Johan Hultdin

Low folate levels may protect against colorectal cancer

Background and aims: Dietary folate is believed to protect against colorectal cancer (CRC). However, few studies have addressed the role of circulating levels of folate. The aim of this study was to relate prediagnostic plasma folate and homocysteine concentrations and the methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C polymorphisms to the risk of developing CRC. Subjects: Subjects were 226 cases and 437 matched referents from the population based Northern Sweden Health and Disease Cohort. Results: We observed a bell-shaped association between plasma folate concentrations and CRC risk; multivariate odds ratio for middle versus lowest quintile 2.00 (95% confidence interval (CI) 1.13–3.56). In subjects with follow up times greater than the median of 4.2 years however, plasma folate concentrations were strongly positively related to CRC risk; multivariate odds ratio for highest versus lowest quintile 3.87 (95% CI 1.52–9.87; p trendu200a=u200a0.007). Homocysteine was not associated with CRC risk. Multivariate odds ratios for the MTHFR polymorphisms were, for 677 TT versus CC, 0.41 (95% CI 0.19–0.85; p trendu200a=u200a0.062), and for 1298 CC versus AA, 1.62 (95% CI 0.94–2.81; p trendu200a=u200a0.028). Interaction analysis suggested that the result for 1298A>C may have been largely due to linkage disequilibrium with 677C>T. The reduced CRC risk in 677 TT homozygotes was independent of plasma folate status. Conclusions: Our findings suggest a decreased CRC risk in subjects with low folate status. This possibility of a detrimental component to the role of folate in carcinogenesis could have implications in the ongoing debate in Europe concerning mandatory folate fortification of foods.

Short Telomeres in Depression and the General Population Are Associated with a Hypocortisolemic State

BACKGROUNDnThe hypothalamic-pituitary-adrenal (HPA) axis plays a central role in stress regulation, and leukocyte telomere length (TL) has been suggested to represent a cumulative measure of stress. Depression is intimately related with stress and frequently exhibits a dysregulated HPA axis. We aimed to study the relationships between TL and biological and psychological facets of stress in recurrent major depressive disorder and controls.nnnMETHODSnLeukocyte TL was measured in 91 subjects with recurrent major depressive disorder and 451 control subjects. Stress was assessed from both a biological perspective, by assessing HPA axis function with a weight-adjusted very-low-dose dexamethasone suppression test (DST), and a psychological perspective, with self-report questionnaires.nnnRESULTSnTL was shorter among patients compared with control subjects (277 base pairs, p = .001). Overall, short TL was associated with a hypocortisolemic state (low post-DST cortisol and high percentage of cortisol reduction after the DST) among both patients and control subjects but more pronounced among patients. This state, which was overrepresented among patients, was characterized by high familial loading of affective disorders among patients (p = .001) and high C-reactive protein levels among control subjects (p = .040). TL was also inversely associated with stress measured with the Perceived Stress Questionnaire (r(s) = -.258, p = .003).nnnCONCLUSIONSnShort TL is associated with depression and hypocortisolism. Because hypocortisolism has been shown to develop from chronic stress exposure, our findings corroborate the concept of TL as a cumulative measure of stress and provide novel insights into the detrimental role of stress in depressive illness and the general population.

Plasma folate, vitamin B12, and homocysteine and prostate cancer risk: A prospective study

