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Choline
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In one pass Choline is a raw material the body needs to build cell membranes and to make a neurotransmitter involved in memory and muscle contraction.
Educational content, not medical advice — consult a clinician.
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Chapter 1
The body can't make enough
Choline is a raw material the body needs to build cell membranes and to make a neurotransmitter involved in memory and muscle contraction. The liver can make a little itself, but usually not enough, so it is still an essential nutrient that has to come from food.
The liver's own route takes a membrane molecule called phosphatidylethanolamine and, step by step, tags it with methyl groups to turn it into phosphatidylcholine (the enzyme that runs this pathway is called PEMT). The methyl groups used as tags come from , the body's main methyl donor, and SAM is a product of the folate and B12 cycle, so choline, folate, and B12 are tied to the same line.
The problem is that this home production is not enough for most people, especially at the peaks of need: pregnancy, breastfeeding, and growth. Estrogen turns up the PEMT pathway, so women before menopause make somewhat more, while men and postmenopausal women depend more on diet; even with the higher estrogen of pregnancy, food is still needed.
That is why there are adequate intakes (): 550 mg/day for men, 425 mg/day for women, 450 mg/day in pregnancy, and 550 mg/day during breastfeeding.
The liver's own route takes a membrane molecule called phosphatidylethanolamine and, step by step, tags it with methyl groups to turn it into phosphatidylcholine (the enzyme that runs this pathway is called PEMT). The methyl groups used as tags come from , the body's main methyl donor, and SAM is a product of the folate and B12 cycle, so choline, folate, and B12 are tied to the same line.
The problem is that this home production is not enough for most people, especially at the peaks of need: pregnancy, breastfeeding, and growth. Estrogen turns up the PEMT pathway, so women before menopause make somewhat more, while men and postmenopausal women depend more on diet; even with the higher estrogen of pregnancy, food is still needed.
That is why there are adequate intakes (): 550 mg/day for men, 425 mg/day for women, 450 mg/day in pregnancy, and 550 mg/day during breastfeeding.
Clinical · Why pregnancy needs enough choline
Choline matters almost as much as folate in pregnancy, yet it is far less famous; it is one of the most underrated stories in nutrition.The fetal hippocampus (the brain region that handles memory) is developing fast, and it needs exactly the three things choline supplies: phosphatidylcholine to build membranes, acetylcholine to use as a neurotransmitter, and methyl groups for methylation (a job shared with folate). The demand is so large that the placenta actively moves choline from the mother's blood toward the fetus, so that concentrations on the fetal side are clearly higher than the mother's. If the mother does not eat enough, what gets drawn down is her own reserve, the phosphatidylcholine in her liver; this is thought to be one possible reason some pregnant women develop mild fatty liver.
Does adding more actually help? Caudill 2018, from Cornell University, was a randomized, double-blind, controlled feeding trial (13 women per group): in late pregnancy one group ate 930 mg of choline a day and the control group 480 mg, and their babies' information-processing speed was tested at 4, 7, 10, and 13 months of age. Babies in the 930 mg group had a faster mean reaction time averaged across the four ages. But this is a small trial with a , it did not measure learning ability, and it still needs larger trials to confirm it.
The problem is that almost nobody eats enough. According to survey data cited by the US NIH Office of Dietary Supplements (ODS), about 90% of pregnant women in the US take in less choline than the of 450 mg/day. Egg yolk is the most efficient source, so women who do not eat eggs find it hard to reach the target from an ordinary diet; skipping yolks, skipping organ meats, and eating vegan all at once during pregnancy is the highest-risk combination.
What to do in practice: 2 egg yolks a day (about 294 mg) plus some beans and lean meat will get close to the AI. Those who cannot eat eggs can consider a choline supplement (phosphatidylcholine or choline bitartrate, 300–500 mg/day) along with more legumes and cruciferous vegetables. Some US medical organizations have begun advising attention to choline in pregnancy, but it is still nowhere near as well known as folate.
