Where is choline in eggs

It is believed that circulating TMAO may promote atherosclerosis by preventing the removal of cholesterol in the liver. However, it was noted that TMAO blood levels were not measured in this study, only choline from foods reported in diet questionnaires.

Other earlier, large epidemiological studies found the contrary, with no association of high choline intakes with a higher risk of cardiovascular diseases, though these studies also did not specifically measure TMAO blood levels. There appears to be an association with diets high in choline-rich foods and cardiovascular disease, but the reasons for this link need further study. In three large cohorts of men and women, higher intakes of phosphatidylcholine were associated with an increased risk of type 2 diabetes mellitus T2DM.

The exact mechanism of this association is unclear and warrants further research. There is a link between choline deficiency and liver disease. Phosphatidylcholine carries fats away from the liver, so a choline deficiency can cause the liver to store too much fat.

This increases the risk for nonalcoholic fatty liver disease NAFLD , which may then progress to cirrhosis an inflammation of liver cells, followed by thickening and hardening of liver tissue , liver cancer, or liver failure. This ultimately interferes with normal liver function. Changes in the metabolism of choline or phosphatidylcholine can also negatively impact certain biochemical pathways that lead to NAFLD. Although a choline deficiency can lead to liver dysfunction, it is not yet clear if dietary choline or choline supplementation can treat NAFLD.

Choline is associated with brain health because it is converted into acetylcholine, which plays a role in memory and thinking. Choline is found in a variety of foods. The richest sources are meat, fish, poultry, dairy, and eggs. Most Americans eat less than the AI for choline but a deficiency is very rare in healthy persons, as the body can make some choline on its own. Also, the amount of dietary choline an individual needs can vary widely and depends on various factors.

For example, premenopausal women may have lower requirements for dietary choline because higher estrogen levels stimulate the creation of choline in the body. A higher choline requirement may be needed in persons who have a genetic variation that interferes with the normal metabolism of choline.

Very high intakes of choline can lead to low blood pressure hypotension and liver toxicity. It may also lead to the excess production of TMAO, which is associated with a higher risk of cardiovascular disease. The Tolerable Upper Intake Level UL for choline for adults 19 years and older is 3, mg daily and is based on the amount that has been shown to produce these side effects.

B Vitamins Vitamins and Minerals. The contents of this website are for educational purposes and are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Contributing to methylation, a metabolic process that helps your body repair and produce DNA. Helping produce acetylcholine, which is an important neurotransmitter that is needed for muscle control, memory, focus, and heartbeat regulation, among other basic functions.

The National Health and Medical Research Council sets out recommendations for choline intake, which varies by age and gender. For adults, the Adequate Intake AI is mg for women and mg per day for men. This AI is only a guideline as there is currently insufficient research to set a specific recommended dietary intake RDI. Eggs are the most common sources of choline in the Australian diet, providing more than double the amount of choline per g than any other commonly eaten food.

Along with a host of other nutrients and vitamins , one large hard-boiled egg contains mg of choline. The egg yolk is key as egg white does not contain any choline. Choline can also be found in foods such as meat, fish and milk, as well as some green vegetables and whole grains.

Other choline rich foods include:. Having a high choline content is one of the best health benefits eggs can provide but they can also help you meet many other nutritional needs. Find out more about the role of eggs in daily nutrition today. The participants were also instructed not to drink alcohol, perform heavy exercise and to avoid choline rich products e.

During each visit, study subjects received either a drink with natural choline from egg yolk phospholipids ELIP, AAK , which included phosphatidylcholine and DHA bound to this phosphatidylcholine, or a control shake with choline added as a salt bitartrate and DHA added as algae oil TAG-bound.

The two test drinks were administered in randomized order by block randomization and blood samples were collected via a catheter before the drink and 30, 60, , and min after consumption of the drink Figure 1. Arachidonic acid was added to the control drink to control for the amount of arachidonic acid bound to the phospholipids in the egg yolk phospholipid drink.

Both drinks contained g commercially available mango juice Albert Heijn, the Netherlands , 20 g whey protein isolate Myprotein, the Netherlands and 40 g maltodextrin Myprotein, the Netherlands. Choline and DHA were added to the control drink to match the content already present in the egg yolk phospholipid drink.

However, DHA in the control drink was 1. The volume of both drinks was approximately mL. Macronutrient composition of the test and control drinks is listed in Table 2. The assay used d 9 -betaine chloride, d 9 -choline chloride, and d 6 -dimethylglycine HCl as internal standards.

The separation was performed using ammonium formate solvent A and acetonitrile solvent B as described in detail [ 29 ]. The measurements of choline, betaine and dimethylglycine were performed at the Central Laboratory of the University Hospital of the Saarland, Germany.