The role of folate metabolism in cancer development is a topic of much current interest, with maintenance of adequate folate status tending to show a protective effect. Aberrant methylation, primarily hypermethylation of certain genes including tumor suppressors, has been implicated in prostate cancer development. Folate, vitamin B12 and homocysteine are essential for methyl group metabolism and thus also for DNA methylation. We related plasma levels of these factors to prostate cancer risk in a prospective study of 254 case subjects and 514 matched control subjects. Increasing plasma levels of folate and vitamin B12 were statistically significantly associated with increased prostate cancer risk, with an odds ratio of 1.60 (95% CI = 1.03–2.49; ptrend = 0.02) for folate and 2.63 (95% CI = 1.61–4.29; ptrend < 0.001) for vitamin B12 for highest vs. lowest quartile. Increasing plasma homocysteine levels were associated with a reduced risk of borderline significance (OR = 0.67; 95% CI = 0.43–1.04; ptrend = 0.08). After adjustment for the other 2 plasma variables, body mass index and smoking, a statistically significant increased risk remained only for vitamin B12 (OR = 2.96; 95% CI = 1.58–5.55; ptrend = 0.001). Adjusted OR for folate and homocysteine were 1.30 (95% CI = 0.74–2.24; ptrend = 0.17) and 0.91 (95% CI = 0.51–1.58; ptrend = 0.60), respectively. Our results suggest that factors contributing to folate status are not protective against prostate cancer. On the contrary, vitamin B12, associated with an up to 3‐fold increase in risk, and possibly also folate, may even stimulate prostate cancer development. These findings are novel and should be explored further in future studies.

Folate, Vitamin B12, and Risk of Ischemic and Hemorrhagic Stroke A Prospective, Nested Case-Referent Study of Plasma Concentrations and Dietary Intake

Background and Purpose— Folate metabolism has been implicated in stroke. However, the possibility of a role for folate and vitamin B12, independent of their effects on homocysteine status, remains to be explored. The aim of this prospective, nested case-referent study was to relate plasma and dietary intake levels of folate and vitamin B12 to risk of stroke, taking into consideration plasma homocysteine concentrations and methylenetetrahydrofolate reductase polymorphisms. Methods— Subjects were 334 ischemic and 62 hemorrhagic stroke cases and matched double referents from the population-based Northern Sweden Health and Disease Cohort. Results— Plasma folate was statistically significantly associated with risk of hemorrhagic stroke in an inverse linear manner, both in univariate analysis and after adjustment for conventional risk factors including hypertension (odds ratio [OR] for highest versus lowest quartile 0.21 (95% confidence interval [CI], 0.06 to 0.71; P for trend=0.008)). Risk estimates were attenuated by inclusion of homocysteine in the model (OR, 0.34; 95% CI, 0.08 to 1.40; P for trend=0.088). A similar pattern was observed for increasing folate intake (multivariate OR, 0.07; 95% CI, 0.01 to 0.55; P for trend=0.031 without homocysteine, and OR, 0.16, 95% CI, 0.02 to 1.23; P for trend=0.118 with homocysteine in the analysis). We found little evidence of an association between plasma or dietary folate and risk of ischemic stroke. Neither plasma nor dietary vitamin B12 was associated with risk of either stroke subtype. Conclusions— The results of this study suggest a protective role for folate, possibly in addition to its effects on homocysteine status, in hemorrhagic but not ischemic stroke.

Hyperhomocysteinemia and Hypofibrinolysis in Young Adults With Ischemic Stroke

BACKGROUND AND PURPOSEnData from epidemiological and case-control studies suggest that increased total homocysteine (tHcy) levels are associated with increased risk for thromboembolic disease. The mechanisms by which hyperhomocysteinemia contributes to thrombogenesis are incompletely understood. The main objectives of this study of young ischemic stroke patients were (1) to examine fasting and post-methionine load levels of tHcy, (2) to ascertain the genotype frequency of the C677CT mutation in the methylenetetrahydrofolate reductase gene (TT genotype), and (3) to study the possible interaction between plasma tHcy levels and fibrinolytic factors.nnnMETHODSnThis case-control study was based on 80 consecutive patients aged 18 to 44 years admitted between January 1992 and May 1996 as a result of a first-ever ischemic stroke. Forty-one healthy control subjects were recruited. Measurement of fasting tHcy and post-methionine load levels and evaluation of the fibrinolytic system were undertaken at least 3 months (mean, 5.1+/-1. 9 months) after admission. Genotyping of the methylenetetrahydrofolate reductase gene was performed.nnnRESULTSnAlthough the increase after methionine loading (ie, postload tHcy minus fasting-level tHcy) was significantly higher among patients, there was no difference in fasting and postload tHcy levels. After adjustment for conventional risk factors, elevated postload increase tHcy levels were associated with a 4.8-fold increased risk of ischemic stroke. There was no difference between patients and control subjects in either TT genotype frequency or T allele frequency. Abnormal response to methionine loading was associated with higher tissue plasminogen activator (tPA) mass concentration, higher plasminogen activator inhibitor-1 levels, and lower tPA activity. After adjustment for age, sex, body mass index, serum cholesterol, and triglycerides, an abnormal increase in postload tHcy levels remained significantly associated with tPA mass concentration levels (P=0.03).nnnCONCLUSIONSnA moderately elevated increase in tHcy levels after methionine loading was associated with an increased risk for ischemic stroke in young adults. In contrast, fasting tHcy levels did not differ between patients and controls. A moderately elevated increase in tHcy after methionine loading may provide a additional thrombogenic risk mediated in part by interactions with the fibrinolytic system. In young stroke patients, a methionine loading test to detect hyperhomocysteinemia should always be considered in the convalescent phase of the disease.

