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Importance of Choline as Essential Nutrient and Its Role in Prevention of Various Toxicities


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Choline is a water-soluble essential nutrient included as a member of the vitamin B12 group owing to its structural similarities with that of the other members of the group. Its roles and functions, however, extend much wider than that of the vitamins with which it is grouped. Choline is vital for maintenance of various key metabolic processes which play a role in the prevention or progression of various health impairments. The occurrence of diseases like neural tube defect (NTD) and Alzheimer's is prevented by the metabolic role of choline. It is also indispensable for mitigation of various forms of toxic contamination. While adequate level of choline in the body is essential, an excess of choline can result in various forms of disorder. To maintain the optimal level of choline in the body can be a challenge. The vital roles played by choline together with the range of contradictions and problems that choline presents make choline an interesting area of study. This paper attempts to summarize and review some recent publications on choline that have opened up new prospect in understanding the multiple role played by choline and in throwing light on the role played by this wonder essential nutrient in mitigating various forms of toxic contamination.
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Choline and Its Role against Toxicities
Prague Medical Report / Vol. 116 (2015) No. 1, p. 515
Importance of Choline as Essential
Nutrient and Its Role in Prevention
of Various Toxicities
Somava Biswas, Sarbani Giri
Department of Life Science and Bioinformatics, Assam University, Silchar, India
Received November 2, 201 4; Accepted March 1 2, 201 5.
Key words: Choline – DNA repair – Fetotoxicity – Neurotoxicity – Neural tube
defect – Antioxidant
Abstract: Choline is a water-soluble essential nutrient included as a member of
the vitamin B12 group owing to its structural similarities with that of the other
members of the group. Its roles and functions, however, extend much wider than
that of the vitamins with which it is grouped. Choline is vital for maintenance of
various key metabolic processes which play a role in the prevention or progression
of various health impairments. The occurrence of diseases like neural tube defect
(NTD) and Alzheimer’s is prevented by the metabolic role of choline. It is also
indispensable for mitigation of various forms of toxic contamination. While
adequate level of choline in the body is essential, an excess of choline can result
in various forms of disorder. To maintain the optimal level of choline in the body
can be a challenge. The vital roles played by choline together with the range of
contradictions and problems that choline presents make choline an interesting area
of study. This paper attempts to summarize and review some recent publications
on choline that have opened up new prospect in understanding the multiple role
played by choline and in throwing light on the role played by this wonder essential
nutrient in mitigating various forms of toxic contamination.
© Charles University in Prague – Karolinum Press, 2015
Mailing Address: Prof. Sarbani Giri, Department of Life Science and Bio-
informatics, Assam University, Silchar-788011, India; e-mail:
Biswas S.; Giri S.
Prague Medical Report / Vol. 116 (2015) No. 1, p. 515
Choline (trimethyl-beta-hydroxyethylammonium) (Figure 1) is a dietary component
that is crucial for normal functioning of all cells (Zeisel and Blusztajn, 1994). It
was discovered by Andreas Strecker in 1862, but was ofcially recognized as an
essential nutrient by the US Institute of Medicine’s Food and Nutrition Board
(Food and Nutrition Board, 1998). Choline is a quaternary ammonium compound
that lacks ester bond and contains three methyl groups which are a vital
requirement for an array of metabolic reactions.
Though choline has often been clubbed with vitamin B12 group, its functions
however, suggest that it is more than just another vitamin. Choline in the diet
is available as free choline or is bound as esters such as phosphocholine (Pho),
glycerophosphocholine (GPCho), sphingomyelin (SM) or phosphatidylcholine
(PtdCho). From these choline esters, choline is freed by pancreatic enzymes.
Dietary choline from a variety of choline containing foods is absorbed by the
intestine and uptake is mediated by choline transporters. The fate of choline is
conversion into PtdCho (also known as lecithin), which occurs in all nucleated
cells (Li and Vance, 2008). PtdCho is the predominant phospholipid (>50%)
in most mammalian membranes (Zeisel, 2006a). Choline is absorbed in small
intestine. Free choline enters the portal circulation and is mostly taken up by the
liver (Le Kim and Betzing, 1976). Lipid soluble PtdCho and SM enter via lymph
and bypass the liver. Therefore, different forms of choline could have different
bioavailability (Cheng et al., 1996). Betaine, a choline derivative, plays an important
role in donation of methyl groups to homocysteine to form the essential amino
acid methionine (Zeisel et al., 2003). Choline uptake by liver, kidney, mammary
gland, placenta and brain is of special importance. Choline and choline containing
compounds are crucial for normal sustenance of life. Choline or its metabolites
are important for the structural integrity of cell membranes, methyl-metabolism,
transmembrane signalling, lipid and cholesterol transport, metabolism and
cholinergic neurotransmission and therefore it is vital during critical periods in
brain development.
Choline was added to the list of essential nutrients only in recently. In 1998,
based on the contemporary research studies, the US Institute of Medicine’s Food
and Nutrition Board, recognized that for the maintenance of normal health,
Figure 1 – Chemical structure of choline.
Choline and Its Role against Toxicities
Prague Medical Report / Vol. 116 (2015) No. 1, p. 515
humans needed to obtain choline from the diet and issued guidelines for its
daily intake. Choline is found in a wide variety of foods, mainly in the form of
phosphatidylcholine, which is often called lecithin. Among the most concentrated
sources of dietary choline are egg yolk and offal, beef, nuts, leafy greens, legumes,
seed oils, grain germs, and dairy products (Shronts, 1997). However, choline can
also be synthesized de novo.
The liver is the primary site for endogenous synthesis of choline. The only
other source of choline apart from normal diet is from the de novo biosynthesis
of phosphatidylcholine (PtdCho). Phosphatidylethanolamine N-methyltransferase
(PEMT) activity catalyses the synthesis of PtdCho by the sequential methylation
of phosphatidylethanolamine (PtdEtn), using S-adenosylmethionine (AdoMet) as
a methyl donor and forms a new choline moiety (Blusztajn et al., 1985).
Several factors such as gender, menopausal status, pregnancy, lactation and
genetic mutation affect choline requirement of an individual and de novo synthesis
of choline alone fails to meet all human requirements for choline; as a result the
recommended adequate intake (AI) for choline has been set at 425 mg/day for
women, 450 mg/day for pregnant women, 550 mg/day for men and lactating women
as well (Food and Nutrition Board, 1998).
