Choline supplements: An update

In this comprehensive review, we examine the main preclinical and clinical investigations assessing the effects of different forms of choline supplementation currently available, including choline alfoscerate (C₈H₂₀NO₆P), also known as alpha-glycerophosphocholine (α-GPC, or GPC), choline bitartrate, lecithin, and citicoline, which are cholinergic compounds and precursors of acetylcholine. Extensively used as food supplements, they have been shown to represent an effective strategy for boosting memory and enhancing cognitive function.

Postnatal Choline Supplementation Rescues Deficits in Synaptic Plasticity Following Prenatal Ethanol Exposure

Prenatal ethanol exposure (PNEE) is a leading cause of neurodevelopmental impairments, yet treatments for individuals with PNEE are limited. Importantly, postnatal supplementation with the essential nutrient choline can attenuate some adverse effects of PNEE on cognitive development; however, the mechanisms of action for choline supplementation remain unclear. This study used an animal model to determine if choline supplementation could restore hippocampal synaptic plasticity that is normally impaired by prenatal alcohol. Throughout gestation, pregnant Sprague Dawley rats were fed an ethanol liquid diet (35.5% ethanol-derived calories). Offspring were injected with choline chloride (100 mg/kg/day) from postnatal days (PD) 10-30, and then used for in vitro electrophysiology experiments as juveniles (PD 31-35). High-frequency conditioning stimuli were used to induce long-term potentiation (LTP) in the medial perforant path input to the dentate gyrus of the hippocampus. PNEE altered synaptic transmission in female offspring by increasing excitability, an effect that was mitigated with choline supplementation. In contrast, PNEE juvenile males had decreased LTP compared to controls, and this was rescued by choline supplementation. These data demonstrate sex-specific changes in plasticity following PNEE, and provide evidence that choline-related improvements in cognitive functioning may be due to its positive impact on hippocampal synaptic physiology.

A Systematic Review of the Dietary Choline Impact on Cognition from a Psychobiological Approach: Insights from Animal Studies

The influence of dietary choline availability on cognition is currently being suggested by animal and human studies which have focused mainly on the early developmental stages. The aim of this review is to systematically search through the available rodent (rats and mice) research published during the last two decades that has assessed the effect of dietary choline interventions on cognition and related attentional and emotional processes for the entire life span. The review has been conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines covering peer-reviewed studies included in PubMed and Scopus databases. After excluding duplicates and applying the inclusion/exclusion criteria we have reviewed a total of 44 articles published in 25 journals with the contribution of 146 authors. The results are analyzed based on the timing and duration of the dietary intervention and the behavioral tests applied, amongst other variables. Overall, the available results provide compelling support for the relevance of dietary choline in cognition. The beneficial effects of choline supplementation is more evident in recognition rather than in spatial memory tasks when assessing nonpathological samples whilst these effects extend to other relational memory tasks in neuropathological models. However, the limited number of studies that have evaluated other cognitive functions suggest a wider range of potential effects. More research is needed to draw conclusions about the critical variables and the nature of the impact on specific cognitive processes. The results are discussed on the terms of the theoretical framework underlying the relationship between the brain systems and cognition.

Lifelong choline supplementation ameliorates Alzheimer's disease pathology and associated cognitive deficits by attenuating microglia activation

Currently, there are no effective therapies to ameliorate the pathological progression of Alzheimer's disease (AD). Evidence suggests that environmental factors may contribute to AD. Notably, dietary nutrients are suggested to play a key role in mediating mechanisms associated with brain function. Choline is a B-like vitamin nutrient found in common foods that is important in various cell functions. It serves as a methyl donor and as a precursor for production of cell membranes. Choline is also the precursor for acetylcholine, a neurotransmitter which activates the alpha7 nicotinic acetylcholine receptor (α7nAchR), and also acts as an agonist for the Sigma-1 R (σ1R). These receptors regulate CNS immune response, and their dysregulation contributes to AD pathogenesis. Here, we tested whether dietary choline supplementation throughout life reduces AD-like pathology and rescues memory deficits in the APP/PS1 mouse model of AD. We exposed female APP/PS1 and NonTg mice to either a control choline (1.1 g/kg choline chloride) or a choline-supplemented diet (5.0 g/kg choline chloride) from 2.5 to 10 months of age. Mice were tested in the Morris water maze to assess spatial memory followed by neuropathological evaluation. Lifelong choline supplementation significantly reduced amyloid-β plaque load and improved spatial memory in APP/PS1 mice. Mechanistically, these changes were linked to a decrease of the amyloidogenic processing of APP, reductions in disease-associated microglial activation, and a downregulation of the α7nAch and σ1 receptors. Our results demonstrate that lifelong choline supplementation produces profound benefits and suggest that simply modifying diet throughout life may reduce AD pathology.

