Folate, vitamin B-12, and cognitive function in the Boston Puerto Rican Health Study

The communication mechanism of the gut-brain axis and its effect on central nervous system diseases: A systematic review

Gut microbiota is involved in intricate and active metabolic processes the host's brain function, especially its role in immune responses, secondary metabolism, and symbiotic connections with the host. Gut microbiota can promote the production of essential metabolites, neurotransmitters, and other neuroactive chemicals that affect the development and treatment of central nervous system diseases. This article introduces the relevant pathways and manners of the communication between the brain and gut, summarizes a comprehensive overview of the current research status of key gut microbiota metabolites that affect the functions of the nervous system, revealing those adverse factors that affect typical communication between the brain-gut axis, and outlining the efforts made by researchers to alleviate these neurological diseases through targeted microbial interventions. The relevant pathways and manners of communication between the brain and gut contribute to the experimental design of new treatment plans and drug development. The factors that may cause changes in gut microbiota and affect metabolites, as well as current intervention methods are summarized, which helps improve gut microbiota brain dialogue, prevent adverse triggering factors from interfering with the gut microbiota system, and minimize neuropathological changes.

Cognitive Benefits of Folic Acid, Docosahexaenoic Acid, and a Combination of Both Nutrients in Mild Cognitive Impairment: Possible Alterations through Mitochondrial Function and DNA Damage

INTRODUCTION

It is uncertain whether folic acid (FA) combined with docosahexaenoic acid (DHA) could improve cognitive performance. This study evaluated the effects of a 12-month FA and DHA supplementation, in combination or alone, on cognitive function, DNA oxidative damage, and mitochondrial function in participants with mild cognitive impairment (MCI).

METHODS

This randomized, double-blind, placebo-controlled trial recruited MCI participants aged 60 years and older. Two hundred and eighty participants were randomly divided in equal proportion into four groups: FA + DHA (FA 800 μg/d + DHA 800 mg/d), FA (800 μg/d), DHA (800 mg/d), and placebo groups daily orally for 12 months. The primary outcome was cognitive function evaluated by the Wechsler Adult Intelligence Scale-Revised (WAIS-RC). Cognitive tests and blood mechanism-related biomarkers were determined at baseline and 12 months.

RESULTS

During the 12-month follow-up, scores of full intelligence quotient (βDHA: 1.302, 95% CI: 0.615, 1.990, p < 0.001; βFA: 1.992, 95% CI: 1.304, 2.679, p < 0.001; βFA+DHA: 2.777, 95% CI: 2.090, 3.465, p < 0.001), verbal intelligence quotient, and some subtests of the WAIS-RC were significantly improved in FA + DHA and single intervention groups compared to the placebo group. Moreover, the FA and DHA intervention combination was superior to either intervention alone (p < 0.001). Meanwhile, FA, DHA, and their combined use significantly decreased 8-OHdG level and increased mitochondrial DNA copy number compared to the placebo (p < 0.05).

CONCLUSIONS

Supplementation of FA and DHA, alone or combined, for 12 months can improve cognitive function in MCI participants, possibly through mitigating DNA oxidative damage and enhancing mitochondrial function. Combined supplementation may provide more cognitive benefit than supplementation alone.

Association between Acid-Lowering Agents, Metformin, and Vitamin B12 among Boston-Area Puerto Ricans

BACKGROUND

Vitamin B12 involves several physiological functions, and malabsorption is reported with medication use.

OBJECTIVES

Studies have reported an inverse association between the use of metformin or acid-lowering agents (ALAs), such as proton pump inhibitors, histamine 2 receptor antagonists, and blood vitamin B12 concentration, because of malabsorption. The concomitant use of these medications is underreported. We sought to examine these associations in a cohort of Boston-area Puerto Rican adults.

METHODS

This analysis was conducted within the Boston Puerto Rican Health Study (BPRHS), an ongoing longitudinal cohort that enrolled 1499 Puerto Rican adults aged 45-75 y at baseline. Our study comprised 1428, 1155, and 782 participants at baseline, wave2 (2.2 y from baseline), and wave3 (6.2 y from baseline), respectively. Covariate-adjusted linear and logistic regression was used to examine the association between baseline medication use and vitamin B12 concentration or deficiency (vitamin B12 <148 pmol/L or methylmalonic acid >271 nmol/L), and long-term medication use (continuous use for ∼6.2 y) and wave3 vitamin B12 concentration and deficiency. Sensitivity analyses were done to examine these associations in vitamin B12 supplement users.

