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 < or = 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 > or = 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.

Cognitive impairment in folate-deficient rats corresponds to depleted brain phosphatidylcholine and is prevented by dietary methionine without lowering plasma homocysteine

Poor folate status is associated with cognitive decline and dementia in older adults. Although impaired brain methylation activity and homocysteine toxicity are widely thought to account for this association, how folate deficiency impairs cognition is uncertain. To better define the role of folate deficiency in cognitive dysfunction, we fed rats folate-deficient diets (0 mg FA/kg diet) with or without supplemental L-methionine for 10 wk, followed by cognitive testing and tissue collection for hematological and biochemical analysis. Folate deficiency with normal methionine impaired spatial memory and learning; however, this impairment was prevented when the folate-deficient diet was supplemented with methionine. Under conditions of folate deficiency, brain membrane content of the methylated phospholipid phosphatidylcholine was significantly depleted, which was reversed with supplemental methionine. In contrast, neither elevated plasma homocysteine nor brain S-adenosylmethionine and S-adenosylhomocysteine concentrations predicted cognitive impairment and its prevention by methionine. The correspondence of cognitive outcomes to changes in brain membrane phosphatidylcholine content suggests that altered phosphatidylcholine and possibly choline metabolism might contribute to the manifestation of folate deficiency-related cognitive dysfunction.

Nutrition and Crohn's disease: an update of print and Web-based guidance

This article reviews the role of nutrition in Crohn's disease, one of the inflammatory bowel diseases. In addition to presenting a comprehensive review of the state-of-the-evidence on nutritional risks and nutritional therapies in Crohn's disease, and making specific nutrient recommendations, this article includes a list of Web-based resources, including websites, blogs, newsletters, and multimedia podcasts that can be utilized by patients and healthcare providers alike to learn more about the etiology, pathophysiology, and nutritional management of Crohn's disease.

Association of plasma total homocysteine levels with subclinical brain injury: cerebral volumes, white matter hyperintensity, and silent brain infarcts at volumetric magnetic resonance imaging in the Framingham Offspring Study

BACKGROUND

Elevated plasma total homocysteine (tHcy) levels have been associated with increased risk of dementia and stroke, but it is uncertain whether the mediating mechanisms are predominantly cellular, vascular, or both.

OBJECTIVE

To evaluate the relationship between tHcy levels and findings at brain magnetic resonance imaging (MRI) in a community-based sample.

DESIGN

Our sample comprised 1965 participants in the Framingham Offspring Study (1050 women; mean [SD] age, 62 [9] years) who were free of clinical stroke, dementia, or other neurologic disease affecting brain MRI and for whom at least 1 measurement of plasma tHcy level (1991-2001) and a brain MRI (1999-2002) were available. We used multivariate regression analysis to relate initial (1991-1995) and concurrent (1998-2001) plasma tHcy levels to total cerebral brain volume and lobar volumes as measures of neuronal loss and atrophy and to the presence or absence of silent brain infarcts and extensive white matter hyperintensity (log-white matter intensity > or =1 SD above the age-adjusted mean) as separate measures of vascular injury.

RESULTS

Mean total cerebral brain volume was 78%. At MRI, 218 participants had silent brain infarcts and 250 demonstrated extensive white matter hyperintensity. Participants with a plasma tHcy level in the highest age- (-0.37%, P = .01) or sex-specific (-0.48%, P < .001) quartile had smaller total cerebral brain volumes compared with participants with lower tHcy levels. Initial tHcy levels were associated with a higher prevalence of silent brain infarct (relative risk, 1.5; 95% confidence interval, 1.1-2.1; P = .02) and concurrent tHcy levels, with smaller frontal (-0.14%, P = .001) and temporal lobar (-0.10%, P = .04) volumes. Prevalence of extensive white matter hyperintensity did not differ according to initial or concurrent plasma tHcy levels (relative risk, both 1.0; 95% confidence interval, 0.7-1.4 and 0.8-1.4, respectively).

CONCLUSIONS

Higher plasma tHcy levels are associated with smaller brain volume and the presence of silent brain infarcts at MRI, even in healthy, middle-aged adults. Thus, both cellular and vascular mechanisms may underlie the association of plasma tHcy level with brain aging, as reflected by the effects on both subclinical and overt disease.

