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food source · 2
←Eggs
One egg has about 147 mg of choline, almost all of it in the yolk. That is the biggest hidden loss when you eat only the whites.
Mechanism · Choline lives in membranes
Choline sits in cell membranes mainly as phospholipid, so foods packed with membranes carry more of it. The yolk is one of the densest everyday sources, while the white has almost none. Choline matters especially for the developing brain of a baby in pregnancy.
Numbers · What two yolks cover
One egg has about 147 mg of choline, almost all in the yolk. The adequate intake (AI) for choline is 550 mg a day for men, 425 mg for women and 450 mg in pregnancy; two yolks a day supply about 290 mg, and with some beans and lean meat added, getting close to that level becomes much easier.
A century egg is a duck egg cured with alkali and salt. Curing neither adds nor removes fat, so the choline in the yolk largely remains. It suits an occasional side dish, one egg at a time, and the number to watch is sodium.
Mechanism · What alkaline curing changes
Minerals are elements: curing can change what they are bound to but cannot make them vanish. Vitamins are molecules, and once alkali breaks their structure they stop working, so curing can only hold vitamins steady or lower them, never raise them. Choline sits in the yolk mainly as phospholipid, and the alkali does not carry it out of the yolk, so a century egg is still a source of choline.
Numbers · One egg and its sodium
Century egg itself is not in the USDA food-composition database, so read its numbers from the raw material, fresh duck egg: 12.8 g of protein and 13.8 g of fat per 100 g. One century egg gives about 50–60 g you can eat, which suits an occasional side dish, not several a day. Sodium is the number to watch: the alkali that sets the egg white into a gel is sodium hydroxide, and the sodium soaks into the egg along with it. The translucent gel needs the alkali to get in, so a low-sodium century egg is hard to make.
synergy · 2
Choline and betaine are the two ends of one methyl ledger. In the liver choline is oxidized to betaine (a one-way step with no route back), and betaine hands over its methyl group to turn homocysteine back into methionine. Run the other way: when choline intake is short, the liver takes the backup line (PEMT) and makes choline-containing phospholipid itself, using up three methyl groups per molecule. So not eating enough choline and a strain on methylation are two descriptions of the same thing in the liver.
There are two routes for turning homocysteine back into methionine: the main one depends on B12 and folate, and a backup uses methyl groups from betaine, which the body makes from choline. When folate is low, the body leans more on the backup, and its need for choline rises.
cofactor · 2
Choline is the raw material for phosphatidylcholine, the phospholipid the liver uses to package fat into very-low-density lipoprotein (VLDL) and ship it out. When choline runs short, the fat cannot be exported and builds up in the liver.
Every phospholipid in your cell membranes is one head plus two tails: the tails come from the fat you eat, and the head is most often choline. Your omega-3 intake affects how fluid the membrane is, and choline decides whether the membrane can be built at all; short on either, it does not get made properly.
regulates · 1
Alpha-GPC and citicoline (CDP-choline) deliver choline to the brain more directly, at a higher price. One thing no form escapes: when you take in a lot of choline, gut bacteria turn part of it into trimethylamine (TMA), which the liver oxidizes to trimethylamine N-oxide (TMAO); some studies link TMAO to cardiovascular risk, with large differences between individuals.