Choline requirement is diminished in premenopausal women because estrogen
induces PEMT (Resseguie et al., 2007), the gene in liver enabling endogenous
biosynthesis of choline moiety. But many women have single nucleotide
polymorphism (SNPs) in the PEMT gene that repeals estrogen-induction of
endogenous synthesis (Resseguie et al., 2011) and these women, therefore, require
dietary choline just as men do. Thus genetic variance can have effects on choline
requirement. Notably, the adequate intake of choline is increased for pregnant and
breastfeeding women to satisfy the needs of the fetus and the baby whose choline
is supplied via placenta and milk (Zeisel et al., 1986). Also, many of the foods that
have high choline content are also high in fats or cholesterol (e.g. eggs). As a result,
many people are decreasing their intake of these foods leading to a situation where
only a few people today adhere to a diet that meets the recommended choline
levels (Food and Nutrition Board, 1998; Jensen et al., 2007).
The reasons mentioned above have resulted in an increasing population with
a choline decient diet which ultimately impedes many normal physiological
processes as well as causes a diverse group of pathological processes. In most
mammals, prolonged (weeks to months) ingestion of a diet decient in choline
leads to consequences that include hepatic, renal, pancreatic, memory and growth
However, excess choline intake has detrimental effect in human too. Choline
doses that are of magnitude greater than estimated intake from food have been
associated with body odor, sweating, salivation, vomiting, gastrointestinal effects,
hypotension and hepatotoxicity in humans (LSRO/FASEB, 1981). These apparently
contradictory facts about choline, makes its maintenance in the body a challenge.
Biswas S.; Giri S.
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In view of the importance of choline as a nutrient it is of utmost importance
to review the protective action of choline against genotoxicity, neurotoxicity,
fetotoxicity and antioxidative potentials. This review summarizes some current
literature ndings on the effects of choline in mitigating various toxicity targeting
DNA and repair system, neurons, development and fetotoxicity.
Methodology of literature sources selection
The Tables in this review contain the summary of original research articles, case-
control and cohort or cross sectional studies published between 2003 and 2013.
A literature search was undertaken using Science Direct, PubMed and Google
using specic key words. Title and abstracts were read and inclusion/exclusion
being decided according to the key words which included choline along with
toxicity, genotoxicity, DNA, DNA damage, apoptosis, teratogenicity, maternal
health, fetal alcohol syndrome, pregnancy, antioxidant properties, neurotoxicity,
neural tube defect, neuroprotection. All the abstracts were read to decide on the
inclusion criteria. Studies were included based on the following parameters: i) if
the focus was on relevant outcomes i.e. role of choline in mitigating genotoxicity,
neurotoxicity, fetotoxicity and antioxidative potentials etc., ii) if the articles were
in English.
Studies were excluded if: i) only abstract was available, ii) primary emphasis were
on other one carbon nutrients like folate, vitamin B6, vitamin B12, methionine
and betaine, iii) focus laid on role of choline in methionine formation via folate
Choline: its role in DNA damage and repair
Choline deciency has been associated with DNA damage (Table 1). DNA
methylation is inuenced by choline that ultimately inuences genomic stability
(Loughery et al., 2011) by altering gene expression for critical genes involved
in DNA mismatch repair, resulting in increased mutation rates. Steven H. Zeisel
(2012) summarized that choline deciency increases leakage of reactive oxygen
species from mitochondria which is due to altered mitochondrial membrane
composition and enhanced fatty acid oxidation. Choline deciency impairs folate
metabolism since the metabolic pathways of these two have a closely knit pathway
of metabolism, resulting in decreased thymidylate synthesis and increased uracil
misincorporation into DNA, with strand breaks resulting during error-prone repair
Choline and neurotoxicity
A number of researches conducted since 1980s have proved that choline
accelerates the synthesis and release of acetylcholine in nerve cells, which is one of
the principal neurotransmitters (Haubrich et al., 1974; Cohen and Wurtman, 1975;
Choline and Its Role against Toxicities
Prague Medical Report / Vol. 116 (2015) No. 1, p. 515
Table 1 Some recent research publications showing choline deciency
association with DNA repair in various test systems
Sl. no. Test system Observed effects References
1. Rats Oxidative damage to DNA by formation of apurinic/
apyrimidinic sites and Ogg1-sensitive sites in DNA
build up due to choline deprivation.
Powell et al.
2. Human Choline deciency in humans is associated
with signicant damage to DNA and with apoptosis
in peripheral lymphocytes.
da Costa
et al. (2006)
3. Male Sprague-
Dawley rats
Choline is an important methyl donor and is involved
in more than 150 one-carbon transfer reactions
including DNA repair and DNA methylation.
et al. (2006)
4. In vivo (male
weaning Fisher
344 (F344) rats)
Choline deciency is correlated with the silencing
of several tumor suppressor genes responsible
for DNA repair.
Pogribny et al.
5. In ovo (chicken
DT40 model
Choline inuences histone methylation,
which in turn is important for the activation
of DNA damage response pathways that consist
of complex signalling networks that detect
and repair DNA damage before the cell divides.
et al. (2011)
Wecker, 1986; Zeisel, 2006a). From diminishing memory loss to preventing neural
tube defects, which are a group of congenital malformations, choline plays a crucial
role in combating neurotoxicity (Table 2). Though the etiology of Alzheimer’s
disease is unknown, postmortem studies of brain samples from Alzheimer’s disease
patients showed lower levels of acetylcholine (Nitsch et al., 1992). In a review,
Zeisel (2006b) observes that dietary intake of choline by a pregnant mother and
later by the infant directly inuences brain development and results in permanent
changes in brain function including memory enhancement and learning functions.
Experiments with animal models testify that choline supplementation during
neonatal period prevents memory decline due to age (Meck and Williams, 2003)
and decreases apoptosis rate in hippocampus of fetus whose mothers consumed
high choline diets (Craciunescu et al., 2003). In a review Ziesel and da Costa
(2009) highlights recent studies which show that choline supplementation during
critical periods of neonatal development can have long-term benecial effects on
memory. The mechanism whereby choline supplementation in mothers results in
a permanent change in memory of their offspring is not clear. It was assumed that
increased brain choline results in subsequent increase in acetylcholine release.
However, further investigations proved that choline supplementation to dams
results in signicantly greater accumulation of phosphocholine and betaine in fetal
brain as compared to fetuses without choline exposure (Garner et al., 1995).
Although there are sufcient data with animal models indicating that choline is a
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Table 2 Some recent articles showing choline deciency association
with neuronal development in various test systems
Sl. no. Test system Observed effects References
1. In vivo (mice
Improvement of the memory and cognitive
dysfunction in Alzheimer’s disease are observed
on choline acetyltransferase supplementation.
Fu et al.
2. Sprague-Dawley
albino rats
Choline supplementation during critical period of
fetal development alters brain morphology including
structure and function of hippocampal pyramidal
cells, larger soma size and increase in number
of primary and secondary dendritic branches.
