age. When the sentinel tumor reached a diameter between 7–9 mm, rats were randomized to receive a diet containing 2 (control), 5, 8, or 10 mg of folic acid/kg diet for up to 12 weeks. Body weight and mammary tumor growth were measured weekly and plasma folate levels at necropsy were determined. At necropsy, the sentinel and all other mammary tumors were excised and histologically analyzed. Results: The final weight of the animals at necropsy was not significantly different among the 4 groups. Animals on the control and 10 mg folic acid/kg diet had significantly faster weight gain than those on the 8 mg folic acid/kg diet (p&amp;lt;0.02) while those on the 5 mg folic acid diet did not differ significantly from either group. Plasma folate levels significantly reflected the supplemental levels of folic acid in a dose-responsive manner (p&amp;lt;0.05). Sentinel tumor growth (mm2/week) was not significantly different among the 4 groups at 4, 7, and 12 post randomization. Sentinel tumor weight at necropsy was lower in the control group compared with the 5 and 8 (p&amp;lt;0.05) and with the 10 (p=0.051) mg folic acid/kg diet groups. Total weight of all mammary tumors was highest in 5 and 8 mg supplemented groups compared to the control group (p&amp;lt; 0.05, p=0.086). Conclusion: Our data suggest that folic acid supplementation may promote the progression of established mammary tumors, although no clear dose-responsive relationship was observed. Given the drastically increased folic acid intake and the mortality and morbidity of breast cancer in North America, the potential adverse effect of folic acid supplementation on breast cancer progression needs to be clarified. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-460. doi:10.1158/1538-7445.AM2011-LB-460

Cognitive function in Chilean elderly with low B12 and high folate status

Other investigators reported an association between low vitamin B12 and higher folate status with poorer cognitive function, raising concern about folic acid fortification for elderly. The objective was to examine these associations in elderly at risk of B12 deficiency and consuming highly fortified flour (2.2 mg folic acid/kg flour). Subjects aged 70–79 y were randomly selected from 15 health centers. Screening identified exclusions; serum B‐12 &gt;700 pmol/L, MiniMental State Exam (MMSE) &lt;20, diabetes, health problems. Cognitive tests were administered to 311 eligible subjects. Overall 30% were B12 deficient and 25% B12 marginal (&lt;148 and 148–220 pmol/L); 18% had high serum folate (≥42 nmol/L). Depression (GDS‐15 ≥5) affected 30%, sig. more in women, B12 deficiency, and high folate (p=0.03) but without B12‐folate interaction. MMSE &lt;25 pcle was unrelated to B12 or folate but there was sig. interaction (p&lt;0.055) between B12 ≤148 pmol/L and folate ≥42 nmol/L controlling for depression and education (n=9). Language (Boston) was poorer with high folate, and verbal memory (CERAD) with B‐12 deficiency (no interaction). No associations were found with working memory, attention, executive function. We conclude B12 and folate status were independently associated with some cognitive performance scores. Only MMSE revealed an interaction but significance was weak and sample size small. Funded by FONDECYT 1070592.

Low maternal B12 status is associated with offspring insulin resistance but B12 or folate supplementation does not alter that risk

There is concern that high maternal folate and low B12 status are associated with offspring insulin resistance (HOMA). We previously reported that maternal micronutrient supplementation had no effect on HOMA. Here, we report the association between maternal folate and B12 status and HOMA. In a substudy (n=1132) of a RCT of vitamin A alone (control) or with folic acid, folic acid-iron, folic acid-iron-zinc, or multiple micronutrient supplements, micronutrient status was assessed in early and late pregnancy (~10 and 36 wks gestation). In the offspring at 6–8 y, insulin resistance was estimated with the HOMA model using fasting insulin and glucose. Child HOMA was not associated with maternal plasma folate or B12 at early (folate β=0.05, p=0.48; B12 β=−0.05, p=0.42) or late (folate β=−0.02, p=0.77; B12 β=−0.09, p=0.21) pregnancy in continuous models. However, children whose mothers were B12 deficient (<148 pmol/L) at enrollment had a 26.7% increase in HOMA (p=0.02); this was not observed for low or high folate levels. Among B12 deficient women, micronutrient supplements containing folate with or without B12 among other nutrients did not affect HOMA (p>0.05 for all). Low B12 but not folate status during pregnancy is associated with insulin resistance in childhood, but maternal micronutrient supplementation that includes B12 does not alter that risk. Funded by the Gates Foundation and USAID.