DHA concentrations were quantified in the triglyceride and phospholipid fractions of EDTA plasma using a modified version of a previously described protocol [ 30 ]. Subsequently, fatty acid methyl esters are formed, which were analysed using gas chromatography coupled to flame ionization detection GC—FID as described before.

Concentrations were calculated via single-point calibration, using the peak area from the C19 internal standards as calibrator. If this interaction term was not significant, it was omitted from the model. All statistical analysis were performed on delta values in order to correct for baseline differences. Incremental area under the curve iAUC values were calculated for each individual by using the trapezoidal method [ 31 ]. Differences in iAUC between interventions were analysed by a paired t -test.

All 18 subjects completed the study. The baseline characteristics of these 18 participants are summarized in Table 3. Evaluation of adverse events AEs demonstrated that some individuals experienced a change of fecal consistency. We recorded seven cases; one participant during both intervention days, four participants after consumption of the egg yolk phospholipid drink and one participant after consumption of the control drink with choline-bitartrate.

Plasma choline, betaine and dimethylglycine concentrations after consumption of both treatments showed different response curves Figure 2 A—C, Table S1. The concentrations of choline increased more pronounced after consumption of the egg yolk phospholipid drink compared to the control drink with choline bitartrate. Although choline plasma concentrations did not yet return to baseline values after six hours, concentrations started to decrease.

Mean changes from baseline in plasma A choline, B betaine and C dimethylglycine concentrations after egg yolk phospholipid and choline bitartrate consumption. Linear mixed model procedures were conducted to determine difference between the responses. Individual response curves clearly demonstrated that these responses were very consistent among individual study participants Figure 3.

Response curves of the individuals that experienced a change of fecal consistency showed no deviating pattern, suggesting that this had no effect on choline uptake. Individual choline responses after egg yolk phospholipid or choline bitartrate consumption. Numbers 1—18 represent individual study participants. Upon uptake, choline is rapidly converted into its metabolites betaine and dimethylglycine.

Plasma concentration of betaine showed similar responses as choline. This was also confirmed when expressed as iAUC over the six-hour time period Table 3. Additionally, dimethylglycine levels were higher after consumption of the egg yolk phospholipid drink compared to the control drink with choline bitartrate, but that difference was not as profound as with choline and betaine Figure 2 C, Table 3.

DHA concentrations in the phospholipid fraction did not show a postprandial response after consumption of both drinks. When expressed as iAUC over the 6-hour time period, the control drink showed a 1.

However, the administered dose of DHA differed between the two test drinks, the DHA content in the control drink was 1.

Changes in plasma concentrations of DHA in the TAG fraction were not different between the test drinks when corrected for this dose difference. Our results clearly demonstrate that choline is better absorbed when it is consumed in the natural form; choline absorption was 4 times higher comparing egg yolk phospholipid consumption with choline bitartrate intake, as determined by the iAUC. This difference in absorption was highly significant and very consistent among participants. Plasma concentrations of both betaine and dimethylglycine were significantly increased after egg yolk phospholipid consumption compared with choline bitartrate intake.

These outcomes are in line with the results of Hirsch et al. In both studies the response of the choline salt was higher in the first half hour, while later in time the phospholipid-bound choline showed an improved absorption.

Although there was a difference, Hirsch and colleagues found that the plasma choline concentrations were still increasing 12 hours postprandially, while concentrations in our study already decreased four hours after consumption of the drinks.

This is probably due to the difference in meal composition between the studies. In the study of Hirsch et al. Liquid foods have a faster gastric emptying rate [ 32 ], hence, a faster absorption rate. Furthermore, in accordance with our results, a more recent study by Lemos et al.

Contrary, in their study, plasma choline concentrations did not increase after choline bitartrate consumption, and plasma betaine concentrations did not rise at all, while in our study both choline and betaine concentrations increased after the two treatments. This difference can probably be explained by the lower choline dose used in the study of Lemos and colleagues [ 33 ]. Our results, together with the studies of Hirsch et al.

It seems that natural phosphatidylcholine, which is especially high in egg yolk, improves choline absorption. We can only speculate about the underlying mechanism of this improved bioavailability. Perhaps the difference in absorption can be explained by the difference in choline carriers, e. Most dietary phospholipids are hydrolysed in the small intestine, resulting in a lysophospholipid and a fatty acid part [ 34 , 35 ].

Via passive diffusion or via the formation of micelles, the lysophospholipids are directly absorbed by the intestinal epithelium [ 34 , 35 ]. When choline is bound to a salt, the choline is transported by a saturable carrier system via passive diffusion in a concentration dependent manner [ 36 ].

