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Choline is essential for life. Without it, cells wouldn’t have membranes, inflammation would run rampant, brain function would suffer, and dietary fats could not be used in the body. In this article we will discuss choline and its metabolites, the roles of choline, dietary sources of choline, choline deficiency symptoms, and how the microbiome influences choline’s metabolism in the body.
What is choline?
Before we get to know this essential nutrient in greater depth, let’s discuss the various forms of choline in the body.
- Choline is a water-soluble compound that can move about freely in the blood.
- Choline is part of phospholipids, such as phosphatidylcholine and sphingomyelin. These compounds are amphipathic, meaning they have a water-soluble side (choline and phosphate) and a fat-soluble side (two fatty acids). The amphipathic nature of phospholipids lends itself nicely to the role of bridging the gap between water and fat-soluble nutrients and their interactions with tissues throughout the body.
- Lecithin, a common emulsifier used in food processing, and phosphatidylcholine are synonymous. Phosphatidylcholine is 13% choline by weight. (3)
- Betaine is derived by the irreversible oxidation of choline in the liver. It can also be obtained directly from food (2).
There are many regulatory pathways involved in choline and phosphatidylcholine homeostasis. Choline balance is determined by choline supply and utilization, with mechanisms in place to convert free choline to fat-soluble choline, and vice-versa, as needed.
What is choline good for?
- Cell Membrane Structure
Every cell has a membrane, and that’s where you’ll find 95% of the body’s choline as a component of the phospholipids that make up the membrane. The cell’s membrane provides structural support and influences the way the cell communicates and interacts with its environment. It provides a barrier that selects which substances are allowed in and out of the cell. Without a functioning membrane, a cell will not survive.
- Brain Health
Choline is the precursor to the neurotransmitter acetylcholine, which modulates nerve transmission regarding circadian rhythms, memory formation, reasoning, and concentration. Acetylcholine synthesis requires vitamin B5, the precursor of Coenzyme A, which puts the “acetyl” in acetylcholine.
- Reduces Inflammation
Betaine, a choline derivative, donates a methyl group in one of the mechanisms that regenerates methionine from homocysteine. Methionine is a precursor to S-adenosyl-L-methionine (SAMe), which is the main source of methyl groups required for biological functions including lipid synthesis, detoxification, and gene expression. Impairment of the methylation cycle leads to increased concentration of homocysteine in the blood which causes inflammation, potentially developing into cardiovascular disease and cognitive dysfunction. (2)
- Lipid Transport
Phosphatidylcholine is essential for the formation of very low density lipoproteins (VLDLs) and their secretion from the liver. Simply put, choline is an essential part of the vehicle that fats require to move around the body. (2)
What foods are rich in choline?
Although the body can synthesize small amounts of this valuable nutrient, choline must be provided in the diet. Luckily, choline is found in a wide variety of foods, mainly in the form of phosphatidylcholine. The average intake (AI) is set at 425 mg/day for women and 550 mg/day for men (1).
- Eggs are among the most choline-rich foods, providing about 125 mg per egg. But don’t skip the yolks, that’s where the choline is!
- Liver is another rich source of choline with over 300 mg per 100g serving. Other animal sources include salmon, shrimp, scallops, chicken, turkey, and beef.
- Plant foods with choline include wheat germ, soy, lima beans, collard greens, Brussels sprouts, broccoli, asparagus, cauliflower, cabbage, mushrooms, and Swiss chard.
- Additives in processed foods, such as soy lecithin, may add a significant amount of choline to the diet (1).
- Foods rich in betaine, such as wheat, shellfish, beets, and spinach, can conserve choline needs in the body.
As the most abundant sources of choline are found in animal-based foods, vegan diets may have an increased risk of choline deficiency (3).
What are the symptoms of choline deficiency?
- Choline deficiency during pregnancy may increase the risk of neural tube defects and other brain development issues in the fetus. Also, phosphatidylcholine is an important component of lung surfactant, which enables a baby to take their first breaths out of the womb.
- NAFLD, or non-alcoholic fatty liver disease, is a consequence of a choline-deficient diet. Dietary fat accumulates in the liver without VLDLs to package lipids and escort them to other tissues, which is dependent on phosphatidylcholine.