One last link is worth remembering: choline and folate share the same methyl cycle. When folate runs short, the body draws on choline to fill in: the liver oxidizes choline to betaine, and betaine hands a methyl group to , standing in for the folate route. The reverse also holds: too little choline adds to the demand for folate. By this mechanism, getting enough of both is safer than minding only one, though no trial has directly compared taking them together with taking either alone.
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Chapter 2
Helps the liver ship fat out
Every day the liver has to ship out the fat it makes, and the hull of that ship is a phospholipid called phosphatidylcholine (PC), which is also the main material of every cell membrane (about 40–50% of it). Choline is the raw material for that hull.
So a choline shortage turns into fatty liver step by step: without enough hull, the fat-carrying very-low-density lipoprotein (VLDL) particles cannot be assembled, the in liver cells cannot be shipped out, and they pile up where they are, which is fatty liver.
This chain has been tested directly in people. Fifty-seven healthy adults first ate plenty of choline and then switched to an almost choline-free diet (less than 50 mg a day) for up to 42 days: 77% of the men and 80% of the postmenopausal women developed fatty liver or muscle damage, against only 44% of the premenopausal women, and once choline was added back to the diet, these changes reversed. The US adequate intake for choline is based on preventing exactly this liver damage.
So a choline shortage turns into fatty liver step by step: without enough hull, the fat-carrying very-low-density lipoprotein (VLDL) particles cannot be assembled, the in liver cells cannot be shipped out, and they pile up where they are, which is fatty liver.
This chain has been tested directly in people. Fifty-seven healthy adults first ate plenty of choline and then switched to an almost choline-free diet (less than 50 mg a day) for up to 42 days: 77% of the men and 80% of the postmenopausal women developed fatty liver or muscle damage, against only 44% of the premenopausal women, and once choline was added back to the diet, these changes reversed. The US adequate intake for choline is based on preventing exactly this liver damage.
Clinical · How too little choline causes fatty liver
Too little choline causing fatty liver is one of the most solid single-nutrient deficiency leading to organ damage chains in clinical nutrition, because it was produced directly in people rather than inferred from population statistics.The Zeisel group at the University of North Carolina (UNC) ran a series of such studies between 1995 and 2009. In the most complete one (Fischer 2007), 57 healthy adults ate an almost choline-free diet (less than 50 mg a day per 70 kg of body weight, under 10% of the AI) for up to 42 days. The results differed sharply by group: 77% of the men and 80% of the postmenopausal women developed raised liver enzymes (, ), fat deposits in the liver visible on MRI, or raised (CK), meaning muscle was being damaged too; among premenopausal women it was only 44%. Adding choline back reversed all of these changes.
Why is the effect so direct? Because about half of the outer shell of VLDL, the particle that carries fat, is phosphatidylcholine (PC). The a liver cell makes have to be wrapped in PC before they can be sent into the blood. No PC means no shell, so the triglycerides pile up where they are, and the result is fatty liver.
This chain may also explain part of a modern puzzle: metabolic dysfunction-associated steatotic liver disease, (formerly NAFLD), also turns up in people who are not overweight. One candidate explanation is low choline intake on top of genetic differences in the PEMT self-production pathway: common variants in the PEMT gene (such as rs7946) weaken the body's own production, and according to the US NIH Office of Dietary Supplements (ODS), at least 40% of women of childbearing age carry a variant that makes PEMT insensitive to estrogen, so they need more choline from food. This is still a hypothesis, not a conclusion.
So in practice: people already diagnosed with MASLD are worth a check on whether they eat enough choline. An ordinary diet with egg yolks, lean meat, fish, and tofu usually reaches the AI. People who never eat yolks and eat almost no meat (vegans or strict vegetarians) are at higher risk and should have a dietary assessment, with a supplement if needed. For treating metabolic dysfunction-associated steatohepatitis (MASH, formerly NASH), the main line is still weight loss, exercise, and diet, with vitamin E for some patients (based on the PIVENS trial) and newer drugs when needed (resmetirom, approved by the US FDA in 2024). Choline is not a treatment, but closing the gap matters.