Since the choline carrier is saturable, choline intake as a salt, may lead to a less efficient choline absorption than after the consumption of phosphatidylcholine, especially when consumed in high concentrations. When choline is not absorbed in the small intestine, it will reach the colon where it will be available for the microbiota and converted to trimethylamine.

Higher levels of trimethylamine are associated with an increased risk of cardio vascular diseases [ 37 ]. Theoretically, faster absorption rates may result in less choline available for the microbiota, hence preventing the formation of trimethylamine. While levels of plasma choline started to decline after 4 hours, those of betaine seemed to reach a steady state and the response of dimethylglycine seems not to reach its maximum by the time the observation time window ended six hours.

Our results show a time-shift between the responses of the three metabolic markers. These results mean that choline from egg yolk has reached the circulation and the liver, where it can be used in several metabolic pathways. Next free choline from egg yolk can undergo mitochondrial oxidation to betaine by choline dehydrogenase and betaine aldehyde dehydrogenase.

Through this oxidation to betaine, choline from egg yolk phospholipids can provide methyl groups coming from the betaine to dimethylglycine conversion via betaine homocysteine methyl transferase.

Through this reaction, homocysteine is converted to methionine. Since dimethylglycine concentrations were also significantly higher after egg yolk phospholipid consumption than after choline bitartrate intake, this could mean that choline from egg yolk phospholipids is a better source of methyl groups and its effect lasted for a longer time than choline bitartrate.

Repeated consumption of egg yolk phospholipid choline could therefore improve liver function in patients with fatty liver [ 38 ] or lowering plasma homocysteine, hence impacting cardiovascular disease risk [ 39 ].

In addition, the enhanced methyl group production from egg yolk phospholipids can provide S -adenosylmethionine that may feed the S -adenosylmethionine-dependent phosphatidylethanolamine N -methyltransferase PEMT that synthesize phosphatidylcholine from phosphatidylethanolamine. Next, the egg yolk phospholipids also contained some phosphatidylethanolamine, which can also be converted to phosphatidylcholine when S -adenosylmethionine is made available.

The greater increase in methyl groups after egg yolk phospholipid consumption together with the phosphatidylcholine made from phosphatidylethanolamine can lead to higher conversion rates of choline to betaine. This will subsequently increase betaine concentrations in the liver and, finally, also in the circulation, which might explain the greater change in betaine than in choline as a function of time.

We expected to find an increase in DHA concentrations in the phospholipid fraction after consumption of the egg yolk phospholipid drink, since in this drink DHA was bound to phospholipids. However, no postprandial increase of DHA in the phospholipid fraction appeared. The fatty acid composition in the phospholipid fraction reflects dietary intake of hours to weeks [ 40 , 41 ], which may explain why we did not find changes in this fraction only a few hours after a single intake.

The DHA concentrations in the TAG fraction did increase after consumption of the drinks, with a greater increase after consumption of the control drink compared with the egg yolk phospholipid drink. This can be explained by the higher DHA dose in the control drink than in the egg yolk phospholipid drink. We found that the difference in iAUC largely matched with the difference in administrated dose. We, therefore, conclude that there was no difference in DHA absorption between the two drinks.

These studies investigated the effects after prolonged intake of at least 4 weeks [ 22 , 23 , 24 , 25 , 26 ] or, if tested in a postprandial study, used a very high dose of DHA mg [ 27 ]. Most likely, sampling time in our study was too short and the single dose of DHA was too low to find this expected difference in DHA absorption between DHA bound to a phospholipid or TAG as has been shown in previous studies.

For infants, phospholipid bound DHA seems to be of great importance. Therefore, phospholipid bound DHA seems to be important for infant development. Recent evidence also indicates that the synergy of choline and DHA, when included in a single product, is of importance for infant development.

A recent study showed similar effects in adult mice, supplementation of choline, with ribose, pyrophosphate and cytosine , together with DHA increased the amount of DHA containing phosphatidylcholine in the brain and improved learning and memory ability compared with DHA or choline supplementation alone [ 45 ]. Furthermore, DHA can only cross the blood brain barrier when bound to a phospholipid [ 46 ].

Consumption of egg yolk phospholipids, containing phosphatidylcholine-bound DHA, may, therefore, be beneficial for infants. Considering the application of choline in infant formula, a limitation of the current study is that it was only performed in healthy adults, not in infants. However, performing this kind of clinical trials in infants is ethically not feasible. It is, however, highly unlikely that choline absorption differs between infants and adults [ 18 , 36 ].

Therefore, absolute concentrations will not be comparable, but the difference in uptake between the different drinks can most likely be extrapolated to infants.