Serum total homocysteine concentration is related to self-reported heart attack or stroke history among men and women in the NHANES III

Associations between homocysteine and B vitamins and stroke: a cross-sectional study

Objective

Homocysteine (Hcy) is a predictor for stroke. B vitamins are required for the metabolism of Hcy. We designed a study to investigate the associations of plasma Hcy and B vitamins with the prevalence of stroke in adults.

Methods

A total of 8,371 adults were included in the National Health and Examination Survey (NHANES) between 2003-2006 in the United States. Multivariate regression analysis and smooth curve fitting were conducted to evaluate the associations of stroke prevalence with Hcy, folate, vitamin B6, and B12. A segmented regression model was used to analyze the threshold effects. Sample weights were calculated to ensure the results' generalizability.

Results

The mean age of all participants was 46.43 years (51.8% women), and the prevalence of stroke was 2.72%. A nonlinear and positive association was found between plasma Hcy levels and the prevalence of stroke. Furthermore, L-shaped associations were found between plasma vitamin B6 and folate levels and stroke, with the turning point at 65.2 nmol/L for vitamin B6 and 26 nmol/L for folate, respectively. Vitamin B12 revealed a U-shaped relationship with stroke, with the turning points at 492.98 pmol/L for vitamin B12.

Conclusion

Non-linear associations of plasma Hcy and B vitamins levels with stroke prevalence were found in American adults. These associations may have an implication that higher plasma Hcy levels should be reduced, and plasma vitamin B6, vitamin B12 and folate levels should be moderately improved in stroke prevention. Future studies are needed to verify the causality of these associations and elucidate the underlying mechanisms.

Homocysteine Levels in Parkinson's Disease: Is Entacapone Effective?

Plasma homocysteine (Hcy) levels may increase in levodopa-treated patients with Parkinson's disease (PD) as a consequence of levodopa methylation via catechol-O-methyltransferase (COMT). Results from previous studies that assessed the effect of COMT inhibitors on levodopa-induced hyperhomocysteinemia are conflicting. We aimed to evaluate the effects of levodopa and entacapone on plasma Hcy levels. A hundred PD patients were enrolled to the study and divided into three treatment groups (group I: levodopa and/or dopamine agonists; group II: levodopa, entacapone, and/or a dopamine agonist; and group III: dopamine agonist alone). We measured the serum B12, folic acid, and Hcy levels in all patients. There were no statistically significant differences between groups in terms of modified Hoehn and Yahr stages, Unified Parkinson's Disease Rating Scale II/III, Standardized Mini-Mental Test scores, and serum vitamin B12 and folic acid levels. Plasma median Hcy levels were found above the normal laboratory values in groups I and II, but they were normal in group III. However, there was no statistically significant difference in plasma Hcy levels between groups. Our results showed that levodopa treatment may cause a slight increase in the Hcy levels in PD compared with dopamine agonists and that COMT inhibitors may not have a significant effect on preventing hyperhomocysteinemia.

Folate and vitamin B-12 biomarkers in NHANES: history of their measurement and use

NHANES measured folate and vitamin B-12 status biomarkers, starting with serum folate from NHANES I (1974-1975) through 2010. Subsequent NHANES measured additional biomarkers [eg, red blood cell folate, serum vitamin B-12, total homocysteine (tHcy), methylmalonic acid, serum folic acid, and 5-methyltetrahydrofolic acid]. Examples of the uses of these data are wide ranging and include public policy applications, the derivation of reference intervals, and research. Periodically, the National Center for Health Statistics and its federal partners convene expert panels to review the use of the folate- and vitamin B-12-related biomarkers in NHANES. These panels have evaluated the need for results to be comparable across time and with published data and the use of crossover studies and adjustment equations to ensure comparability. With the recent availability of reference methods and materials for serum folate and tHcy, NHANES has started to use traceability approaches to enhance the accuracy and comparability of its results. A major user concern over the years has been the use of cutoffs to estimate the prevalence of inadequate folate and vitamin B-12 status. Because these cutoffs depend on the measurement procedure, several expert panels suggested approaches for dealing with cutoff challenges. This review summarizes the history and use of folate- and vitamin B-12-related biomarkers beginning with NHANES I (1974-1975) through 2010.