One-Carbon Metabolism and Prostate Cancer Risk: Prospective Investigation of Seven Circulating B Vitamins and Metabolites

Purpose: Components of one-carbon metabolism are believed to influence cancer development with suggested mechanisms, including DNA methylation and DNA repair mechanisms. However, few prospective studies have investigated one-carbon metabolism in relation to prostate cancer risk, and the results have been conflicting. The aim of this study was to do a comprehensive investigation of the components of one-carbon metabolism in relation to prostate cancer risk. A panel of seven circulating B vitamins and related metabolites was selected, most of which have not been studied before. Materials and Methods: We analyzed plasma concentrations of betaine, choline, cysteine, methionine, methylmalonic acid (MMA), vitamin B2, and vitamin B6 in 561 cases and 1,034 controls matched for age and recruitment date, nested within the population-based Northern Sweden Health and Disease Cohort. Relative risks of prostate cancer were estimated by conditional logistic regression. Results: Positive associations with prostate cancer risk were observed for choline and vitamin B2, and an inverse association was observed for MMA. The relative risks for a doubling in concentrations were 1.46 [95% confidence interval (95% CI), 1.04-2.05; Ptrend = 0.03] for choline, 1.11 (95% CI, 1.00-1.23; Ptrend = 0.04) for vitamin B2, and 0.78 (95% CI, 0.63-0.97; Ptrend = 0.03) for MMA. Concentrations of betaine, cysteine, methionine, and vitamin B6 were not associated with prostate cancer risk. Conclusion: The results of this large prospective study suggest that elevated plasma concentrations of choline and vitamin B2 may be associated with an increased risk of prostate cancer. These novel findings support a role of one-carbon metabolism in prostate cancer etiology and warrant further investigation. (Cancer Epidemiol Biomarkers Prev 2009;18(5):1538–43)

Preanalytical effects of pneumatic tube transport on routine haematology, coagulation parameters, platelet function and global coagulation

Abstract Background: Pneumatic tube transport of blood samples reduces turnaround times and labour. However, the preanalytical effects on new clinical chemistry parameters and instruments are not fully known. The aim of this study was to evaluate the effect of pneumatic tube transport on haematology and coagulation parameters, including platelet function with PFA-100®, and global coagulation with a thromboelastograph. Methods: Paired venous blood samples from healthy volunteers were obtained before and after 1 week of treatment with acetylsalicylic acid. One sample was transported by pneumatic tube transport, while the other remained in the laboratory. Results: No preanalytical effect of pneumatic tube transport could be seen for most haematology and coagulation parameters, as well as analysis with PFA-100®. For the thromboelastographic analysis, time to clot formation was shorter (–16%, p=0.037) in the transported samples. Treatment with acetylsalicylic acid had no effect on the majority of the test results. Conclusions: Pneumatic tube transport does not introduce preanalytical errors when transporting samples for analysis of routine haematology, coagulation parameters and platelet function with the PFA-100®. We recommend manual transport of samples for analysis with thromboelastographic techniques. Clin Chem Lab Med 2008;46:1443–9.

Validity of food frequency questionnaire estimated intakes of folate and other B vitamins in a region without folic acid fortification.