Li et al.
3. Human female
(population based
case control study)
Decient maternal dietary intake of choline during
pregnancy in humans may lead to an increased risk
of having a baby with a neural tube defect.
Shaw et al.
4. Female Sprague-
Dawley rats
Sensory inhibition gets reduced with gestational
choline deciency.
et al. (2008)
5. In ovo (chick
Choline at low dose (25 µg/µl) protected against
sodium-arsenite induced NTDs in chick embryos by
reversed DNA hypomethylation and cell apoptosis.
Song et al.
6. Female rats Supplemental dietary choline, when received during
development, has anxiolytic effects and may inoculate
an individual against stress and psychological
disorders like depression.
Glenn et al.
necessary nutrient in reducing cognitive decline and it aids in brain hippocampal
development and that choline supplementation during pregnancy results in multiple
modications in the patterns of gene expression known to inuence learning and
memory, yet there are insufcient human studies to conrm the same (Mellott et
al., 2007). Also, several studies hypothesize that choline may play the protective role
against neural tube defects (NTDS) by contributing methyl groups through betaine
and lowering homocysteine concentration.
Choline and teratogenicity/fetotoxicity
Maternal nutrition is important for normal human development and in particular
the supply of methyl groups is vital at all stages from conception to early infancy.
Adequate maternal choline intake is vital to a healthy pregnancy. A number of
studies have demonstrated the protective role of maternal choline supplementation
(Table 3). Maternal choline intake is critical not only for proper fetal brain
development, but also for maintaining normal maternal homocysteine levels.
Elevated maternal homocysteine has been associated with an increased incidence
of birth defects, such as neural tube defect, spontaneous abortions and low birth
weight babies.
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Table 3 – Some research articles showing association of choline
with developmental disorder mitigation in various test systems
Sl. no. Test system/
Observed effects References
1. Population based
control study
in human
Periconceptional intake of choline may contribute
to reduced risk of orofacial clefts.
Shaw et al.
2. Sprague-Dawley
Choline availability during pregnancy has an enduring
impact on hippocampal neurogenesis of the offspring
i.e. prenatally choline supplemented animals showed
increased adult neurogenesis.
Glenn et al.
3. Mouse models Prenatal or postnatal choline supplementation
attenuates the motor coordination decits
and improves neuronal integrity, proliferation
and survival in Rett syndrome.
Nag et al.
(2008), Ward
et al. (2009)
4. In vivo (Sprague-
Dawley rats)
Nutritional supplementation with choline in rats
exposed to ethanol in utero almost completely
mitigates the degenerative effects of ethanol on
development and behavior. Further, the therapeutic
window of choline, being quite large, can effectively
attenuate ethanol’s teratogenic effects whether
administered during prenatal ethanol exposure
or after the alcohol insult is complete.
Thomas et al.
(2009, 2010)
5. Human Supplementation of choline to mothers may mitigate
the effects of the alcohol and reduce the severity
or prevalence of FAS.
Ballard et al.
Choline as antioxidant
An undisturbed choline transport and distribution throughout the body essentially
plays a vital role in multiple clinical manifestations. The methyl donation function of
choline is of major importance in maintaining balanced cellular antioxidant defence
systems thereby checking oxidative stress and apoptosis (Table 4). A recent review
(Corbin and Zeisel, 2012) sites a battery of works which attempts to establish the
intricate connection between choline deciency and development of non-alcoholic
fatty liver disease (NAFLD) which may ultimately progress to hepatocarcinogenesis.
Studies in human as well as in mouse, conrm that a deletion of choline-related
genes, alteration of mitochondrial membrane composition owing to choline
deciency, chronic endoplasmic reticulum stress, levels of gut microbiome
modulating the availability of choline may enhance the fatty liver disease.
Discussion and Conclusion
The recognition to choline as an essential nutrient is not a new concept. In the
past choline has been recognized as an essential nutrient as being biologically
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Table 4 – List of some recent studies on antioxidative role of choline
Sl. no. Test system/
Observed effects References
1. Weanling Wistar
male rats
Choline deciency produces oxidative damage in the
liver, heart, kidney, and brain, with an increased lipid
peroxidation of subcellular organelles and a decrease
in tissue antioxidants.
Ossani et al.
2. Male Fisher
344 rats
Chronic methyl group deciency due to low levels
of dietary choline leads to an imbalance in cellular
antioxidant defence systems, increased oxidative
stress, and apoptosis.
et al. (2008)
3. Male Swiss
Folate deprivation and radiation interact to mobilize
additional choline reserves of hepatic tissue for
redistribution to other organs, which could not be
utilized by folate deciency alone and thereafter
trigger utilization of choline as substitute for selected
one-carbon transfer reactions.
Batra et al.
4. Weanling male
Wistar rats
Decreased antioxidant content and increased lipid
peroxidation are earlier biochemical alterations that
precede and lead to histological cell death by necrosis
in choline deciency.
Repetto et al.
5. Rodent model
(C57BL/6J wild-
type mice)
Adverse effects of choline deciency on hepatic
mitochondrial structure and function could be linked
to the unique signature of hepatic lipid accumulation,
inammation, and cellular and mitochondrial injury
induced in mice maintained on a very high fat,
protein-restricted, very low carbohydrate and
ketogenic diet.
Schugar et al.
important, without a complete understanding about the underlying reasons. The
earlier recognition was not backed up by studied evidence about its precise
functions in the various complex biological processes. But there is a vital difference
in the approach to the recognition following newer ndings. The recent studies
provide a clear insight into the molecular basis of various roles played by choline
and its metabolites, leading to better understanding about the functions of
these substances in health and disease development and control processes. This
understanding based on the recent ndings establishes choline as a vital component
of our diet requirement and opens up newer areas of knowledge, ways in which
many physiological conditions take place and the role played by choline in these
processes. The understanding offers a clue into the mechanisms associated with
diseases like Alzheimer’s, non-alcoholic fatty liver disease, fetal alcohol syndrome
and neural tube defects with the prospect to control, minimize and even to cure
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... Нарушения, вызванные дефицитом холина, особенно в первые 1000 дней, могут нанести необратимый ущерб метаболизму и развитию мозга [26]. Доказано, что холин проникает через гематоэнцефалический барьер за счет простой диффузии, хранится в структуре мембранных фосфолипидов головного мозга, которые метаболизируются по мере необходимости до холина и ацетилхолина [27]. Кроме того, холин тесно связан с витаминами группы В, и в некоторых научных трудах он называется витамином В4. ...
... Кроме того, холин тесно связан с витаминами группы В, и в некоторых научных трудах он называется витамином В4. Химически холин тесно связан с семейством витаминов группы В [27]. В исследованиях последних лет показано, что холин является предшественником метаболитов кишечных бактерий [28]. ...