Choline Supplementation in Cystic Fibrosis-The Metabolic and Clinical Impact

Background: Choline is essential for the synthesis of liver phosphatidylcholine (PC), parenchymal maintenance, bile formation, and lipoprotein assembly to secrete triglycerides. In choline deficiency, the liver accretes choline/PC at the expense of lung tissue, thereby impairing pulmonary PC homoeostasis. In cystic fibrosis (CF), exocrine pancreas insufficiency results in impaired cleavage of bile PC and subsequent fecal choline loss. In these patients, the plasma choline concentration is low and correlates with lung function. We therefore investigated the effect of choline supplementation on plasma choline/PC concentration and metabolism, lung function, and liver fat. Methods: 10 adult male CF patients were recruited (11/2014–1/2016), and orally supplemented with 3 × 1 g choline chloride for 84 (84–91) days. Pre-/post-supplementation, patients were spiked with 3.6 mg/kg [methyl-D₉]choline chloride to assess choline/PC metabolism. Mass spectrometry, spirometry, and hepatic nuclear resonance spectrometry served for analysis. Results: Supplementation increased plasma choline from 4.8 (4.1–6.2) µmol/L to 10.5 (8.5–15.5) µmol/L at d84 (p < 0.01). Whereas plasma PC concentration remained unchanged, D₉-labeled PC was decreased (12.2 [10.5–18.3] µmol/L vs. 17.7 [15.5–22.4] µmol/L, p < 0.01), indicating D₉-tracer dilution due to higher choline pools. Supplementation increased Forced Expiratory Volume in 1 second percent of predicted (ppFEV1) from 70.0 (50.9–74.8)% to 78.3 (60.1–83.9)% (p < 0.05), and decreased liver fat from 1.58 (0.37–8.82)% to 0.84 (0.56–1.17)% (p < 0.01). Plasma choline returned to baseline concentration within 60 h. Conclusions: Choline supplementation normalized plasma choline concentration and increased choline-containing PC precursor pools in adult CF patients. Improved lung function and decreased liver fat suggest that in CF correcting choline deficiency is clinically important. Choline supplementation of CF patients should be further investigated in randomized, placebo-controlled trials.

Effects of Egg Consumption and Choline Supplementation on Plasma Choline and Trimethylamine-N-Oxide in a Young Population

Background: Plasma trimethylamine-N-oxide (TMAO) concentrations have been associated with cardiovascular disease risk. Eggs are a rich source of choline, which is a precursor of TMAO.Objective: The effects of egg intake versus daily choline supplementation were evaluated on plasma choline and TMAO in a young, healthy population.Methods: Thirty participants (14 males, 16 females; 25.6 ± 2.3 years; body mass index = 24.3 ± 2.9 kg/m²) were enrolled in this 13-week crossover intervention. After a 2-week washout, participants were randomized to consume either 3 eggs/d or a choline bitartrate supplement (∼ 400 mg choline total in eggs or supplement) for 4 weeks. Following a 3-week washout, participants were switched to the alternate treatment. Dietary records were measured at the end of each period. Plasma TMAO and choline were measured at baseline and at the end of each dietary intervention. Gene expression of scavenger receptors associated with plasma TMAO were quantified at the end of each intervention.Results: Compared to the choline supplement, intake of total fat, cholesterol, selenium, and vitamin E were higher (p < 0.05), whereas carbohydrate intake was lower (p < 0.001) with consumption of 3 eggs/d. Fasting plasma choline increased 20% (p = 0.023) with egg intake, while no changes were observed with choline supplementation. Plasma TMAO levels were not different between dietary treatments or compared to baseline.Conclusions: Dietary choline appears to be more bioavailable via egg consumption when compared to a choline supplement. Plasma TMAO concentrations were not affected in healthy participants after 4 weeks of taking ∼400 mg/d choline either via eggs or choline supplementation.

