Does Exercise Reduce Choline? Understanding the Impact on Your Body

January 2, 2026 •

4 min read

Studies on marathon runners have shown significant drops in plasma choline levels, sometimes by as much as 40%. This phenomenon is especially relevant for endurance athletes and can have measurable effects on physical performance and fatigue.

Quick Summary

Intense, long-duration exercise depletes circulating choline levels, which can affect muscle function and endurance. The effect is most pronounced in strenuous activities like marathons, though supplementation can help mitigate the decline.

Key Points

Duration and Intensity are Key: Significant drops in choline primarily occur during long-duration, high-intensity endurance exercise like marathons, not shorter, less strenuous activity.
Choline is an Acetylcholine Precursor: Exercise increases the demand for the neurotransmitter acetylcholine, which is synthesized from choline, leading to its depletion from the bloodstream.
Supplementation Can Prevent Depletion: Studies show that consuming choline supplements before or during prolonged exercise can prevent the exercise-induced reduction of choline levels.
Depletion May Affect Performance: A drop in free choline can weaken nerve impulse transmission to muscles, potentially contributing to exercise-induced fatigue and impacting performance.
Dietary Intake is Crucial: Since the body cannot synthesize sufficient choline, dietary sources like eggs, meat, and soy are important, especially for athletes or individuals with lower intake.
Cell Membrane Integrity is at Risk: In cases of prolonged, severe choline deficiency, the body may break down cell membranes (made of phosphatidylcholine) to meet demand, potentially leading to muscle damage.

The Role of Choline in the Body

Choline is an essential, water-soluble nutrient vital for numerous physiological processes, from neurotransmission to cellular structure and metabolism. While the body can produce some choline internally, dietary intake is necessary to meet overall needs. For athletes and those who are regularly physically active, understanding choline's role is particularly important.

The Choline-Acetylcholine Connection

One of choline's most critical functions is its role as a precursor to acetylcholine (ACh). This neurotransmitter is responsible for relaying signals from the brain to the muscles, initiating muscle contraction and force generation. During physical activity, especially sustained efforts, the demand for ACh increases dramatically. As ACh is broken down and resynthesized at the neuromuscular junctions, the body draws on its circulating choline reserves. This elevated demand is the primary driver behind the observed reduction in blood choline levels during intense exercise.

Choline and Cellular Integrity

Beyond its role in neurotransmission, choline is a key building block for phosphatidylcholine (PC), a primary component of cell membranes. In situations of prolonged or severe choline deficiency, the body may begin to mobilize PC from its own cell membranes, including muscle cells, to maintain circulating choline levels. This process compromises the integrity of the cell membranes, leaving muscle fibers vulnerable to damage and contributing to muscle fatigue and other issues. Indicators of muscle damage, like elevated creatine kinase (CK) in the blood, have been noted in cases of extreme choline deficiency.

Exercise and Choline Depletion

The extent to which exercise affects choline levels is not uniform across all types of physical activity. Evidence strongly suggests that the duration and intensity of the exercise are the most significant factors determining the degree of choline reduction.

Duration and Intensity Matter

Numerous studies confirm that intense and prolonged endurance exercise is most likely to cause a significant drop in blood choline levels. For instance, runners in the Boston Marathon experienced decreases of up to 40%. This was not observed in shorter or less intense exercises. The physiological stress of a long-haul effort, typically exceeding two hours at a high percentage of maximal oxygen uptake (VO2max), pushes the body's demand for choline beyond what can be readily supplied, leading to depletion.

Key factors contributing to exercise-induced choline depletion include:

Increased Acetylcholine Synthesis: High rates of muscle contraction during prolonged exercise necessitate continuous production of ACh, consuming choline.
Enhanced Methyl Group Metabolism: Intense physiological stress increases the demand for methyl groups, for which choline is a donor. This process further draws down choline reserves.
Cell Membrane Breakdown: In cases of insufficient free choline, the body may turn to structural phosphatidylcholine in cell membranes, weakening them and causing damage.