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Chapter 3
Raw material for acetylcholine
When you decide to lift a finger, the last stop of the brain's command is a small molecule called acetylcholine (ACh), sprayed from a nerve ending onto the muscle. At the junction between nerve and muscle it is the only neurotransmitter, and it is made from choline on the spot.
It handles two other jobs as well: the parasympathetic nerves use it to slow the heart and speed up digestion, and a group of neurons in the brain's basal forebrain use it to regulate learning and memory. The enzyme that makes it, choline acetyltransferase (ChAT), joins choline to acetyl-CoA.
But more raw material does not mean a stronger signal: when blood choline rises, acetylcholine in the synapse does not follow, because ChAT's activity and recycling at the synapse are the real bottlenecks. So high-dose choline supplements will not make you smarter or your muscles stronger, while a severe shortage really does drag down the most basic nerve functions.
It handles two other jobs as well: the parasympathetic nerves use it to slow the heart and speed up digestion, and a group of neurons in the brain's basal forebrain use it to regulate learning and memory. The enzyme that makes it, choline acetyltransferase (ChAT), joins choline to acetyl-CoA.
But more raw material does not mean a stronger signal: when blood choline rises, acetylcholine in the synapse does not follow, because ChAT's activity and recycling at the synapse are the real bottlenecks. So high-dose choline supplements will not make you smarter or your muscles stronger, while a severe shortage really does drag down the most basic nerve functions.
Myth · Can choline prevent or treat Alzheimer's?
Take lecithin or choline, raise acetylcholine, and prevent or treat Alzheimer's disease (AD) has been a classic supplement-industry story for 30 years. It is worth taking apart link by link, because the first half is true.The true part: in AD, the cholinergic neurons of the basal forebrain (the nucleus basalis of Meynert) really do degenerate; this was found around 1976 and grew into the cholinergic hypothesis. And the acetylcholinesterase inhibitors actually used in the clinic (donepezil, rivastigmine, galantamine) improve symptoms precisely by breaking down less of the acetylcholine that has already been released, which in turn shows that the cholinergic system does play a part in AD.
What does not hold is the next step of the argument. A 2003 Cochrane systematic review by Higgins and Flicker pooled 12 randomized trials of lecithin (soy lecithin) or phosphatidylcholine for dementia and found no clear clinical benefit; later systematic reviews also found no clear cognitive gain from choline supplements in healthy adults.
Why it fails has a mechanistic answer that was available all along. First, the rise in blood choline from oral choline is not enough to noticeably change acetylcholine production: ChAT, which makes acetylcholine, is not the rate-limiting step, so raw material is not the bottleneck. Second, the neurons of the basal forebrain have already degenerated; that is structural damage, not a shortage of raw material, and sending supplies to a collapsed workshop achieves nothing. Third, choline in the circulating blood and acetylcholine in the synapse are simply not linked that closely.
There are reasonable uses, but they are limited. In small studies of early mild cognitive impairment (MCI), choline, citicoline, or alpha-glycerylphosphorylcholine (Alpha-GPC) improved some cognitive test scores, but the clinical significance is limited and the certainty of evidence is low (small trials only). In recovery from stroke and traumatic brain injury (TBI), citicoline has shown some benefit in certain clinical studies, but it is used mainly in Europe as a prescription drug and the US FDA has not approved it as a drug.
So: choline supplements to prevent AD have no supporting evidence; keeping choline adequate throughout life to support cognition is reasonable but needs no mega-doses; and high-dose lecithin to treat diagnosed AD wastes time and money, so use approved medicines.