RESULTS

At baseline, we observed an association between metformin use (β = -0.069; P = 0.03) and concomitant ALA and metformin use (β = -0.112; P = 0.02) and vitamin B12 concentration, but not a deficiency. We did not observe associations between ALA, proton pump inhibitors, or histamine 2 receptor antagonists, individually, with vitamin B12 concentration or deficiency.

CONCLUSIONS

These results suggest an inverse relationship between metformin, concomitant ALA, metformin use, and serum vitamin B12 concentration.

Vitamin B12: For more than just the treatment of megaloblastic anemia?

Vitamin B12, or cobalamin, belongs to the group of water-soluble vitamins and is ingested through food of animal origin such as eggs, milk, red meat and poultry, fish, and shellfish. Its clinical indication is the treatment of hypovitaminosis B12 administered orally or intramuscularly in the form of hydroxocobalamin. Hypovitaminosis B12 is mainly caused by deficient dietary intake (individuals with malnutrition, vegetarians or vegans, older adults, pregnant people, individuals with alcohol use disorder); when intestinal absorption is reduced (atrophic gastritis, malabsorption syndrome, gastrointestinal surgery); and for causes associated with the intake of drugs (antacids, metformin). Hypervitaminosis B12 has been associated with renal failure; liver diseases such as cirrhosis and acute-phase hepatitis; alcohol use disorder with or without liver involvement; solid tumors of the lung, liver, esophagus, pancreas, and colorectum; and in hematological malignancies such as leukemia and bone marrow dysplasia.

Intermediate role of gut microbiota in vitamin B nutrition and its influences on human health

Vitamin B consists of a group of water-soluble micronutrients that are mainly derived from the daily diet. They serve as cofactors, mediating multiple metabolic pathways in humans. As an integrated part of human health, gut microbiota could produce, consume, and even compete for vitamin B with the host. The interplay between gut microbiota and the host might be a crucial factor affecting the absorbing processes of vitamin B. On the other hand, vitamin B supplementation or deficiency might impact the growth of specific bacteria, resulting in changes in the composition and function of gut microbiota. Together, the interplay between vitamin B and gut microbiota might systemically contribute to human health. In this review, we summarized the interactions between vitamin B and gut microbiota and tried to reveal the underlying mechanism so that we can have a better understanding of its role in human health.

Association of folate and vitamin B12 imbalance with adverse pregnancy outcomes among 11,549 pregnant women: An observational cohort study

Objective

This study aimed to evaluate maternal serum levels of folate, vitamin B12, and their ratio on admission for labor and determine whether an imbalance between folate and vitamin B12, represented by a higher or lower serum folate to vitamin B12 ratio (SFVB12R), was associated with adverse pregnancy outcomes.

Methods

A retrospective cohort study of 11,549 pregnant women attending a district specialized hospital and who had serum folate (SF) and serum vitamin B12 (SVB12) levels measured at delivery was performed. The levels of SF, SVB12, and SFVB12R were defined as high (>95th percentile), normal (5–95th percentile), and low (<5th percentile). Information on pregnancy outcomes was retrieved from medical records. Linear regression was performed to examine the association of abnormal SF, SVB12, and SFVB12R levels with fetal growth indicators. Logistic regression was applied to estimate the association between abnormal SF, SVB12, and SFVB12R levels and pregnancy outcomes.

Results

Lower SF levels were associated with higher risks of intrahepatic cholestasis of pregnancy (ICP, OR 1.58; 95% CI 1.15–2.17), pre-eclampsia (PE, OR 1.89; 95% CI 1.28–2.81), and a lower risk of gestational diabetes mellitus (GDM, OR 0.40; 95% CI 0.23–0.70), whereas higher SVB12 levels were associated with a higher risk of ICP (OR 2.22; 95% CI 1.67–2.96), PE (OR 1.69; 95% CI 1.04-2.74), and GDM (OR 1.62; 95% CI 1.24–2.11). A higher SFVB12R increased birthweight (β 60.99; 95% CI 29.52–92.45) and was associated with a higher risk of large-for-gestational-age (LGA) newborns (OR 3.08; 95% CI 1.63–5.83); a lower SFVB12R decreased birthweight (β −43.81; 95% CI −75.62, −12.00) and was associated with a lower risk of LGA newborns (OR 0.75; 95% CI 0.56–1.00), and with higher risks of ICP (OR 2.03; 95% CI 1.54–2.67) and pregnancy-induced hypertension (PIH, OR 1.81; 95% CI 1.09–3.00).