Stroke: roles of B vitamins, homocysteine and antioxidants

In the present review concerning stroke, we evaluate the roles of B vitamins, homocysteine and antioxidant vitamins. Stroke is a leading cause of death in developed countries. However, current therapeutic strategies for stroke have been largely unsuccessful. Several studies have reported important benefits on reducing the risk of stroke and improving the post-stroke-associated functional declines in patients who ate foods rich in micronutrients, including B vitamins and antioxidant vitamins E and C. Folic acid, vitamin B6and vitamin B12are all cofactors in homocysteine metabolism. Growing interest has been paid to hyperhomocysteinaemia as a risk factor for CVD. Hyperhomocysteinaemia has been linked to inadequate intake of vitamins, particularly to B-group vitamins and therefore may be amenable to nutritional intervention. Hence, poor dietary intake of folate, vitamin B6and vitamin B12are associated with increased risk of stroke. Elevated consumption of fruits and vegetables appears to protect against stroke. Antioxidant nutrients have important roles in cell function and have been implicated in processes associated with ageing, including vascular, inflammatory and neurological damage. Plasma vitamin E and C concentrations may serve as a biological marker of lifestyle or other factors associated with reduced stroke risk and may be useful in identifying those at high risk of stroke. After reviewing the observational and intervention studies, there is an incomplete understanding of mechanisms and some conflicting findings; therefore the available evidence is insufficient to recommend the routine use of B vitamins, vitamin E and vitamin C for the prevention of stroke. A better understanding of mechanisms, along with well-designed controlled clinical trials will allow further progress in this area.

The evidence for dietary prevention and treatment of cardiovascular disease

During the past few decades numerous studies have reported the atherogenic potential of saturated fatty acids, trans-fatty acids, and cholesterol, and beneficial effects of fiber, phytostanols/phytosterols, n-3 fatty acids, a Mediterranean diet, and other plant-based approaches. The purpose of this article is to provide a comprehensive and systematic review of the evidence associated with key dietary factors and risk of cardiovascular disease-an umbrella term encompassing diseases that affect the heart and blood vessels, including coronary heart disease, coronary artery disease, dyslipidemia, and hypertension-in conjunction with the work of the American Dietetic Association Evidence Analysis Library review on diet and lipids, updated with new evidence from the past 2 years. The criteria used and results cited provide scientific rationale for food and nutrition professionals and other health professionals for counseling patients. Details of these searches are available within the American Dietetic Association Evidence Analysis Library online (http://adaevidencelibrary.com). Potential mechanisms and needs for future research are summarized for each relevant nutrient, food, or food component.

Subclinical hypothyroidism, hyperhomocysteinemia and dyslipidemia: investigating links with ischemic stroke in Turkish patients

OBJECTIVES

Hyperhomocysteinemia is a risk factor for ischemic stroke. Hypothyroidism may cause hyperhomocysteinemia. To date, no works have examined the association between hypothyroidism and hyperhomocysteinemia in ischemic stroke. We aimed to investigate the roles of hypothyroidism and hyperhomocysteinemia in ischemic stroke, and whether any relationship exists between hypothyroidism and hyperhomocysteinemia in ischemic stroke patients.

METHODS

The study included 249 ischemic stroke patients and 102 patients with no history of stroke. Patients were evaluated for conventional risk factors and levels of homocysteine, thyroid-stimulating hormone, vitamin B12 and folic acid.

RESULTS

Ten (4%) patients in the ischemic stroke group had subclinical hypothyroidism. We did not find any overt or subclinical hypothyroidism in the control group. Hypothyroidism was higher to a statistically significant degree in the ischemic stroke group (p<0.05). Both hyperhomocysteinemia and hypothyroidism were associated with ischemic stroke patients. However, no association was found between hyperhomocysteinemia and hypothyroidism. Ischemic stroke patients with hypothyroidism had lower levels of HDL cholesterol and levels of total cholesterol/HDL-C and LDL-C/HDL-C were higher than those of ischemic stroke patients without hypothyroidism.