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Choline, a substance essential for the existence of any organism, is the basis for the synthesis of phosphatidylcholine and sphingomyelin, the two main phospholipids of cell membranes. Acetylcholine is the main neurotransmitter of the parasympathetic nervous system, i.e. part of the autonomic nervous system. It affects smooth muscles, vascular wall tone, heart rate and regulates metabolism as a source of methyl groups. Choline enters the body through food and is partially synthesized endogenously. Choline plays an important role in gene expression, cell membrane signalling, lipid transport and metabolism, and early infant brain development. Choline deficiency increases the risk of cardiovascular and metabolic disorders. Current scientific evidence suggests a negative effect of choline deficiency on the development of non-alcoholic fatty liver disease. Choline deficiency is associated with impaired memory, concentration, and cognitive functions. This article deals with the mechanisms of choline influence on the organism and possibility of choline deficiency correction in the organism.
... The AChE inhibition observed in acetone and methanol extracts of C. minutissima may be due to the presence of specific bioactive metabolites such as choline, benzothiazole, fatty acid amide (erucamide), and reserpine (alkaloid). In detail, choline is a member of vitamin B 12 that serves as an essential nutrient [66]. The supplementation of choline tends to accelerate the synthesis of acetylcholine neurotransmitter in nerve cells which prevent memory loss due to age as observed in the case of Alzheimer's disease [66,67]. ...
... In detail, choline is a member of vitamin B 12 that serves as an essential nutrient [66]. The supplementation of choline tends to accelerate the synthesis of acetylcholine neurotransmitter in nerve cells which prevent memory loss due to age as observed in the case of Alzheimer's disease [66,67]. Also, choline balances the antioxidant defense system in the cells by donating the methyl group during the oxidative stress condition [68]. ...
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In this study, Chlorella minutissima was evaluated for its nutritional properties and antioxidant potential in macromolecular and food model systems. Additionally, the evaluation of α-glucosidase and acetylcholinesterase enzyme inhibition targeting diabetes and Alzheimer’s disease was done, respectively. Dry biomass of C. minutissima recorded total carbohydrate, lipid, and protein content of 16.10%, 11.56%, and 27.83%, respectively. Also, it is a better source for sodium, iron, and zinc as 2249.06, 601.18, and 198.49 µg g⁻¹, respectively. Acetone extract of C. minutissima exhibited significantly higher antioxidant activities under in vitro conditions and was found to protect DNA and protein from oxidative damage between 0.078 and 10 mg mL⁻¹ concentration. Besides, it effectively reduced the oxidation of β-carotene and meat to 79.75% at 200 ppm and 97.97% at 300 ppm concentrations, respectively. Metabolomic analysis of C. minutissima extracts revealed the presence of metabolites whose function supports our findings. Also, they were reported for their broad biological activities. Graphical abstract
... Lack of these nutrients in the diet causes a disturbance in the metabolic functions such as lipid absorption, β-oxidation and lipoprotein synthesis that leads to excessive fat accumulation in the liver (Zeisel and Da Costa, 2009). More specifically, choline, a vitamin like water-soluble micronutrient and a lipotropic agent, plays a preventive role by enabling the fat utilization and transportation from the hepatic to the extrahepatic tissues (Biswas and Giri, 2015). It was reported that a diet with low choline content causes fatty liver syndrome due to low availability of carrier lipoproteins (Fon Tacer and Rozman, 2011), growth retardation and perosis in fast-growing broiler strains. ...
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This study was conducted to evaluate the effect of polyherbal (phytogenic) formulation (PHF: containing Acacia nilotica and Curcuma longa) on performance parameters, liver histopathology and prevention of fatty liver in broilers. 700 day-old chicks were randomly distributed to seven groups (10 replicates / group; 10 birds each), namely positive control (T1) fed with basal diet + choline chloride (CCL) 60% (1000g), negative control (T2) fed with high energy (5% increment), low protein (24% reduction), high cholesterol (2% increment) diet, T3 (T2 + PHF; 1000g-full cycle), T4 (T2 + PHF; 2000g-full cycle), T5 (T2 + CCL 60% (1000g-full cycle)), T6 (T5 + PHF; 1000g-grower and finisher stage), T7 (T5 + PHF; 2000g-finisher stage). Average daily gain (ADG; g), average daily feed intake (ADFI; g) and feed conversion ratio (FCR) were calculated at 1-14 days, 15-28 days, 29-42 days, and 1-42 days. Serum triglycerides analysis, gross and histopathological observations of liver morphology were performed for the samples of control and experimental groups on day 42. The performance parameters; ADG, ADFI, FCR, and liveability were found to be improved in all the groups as compared to the negative control group. However, better performance was observed in PHF (2000g) top-up group (during the finisher stage) as compared to the negative control group. Serum triglyceride levels were increased non-significantly as compared to the negative control indicating that more fat is mobilized from liver to serum. In addition, PHF supplementation at 2000g during the finisher phase had restored the liver tissue architecture as well as improved the liver score when compared to the negative control group. It is concluded that PHF (2000g/ton) during the finisher stage can be used as a top-up to improve the performance parameters as well as to prevent the fatty liver condition in broiler chickens.
... Choline is involved protection against salt stress in halophytes [69] and other plants, such as spinach [70], because this compound is a precursor of glycine-betaine, which has been related to heavy metal tolerance in plants [71]. Choline is considered a very necessary but often forgotten essential nutrient [72], needed for the proper function of skeletal muscle and to prevent neurological diseases [73,74]. On the other hand, chlorogenic acid did not show increased levels upon inoculation, but was enhanced by the presence of metals ( Figure 3D). ...