Translating nutrition science into policy as witness and actor

The sustained effort to witness and participate in the targeted translation of nutritional science and policy forms the structure of this narrative. The memoir starts with an early career-directing experience with nutrition and cholera and proceeds with a long thread of interest in folic acid malabsorption as one of the determinants of nutritional anemia in Asia and the tropics. The thread continues with the relationship of folate and associated vitamins to brain function and aging as a prototype of the study of the interface of aging biology and nutritional biology. My current interest in world hunger and famine and their impact on human security may circle back to studies of the great Bengal famine and the first Bangladesh survey of malnutrition.

Preliminary evidence shows that folic acid fortification of the food supply is associated with higher methotrexate dosing in patients with rheumatoid arthritis

BACKGROUND

Fortification of the diet with folate has been used in the United States since 1997 to prevent neural tube defects in newborn babies. However, an increase in dietary folate intake could theoretically reduce the effectiveness of the anti-folate medication, methotrexate (MTX) in treating rheumatoid arthritis (RA) and other inflammatory diseases.

OBJECTIVE

To investigate whether dietary fortification with folic acid interferes with MTX function in patients with RA.

METHODS

We computed MTX dose per patient per year for the years 1988 to 1999 and plotted these against time, comparing the overall mean MTX dose before and after 1997, when dietary fortification with folic acid was instituted in the USA. Thirty-six subjects met eligibility criteria.

RESULTS

Mean annual MTX dose was stable between 1988 and 1996 (12.4 +/- 4.0mg), but then rose linearly from 1997 to 1999 (16.6 +/- 5.1 mg, p < 0.001).

CONCLUSIONS

This preliminary study suggests that folic acid supplementation may contribute to higher MTX dosing in patients with RA.

Aging modifies brain region-specific vulnerability to experimental oxidative stress induced by low dose hydrogen peroxide

Our previous studies demonstrated a significant decline in brain function and behavior in Fischer 344 (F344) rats with age. The present study was designed to test the hypothesis that dysregulation in calcium homeostasis (as assessed through (45)Ca flux) may contribute to the increase in age-related vulnerability to oxidative stress in brain regions, and result in a deficit in behavior-mediated signaling. Crude membrane (P-2) and more purified synaptosomal fractions were isolated from the striatum, hippocampus, and frontal cortex of young (6 months) and old (22 months) F344 rats and were assessed for calcium flux and extracellular-regulated kinase activity 1 (ERK) under control and oxidative stress conditions induced by low dose hydrogen peroxide (final concentration 5 microM). The level of oxidative stress responses was monitored by measuring reactive oxygen species (ROS) and glutathione (GSH). The results showed a significant difference in oxidative stress responses between young and old rats in evaluated brain regions. Old rats showed higher sensitivity to oxidative stress than young rats. The present findings show the differential effects of oxidative stress on calcium flux in brain regions with age that are dependent upon the brain areas examined and the fraction assessed. The accumulation of ROS and the decrease in GSH in the frontal cortex were sufficient to decrease ERK activity in old rats. This is the first study, to our knowledge, that demonstrates age-related differential sensitivity to oxidative stress expressed as a function of behavior-mediated signaling and stress levels among different fractions isolated from brain regions controlling behavior.

A temporal association between folic acid fortification and an increase in colorectal cancer rates may be illuminating important biological principles: a hypothesis

Nationwide fortification of enriched uncooked cereal grains with folic acid began in the United States and Canada in 1996 and 1997, respectively, and became mandatory in 1998. The rationale was to reduce the number of births complicated by neural tube defects. Concurrently, the United States and Canada experienced abrupt reversals of the downward trend in colorectal cancer (CRC) incidence that the two countries had enjoyed in the preceding decade: absolute rates of CRC began to increase in 1996 (United States) and 1998 (Canada), peaked in 1998 (United States) and 2000 (Canada), and have continued to exceed the pre-1996/1997 trends by 4 to 6 additional cases per 100,000 individuals. In each country, the increase in CRC incidence from the prefortification trend falls significantly outside of the downward linear fit based on nonparametric 95% confidence intervals. The statistically significant increase in rates is also evident when the data for each country are analyzed separately for men and women. Changes in the rate of colorectal endoscopic procedures do not seem to account for this increase in CRC incidence. These observations alone do not prove causality but are consistent with the known effects of folate on existing neoplasms, as shown in both preclinical and clinical studies. We therefore hypothesize that the institution of folic acid fortification may have been wholly or partly responsible for the observed increase in CRC rates in the mid-1990s. Further work is needed to definitively establish the nature of this relationship. In the meantime, deliberations about the institution or enhancement of fortification programs should be undertaken with these considerations in mind.