Conclusion

An imbalance between folate and vitamin B12, represented by a higher or lower SFVB12R before delivery, was significantly associated with adverse pregnancy outcomes (ICP/PIH/LGA).

Association Between Methylmalonic Acid and Cognition: A Systematic Review and Meta-Analysis

BACKGROUND

Methylmalonic acid (MMA) is an intermediate metabolite of human body. The content of MMA in the blood of healthy people is very low, and its concentration will increase in some diseases and elderly people. Recent studies have shown that MMA has a variety of biological functions. The correlation between MMA and cognition, one of the important functions of the nervous system, is still uncertain.

OBJECTIVE

Meta-analyses were performed to assess whether elevated MMA was associated with the risk of cognitive decline.

MATERIALS AND METHODS

Cross-sectional studies, randomized controlled studies, and case-control studies on the relationship between MMA and cognition were obtained by searching PubMed, Web of Science, EMBASE, ProQuest, WANFANG MED ONLINE, China National Knowledge Infrastructure (CNKI) and Chongqing VIP until May 2022. Two researchers independently selected studies according to inclusion and exclusion criteria, evaluated study quality and extracted data. Meta-analyses were performed using Review Manager 5.4 software. The sensitivity analysis of meta-analysis was performed by One by one exclusion method.

RESULTS

A total of 11 studies were included, including six cross-sectional studies, two randomized controlled studies, and three case-control studies, with a sample of 16,533 subjects. Meta-analysis showed that there was no significant difference in cognitive level between high-level MMA subjects and low-level MMA subjects in the general population [SMD = -2.19, 95% CI (-4.76 ∼ 0.38), Z = 1.67, P = 0.09]. In the population supplemented with VitB12, the increase of MMA level caused by VitB12 supplementation was not related to the change of cognition [SMD = 0.32, 95% CI (-0.19 ∼ 0.84) z = 1.22, P = 0.22]. There was also no significant difference in MMA levels between patients with dementia and the control group [WMD = 20.89, 95% CI (-5.13 ∼ 46.92), z = 1.57, P = 0.12].

CONCLUSION

In the general population, whether VitB12 is supplemented or not, there is no correlation between the increase of MMA level and the decrease of cognitive level. In dementia diseases, the level of MMA did not change significantly. High levels of MMA may not be a risk factor for cognitive impairment. The exact relationship between MMA and cognition needs further research.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021266310], identifier [CRD42021266310].

Nutrient Effects on Motor Neurons and the Risk of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is an incurable chronic progressive neurodegenerative disease with the progressive degeneration of motor neurons in the motor cortex and lower motor neurons in the spinal cord and the brain stem. The etiology and pathogenesis of ALS are being actively studied, but there is still no single concept. The study of ALS risk factors can help to understand the mechanism of this disease development and, possibly, slow down the rate of its progression in patients and also reduce the risk of its development in people with a predisposition toward familial ALS. The interest of researchers and clinicians in the protective role of nutrients in the development of ALS has been increasing in recent years. However, the role of some of them is not well-understood or disputed. The objective of this review is to analyze studies on the role of nutrients as environmental factors affecting the risk of developing ALS and the rate of motor neuron degeneration progression.

METHODS

We searched the PubMed, Springer, Clinical keys, Google Scholar, and E-Library databases for publications using keywords and their combinations. We analyzed all the available studies published in 2010-2020.

DISCUSSION

We analyzed 39 studies, including randomized clinical trials, clinical cases, and meta-analyses, involving ALS patients and studies on animal models of ALS. This review demonstrated that the following vitamins are the most significant protectors of ALS development: vitamin B12, vitamin E > vitamin C > vitamin B1, vitamin B9 > vitamin D > vitamin B2, vitamin B6 > vitamin A, and vitamin B7. In addition, this review indicates that the role of foods with a high content of cholesterol, polyunsaturated fatty acids, urates, and purines plays a big part in ALS development.

CONCLUSION

The inclusion of vitamins and a ketogenic diet in disease-modifying ALS therapy can reduce the progression rate of motor neuron degeneration and slow the rate of disease progression, but the approach to nutrient selection must be personalized. The roles of vitamins C, D, and B7 as ALS protectors need further study.