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Plant-growth-promoting bacteria (PGPB) help plants thrive in polluted environments and increase crops yield using fewer inputs. Therefore, the design of tailored biofertilizers is of the utmost importance. The purpose of this work was to test two different bacterial synthetic communities (SynComs) from the microbiome of Mesembryanthemum crystallinum, a moderate halophyte with cosmetic, pharmaceutical, and nutraceutical applications. The SynComs were composed of specific metal-resistant plant-growth-promoting rhizobacteria and endophytes. In addition, the possibility of modulating the accumulation of nutraceutical substances by the synergetic effect of metal stress and inoculation with selected bacteria was tested. One of the SynComs was isolated on standard tryptone soy agar (TSA), whereas the other was isolated following a culturomics approach. For that, a culture medium based on M. crystallinum biomass, called Mesem Agar (MA), was elaborated. Bacteria of three compartments (rhizosphere soil, root endophytes, and shoot endophytes) were isolated on standard TSA and MA media, stablishing two independent collections. All bacteria were tested for PGP properties, secreted enzymatic activities, and resistance towards As, Cd, Cu, and Zn. The three best bacteria from each collection were selected in order to produce two different consortiums (denominated TSA- and MA-SynComs, respectively), whose effect on plant growth and physiology, metal accumulation, and metabolomics was evaluated. Both SynComs, particularly MA, improved plant growth and physiological parameters under stress by a mixture of As, Cd, Cu, and Zn. Regarding metal accumulation, the concentrations of all metals/metalloids in plant tissues were below the threshold for plant metal toxicity, indicating that this plant is able to thrive in polluted soils when assisted by metal/metalloid-resistant SynComs and could be safely used for pharmaceutical purposes. Initial metabolomics analyses depict changes in plant metabolome upon exposure to metal stress and inoculation, suggesting the possibility of modulating the concentration of high-value metabolites. In addition, the usefulness of both SynComs was tested in a crop plant, namely Medicago sativa (alfalfa). The results demonstrate the effectiveness of these biofertilizers in alfalfa, improving plant growth, physiology, and metal accumulation.
... Our body can take choline from various foods, such as phosphatidylcholine or lecithin. The uptake of choline by the brain, kidneys, placenta, liver and mammary glands is vital to sustain life (Zeisel and da Costa, 2009;Biswas and Giri, 2015). Our study reported the pharmacologically significant compounds mentioned above in this V. mengtzeanum species from both the above and underground parts. ...
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Veratrum mengtzeanum is the main ingredient for Chinese folk medicine known as “Pimacao” due to its unique alkaloids. A diverse class of plant-specific metabolites having key pharmacological activities. There are limited studies on alkaloid synthesis and its metabolic pathways in plants. To elucidate the alkaloid pathway and identify novel biosynthetic enzymes and compounds in V. mengtzeanum, transcriptome and metabolome profiling has been conducted in leaves and roots. The transcriptome of V. mengtzeanum leaves and roots yielded 190,161 unigenes, of which 33,942 genes expressed differentially (DEGs) in both tissues. Three enriched regulatory pathways (isoquinoline alkaloid biosynthesis, indole alkaloid biosynthesis and tropane, piperidine and pyridine alkaloid biosynthesis) and a considerable number of genes such as AED3-like, A4U43, 21 kDa protein-like, 3-O-glycotransferase 2-like, AtDIR19, MST4, CASP-like protein 1D1 were discovered in association with the biosynthesis of alkaloids in leaves and roots. Some transcription factor families, i.e., AP2/ERF, GRAS, NAC, bHLH, MYB-related, C3H, FARI, WRKY, HB-HD-ZIP, C2H2, and bZIP were also found to have a prominent role in regulating the synthesis of alkaloids and steroidal alkaloids in the leaves and roots of V. mengtzeanum. The metabolome analysis revealed 74 significantly accumulated metabolites, with 55 differentially accumulated in leaves compared to root tissues. Out of 74 metabolites, 18 alkaloids were highly accumulated in the roots. A novel alkaloid compound viz; 3-Vanilloylygadenine was discovered in root samples. Conjoint analysis of transcriptome and metabolome studies has also highlighted potential genes involved in regulation and transport of alkaloid compounds. Here, we have presented a comprehensive metabolic and transcriptome profiling of V. mengtzeanum tissues. In earlier reports, only the roots were reported as a rich source of alkaloid biosynthesis, but the current findings revealed both leaves and roots as significant manufacturing factories for alkaloid biosynthesis.
... Choline is an important ingredient or vitamin that regulates lipid metabolism and helps to maintain cell integrity. It is also a source of phosphatidylcholine and free methyl groups, both of which are necessary for optimal growth and the suppression of fat deposition (Biswas & Giri, 2015). ...
In the era of intensification of fish farms, the high‐fat diet (HFD) has been applied to promote growth and productivity, provide additional energy and substitute partial protein in fish feeds. Certainly, HFD within specific concentrations was found to be beneficial in boosting fish performance throughout a short‐term feeding. However, excessive dietary fat levels displayed vast undesirable impacts on growth, feed efficiency, liver function, antioxidant capacity and immune function and finally reduced the economic revenue of cultured fish. Moreover, studies have shown that fish diets containing a high level of fats resulted in increasing lipid accumulation, stimulated endoplasmic reticulum stress and suppressed autophagy in fish liver. Investigations showed that HFD could impair the intestinal barrier of fish via triggering inflammation, metabolic disorders, oxidative stress and microbiota imbalance. Several approaches have been widely used for reducing the undesirable influences of HFD in fish. Dietary manipulation could mitigate the adverse impacts triggered by HFD, and boost growth and productivity via reducing blood lipids profile, attenuating oxidative stress and hepatic lipid deposition and improving mitochondrial activity, immune function and antioxidant activity in fish. As well, dietary feed additives have been shown to decrease hepatic lipogenesis and modulate the inflammatory response in fish. Based on the literature, previous studies indicated that phytochemicals could reduce apoptosis and enhance the immunity of fish fed with HFD. Thus, the present review will explore the potential hazards of HFD on fish species. It will also provide light on the possibility of employing some safe feed additives to mitigate HFD risks in farmed fish.
... Vitamins are additives that have beneficial effects on the immune system by reducing oxidative stress, increasing the phagocytic and bactericidal activity, and improving the overall performance in bovine (Duff and Galyean, 2007). Associated with B vitamins, choline is a water-soluble nutrient extracted from plants that can be a used as a potential feed additive for growing animals (Zeisel and Costa, 2009;Hollenbeck, 2012;Biswas and Giri, 2015). ...
This experiment was conducted to determine the effect of earlier weaning in addition to biocholine supplementation on age at puberty of Brangus heifers. Brangus calves were randomized and divided into three weaning ages groups, at 30 (Hyper-early weaning; HW), 75 (Early weaning; EW) and 180 days (Conventional weaning; CW). Then, calves were supplemented using the additive Biocholine (BIO) or not (CON). Animals were subjected to puberty induction and the presence of estrus was observed for 7 days. In addition, transrectal ultrasonography was performed to assess the ovarian activity and the presence of corpus luteum to determine heifer puberty. We also evaluated the body weight (BW; Kg), hip height (HH; cm), thoracic perimeter (TP; cm) and BW:HH ratio during the experimental period. BIO group showed higher ADG (>226 g/day) when the animals were exposed to ryegrass pasture compared to CON (P < 0.05). We observed an interaction between weaning x biocholine and CW-BIO heifers showed greater HH more compared to CW-CON (P < 0.05). Overall, animals that have reached puberty at day 8 after puberty induction showed 331.0 ± 5.04 kg BW, 122.0 ± 0.56 cm HH and 165.4 ± 0.75 cm TP and 2.7 ± 0.03 BW:HH. At the time of ovulation detection, the heifers from the HW group had 32.1 kg BW, 3.93 cm HH and 0.18 cm BW:HH greater compared to CW (P < 0.05). The BIO supplementation together with ryegrass pasture, led to an increase in ADG weight throughout the evaluated period. We concluded that HW heifers showed an adequate body development throughout the experimental period until puberty appearance at the same age as others weaned groups.
