Choline is required for many biological processes, including proper muscle function. In a previous study it was observed that low choline intake in older people hinders muscle building, which a recent randomized trial now seems to confirm.

The role of choline in the functioning of muscles

We need choline to produce a chemical messenger, acetylcholine, which regulates muscle contraction and effort, among other things, but it is also essential for the production of betaine and creatine.

Many of you will have heard of the benefits of creatine for muscle and strength development, but betaine from choline can also improve physical performance. (1) It is therefore not surprising that insufficient choline intake can reduce our progress during exercise.

Although our bodies can produce choline, this is only a fraction of our daily requirement; if not met, liver, muscle and nervous system damage can develop over time. (2)

The link between choline and physical performance

The recommended daily intake is between 400 and 550 mg, of which a significant proportion of people consume only a fraction. (3,4)

Although supplementation with much higher than recommended levels of choline did not significantly improve physical performance, (5) it has been suggested that low intakes may have negative effects on muscle function and may reduce progress after resistance training. This hypothesis was then tested in two studies in 2023.

Effects of low and of adequate choline intake

The aim of the first study was to investigate the relationship between choline intake and progress after resistance training. (6)

This involved 46 elderly individuals, aged between 60 and 69, following an effective resistance training program for 12 weeks. Their body composition was assessed using one of the most accurate (DEXA) tests for this purpose before and after the experiment, and single repetition maxima were assessed to study the change in strength level in the main exercises.

The average choline intake of the participants was calculated using dietary diaries, on the basis of which they were divided into three groups:

• Low - less than 50% of recommended intake
• Moderately low - ~63% of recommended intake
• Fair - ~85% of recommended intake

Results

After 12 weeks, the rate of force increase (leg kicks+ chest presses) was much lower in the low choline intake group compared to the other groups (low: ~31%, medium low: ~70.3%, adequate: ~81.9%).

Protein, dietary cholesterol and other nutrient intakes did not significantly change the above results. In addition to the slowing of strength gains, participants in the low choline group also built significantly less muscle over the 12 weeks, averaging only 1.3 kg compared to 3.2 kg in the high choline group.

 

(Force level as percentage

Low – middle – sufficient

Average choline intake)

*The figure below illustrates the change in the force level.

The second study

This startling result led to a better controlled randomized trial in which older people aged 50-69 years followed a 12-week exercise programmer and were similarly divided into 3 groups - in this study, however, they were also supplemented with varying amounts of extra choline in the form of egg yolk. (7)

With supplementation, the choline intake of the three groups was as follows:

• Low group - 51% of the recommended intake
• Medium group - 68% of recommended intake (same diet +1 egg yolk per day)
• High group - 118% of recommended intake (same diet +3 egg yolks per day)

The participants' diets were identical in macronutrient and calorie content and their composition was in line with official dietary recommendations, except for dietary cholesterol.

As egg yolks are very nutrient-dense, choline intake was associated with higher intakes of other micronutrients, including vitamins B5, B6, B9, B12, and so these were also taken into account in the analysis of the tests.

Results

Compared to the low-intake group, members of both the medium and high choline intake groups gained more than twice as much weight after 12 weeks. No significant difference was found in terms of muscle mass, although here too, on average, those who consumed more choline gained about 1 kg more muscle mass.

 

(Change in force level as percentage

low – middle – high

Average choline intake)

*The below figure shows the difference.

The two studies show that an excessively low intake of choline - about half of the officially recommended intake (~200 mg/day) - already significantly reduces post-exercise development, both in terms of strength and muscle mass. At less than ~65% of daily intake (~250 mg), an increasing decline in performance can be expected.

The anabolic and performance enhancing effects of eggs

Long before modern research, bodybuilders and other athletes observed the benefits of egg consumption for muscle mass growth and improved athletic performance. It was not uncommon for some athletes to consume as many as 12-24 eggs a day.

Eggs are one of the best utilized sources of protein, (8) but they also contain a whole host of vitamins, minerals and other special substances. Think about it: a single egg provides enough nutrients for a chick to grow.    

Egg yolks and liver are by far the richest sources of choline, (9) so anyone who eats egg dishes on a daily basis need not worry about a lack of it. But that's not the only reason egg yolks can be beneficial: some research suggests that their cholesterol content also promotes muscle growth. (10) Although many people think of cardiovascular disease when they hear the word cholesterol, in fact everyone needs it and it has many beneficial biological functions within our bodies.

Of course, too high a level can be a problem, but dietary cholesterol intake is not significantly associated with cardiovascular risk, which is why the dietary recommendations have been removed. (11) Egg yolks have a balanced fatty acid profile, mainly containing the same monounsaturated fatty acid as olive oil. (12)

During a 12-week exercise programmer, older individuals with higher dietary cholesterol intakes gained significantly more muscle mass, (13) while a 2017 study demonstrated that eating a whole egg boosts protein synthesis more than egg white. (14) Egg yolks are rich in choline, dietary cholesterol, protein and fat, which may all explain this result. 

Summary

Choline is essential for biological processes such as proper muscle function and recovery after exercise.

Consuming less than ~65% of the daily recommended intake can significantly reduce physical performance and negatively affect strength and muscle mass. The majority of people do not reach the recommended daily intake of choline, especially those who do not consume liver or eggs on a daily basis - the latter being the best way to meet our choline needs. A couple of eggs a day is almost nothing to be afraid of: they are very good for your health, especially if they are not cooked in heavy fat or oil.

As well as eggs, there are some more specific foods that are particularly good sources of choline, which you can find in our brief summary of choline and in the 'What it's found in' tab.