Predictors and Health Consequences of Epigenetic Changes Associated with Excess Body Weight in Women of Child-bearing Age

Abstract Background: Epigenetic alterations occurring during pregnancy have recently emerged as important factors for developmental programming of the fetus leading to obesity-related diseases in children. However, the role of excess body weight (EBW) in the modification of epigenetic patterns or its health consequences during child-bearing age is largely unknown. Because a lower degree of DNA methylation of long interspersed nucleotide element-1 (LINE-1) in PBMCs was shown to be associated with a higher risk of developing obesity-related diseases, for example cancer, the purpose of this study was to (1) evaluate the influence of indicators of obesity (BMI, WC, and % body fat) on PBMC LINE-1 methylation, (2) determine the predictors of PBMC LINE-1 methylation, and (3) determine the influence of PBMC LINE-1 methylation on biomarkers of obesity-related diseases. Methods: The study population consisted of 470 child-bearing age women. We quantified the degree of PBMC LINE-1 methylation by pyrosequencing. Folate concentrations were measured using a microbiological assay. The degree of LINE-1 methylation (&amp;gt; median vs. ≤ median) was the dependent variable in logistic models that specified BMI (&amp;gt;25 vs. ≤ 25), WC (&amp;gt;88 cm vs. ≤ 88 cm), or % body fat (&amp;gt;33% vs. ≤ 33%) separately as the independent predictors of primary interest, adjusting for other relevant variables. The predictors and determinants of lower LINE-1 methylation were evaluated among women with EBW. Results: Women with higher BMI, WC, or % body fat were 2.0, 1.9, and 1.8 times more likely to have lower LINE-1 methylation, respectively (P = 0.003, 0.005, and 0.01). The predictors and determinants of lower LINE-1 methylation yielded similar patterns with all three indicators of obesity. The following results are based on models run with BMI as the indicator for EBW. Women with higher plasma folate concentrations were less likely to have lower LINE-1 methylation (OR = 0.54, P = 0.0009). Higher LINE-1 methylation was associated with lower insulin resistance as indicated by HOMA (OR = 0.50, P = 0.02). Conclusions: EBW-associated lower LINE-1 methylation in women of child-bearing age appears to have significant, and potentially transgenerational, health consequences. Higher folate status may exert beneficial effects on obesity-related health outcomes.

Folate status of reproductive age women and neural tube defect risk: the effect of long-term folic acid supplementation at doses of 140 µg and 400 µg per day.

Primary prevention of most folate-responsive neural tube defects (NTDs) may not require 400 μg folic acid/day but may be achieved by attaining a high maternal folate status. Using RBC folate ≥906 nmol/L as a marker for NTD risk reduction, the study aimed to determine the change in blood folate concentrations in reproductive age women in response to long-term folic acid supplementation at 400 µg/day and 140 µg/day (dose designed to mimic the average daily folic acid intake received from New Zealand’s proposed mandatory bread fortification program). Participants were randomly assigned to a daily folic acid supplement of 140 µg (n = 49), 400 µg (n = 48) or placebo (n = 47) for 40 weeks. RBC folate concentrations were measured at baseline, and after 6, 12, 29 and 40 weeks. At 40 weeks, the overall prevalence of having a RBC folate <906 nmol/L decreased to 18% and 35% in the 400 µg and 140 µg groups, respectively, while remaining relatively unchanged at 58% in the placebo group. After 40 weeks, there was no evidence of a difference in RBC folate between the two treatment groups (P = 0.340), nor was there evidence of a difference in the odds of a RBC folate <906 nmol/L (P = 0.078). In conclusion, the average daily intake of folic acid received from the proposed fortification program would increase RBC folate concentrations in reproductive age women to levels associated with a low risk of NTDs.