Conference Paper
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Con la finalidad de determinar afecciones que ocasionan muertes de bovinos en un sistema intensivo y asociarlas con el ITH, se agruparon los decesos de acuerdo con el sistema/aparato afectado del animal en una unidad de producción pecuaria (UPP) especializada en confinamiento localizada en la zona centro del estado de Veracruz, México. Además se obtuvieron registros climatológicos de una estación climática cercana al sitio de estudio para determinar los meses, estaciones y épocas con variabilidad climática (VC) y grados de ITH. Se obtuvieron tablas de frecuencia, analizadas con Xi2 para encontrar diferencias (p<0.05) entre grupos de afecciones, estaciones, épocas y meses con mayor ITH. Se reportan dos épocas del año diferentes (p<0.05), que fueron Sequia (noviembre-mayo) Lluvia (junio-octubre), meses con mayores ITH, marzo-noviembre (p<0.05). Se clasificaron N=2118 decesos diagnosticados por necropsia en: respiratorio (n=822, 38.81%), digestivo (n=491, 23.18%), locomotor (n=97, 4.58%), circulatorio (n=83, 3.92%), nervioso (n=47, 2.22%), urogenital (n=24, 1.13%), otras (n=554, 26.16%). La época y la estación muestran diferencias (p<0.05) en dos grupos de afecciones: digestivo y respiratorio para sequía vs lluvia. El ITH elevado se asocia (p<0.05) con dos grupos de afecciones: digestivo y respiratorio. La estación, la época del ÁREA VI 734 año y el ITH elevado se asocian con decesos relacionados con el aparato digestivo y respiratorio en la engorda de bovinos en confinamiento
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The Sistemas Agroforestales (AFS) have gained significant importance as a sustainable agricultural model. The implementation of biodiverse FFS can be a relevant tool in the development of public policies to promote environmental sustainability and ensure food sovereignty in family farming and traditional peoples. The present study aimed to evaluate soil chemical properties in three biodiverse FFS. The study was conducted at the IF Baiano Campus Valença, Bahia-Brazil. Soil samples were taken at depths of 0-10 cm, 10-20 cm, and 20-40 cm in the three areas. The soil was classified as Red-Yellow Latosol (Santos, 2018), of clayey texture. Soil samples were airdried, passed through a 2 mm mesh sieve, and analyzed for pH H2O; P and K (extractable by Mehlich-1), Ca, Mg and Al (exchangeable by KCl 1 mol L-1), and CTC and base saturation were calculated. The results of the soil chemical analysis indicated that soil management with the use of leveled ditches and legumes as soil improvers may have influenced the increased availability of nutrients, particularly P and K for PBS 2 and 3.
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BACKGROUND: Approximately, 6-31% of nutritional deficits are present before the stroke and worsen during hospitalization. Besides affecting the patient’s physical and mental abilities, stroke can also cause a decrease in nutritional status, which has a major influence on the rate of death and disability. One intervention to overcome stroke patients’ nutritional problems is giving oral nutritional supplementation. The role of oral nutritional supplementation in stroke severity in patients with acute ischemic stroke has not yet been extensively studied. AIM: This study aimed to evaluate the effect of oral nutritional supplementation on the National Institute of Health Stroke Scale (NIHSS) in patients with acute ischemic stroke. METHODS: This was an experimental study with a pre- and post-study group method. Twenty-eight patients with acute ischemic stroke were referred to Adam Malik General Hospital, Medan, Indonesia, and were allocated randomly into two groups. Fourteen patients as control group received the normal hospital diet and 14 patients as intervention group received normal hospital diet plus oral nutritional supplementation for 7 days. The NIHSS scores were assessed on the first day and the eighth day after intervention in each group. RESULTS: There were significant reductions in NIHSS scores between day 1 and day 8 in both groups (p < 0.001). The mean delta NIHSS scores were −2.28 ± 1.63 and −2.57 ± 1.98 in the intervention and control groups, respectively. There was no significant difference in NIHSS scores between the intervention and control groups (p = 0.682). CONCLUSION: The effect of oral nutritional supplementation significantly reduced the NIHSS scores in acute ischemic stroke, but there was no significant difference compared to the normal hospital diet.
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Though widely employed for clinical intervention in obesity, metabolic syndrome, seizure disorders and other neurodegenerative diseases, the mechanisms through which low carbohydrate ketogenic diets exert their ameliorative effects still remain to be elucidated. Rodent models have been used to identify the metabolic and physiologic alterations provoked by ketogenic diets. A commonly used rodent ketogenic diet (Bio-Serv F3666) that is very high in fat (~94% kcal), very low in carbohydrate (~1% kcal), low in protein (~5% kcal), and choline restricted (~300 mg/kg) provokes robust ketosis and weight loss in mice, but through unknown mechanisms, also causes significant hepatic steatosis, inflammation, and cellular injury. To understand the independent and synergistic roles of protein restriction and choline deficiency on the pleiotropic effects of rodent ketogenic diets, we studied four custom diets that differ only in protein (5% kcal vs. 10% kcal) and choline contents (300 mg/kg vs. 5 g/kg). C57BL/6J mice maintained on the two 5% kcal protein diets induced the most significant ketoses, which was only partially diminished by choline replacement. Choline restriction in the setting of 10% kcal protein also caused moderate ketosis and hepatic fat accumulation, which were again attenuated when choline was replete. Key effects of the 5% kcal protein diet - weight loss, hepatic fat accumulation, and mitochondrial ultrastructural disarray and bioenergetic dysfunction - were mitigated by choline repletion. These studies indicate that synergistic effects of protein restriction and choline deficiency influence integrated metabolism and hepatic pathology in mice when nutritional fat content is very high, and support the consideration of dietary choline content in ketogenic diet studies in rodents to limit hepatic mitochondrial dysfunction and fat accumulation.