Multivitamin use and B vitamin status in a homebound elderly population

OBJECTIVE

Homebound elderly are at increased risk for micronutrient deficiencies and nutritional status in this population has not been adequately described. There is evidence for beneficial effects of multivitamin use and a greater understanding of their nutritional contribution could identify behaviors that may help alleviate excess chronic disease. The purpose of this analysis is to investigate, in a racially diverse group of homebound elders, the association of multivitamin use with measures of plasma B vitamin concentrations.

DESIGN

We examined the cross-sectional association between multivitamin use and plasma concentrations of B vitamins and homocysteine in 236 white and 182 black homebound elders (65-99y). Dietary intake was assessed and demographic and health information was ascertained.

RESULTS

White and black elders had a high prevalence of dietary intakes below the Estimated Average Requirement for folate (38.1 and 40.7%), vitamin B6 (16.9 and 19.2%.), and vitamin B12 (3 and 3.9%) respectively. Multivitamin use was associated with higher mean plasma B vitamin concentrations in each group. In whites, multivitamin users had higher concentrations of vitamin B6 (64.6 vs. 32.4 nmol/L; p < 0.001), vitamin B12 (398 vs. 324 pmol/L;p < 0.001) and folate (39.4 vs. 30.4 nmol/L;p < 0.001). Black multivitamin users had higher concentrations of vitamin B6 (53.7 vs. 29.5 nmol/L; p < 0.001), B12 (427 vs. 372 pmol/L; p < 0.05) and folate (35.7 vs. 25.4 nmol/L; < 0.001) than non-users.

CONCLUSIONS

Multivitamin supplementation was associated with higher mean plasma concentrations of vitamins B6, B12, and folate and lower prevalence of low plasma B vitamin status in a biracial homebound elderly.

Heterogeneity and lack of good quality studies limit association between folate, vitamins B-6 and B-12, and cognitive function

We conducted a systematic review to evaluate the association between folate, vitamin B-6, vitamin B-12, and cognitive function in the elderly. Our search was conducted in Medline for English-language publications of human subjects from 1966 through November 2006; we supplemented these results with information from article reviews and domain experts. We included longitudinal cohort and case-control studies of B vitamins and analyses of cognitive tests or Alzheimer's disease. We evaluated the quality and heterogeneity of study outcomes and assessed 30 different cognitive function tests. Of 24 studies that met eligibility criteria, 16 were determined to be of fair quality. A majority of the studies reviewed 2 or more B vitamins. Considerable heterogeneity was found among B-vitamin-level thresholds, comparisons, and data analyses. Six of 10 folate studies reported a significant association between low baseline blood folate concentrations and subsequent poor test performance in the global cognitive domain, and 4 of 9 folate studies found associations between low blood folate concentrations and increased prevalence of Alzheimer's disease. Studies did not reveal an association of vitamin B-6 and vitamin B-12 blood concentrations with cognitive-test performance or Alzheimer's disease, nor was B-vitamin dietary intake associated with cognitive function. Higher plasma homocysteine concentrations were associated with poorer cognitive function. Although the majority of studies indicated that low blood folate concentrations predicted poorer cognitive function, data supporting this association were limited because of the heterogeneity in cognition-assessment methodology, and scarcity of good quality studies and standardized threshold levels for categorizing low B-vitamin status.

Vitamin B6, B12, and folic acid supplementation and cognitive function: a systematic review of randomized trials

BACKGROUND

Despite their important role in cognitive function, the value of B vitamin supplementation is unknown. A systematic review of the effect of pyridoxine hydrochloride (hereinafter "vitamin B(6)"), cyanocobalamin or hydroxycobalamin (hereinafter "vitamin B(12)"), and folic acid supplementation on cognitive function was performed.

METHODS

Literature search conducted in MEDLINE with supplemental articles from reviews and domain experts. We included English language randomized controlled trials of vitamins B(6) and/or B(12) and/or folic acid supplementation with cognitive function outcomes.