DISCUSSION

Hypothyroidism is associated with ischemic stroke. Low HDL cholesterol, high total cholesterol/HDL-C and high LDL-C/HDL-C were associated in ischemic stroke patients with hypothyroidism. Hyperhomocysteinemia was not found to be associated with ischemic stroke patients with hypothyroidism.

Sleep disturbances, oxidative stress and cardiovascular risk parameters in postmenopausal women complaining of insomnia

OBJECTIVE

The aim of this work was to investigate cardiovascular risk factors and oxidative stress parameters as well as sleep disturbances in polysomnography recordings of 38 postmenopausal women with insomnia.

METHODS

Polysomnography recordings were performed on subjects for sleep analysis. Oxidative stress parameters were analyzed by measuring blood concentration of catalase, superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS) and glutathione. For cardiovascular risk factors, we measured plasma levels of homocysteine, folic acid and vitamin B6.

RESULTS

Findings of polysomnography recordings revealed: 68% experienced decreased sleep efficiency, 50% had apnea, 7.8% had periodic leg movements and 2.6% had bruxism (involuntary gnashing and grinding of the teeth during sleep). Our results showed that the majority of our subjects presented normal concentrations of the parameters studied according to standards reached in our laboratory. The only notable exception was TBARS. In this case, only 21% displayed normal values. We also found inverse correlations between SOD activity and both age and time of menopause.

CONCLUSIONS

Although all women complained of insomnia, 50% of them demonstrated apnea during polysomnography recordings. Of the parameters measuring oxidative stress, only TBARS levels were increased in our sample. Some clinical data, such as time of onset of menopause, may be associated with the oxidative stress status of these women, probably due to the lack of estrogen and to sleep disturbances, such as apnea.

Reduced plasma homocysteine levels in levodopa/entacapone treated Parkinson patients

Hyperhomocysteinemia is not only a major risk factor for atherothrombotic disease, but is also strongly associated with an increased risk of dementia and cognitive impairment, both of which are common in the course of Parkinson's disease (PD). Previous work has found that levodopa increases plasma homocysteine concentrations. Animal studies have indicated that the catechol-O-methyltransferase (COMT) inhibitors can prevent levodopa-induced elevation of homocysteine concentrations by reducing the O-methylation of levodopa. The objective of our study was to assess the impact of entacapone, a COMT inhibitor, on plasma levels of homocysteine, serum folate, and vitamin B12 in levodopa-treated PD patients. Nineteen PD patients receiving only levodopa and 21 PD patients on a combination of levodopa and entacapone participated in the cross-sectional study. The control group consisted of 17 subjects on dopamine agonists. The mean plasma homocysteine concentration in the subjects on only levodopa was higher than that in the subjects on a combination of levodopa and entacapone (P=0.001) or in the control group (P=0.0001). Concentrations of serum vitamin B12 and serum folate were on average normal in all groups, but levodopa-treated subjects (with or without entacapone therapy) were more prone to have hypovitaminosis B12 (45%) than controls on dopamine agonists (6%). We suggest that the COMT inhibition may play a promising role in successfully controlling levodopa-induced hyperhomocysteinemia and in reducing the risk of pathologies probably linked to it. These preliminary findings and postulated hypotheses must now be confirmed in prospective studies.