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DNA methyltransferase 1 (DNMT1) maintains methylation at CpG dinucleotides, important for transcriptional silencing at many loci. It is also implicated in stabilizing repeat sequences: DNMT1 deficiency causes microsatellite instability in mouse embryonic stem cells, but it is unclear how this occurs, how repeats lacking CpG become unstable and whether the effect is confined to stem cells. To address these questions, we transfected hTERT-immortalized normal human fibroblasts (hTERT-1604) with a short hairpin RNA construct targeting DNMT1 and isolated stable integrants with different levels of protein. DNMT1 expression levels agreed well with methylation levels at imprinted genes. Knockdown cells showed two key characteristics of mismatch repair (MMR) deficiency, namely resistance to the drug 6-thioguanine and up to 10-fold elevated mutation rates at a CA(17) microsatellite reporter, but had limited viability. The likely cause of MMR defects is a matching drop in steady-state protein levels for key repair components in DNMT1 knockdown cells, affecting both the MutLα and MutSα complexes. This indirect effect on MMR proteins was also seen using a different targeting method in HT29 colon cancer cells and did not involve transcriptional silencing of the respective genes. Decreased levels of MMR components follow activation of the DNA damage response and blocking this response, and in particular poly(ADP-ribose) polymerase (PARP) overactivation, rescues cell viability in DNMT1-depleted cells. These results offer an explanation for how and why unmethylated microsatellite repeats can be destabilized in cells with decreased DNMT1 levels and uncover a novel and important role for PARP in this process.
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Dot1L, a histone methyltransferase that targets histone H3 lysine 79 (H3K79), has been implicated in gene regulation and the DNA damage response although its functions in these processes remain poorly defined. Using the chicken DT40 model system, we generated cells in which the Dot1L gene is disrupted to examine the function and focal recruitment of the 53Bp1 DNA damage response protein. Detailed kinetic and dose response assays demonstrate that, despite the absence of H3K79 methylation demonstrated by mass spectrometry, 53Bp1 focal recruitment is not compromised in these cells. We also describe, for the first time, the phenotypes of a cell line lacking both Dot1L and 53Bp1. Dot1L⁻/⁻ and wild type cells are equally resistant to ionising radiation, whereas 53Bp1⁻/⁻/Dot1L⁻/⁻ cells display a striking DNA damage resistance phenotype. Dot1L and 53Bp1 also affect the expression of many genes. Loss of Dot1L activity dramatically alters the mRNA levels of over 1200 genes involved in diverse biological functions. These results, combined with the previously reported list of differentially expressed genes in mouse ES cells knocked down for Dot1L, demonstrates surprising cell type and species conservation of Dot1L-dependent gene expression. In 53Bp1⁻/⁻ cells, over 300 genes, many with functions in immune responses and apoptosis, were differentially expressed. To date, this is the first global analysis of gene expression in a 53Bp1-deficient cell line. Taken together, our results uncover a negative role for Dot1L and H3K79 methylation in the DNA damage response in the absence of 53Bp1. They also enlighten the roles of Dot1L and 53Bp1 in gene expression and the control of DNA double-strand repair pathways in the context of chromatin.
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When dietary choline is restricted, most men and postmenopausal women develop multiorgan dysfunction marked by hepatic steatosis (choline deficiency syndrome (CDS)). However, a significant subset of premenopausal women is protected from CDS. Because hepatic PEMT (phosphatidylethanolamine N-methyltransferase) catalyzes de novo biosynthesis of choline and this gene is under estrogenic control, we hypothesized that there are SNPs in PEMT that disrupt the hormonal regulation of PEMT and thereby put women at risk for CDS. In this study, we performed transcript-specific gene expression analysis, which revealed that estrogen regulates PEMT in an isoform-specific fashion. Locus-wide SNP analysis identified a risk-associated haplotype that was selectively associated with loss of hormonal activation. Chromatin immunoprecipitation, analyzed by locus-wide microarray studies, comprehensively identified regions of estrogen receptor binding in PEMT. The polymorphism (rs12325817) most highly linked with the development of CDS (p < 0.00006) was located within 1 kb of the critical estrogen response element. The risk allele failed to bind either the estrogen receptor or the pioneer factor FOXA1. These data demonstrate that allele-specific ablation of estrogen receptor-DNA interaction in the PEMT locus prevents hormone-inducible PEMT expression, conferring risk of CDS in women.
Previously, we had shown that human milk and infant formulas contained choline, phosphocholine (PCho), glycerophosphocholine (GPCho), and phosphatidylcholine (PtdCho). The relative bioavailability of these choline-containing compounds in milk has not previously been studied. Using a rat pup model, infant formula (S.M.A.TM, Wyeth-Ayerst) containing either [14C-methyl]-choline chloride (14C-Cho) [14C-methyl]-PCho, [14C-methyl]-GPCho), or [L-α-dipalmitoyl-14C-methyl]-PtdCho was fed intragastrically by a single intubation into 15-day-old postnatal rat pups. Label from the water-soluble metabolites of choline (choline, phosphocholine, and glycerophosphocholine) appeared rapidly within blood and liver, reaching peak levels within 1 to 5 hr, and label in brain continued to increase for more than 24 hr. Label from the lipid soluble metabolite, phosphatidylcholine, took much longer to appear in blood and liver (5 to 8 hr) and label remained elevated in blood for at least 24 hr. Label in brain continued to increase for more than 24 hr, but always remained lower than that attained after treatment with the labeled water-soluble choline metabolites. The liver is a major storage site for choline metabolites, and provides a sensitive indicator of dietary choline status. In liver, a large portion of the label derived from the water-soluble choline metabolites was in the form of betaine at 4 hr post dose. At the same time, most of the PtdCho-derived label was still present as PtdCho in liver. At 24 hr after dose, most of the label derived from choline and PCho in liver was present as betaine (85%) and PtdCho (15%), label derived from GPCho was found as betaine (54%), PtdCho (15%), PCho (11%), GPCho (2%), and choline (18%). Label derived from PtdCho was found as betaine (13%) PCho (2%), and PtdCho (85%). We conclude that 15-day-old postnatal rat pups can absorb the various choline compounds in milk. Choline and PCho appear to be essentially identical in their absorption and metabolic fate. GPCho and PtdCho have different rates of absorption and/or metabolism. Thus, we conclude that there are significant differences in bioavailability, tissue uptake and metabolism among the choline compounds that are present in milk.