Background/Objectives:B vitamins have been implicated in major chronic diseases but results have been inconsistent. This study evaluated the accuracy of dietary intakes of folate, vitamin B12, riboflavin and vitamin B6 as measured by the Northern Sweden Food Frequency Questionnaire (FFQ) against repeated 24-h recalls (24HR) and plasma levels, taking into consideration the MTHFR 677C>T polymorphism.Subjects/Methods:B vitamin intakes assessed by a semi-quantitative FFQ designed to measure the intake over the previous year were compared with those from 10 24HR, as well as to plasma levels of folate and vitamin B12, in randomly selected men (n=96) and women (n=99) aged 30–60 years. FFQ-based B-vitamin intakes were also compared with plasma levels of B-vitamins and with MTHFR 677C4T genotype in 878 men, aged 40–61 years.Results:Intakes of vitamins B12 and riboflavin were similar, whereas folate and B6 intakes were 16–27% higher, as estimated by FFQ versus 24HR. Spearman correlation coefficients between the two methods ranged from 0.31 to 0.63 (all P⩽0.002), and were lowest for vitamin B12. Intakes estimated by FFQ were correlated with plasma levels, but coefficients were lower (range: 0.13–0.33), particularly for vitamin B12 in men (0.15–0.18). Folate intake was not correlated with plasma levels in subjects with the MTHFR 677 T/T genotype.Conclusions:The validity of the Northern Sweden FFQ for assessing B vitamin intake is similar to that of many other FFQs used in large-scale studies. The FFQ is suitable for ranking individuals by intake of folate, riboflavin, vitamin B6 and to a lesser extent vitamin B12.

Increased Fibrinogen Levels and Acquired Hypofibrinolysis in Young Adults With Ischemic Stroke

BACKGROUND AND PURPOSEnElevated fibrinogen levels and abnormalities in the fibrinolytic system are related to the occurrence of cardiovascular events. However, the role of these factors in the evolution of cerebrovascular disease has received less attention, in particular in young stroke patients. The aim of this study was to evaluate possible abnormalities in plasma fibrinogen levels and the state of the fibrinolytic system in young adults with a first-ever ischemic stroke.nnnMETHODSnThis study is based on 102 consecutive patients aged 18 to 44 years admitted between January 1991 and May 1996 as a result of a first ischemic stroke. Forty-one healthy controls were recruited. Evaluations of anthropometric/metabolic variables, plasma fibrinogen levels, and the fibrinolytic system were undertaken >/=3 months (mean, 5.4+/-2.0 months) after admission.nnnRESULTSnPatients had lower tissue plasminogen activator activity and increased plasminogen activator inhibitor type 1 activity at baseline, as well as increased tissue plasminogen activator mass concentration both at baseline and after a venous occlusion test. Overall, there were no significant differences between the main etiologic subgroups regarding plasma fibrinogen levels and fibrinolytic variables. Baseline fibrinolytic variables were strongly correlated with body mass index, serum triglycerides, and cholesterol levels. After adjustments in multivariate models, fibrinogen levels and tissue plasminogen activator mass concentration both at baseline and after venous occlusion test remained significantly increased in patients. Logistic multiple regression analyses indicated that plasma fibrinogen was a strong predictor of ischemic stroke (odds ratio, 11.25; 95% CI, 3.27 to 38. 69).nnnCONCLUSIONSnIncreased fibrinogen levels and tissue plasminogen activator mass concentration are independently associated with ischemic stroke in young adults. Metabolic perturbations are closely interrelated with aberrations in tissue plasminogen activator and plasminogen activator inhibitor type 1 activity in these patients, findings consistent with an acquired hypofibrinolysis.

Homocysteine and holo‐transcobalamin and the risk of dementia and Alzheimers disease: a prospective study

Background:u2002 Elevated total homocysteine (tHcy) levels may be caused by vitamin B12 deficiency and are linked to Alzheimers disease (AD) in some studies, although the evidence is mixed. Another marker of vitamin B12 deficiency, holo‐transcobalamin (holo‐TC), has not been studied in a prospective setting.