Immunogenetic Susceptibility of Atherosclerotic Stroke

The understanding of the pathophysiology governing atherosclerosis supports a prominent role for inflammation pathways in plaque initiation and progression that result in stroke and myocardial infarction. Elevated levels of inflammatory markers in the blood, such as C-reactive protein and CD40 ligand/CD40, in concert with increased expression of adhesion molecules, chemokines, cytokines, matrix metalloproteinases (MMP), and inflammatory cells in the plaque, characterize the symptomatic atherothrombotic state. Advances in predictive capabilities of vascular events using a number of these biomarkers are beginning to remodel our clinical practice in the use of medications such as statins and angiotensin receptor blockers for stroke prevention. Although the general inflammatory features of atherosclerosis are becoming widely recognized, factors resulting in individual variability in plaque formation and instability remain poorly defined. Emerging literature points toward several acquired and innate susceptibility factors in the immune pathways that may provide insight into why many plaques rapidly evolve from a “stable” to an “unstable” or symptomatic state. First, exposure of plaque memory T-lymphocytes to infectious or endogenous antigens may result in rapid clonal expansion of T-cell variable β chain subtypes and stimulate macrophages to release MMPs, causing plaque destabilization. The effects of infectious agents can further be influenced by an individual’s major histocompatibility complex class II molecule profiles, which can affect susceptibility to specific organisms. Second, functional polymorphisms of genes that regulate the immune pathway can predispose patients to a more robust inflammatory expression after risk factor exposure. Identification of a susceptibility gene profile and immunologic mediators that promote T-cell activation provides a unique opportunity for early identification of stroke risk and targets for future therapy.

Breakfast cereal fortified with folic acid, vitamin B-6, and vitamin B-12 increases vitamin concentrations and reduces homocysteine concentrations: a randomized trial

BACKGROUND

High homocysteine and low B vitamin concentrations have been linked to the risk of vascular disease, stroke, and dementia and are relatively common in older adults.

OBJECTIVE

We assessed the effect of breakfast cereal fortified with folic acid, vitamin B-6, and vitamin B-12 on vitamin and homocysteine status.

DESIGN

A randomized, double-blind trial was conducted in 189 volunteers aged 50-85 y. The subjects had no history of hypertension, anemia, asthma, cancer, or cardiovascular or digestive disease and did not regularly consume multiple or B vitamin supplements or highly fortified breakfast cereal. Subjects were randomly assigned to consume 1 cup (0.24 L) breakfast cereal fortified with 440 microg folic acid, 1.8 mg vitamin B-6, and 4.8 microg vitamin B-12 or placebo cereal for 12 wk. Blood was drawn at 0, 2, 12, and 14 wk. Methionine-loading tests were conducted at baseline and week 14.

RESULTS

Final baseline-adjusted plasma homocysteine concentrations were significantly lower and B vitamin concentrations were significantly higher in the treatment group than in the placebo group (P < 0.001). The percentage of subjects with plasma folate concentrations < 11 nmol/L decreased from 2% to 0%, with vitamin B-12 concentrations < 185 pmol/L from 9% to 3%, with vitamin B-6 concentrations < 20 nmol/L from 6% to 2%, and with homocysteine concentrations > 10.4 micromol/L (women) or > 11.4 micromol/L (men) from 6.4% to 1.6%. The percentage of control subjects with values beyond these cutoff points remained nearly constant or increased.

CONCLUSIONS

In this relatively healthy group of volunteers, consumption of 1 cup fortified breakfast cereal daily significantly increased B vitamin and decreased homocysteine concentrations, including post-methionine-load homocysteine concentrations.

Serum homocysteine in relation to mortality and morbidity from coronary heart disease: a 24-year follow-up of the population study of women in Gothenburg

BACKGROUND

Elevated serum total homocysteine (tHcy) is an established risk factor for cardiovascular disease (CVD), especially in men. However, there are few prospective population studies on female cohorts, and none of these has been longer than 13 years.