The prevention that carries real weight is elsewhere. The 2024 report of the Lancet Commission listed 14 modifiable risk factors, including high blood pressure, diabetes, smoking, heavy drinking, physical inactivity, hearing and vision loss, social isolation, and high (low-density lipoprotein) cholesterol; together, about 45% of dementia could in theory be prevented or delayed through them. No supplement has shown anything like that.
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Chapter 4
Gut bacteria and the TMAO debate
Not all the choline you eat reaches your own cells. Some of it is intercepted in the large intestine by particular gut bacteria and split into a small, foul-smelling molecule called trimethylamine (TMA). TMA travels in the blood to the liver, where FMO enzymes oxidize it into trimethylamine N-oxide (TMAO), which is released back into the blood. L-carnitine and betaine take the same route; the carnitine route was found by Koeth 2013 in mice and people, and the choline route was first reported by Wang 2011.
In observational studies (including prospective cohorts followed for several years), people with higher blood TMAO did have somewhat more cardiovascular events. Since 2011, this association has been at the center of the argument over choline and red meat.
But several things do not add up:
It is an association; cause and effect have not been established in Several large cohorts that looked directly at choline intake mostly found no more cardiovascular disease in people who ate more of itFish and seafood already contain large amounts of ready-made TMAO, yet eating fish is linked to lower cardiovascular riskPeople on mainly plant-based diets have fewer TMA-producing gut bacteria and lower TMAO
The honest conclusion: TMAO is an interesting marker and may be a real pathway, but it is not strong enough to rewrite dietary advice on choline or red meat. The overall eating pattern matters more than fixating on a single molecule.
In observational studies (including prospective cohorts followed for several years), people with higher blood TMAO did have somewhat more cardiovascular events. Since 2011, this association has been at the center of the argument over choline and red meat.
But several things do not add up:
It is an association; cause and effect have not been established in Several large cohorts that looked directly at choline intake mostly found no more cardiovascular disease in people who ate more of itFish and seafood already contain large amounts of ready-made TMAO, yet eating fish is linked to lower cardiovascular riskPeople on mainly plant-based diets have fewer TMA-producing gut bacteria and lower TMAO
The honest conclusion: TMAO is an interesting marker and may be a real pathway, but it is not strong enough to rewrite dietary advice on choline or red meat. The overall eating pattern matters more than fixating on a single molecule.
Evidence · Are eggs bad for the heart?
Whether eggs are healthy has been argued in nutrition for 50 years, and now a new worry about TMAO and the heart has been layered on top. Line up the generations of worry in order and you see that the conclusion has hardly changed; only the reason has.The 1980s–2010s version was egg yolk is full of cholesterol, so it hurts the heart, and the old advice therefore said at most 3–4 eggs a week. That version later fell apart: Shin 2013, a pooling prospective cohorts (observational), found that in the general population eating more eggs was not associated with cardiovascular disease or with dying of heart disease, though among people with diabetes those who ate more eggs had more cardiovascular disease. The 2015 US dietary guidelines dropped the daily cholesterol limit altogether. From 2017 on, TMAO research from the Hazen group pushed eggs hurt the heart back in with a new reason.
The new version has its own problems. The first is the fish paradox: fish (especially deep-sea fish) contain very high amounts of TMAO themselves (roughly 10–50× that of eggs), yet eating fish goes with lower cardiovascular risk. The second is individual variation: converting choline to TMAO depends on gut bacteria and the liver enzyme FMO3 together, and people can differ by 10×, so the same yolk is simply not the same event in two people. The third matters most: to this day no has shown that lowering TMAO reduces heart attacks, so the causal end of the chain is still empty.
So the common practical advice sits in the middle. For most healthy adults, 1–2 eggs a day has shown no harm (observational evidence), and eggs are very nutrient-dense (protein, choline, vitamin A, B12, selenium, lutein). People who already have cardiovascular disease, type 2 diabetes, or poorly controlled are on safer ground cutting to 3–4 eggs a week while firming up their overall eating pattern (such as the DASH or Mediterranean diet). And swapping eggs for processed foods to avoid them is clearly a worse trade.