CA1 pyramidal neuron gene expression mosaics in the Ts65Dn murine model of Down syndrome and Alzheimer's disease following maternal choline supplementation

Although there are changes in gene expression and alterations in neuronal density and afferent inputs in the forebrain of trisomic mouse models of Down syndrome (DS) and Alzheimer's disease (AD), there is a lack of systematic assessments of gene expression and encoded proteins within individual vulnerable cell populations, precluding translational investigations at the molecular and cellular level. Further, no effective treatment exists to combat intellectual disability and basal forebrain cholinergic neurodegeneration seen in DS. To further our understanding of gene expression changes before and following cholinergic degeneration in a well-established mouse model of DS/AD, the Ts65Dn mouse, we assessed RNA expression levels from CA1 pyramidal neurons at two adult ages (∼6 months of age and ∼11 months of age) in both Ts65Dn and their normal disomic (2N) littermates. We further examined a therapeutic intervention, maternal choline supplementation (MCS), which has been previously shown to lessen dysfunction in spatial cognition and attention, and have protective effects on the survival of basal forebrain cholinergic neurons in the Ts65Dn mouse model. Results indicate that MCS normalized expression of several genes in key gene ontology categories, including synaptic plasticity, calcium signaling, and AD-associated neurodegeneration related to amyloid-beta peptide (Aβ) clearance. Specifically, normalized expression levels were found for endothelin converting enzyme-2 (Ece2), insulin degrading enzyme (Ide), Dyrk1a, and calcium/calmodulin-dependent protein kinase II (Camk2a), among other relevant genes. Single population expression profiling of vulnerable CA1 pyramidal neurons indicates that MCS is a viable therapeutic for long-term reprogramming of key transcripts involved in neuronal signaling that are dysregulated in the trisomic mouse brain which have translational potential for DS and AD.

Prenatal Choline Supplementation Diminishes Early-Life Iron Deficiency-Induced Reprogramming of Molecular Networks Associated with Behavioral Abnormalities in the Adult Rat Hippocampus

BACKGROUND

Early-life iron deficiency is a common nutrient deficiency worldwide. Maternal iron deficiency increases the risk of schizophrenia and autism in the offspring. Postnatal iron deficiency in young children results in cognitive and socioemotional abnormalities in adulthood despite iron treatment. The rat model of diet-induced fetal-neonatal iron deficiency recapitulates the observed neurobehavioral deficits.

OBJECTIVES

We sought to establish molecular underpinnings for the persistent psychopathologic effects of early-life iron deficiency by determining whether it permanently reprograms the hippocampal transcriptome. We also assessed the effects of maternal dietary choline supplementation on the offspring's hippocampal transcriptome to identify pathways through which choline mitigates the emergence of long-term cognitive deficits.

METHODS

Male rat pups were made iron deficient (ID) by providing pregnant and nursing dams an ID diet (4 g Fe/kg) from gestational day (G) 2 through postnatal day (PND) 7 and an iron-sufficient (IS) diet (200 g Fe/kg) thereafter. Control pups were provided IS diet throughout. Choline (5 g/kg) was given to half the pregnant dams in each group from G11 to G18. PND65 hippocampal transcriptomes were assayed by next generation sequencing (NGS) and analyzed with the use of knowledge-based Ingenuity Pathway Analysis. Real-time polymerase chain reaction was performed to validate a subset of altered genes.

RESULTS

Formerly ID rats had altered hippocampal expression of 619 from >10,000 gene loci sequenced by NGS, many of which map onto molecular networks implicated in psychological disorders, including anxiety, autism, and schizophrenia. There were significant interactions between iron status and prenatal choline treatment in influencing gene expression. Choline supplementation reduced the effects of iron deficiency, including those on gene networks associated with autism and schizophrenia.

CONCLUSIONS

Fetal-neonatal iron deficiency reprograms molecular networks associated with the pathogenesis of neurologic and psychological disorders in adult rats. The positive response to prenatal choline represents a potential adjunctive therapeutic supplement to the high-risk group.