METHODS AND RESULTS

The Population Study of Women in Gothenburg began in 1968/1969, at which time a representative population-based cohort of women aged 38, 46, 50, 54, and 60 years was recruited. The present cohort is a prospective follow-up of 1368 women in the original cohort for whom blood samples were stored and who were free of previous acute myocardial infarction (AMI) at the 1968/1969 baseline. Homocysteine was analyzed in 2001 with frozen serum from the baseline study and related to AMI incidence and mortality during 24 years of follow-up. Cox regression analyses were used with adjustment for age, traditional risk factors, and tHcy modifiers. For the fifth tHcy quintile, relative risk was 1.86 (95% CI 1.06 to 3.26) for AMI and 5.14 (95% CI 2.22 to 11.92) for death due to AMI. Age-standardized Kaplan-Meier plots for the fifth tHcy quintile versus others showed significant differences both for AMI and for death due to AMI that were apparent after 15 years of follow-up.

CONCLUSIONS

Homocysteine in middle-aged women is an independent risk factor for myocardial infarction and in particular mortality due to myocardial infarction. The study illustrates that long-term prospective studies might be necessary to show effects of homocysteine levels on AMI morbidity and mortality in women.

Serum total homocysteine concentrations in children and adolescents: results from the third National Health and Nutrition Examination Survey (NHANES III)

Although the elevation of circulating total serum homocysteine (tHcy) concentration in a fasting state is associated with an increased risk of occlusive vascular disease in adults, the implications of elevated levels in children are not known. The goals of this study were to describe the distribution of tHcy among a representative sample of children and adolescents in the United States, and to test for differences in tHcy among sex, age and race-ethnicity categories. Using surplus sera from Phase 2 of the third National Health and Nutrition Examination Survey, we measured tHcy for a nationally representative sample of 942 boys and 1085 girls aged 4-19 y. The age-adjusted geometric mean tHcy concentrations were 6.2 and 5.8 micro mol/L in non-Hispanic Caucasian boys and girls, 6.4 and 6.1 micro mol/L in non-Hispanic African-American boys and girls, and 6.4 and 5.5 micro mol/L in Mexican American boys and girls, respectively. A significant interaction between age and sex (P < 0.01) reflected the divergence of tHcy concentrations at about age 10 y, with higher concentrations in boys than in girls throughout adolescence. These first data on homocysteine concentrations in a nationally representative sample of American youth suggest that sexual dimorphism of tHcy concentrations occurs earlier, at approximately 10 y of age, than previously reported on the basis of smaller nonrepresentative samples. Improved understanding of the determinants of levels during growth and development may provide important clues to the etiology of adult disease.

Plasma homocysteine and parental myocardial infarction in young adults in Jerusalem

BACKGROUND

A causal role for mildly elevated plasma homocysteine (tHcy) in cardiovascular disease remains undetermined. To address the unresolved issue of the antecedent-consequent directionality of the relationship, we assessed the familial association of tHcy with parental myocardial infarction (MI) in young Israeli men and women. We also compared tHcy concentrations in Jerusalem, where rates of coronary heart disease (CHD) are high, with the United States Third National Health and Examination Survey (NHANES III).

METHODS AND RESULTS

A total of 8646 17-year-olds and 6952 parents were examined from 1976 to 1979 in Jerusalem. At ages 28 to 32 years, offspring of parents who experienced a documented MI during a 10-year follow-up (n=133 men, 62 women; 72% response) and offspring of CHD-free parents (n=389 men, 208 women; 71% response) were reexamined. tHcy levels were determined by the same laboratory for the NHANES non-Hispanic white population aged 25 to 34 years (n=379) and the Jerusalem population sample (n=858). Men from Jerusalem, but not women, had clearly higher tHcy levels than the sample from the United States (90th percentile, 23 versus 14 micromol/L). This difference was largely attributable to lower plasma vitamin B12 levels in the Israeli population. Male case offspring had higher adjusted tHcy than did controls (1.9 micromol/L, P=0.002). Logistic modeling revealed a graded increase in risk of parental MI across quintiles of offspring tHcy, with an adjusted odds ratio of 2.7 in the 5th quintile (P=0.0026 for trend).

CONCLUSIONS

The higher tHcy in young male offspring of parents with CHD suggests that elevated tHcy precedes manifestation of CHD. The elevated population tHcy in men may contribute to the high incidence of CHD in Israel.