Remember the ranking: eating pattern > single food > single molecule. TMAO is not enough reason to throw away one of the most nutrient-dense whole foods there is.
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Chapter 5
Foods rich in choline
Choline sits in cell membranes as part of phospholipids, so the more membrane a food has, the more choline it carries:
Egg yolk: about 147 mg per egg, the richest everyday source (see Eggs)Organ meat: beef liver, about 356 mg per 85 g (Organ Meat)Beef: lean beef, about 117 mg per 85 gFish (salmon): about 63 mg per 75 g (see Salmon)Plants: soybeans (about 47 mg per 85 g), Brussels sprouts (about 32 mg per half cup), cauliflower (about 24 mg per half cup)
A century egg is still a duck egg underneath, and the choline is still in the yolk (Century Egg).
But most people do not get enough: US surveys show that most people's choline intake is below the , and women especially so. Eating fewer yolks and organ meats may be part of the reason, a debt left over, to some extent, from the old fear of cholesterol.
Can you eat yolks every day? For healthy people, eating egg yolk usually affects blood less than saturated fat does. Whether to eat them daily depends on the overall diet, not on the cholesterol number alone.
Egg yolk: about 147 mg per egg, the richest everyday source (see Eggs)Organ meat: beef liver, about 356 mg per 85 g (Organ Meat)Beef: lean beef, about 117 mg per 85 gFish (salmon): about 63 mg per 75 g (see Salmon)Plants: soybeans (about 47 mg per 85 g), Brussels sprouts (about 32 mg per half cup), cauliflower (about 24 mg per half cup)
A century egg is still a duck egg underneath, and the choline is still in the yolk (Century Egg).
But most people do not get enough: US surveys show that most people's choline intake is below the , and women especially so. Eating fewer yolks and organ meats may be part of the reason, a debt left over, to some extent, from the old fear of cholesterol.
Can you eat yolks every day? For healthy people, eating egg yolk usually affects blood less than saturated fat does. Whether to eat them daily depends on the overall diet, not on the cholesterol number alone.
In practice · Choosing a choline supplement
When dietary choline is genuinely short and an assessment says a supplement is needed, start by reading the label. The milligrams on the bottle are usually the weight of the whole molecule, and only part of that is choline you can use; the rest is the other groups attached to it. The usable part is called elemental choline, and it varies widely between forms, which decides how much you actually get from each pill:Choline bitartrate: the cheapest, about 41% elemental choline; high doses can cause a fishy body odor (whatever is not absorbed is turned into trimethylamine, TMA, by gut bacteria, the same route described in the TMAO chapter)
Choline chloride: chemically equivalent, with similar side effects
Phosphatidylcholine (PC, the main component of lecithin): already in phospholipid form, about 13% elemental choline; it is often said to absorb more steadily with less odor, but according to the US NIH Office of Dietary Supplements (ODS), no study has directly compared absorption across the different forms
Alpha-glycerylphosphorylcholine (Alpha-GPC): about 40% elemental choline, and it crosses the blood-brain barrier; some studies show improvements in exercise or cognition, and it costs more
CDP-choline (citicoline): about 18% elemental choline, used in research on recovery from stroke and traumatic brain injury; a prescription drug in Europe and an over-the-counter supplement in the US
For dosing, first remember the line to reach: the is 550 mg/day for men, 425 for women, 450 in pregnancy, and 550 during breastfeeding. People whose diet is close but slightly short can make it up with 250–500 mg/day of choline bitartrate or 1–2 g/day of PC. A pregnant woman who does not eat eggs should aim for 450 mg/day; prenatal multivitamins usually contain little or no choline, so extra may be needed. Athletes and people trying to optimize cognition often use 300–600 mg/day of Alpha-GPC, but the evidence for this is weak. In recovery from stroke or traumatic brain injury, 500–2000 mg/day of citicoline must be used under a doctor's guidance.