- Cardiovascular disease, which may be triggered by homocysteine accumulation in the body, is a consequence of choline deficiency. Choline is one of the two dominant mechanisms that adds a methyl group to homocysteine to restore methionine in the body. The second mechanism requires folate and vitamin B12. Inadequate folate and/or vitamin B12 intake can trigger a secondary deficiency of choline due to increased requirements for the methylation of homocysteine. (2)
- Cognitive dysfunction, including Alzheimer’s disease, may result from or worsen due to choline deficiency. Chronic inflammation in the brain can lead to the development of beta amyloid plaques and neurofibrillary tangles that are characteristic of Alzheimer’s disease. Inflammation also damages the neurons that produce and regulate acetylcholine in the brain, in addition to choline’s requirement for synthesis of this neurotransmitter. (3)
Can the microbiome turn choline against us?
Microbiota in the digestive tract have a profound influence on the ability to break down and absorb nutrients in the body.
Certain gut bacteria can metabolize choline, and also betaine and carnitine, into trimethylamine (TMA). TMA is oxidized in the liver to form trimethylamine N-oxide (TMAO), which has been linked to increased inflammation and the development of cardiovascular disease.
New research has discovered several strains of bacteria that are capable of producing TMA from choline and other derivatives, potentially leading to a secondary deficiency of choline, but it concluded that dietary choline intake did not impact the abundance of TMA-producing bacteria in the gut. Meaning, it may not be necessary to abandon choline-rich foods such as red meat, eggs, poultry, and fish to mitigate cardiovascular disease risk on account of TMA production, but to focus on what causes these bacteria to colonize in the digestive tract.
Other recent research has shown the effects of popular diets on microbial populations and their potential effects on the production of TMAO. In this study, strict paleo dieters show increased TMA-producing bacteria compared to controls and pseudo paleo dieters, who don’t follow the diet as strictly. The researchers conclude that the omission of grains and legumes in the diet leads to less consumption of resistant starches, which contribute to the diversity of beneficial microbial species in the gut. This combined with an increase in consumption of animal-based foods may potentially lead to the growth of TMA-producing bacteria. Plant-based diets also show the reduced presence of gut bacteria that converts choline to TMA.
Takeaway: The microbiome can affect choline status in the body, potentially leading to increased production of TMA and decreased bioavailability of choline, which is correlated to cardiovascular disease. However, it is more important to encourage microbial diversity with a variety of plant foods that provide resistant starch than to eliminate animal-based sources of choline to prevent the production of TMA.
Is it safe to take choline?
The tolerable upper intake, meaning the highest daily intake of a particular nutrient that is unlikely to pose health risks, is set at 3500 mg/day. Toxicity symptoms may include low blood pressure, sweating, diarrhea, and a fishy body odor (due to increased production of TMA). (2)
Shockingly, up to 90% of Americans are not meeting the adequate intakes for this nutrient daily. Consumption of choline-rich foods such as eggs, liver, and animal products has declined significantly due to the unwarranted fear that cholesterol and saturated fat cause heart disease, yet deprivation of the choline in these foods may negatively impact cardiovascular, liver, and brain function as well. (2)
To boost choline intake in your diet, the safest and best way is to consume a variety of choline-rich foods including egg yolks, liver, pastured meats, wild caught fish, lima beans, and cruciferous vegetables. For vegan and vegetarian diets, it may also be wise to consume supplements of phosphatidylcholine, choline salts, or citicoline to boost choline intake. (3)
In conclusion, choline is a nutrient you should know for its ubiquitous presence in the body and important roles in cellular metabolism and brain health. Choline is found in many foods, but the digestion and absorption of this essential nutrient is dependent on the health of microbiota that assist these functions in the gut. Microbial imbalances and other nutrient deficiencies, specifically folate and vitamin B12, can affect internal choline homeostasis and should be addressed in addition to the consumption of choline-rich foods in the diet.
- https://www.ncbi.nlm.nih.gov/books/NBK114308/ “Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline.”
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2782876/ “Choline: An Essential Nutrient for Human Health”
- https://lpi.oregonstate.edu/mic/other-nutrients/choline Linus Pauling Institute
About the author:
Karyn Lane is a current student of NTI’s Nutrition Therapist Master Program. She finds her chemistry degree a useful tool in her study of nutrition and loves to treat herself as a laboratory for new recipes and cooking techniques. You can follow her on Instagram @feel.alive.nourishment.
Learn more about our school by attending an informational webinar.
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