Circulating unmetabolized folic acid and 5-methyltetrahydrofolate in relation to anemia, macrocytosis, and cognitive test performance in American seniors

Folate deficiency has serious consequences for the fetus. Folic acid fortification of food addresses this problem. However, clinical consequences of vitamin B-12 deficiency may be worsened by high folic acid intakes, perhaps as a direct result of unmetabolized folic acid, which does not occur naturally in body tissues. We attempted to attribute associations that we previously found between higher folate status and anemia and cognitive test performance to circulating unmetabolized folic acid or 5-methyltetrahydrofolate (5MeTHF). The subjects (n = 1858) were senior participants in the US National Health and Nutrition Examination Survey (1999-2002) who had normal renal function and reported no history of stroke, recent anemia therapy, or diseases of the liver, thyroid, or coronary arteries. Subjects had undergone a phlebotomy, a complete blood count, and cognitive and dietary assessments. Circulating unmetabolized folic acid was detected in approximately 33% of the subjects and was related to an increased odds of anemia in alcohol users. In seniors with a serum vitamin B-12 concentration <148 pmol/L or a plasma methylmalonic acid concentration > or =210 nmol/L, the presence compared with the absence of detectable circulating unmetabolized folic acid was related to lower cognitive test scores and lower mean cell volume. In the same subgroup, higher serum 5MeTHF was related to an increased odds of anemia and a marginally significantly decreased odds of macrocytosis. In seniors with a normal vitamin B-12 status, a higher serum 5MeTHF concentration was related to higher cognitive test scores. Results of this epidemiologic study were somewhat consistent with reports on the folic acid treatment of patients with pernicious anemia, but some findings were unexpected.

Abstract PL04-03: Folate and cancer: Is timing everything?

Abstract Folate is an essential B vitamin utilized for one-carbon transfer reactions, including those related to the methylation of DNA and nucleotide synthesis. Epidemiologic and experimental studies show that a low-folate status is associated with an increased risk of colorectal neoplasia. However, the actions of folate in cancer prevention appear to be modulated by both genetic susceptibility and timing with respect to carcinogenic progression. Functional polymorphisms in genes encoding several key enzymes in folate metabolism have been linked to cancer risk and exemplify the importance of nutrigenetic interactions in this biologic pathway. Yet, perhaps more importantly, the timing of folate administration during carcinogenesis may also impact the outcome and result in opposing effects: A higher folate status is expected to protect against mutations and, thus, may reduce the progression from normal tissue to pre-malignant lesions; however, a higher folate status may subsequently enhance the growth of pre-malignant lesions or any existing tumors, due to the supporting role of folate in the provision of nucleotides for DNA synthesis. Data from clinical trials suggest potential increases in risk of colorectal polyps and prostate cancer in folic acid intervention arms. Mathematical models from our group suggest that supplementation early in life could be beneficial, but adversely affect cancer rates later in life. These influences appear predominantly driven by effects on thymidylate synthesis. Because at this point available data are incomplete, prior to making recommendations, investigation is needed of the effects of folate supplementation among cancer patients, who are at risk of recurrence, as well as among individuals with cancer precursors. Citation Information: Cancer Prev Res 2010;3(1 Suppl):PL04-03.

Folate–vitamin B-12 interaction in relation to cognitive impairment, anemia, and biochemical indicators of vitamin B-12 deficiency

Previous reports on pernicious anemia treatment suggested that high folic acid intake adversely influences the natural history of vitamin B-12 deficiency, which affects many elderly individuals. However, experimental investigation of this hypothesis is unethical, and the few existing observational data are inconclusive. With the use of data from the 1999–2002 National Health and Nutrition Examination Survey (NHANES), we evaluated the interaction between high serum folate and low vitamin B-12 status [ie, plasma vitamin B-12 < 148 pmol/L or methylmalonic acid (MMA) > 210 nmol/L] with respect to anemia and cognitive impairment. With subjects having both plasma folate ≤ 59 nmol/L and normal vitamin B-12 status as the referent category, odds ratios for the prevalence of anemia compared with normal hemoglobin concentration and impaired compared with unimpaired cognitive function were 2.1 (95% CI: 1.1, 3.7) and 1.7 (95% CI: 1.01, 2.9), respectively, for those with low vitamin B-12 status but normal serum folate and 4.9 (95% CI: 2.3, 10.6) and 5.0 (95% CI: 2.7, 9.5), respectively, for those with low vitamin B-12 status and plasma folate > 59 nmol/L. Among subjects with low vitamin B-12 status, mean circulating vitamin B-12 was 228 pmol/L for the normal-folate subgroup and 354 pmol/L for the high-folate subgroup. We subsequently showed increases in circulating homocysteine and MMA concentrations with increasing serum folate among NHANES participants with serum vitamin B-12 < 148 pmol/L, whereas the opposite trends occurred among subjects with serum vitamin B-12 ≥ 148 pmol/L. These interactions, which were not seen in NHANES III before fortification, imply that, in vitamin B-12 deficiency, high folate status is associated with impaired activity of the 2 vitamin B-12–dependent enzymes, methionine synthase and MMA–coenzyme A mutase.