The safety margin is wide but not unlimited: the adult tolerable upper intake level () is 3.5 g/day. At high doses the most common problem is a fishy body odor (from the TMA by-product), and sweating, salivation, vomiting, low blood pressure, and even liver damage can occur. Taking choline supplements long-term at high doses as general wellness is not recommended: there is no evidence of benefit, and there is a rather awkward social cost.
Finally, back to meals: 2 egg yolks a day plus some beans and lean meat almost certainly reaches the AI. The situations that truly call for a supplement are few: pregnancy without eggs, a strict vegan diet, low intake found during an assessment for , a known PEMT variant with high needs, extremely heavy training, and recovery from stroke.
References · 10
- National Institutes of Health, Office of Dietary Supplements. (2022). Choline — Fact Sheet for Health Professionals. Fact sheet (updated June 2, 2022; Wayback snapshot 21 September 2026): AIs 550 mg/day men, 425 women, 450 pregnancy, 550 lactation; premenopausal women might need less dietary choline because estrogen induces the gene (PEMT) for choline biosynthesis, although at least 40% of women of childbearing age carry a polymorphism that makes it insensitive to estrogen; prenatal supplements typically contain little if any choline; Table 2: beef liver, 3 ounces, 356 mg; egg, 1 large, 147 mg; beef top round, 3 ounces, 117 mg (fact sheet). ods.od.nih.gov/factsheets/Choline-HealthProfessional
- Institute of Medicine. (1998). Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. National Academies Press. www.ncbi.nlm.nih.gov/books/NBK114310
- Wiedeman, A. M., Barr, S. I., Green, T. J., Xu, Z., Innis, S. M., & Kitts, D. D. (2018). Dietary choline intake: current state of knowledge across the life cycle. Nutrients, 10(10), 1513. 10.3390/nu10101513
- Zeisel, S. H., & da Costa, K. A. (2009). Choline: an essential nutrient for public health. Nutrition Reviews, 67(11), 615-623. 10.1111/j.1753-4887.2009.00246.x
- U.S. Department of Agriculture & U.S. Department of Health and Human Services. (2020). Dietary Guidelines for Americans, 2020-2025 (9th ed.). www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf
- Wang, Z., Klipfell, E., Bennett, B. J., et al. (2011). Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease. Nature, 472(7341), 57-63. 10.1038/nature09922
- Tang, W. H. W., Wang, Z., Levison, B. S., et al. (2013). Intestinal microbial metabolism of phosphatidylcholine and cardiovascular risk. The New England Journal of Medicine, 368(17), 1575-1584. 10.1056/NEJMoa1109400
- Koeth, R. A., Wang, Z., Levison, B. S., Buffa, J. A., Org, E., Sheehy, B. T., et al. (2013). Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nature Medicine, 19(5), 576-585. Gut microbiota convert red-meat L-carnitine to TMA, then hepatic TMAO, accelerating atherosclerosis in mice; omnivores produce more TMAO than vegans/vegetarians. Human association: plasma L-carnitine in 2,595 patients undergoing cardiac evaluation predicted prevalent CVD and incident major adverse cardiac events only when TMAO was also high (abstract, PMID 23563705). 10.1038/nm.3145
- Mozaffarian, D., & Wu, J. H. Y. (2011). Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events. Journal of the American College of Cardiology, 58(20), 2047–2067. 10.1016/j.jacc.2011.06.063
- Wallace, T. C., & Fulgoni, V. L. (2017). Usual choline intakes are associated with egg and protein food consumption in the United States. Nutrients, 9(8), 839. NHANES 2009-2014 usual intakes: only 8.03% of adults and 8.51% of pregnant women meet the choline AI; egg consumers had almost double the intake of non-consumers (525 vs 294 mg/day) and 57.3% vs 2.43% met the AI; no subgroup exceeded the UL. First author consults for Balchem and the Egg Nutrition Center (abstract, PMID 28783055). 10.3390/nu9080839