RESULTS

Fourteen trials met our criteria; most were of low quality and limited applicability. Approximately 50 different cognitive function tests were assessed. Three trials of vitamin B(6) and 6 of vitamin B(12) found no effect overall in a variety of doses, routes of administration, and populations. One of 3 trials of folic acid found a benefit in cognitive function in people with cognitive impairment and low baseline serum folate levels. Six trials of combinations of the B vitamins all concluded that the interventions had no effect on cognitive function. Among 3 trials, those in the placebo arm had greater improvements in a small number of cognitive tests than participants receiving either folic acid or combination B-vitamin supplements. The evidence was limited by a sparsity of studies, small sample size, heterogeneity in outcomes, and a lack of studies that evaluated symptoms or clinical outcomes.

CONCLUSION

The evidence does not yet provide adequate evidence of an effect of vitamin B(6) or B(12) or folic acid supplementation, alone or in combination, on cognitive function testing in people with either normal or impaired cognitive function.

Challenges and opportunities in the translation of the science of vitamins

Some 100 y after the description and naming of the first vitamin, this conference on the state-of-the-science has shown that remarkable and exciting advances have been made in our understanding of the biology, chemistry, and metabolism of vitamins, explaining their essentiality in the diet. A great deal more needs to be done in the translation of this knowledge into an understanding of the benefit of vitamin supplements to disease prevention and to health and well-being. Not only are advances in fundamental science and biology necessary, but more attention must be paid to genomics, epigenetics, behavioral science, and new techniques for evidence analysis of studies. Information relating individual vitamins or small combinations of vitamins to disease prevention is stronger than that for multivitamins, formulations that cry out for greater standardization. This large task of translating emerging science to better policy in the field of vitamin and multivitamin-mineral supplement use should occupy our attention intensively in the years to come. Issues needing more attention include the content and labeling of such products and the effects of the products on nutrient adequacy as well as in chronic degenerative disease prevention. In this quest, the development of more and better surrogate markers will be critical. Dose-response assessments of safety are badly needed for updating Tolerable Upper Intake Levels. At its best, all of these disparate types of research will require a robust interaction between the public and private sectors in a regulatory framework that supports and rewards investment in good science.

Folate and vitamin B-12 status in relation to anemia, macrocytosis, and cognitive impairment in older Americans in the age of folic acid fortification

BACKGROUND

Historic reports on the treatment of pernicious anemia with folic acid suggest that high-level folic acid fortification delays the diagnosis of or exacerbates the effects of vitamin B-12 deficiency, which affects many seniors. This idea is controversial, however, because observational data are few and inconclusive. Furthermore, experimental investigation is unethical.

OBJECTIVE

We examined the relations between serum folate and vitamin B-12 status relative to anemia, macrocytosis, and cognitive impairment (ie, Digit Symbol-Coding score < 34) in senior participants in the 1999-2002 US National Health and Nutrition Examination Survey.

DESIGN

The subjects had normal serum creatinine concentrations and reported no history of stroke, alcoholism, recent anemia therapy, or diseases of the liver, thyroid, or coronary arteries (n = 1459). We defined low vitamin B-12 status as a serum vitamin B-12 concentration < 148 pmol/L or a serum methylmalonic acid concentration > 210 nmol/L-the maximum of the reference range for serum vitamin B-12-replete participants with normal creatinine.

RESULTS

After control for demographic characteristics, cancer, smoking, alcohol intake, serum ferritin, and serum creatinine, low versus normal vitamin B-12 status was associated with anemia [odds ratio (OR): 2.7; 95% CI: 1.7, 4.2], macrocytosis (OR: 1.8; 95% CI: 1.01, 3.3), and cognitive impairment (OR: 2.5; 95% CI: 1.6, 3.8). In the group with a low vitamin B-12 status, serum folate > 59 nmol/L (80th percentile), as opposed to < or = 59 nmol/L, was associated with anemia (OR: 3.1; 95% CI: 1.5, 6.6) and cognitive impairment (OR: 2.6; 95% CI: 1.1, 6.1). In the normal vitamin B-12 group, ORs relating high versus normal serum folate to these outcomes were < 1.0 (P(interaction) < 0.05), but significantly < 1.0 only for cognitive impairment (0.4; 95% CI: 0.2, 0.9).

CONCLUSION

In seniors with low vitamin B-12 status, high serum folate was associated with anemia and cognitive impairment. When vitamin B-12 status was normal, however, high serum folate was associated with protection against cognitive impairment.