Choline, found in ample amounts in egg yolks, was first discovered in 1862. 1 Since then, we've learned that this is a truly essential nutrient for a healthy brain, nervous system and cardiovascular function. It's particularly crucial during fetal development, 2 so choline requirements rise exponentially in pregnant women. 3
Importantly, choline is used in the synthesis of phospholipids in your body, the most common of which is phosphatidylcholine, better known as lecithin, which is required for the composition of your cell membranes. 4 As noted in a 2013 paper: 5
"Humans must eat diets containing choline because its metabolite phosphatidylcholine constitutes 40 to 50 percent of cellular membranes and 70 to 95 percent of phospholipids in lipoproteins, bile and surfactants …
[It] is needed to form acetylcholine, an important neurotransmitter; its metabolite betaine is needed for normal kidney glomerular function, and perhaps for mitochondrial function; and it provides one-carbon units, via oxidation to betaine, to the methionine cycle for methylation reactions.
There is a recommended adequate intake for choline (about 550 mg/day), but choline intake in the diet has been estimated to vary by as much as threefold — the lowest quartile and the highest quartile of intake were approximately 150 mg and 500 mg/day choline equivalents, respectively…"
Studies also stress its importance for liver health, and it may actually be a crucial key for the prevention of fatty liver disease — including nonalcoholic fatty liver disease (NAFLD), which is largely driven by high-sugar diets as opposed to excess alcohol consumption.
Nine in 10 Americans Are Deficient in Choline
Although a small amount of choline is produced by your liver, 6 the rest must be supplied through your diet. Unfortunately, an estimated 90 percent of the U.S. population are deficient in choline. 7 People who are at particularly high risk for deficiency include:
- Pregnant mothers — Choline is required for proper neural tube closure, 8 brain development and healthy vision. 9 Research shows mothers who get sufficient choline impart lifelong memory enhancement to their child due to changes in the development of the hippocampus (memory center) of the child's brain. 10 Choline deficiency also raises your risk of premature birth, low birth weight and preeclampsia.
- Athletes — During endurance exercise, such as a marathon, choline levels deplete. Choline supplementation before severe physical stress has demonstrated a number of advantageous effects in studies. 11 , 12 Choline supplementation may also reduce body mass without side effects. 13
- High alcohol consumers — Excess alcohol consumption can increase your need for choline and raise your risk of deficiency. 14
- Postmenopausal women — Lower estrogen concentrations in postmenopausal women increases their risk of organ dysfunction in response to a low-choline diet, so their requirements are higher than those of premenopausal women. 15
- Vegans — Choline supplementation may also be important for this demographic, as they have an elevated risk for deficiency if they avoid choline-rich foods such as eggs and meats. 16
Choline Is Required for Optimal Health
Choline was officially recognized as an essential nutrient for human health by the Institute of Medicine in 1998. 17 It's required for:
- Cell messaging, by producing cell-messaging compounds 18
- Cell structure; making fats to support the composition of your cell membranes
- Fat transport and metabolism, as choline is needed to carry cholesterol from your liver, and a choline deficiency could result in excess fat and cholesterol buildup 19
- DNA synthesis
- Nervous system health (choline is necessary for making acetylcholine, a neurotransmitter involved in healthy muscle, heart and memory performance)
Studies have linked higher choline intake to a range of benefits, including a decreased risk for heart disease, 20 a 24 percent decreased risk for breast cancer, 21 and the prevention of NAFLD. In fact, choline appears to be a key controlling factor in the development of fatty liver, likely by enhancing secretion of very low density lipoprotein (VLDL) particles in your liver. 22
Choline Plays Crucial Role in NAFLD
In a 2010 article, Chris Masterjohn, who has a Ph.D. in nutrition, writes: 23
"After studying the relevant literature and tracing it much further back in time than anyone else ever bothers to, I've come to the conclusion that neither fat nor sugar nor booze are the master criminals here.
Rather, these mischievous dudes are just the lackeys of the head honcho, choline deficiency. That's right, folks, it's the disappearance of liver and egg yolks from the American diet that takes most of the blame [for rising rates of fatty liver disease].
More specifically, I currently believe that dietary fat, whether saturated or unsaturated, and anything that the liver likes to turn into fat, like fructose and ethanol, will promote the accumulation of fat as long as we don't get enough choline."
The curious link between choline and fatty liver emerged from research into Type 1 diabetes. Studies in the 1930s demonstrated that lecithin in egg yolk (which contains high amounts of choline) could cure fatty liver disease in Type 1 diabetic dogs. They later found choline alone provided the same benefit. Masterjohn goes on to explain: 24
"We now know that choline is necessary to produce a phospholipid called phosphatidylcholine (PC) … a critical component of the very low density lipoprotein (VLDL) particle, which we need to make in order to export fats from our livers.
The amino acid methionine can act as a precursor to choline and can also be used to convert a different phospholipid called phosphatidylethanolamine directly into PC. Thus, the combined deficiency of choline and methionine will severely impair our abilities to package up the fats in our livers and to send them out into the bloodstream."