Comparison Table: Exercise Type and Choline Impact


Exercise Type	Duration/Intensity	Choline Level Impact	Key Mechanism
Marathon Running	Prolonged (>2h), high intensity	Significant decrease (up to 40%)	High demand for acetylcholine for continuous muscle contraction
Sprint/Olympic Triathlons	Shorter duration, high intensity	Moderate decrease (e.g., ~15%)	Elevated but less sustained acetylcholine demand than ultra-endurance
Weight Training	Variable, often shorter duration	Minimal to no significant decrease	Less reliance on sustained cholinergic nerve signaling during resistance exercise
Moderate Cycling	Shorter duration (<2h), medium intensity	Often no change or minimal effect	Lower overall demand for free choline from circulation

The Role of Choline Supplementation

For endurance athletes, supplementation can be a viable strategy to prevent or mitigate exercise-induced choline depletion.

Counteracting Depletion

Research has shown that consuming choline supplements, such as phosphatidylcholine (PC) or choline salts, before and during prolonged exercise can prevent the decline in plasma choline levels. One study involving cyclists found that supplementing with PC allowed plasma choline concentrations to remain stable during a two-hour cycling session, whereas the placebo group experienced a drop. Supplementation may be most beneficial for athletes starting with lower baseline choline levels.

Potential Performance Effects

While the evidence is not universally conclusive, some studies suggest that maintaining choline levels through supplementation may benefit performance in ultra-endurance events. Some runners and swimmers experienced improved performance outcomes and reduced perceived fatigue when supplemented with choline. However, other studies on shorter duration or less intense exercise found no performance benefit from choline supplementation, reinforcing the importance of exercise type.

Dietary Sources of Choline

Ensuring adequate dietary intake is the foundation of preventing choline depletion. Choline is found in a variety of foods, though many of the richest sources are animal-based.

Rich dietary sources include:

Eggs: A single egg yolk is one of the densest sources of choline.
Meat and Organ Meats: Beef, chicken, and especially liver are excellent sources.
Fish: Certain fish species provide significant amounts of choline.
Soybeans and Cruciferous Vegetables: For vegetarians and vegans, soybeans, broccoli, and Brussels sprouts are good options.

Given that estimates suggest a significant portion of the population may not meet adequate choline intake, active individuals might need to be more conscious of their dietary choices.

Conclusion

In summary, exercise does reduce choline, but this effect is largely dependent on the duration and intensity of the activity. Strenuous, prolonged endurance events are the primary culprit, causing a drop in circulating choline by increasing the demand for acetylcholine and other metabolic processes. This can impact muscle function and contribute to fatigue. For athletes engaged in such activities, strategic choline supplementation, in conjunction with a diet rich in choline-containing foods, can help counteract this depletion and support performance. While more research is always beneficial, current evidence suggests that proper choline intake is a valuable consideration for anyone pushing their body's endurance limits, safeguarding both muscle and cellular integrity during prolonged exertion.

For more detailed physiological insights, a review published in the Journal of the International Society of Sports Nutrition provides further analysis: Phospholipids and sports performance - PMC.

Frequently Asked Questions

No, significant reductions in choline levels are primarily associated with prolonged, high-intensity endurance exercise, such as marathon running or long-distance cycling. Shorter or less strenuous workouts typically do not deplete choline.

Strenuous exercise depletes choline because of the increased demand for acetylcholine, a neurotransmitter essential for muscle contraction, as well as an increased need for choline's methyl groups in other metabolic processes.

While supplementation can prevent the drop in choline levels during prolonged exercise, studies have mixed results on performance improvements. Some suggest a benefit during ultra-endurance events, but not all research confirms a direct performance enhancement.

Low choline levels can lead to premature fatigue by reducing acetylcholine synthesis. In cases of severe, prolonged deficiency, the body may break down cell membranes, causing muscle damage and potentially impacting nerve function.

Excellent dietary sources of choline include eggs, beef, chicken, liver, and some types of fish. Plant-based sources include soybeans, broccoli, and Brussels sprouts, which are important for those with lower consumption of animal products.

Choline is a precursor for acetylcholine (ACh). During exercise, nerve signals trigger the release and synthesis of more ACh. As ACh is rapidly used and recycled, the body pulls from its circulating choline reserves to keep up with the increased demand.

Yes, studies have shown that supplementation with krill oil, a source of phosphatidylcholine, can help maintain or increase circulating choline levels during endurance competitions compared to a placebo.