Association Between MTHFR Polymorphism (C677T) With Nonfamilial Colorectal Cancer

The enzyme 5,10-methylene-tetrahydrofolate reductase (MTHFR) is linked to DNA methylation, synthesis, and repair. C677T is one of the most important polymorphisms in the MTHFR gene. The single nucleotide polymorphism C677T has been found to be associated with decreased enzyme activity and plasma folate, and thus may play a crucial role in the etiology of colorectal cancer. This decrease was observable in people with either high or low folate status. We aimed to test the hypothesis that the C677T genotype is involved in colorectal cancer. Using pyrosequencing, we analyzed the MTHFR genotypes in 234 colorectal cancer patients and 257 matched controls. We examined the polymorphisms in MTHFR and folate intake in relation to risk of colon cancer in an Iranian population-based case-control study. Our finding revealed that the CC, CT, and TT genotypes of MTHFR among the colorectal cancer patients were 50%, 29.1%, and 20.9%, respectively. On the other hand, we could find 29.5% of 677CC, 46% of 677CT and 24.5% of 677TT in the controls. A decreased risk of colon cancer for participants with wild-type genotype was observed. Interestingly, this association was stronger at higher levels of folate intake. Our study corroborates previous findings of an inverse association of the MTHFR 677TT genotype with colorectal cancer, in particular at high levels of folate.

Too much folate: a risk factor for cancer and cardiovascular disease?

The intent of this evidence-based review is to analyze the role of folate in chronic diseases, focusing on cancer and cardiovascular disease. Low folate status has been shown to be a risk factor for cancer and cardiovascular disease. Although epidemiological data suggest an inverse association between folate status and disease risk, intervention studies give equivocal results, suggesting the response to folate intake does not follow a linear continuum. Moreover, recent folate intervention trials raise concern about possible adverse effects of folate supplementation and suggest that too much folate in inopportune settings may be potentially harmful in individuals at higher risk for cardiovascular disease and cancer. Although folate intake at sufficient levels appears to be an effective cancer chemopreventive strategy, high-dose supplementation of folate has generally not been effective in reducing recurrence of cardiovascular events or colorectal adenomas in clinical intervention trials. Although controversial, high folate status achieved through folate fortification or supplementation may increase the risk of certain chronic diseases among certain individuals, possibly by interfering with the homeostasis of one-carbon metabolism. Further research is urgently needed to accurately define the relationship between supraphysiological intake of folate and chronic diseases.

Folate and vitamin B12status in relation to cognitive impairment and anaemia in the setting of voluntary fortification in the UK

Concerns about risks for older people with vitamin B12 deficiency have delayed the introduction of mandatory folic acid fortification in the UK. We examined the risks of anaemia and cognitive impairment in older people with low B12 and high folate status in the setting of voluntary fortification in the UK. Data were obtained from two cross-sectional studies (n 2403) conducted in Oxford city and Banbury in 1995 and 2003, respectively. Associations (OR and 95 % CI) of cognitive impairment and of anaemia with low B12 status (holotranscobalamin < 45 pmol/l) with or without high folate status (defined either as serum folate >30 nmol/l or >60 nmol/l) were estimated after adjustment for age, sex, smoking and study. Mean serum folate levels increased from 15.8 (sd 14.7) nmol/l in 1995 to 31.1 (sd 26.2) nmol/l in 2003. Serum folate levels were greater than 30 nmol/l in 9 % and greater than 60 nmol/l in 5 %. The association of cognitive impairment with low B12 status was unaffected by high v. low folate status (>30 nmol/l) (OR 1.50 (95 % CI 0.91, 2.46) v. 1.45 (95 % CI 1.19, 1.76)), respectively. The associations of cognitive impairment with low B12 status were also similar using the higher cut-off point of 60 nmol/l for folate status ((OR 2.46; 95 % CI 0.90, 6.71) v. (1.56; 95 % CI 1.30, 1.88)). There was no evidence of modification by high folate status of the associations of low B12 with anaemia or cognitive impairment in the setting of voluntary fortification, but periodic surveys are needed to monitor fortification.