Arsenic passes through the placenta and accumulates in the neuroepithelium of embryo, whereby inducing congenital malformations such as neural tube defects (NTDs) in animals. Choline (CHO), a methyl-rich nutrient, functions as a methyl donor to participate in methyl group metabolism. Arsenic methylation has been regarded as a detoxification process and choline (CHO) is the major source of methyl-groups. However, whether CHO intake reverses the abnormal embryo development induced by sodium arsenite (SA) and the relationship between CHO intake and arsenite-induced NTDs are still unclear. In this study, we used chick embryos as animal model to investigate the effects of SA and CHO supplementation on the early development of nervous system. Our results showed that the administration of SA led to reduction in embryo viability, embryo body weight and extraembryonic vascular area, accompanied by a significantly increased incidence of the failed closure of the caudal end of the neural tube. CHO, at low dose (25μg/μL), reversed the decrease in embryo viability and the increase in the failed closure of the caudal end of the neural tube, which were induced by SA. In addition, CHO (25μg/μL) inhibited not only the SA-induced cell apoptosis by up-regulating Bcl-2 level, but also the global DNA methylation by increasing the expressions of DNMT1 and DNMT3a. However, less significant difference was found between the embryos co-treated with SA and CHO (50μg/μL) and the ones treated with SA alone. Taken together, these findings suggest that low dose CHO could protect chick embryos from arsenite-induced NTDs by a possible mechanism related to the methyl metabolism.
Perinatal choline supplementation in rats is neuroprotective against insults such as fetal alcohol exposure, seizures, and advanced age. In the present study we explored whether dietary choline supplementation may also confer protection from psychological challenges, like stress, and act as a natural buffer against stress-linked psychological disorders, like depression. We previously found that choline supplementation increased adult hippocampal neurogenesis, a function compromised by stress, lowered in depression, and boosted by antidepressants; and increased levels of growth factors linked to depression, like brain-derived neurotrophic factor. Together, these were compelling reasons to study the role of choline in depressed mood. To do this, we treated rats with a choline supplemented diet (5 mg/kg choline chloride in AIN76A) prenatally on embryonic days 10-22, on postnatal days (PD) 25-50, or as adults from PD75 onward. Outside of these treatment periods rats were fed a standard diet (1.1 mg/kg choline chloride in AIN76A); control rats consumed only this diet throughout the study. Starting on PD100 rats' anxiety-like responses to an open field, learning in a water maze, and reactivity to forced swimming were assessed. Rats given choline supplementation during pre- or post-natal development, but not adult-treated rats, were less anxious in the open field and less immobile in the forced swim test than control rats. These effects were not mediated by a learning deficit as all groups performed comparably and well in the water maze. Thus, we offer compelling support for the hypothesis that supplemental dietary choline, at least when given during development, may inoculate an individual against stress and major psychological disorders, like depression.
It is recognized that alcohol consumption during pregnancy is associated with fetal alcohol syndrome (FAS). Alcohol can trigger a pattern of neurodegeneration in rat brains similar to other known gamma-aminobutyric acid (GABA) specific agonists. However this does not seem to explain FAS entirely, as impoverished care-giving environments have been shown to increase the risk of FAS. Individuals living under the poverty level are at risk for micronutrient deficiencies due to insufficient intake. In particular, three nutrients commonly found to be deficient are folate, choline and vitamin A. There is evidence to suggest that ethanol alone may not explain the entire spectrum of anomalies seen in individuals with FAS. It is hypothesized that FAS may be caused more by the nutritional deficiencies that are exacerbated by alcohol than by direct alcoholic neurotoxicity. It is known that ethanol inhibits folate, choline, and vitamin A/retinoic acid metabolism at multiple steps. Additionally, mice exposed to ethanol demonstrated epigenetic changes, or variations in the methylation of DNA to control gene expression. Folate is important in the production of methyl groups, which are subsequently used to create and methylate DNA. Choline (which is metabolized to acetylcholine) is important in neurotransmission and neurodevelopment. It is also involved in an alternative pathway in the production of methyl groups. In fact a study by Thomas et al. in 2009 found that nutritional supplementation with choline in rats exposed to ethanol in utero almost completely mitigated the degenerative effects of ethanol on development and behaviour. Lastly, vitamin A and retinoic acid metabolism is associated with the regulation of one sixth of the entire proteome. Thus supplementation of folate, choline and vitamin A to mothers may mitigate the effects of the alcohol and reduce the severity or prevalence of FAS.
Choline is an essential nutrient and the liver is a central organ responsible for choline metabolism. Hepatosteatosis and liver cell death occur when humans are deprived of choline. In the last few years, there have been significant advances in our understanding of the mechanisms that influence choline requirements in humans and in our understanding of choline's effects on liver function. These advances are useful in elucidating why nonalcoholic fatty liver disease (NAFLD) occurs and progresses sometimes to hepatocarcinogenesis. Humans eating low-choline diets develop fatty liver and liver damage. This dietary requirement for choline is modulated by estrogen and by single-nucleotide polymorphisms in specific genes of choline and folate metabolism. The spectrum of choline's effects on liver range from steatosis to development of hepatocarcinomas, and several mechanisms for these effects have been identified. They include abnormal phospholipid synthesis, defects in lipoprotein secretion, oxidative damage caused by mitochondrial dysfunction, and endoplasmic reticulum stress. Furthermore, the hepatic steatosis phenotype can be characterized more fully via metabolomic signatures and is influenced by the gut microbiome. Importantly, the intricate connection between liver function, one-carbon metabolism, and energy metabolism is just beginning to be elucidated. Choline influences liver function, and the dietary requirement for this nutrient varies depending on an individual's genotype and estrogen status. Understanding these individual differences is important for gastroenterologists seeking to understand why some individuals develop NAFLD and others do not, and why some patients tolerate total parenteral nutrition and others develop liver dysfunction.
Dietary choline is an important modulator of gene expression (via epigenetic marks) and of DNA integrity. Choline was discovered to be an essential nutrient for some humans approximately one decade ago. This requirement is diminished in young women because estrogen drives endogenous synthesis of phosphatidylcholine, from which choline can be derived. Almost half of women have a single nucleotide polymorphism that abrogates estrogen-induction of endogenous synthesis, and these women require dietary choline just as do men. In the US, dietary intake of choline is marginal. Choline deficiency in people is associated with liver and muscle dysfunction and damage, with apoptosis, and with increased DNA strand breaks. Several mechanisms explain these modifications to DNA. Choline deficiency increases leakage of reactive oxygen species from mitochondria consequent to altered mitochondrial membrane composition and enhanced fatty acid oxidation. Choline deficiency impairs folate metabolism, resulting in decreased thymidylate synthesis and increased uracil misincorporation into DNA, with strand breaks resulting during error-prone repair attempts. Choline deficiency alters DNA methylation, which alters gene expression for critical genes involved in DNA mismatch repair, resulting in increased mutation rates. Any dietary deficiency which increases mutation rates should be associated with increased risk of cancers, and this is the case for choline deficiency. In rodent models, diets low in choline and methyl-groups result in spontaneous hepatocarcinomas. In human epidemiological studies, there are interesting data that suggest that this also may be the case for humans, especially those with SNPs that increase the dietary requirement for choline.