Diets High in Saturated Fat Increase Your Choline Requirement
According to Masterjohn, while saturated fats are beneficial to health, they increase your choline requirement — and to a greater degree than unhealthy fats such as corn oil (about 30 percent greater) — so in the absence of sufficient choline, even these healthy fats can contribute to fatty liver. In a nutshell, choline is a necessary ingredient that helps minimize liver fat, no matter what the cause.
While dietary fats can contribute to fatty liver if and when choline levels are low, the greatest culprit in NAFLD is excessive sugar, especially fructose, as all of it must be metabolized by your liver and is primarily converted into body fat opposed to being used for energy like glucose. According to Masterjohn:
"In 1949 … researchers showed that sucrose and ethanol had equal potential to cause fatty liver and the resulting inflammatory damage, and that increases in dietary protein, extra methionine, and extra choline could all completely protect against this effect. 25
Conversely, much more recent research has shown that sucrose is a requirement for the development of fatty liver disease in a methionine- and choline-deficient (MCD) model …
The MCD model produces not only the accumulation of liver fat, but massive inflammation similar to the worst forms of fatty liver disease seen in humans. What no one ever mentions about this diet is that it is primarily composed of sucrose and its fat is composed entirely of corn oil! …
The picture that is clearly emerging from all of these studies is that fat, or anything from which fat is made in the liver, such as fructose and ethanol, are required for the development of fatty liver. But in addition to this some factor — overwhelmingly, it appears to be choline deficiency — must deprive the liver of its ability to export that fat."
More recent research 26 has also discovered evidence of epigenetic mechanisms of choline, which also helps explain how choline helps maintain healthy liver function.
Healthy Choline Sources
In the '70s, many doctors told their patients not to eat eggs, or at least egg yolks, in order to minimize their cholesterol and saturated fat intake. In reality, both of those are good for you, and eggs are one of the most important health foods available.
A single hard-boiled egg can contain anywhere from 113 milligrams 27 (mg) to 147 mg 28 of choline, or about 25 percent of your daily requirement, making it one of the best choline sources in the American diet. 29 Only grass fed beef liver beats it, with 430 mg of choline per 100-gram serving. 30 As noted in the Fatty Liver Diet Guide: 31
"Eggs rank very high on the list of foods that are high in either lecithin, which converts to choline, or in choline itself. Note that this is the egg yolks only, not egg whites, which only have traces of this micronutrient.
Choline is essential in the production of phosphatidylcholine, a fat molecule called a phospholipid. But wait! Isn't all fat bad? No — especially if it is essential to overall health and in particular, liver health. Simply put — if you don't have enough choline, your liver can't move out fat. It instead begins to collect within your liver, creating fatty liver."
Other healthy choline sources include wild-caught Alaskan salmon , 32 organic pastured chicken, vegetables such as broccoli , cauliflower and asparagus (one-half cup contains about 31 mg, 24 mg and 23.5 mg of choline respectively), shiitake mushrooms and krill oil. One 2011 study 33 , 34 found 69 choline-containing phospholipids in krill oil, including 60 phosphatidylcholine substances.
Phophatidyl choline (PC) is one of the best sources of choline and although eggs have a fair amount, krill oil per volume is higher as about 40% of krill oil is PC. Only about 13% of PC is choline so two krill oil capsules will provide about 400 mg of PC but around 50 mg of choline. This is one of the reasons why I personally take about 10 krill oil capsules a day which provide about 500 mg of choline.
Are You Getting Enough Choline to Protect Your Health?
While a dietary reference intake value has not yet been established for choline, the Institute of Medicine set an "adequate daily intake" value of 425 mg per day for women, 550 mg for men 35 and 250 mg for children 36 to help prevent a deficiency and potential organ and muscle damage.
Keep in mind, however, that requirements can vary widely, depending on your overall diet, age, ethnicity 37 and genetic makeup. As noted in one paper, 38 "People with one of several very common genetic polymorphisms in the genes of choline metabolism are more likely to develop hepatic dysfunction when deprived of choline."
Also, as discussed above, eating a diet high in (otherwise healthy) saturated fats may actually increase your choline requirement. Pregnant and breastfeeding women, athletes and postmenopausal women also need higher amounts.
If you already have NAFLD, you'd be wise to pay careful attention to choline as well. A study on the severity of 664 people with NAFLD found that decreased choline intake significantly increased their symptoms, including fibrosis (the thickening and scarring of connective tissue). 39
The tolerable upper intake level for choline is 3.5 grams per day. Side effects of excessive choline include low blood pressure, sweating, diarrhea and a fishy body odor. 40 As mentioned, eggs are a primary source of choline in the diet; with more than 100 mg of choline per egg yolk, they're an easy way to ensure sufficiency. That said, supplementation is an option if you're concerned about getting enough choline from your diet.