Does Choline Constipate You? The Unexpected Link to Diarrhea, Not Blockage

November 23, 2025 •

3 min read

Over 90% of Americans do not meet the recommended adequate intake of choline through diet alone. Given this widespread deficiency and the growing popularity of choline supplements, it's natural to question the potential side effects, including: does choline constipate you?

Quick Summary

Choline does not cause constipation; instead, high supplemental doses are known to cause diarrhea and other gastrointestinal distress. A deficiency in this essential nutrient is more closely associated with a risk of constipation due to its role in gut motility.

Key Points

Diarrhea is a side effect, not constipation: High doses of supplemental choline, typically exceeding the 3.5 gram UL, can cause diarrhea and other gastrointestinal upset.
Deficiency may cause constipation: A diet lacking in choline is associated with health problems, and low intake can actually contribute to constipation by hindering proper gut function.
Choline supports gut motility: As a precursor to the neurotransmitter acetylcholine, choline promotes the muscle contractions necessary for healthy bowel movements.
Dosage is key to avoiding issues: Side effects like digestive distress are linked to excessive supplemental intake, not normal dietary levels.
Consider your food sources: Dietary sources of choline like eggs and liver are unlikely to cause digestive problems due to excessive intake.
Check supplement form: Different forms of choline, like citicoline, may be better tolerated than bulk choline salts.

Choline's Role in Gut Function

Choline is an essential nutrient vital for various bodily functions, including metabolism, nerve signaling, and cell maintenance. In the context of digestive health, choline plays a critical role as a precursor to the neurotransmitter acetylcholine. Acetylcholine is a key chemical messenger in the enteric nervous system (ENS), which is the nervous system that governs the function of the gastrointestinal tract.

How Acetylcholine Affects Bowel Movements

Promotes Gut Motility: Acetylcholine signals the muscles in the digestive tract to contract and relax in a coordinated manner, a process known as peristalsis. This smooth muscle movement is what propels food and waste through the intestines.
Influences Secretion: It is also involved in the secretion of digestive juices and bile, which are necessary for proper digestion and healthy bowel movements.

Because choline is a precursor to this motility-promoting neurotransmitter, sufficient levels are actually supportive of healthy, regular bowel movements, not a cause of constipation.

Choline Deficiency vs. Choline Excess

Understanding the distinction between getting too little and too much choline is crucial for addressing the question of constipation. The side effects on the digestive system differ significantly depending on the intake level.

Symptoms of Choline Deficiency

A choline deficiency, which is quite common, is associated with a number of health issues, including liver problems. Interestingly, a poorly balanced diet leading to low choline intake has also been linked to constipation, along with other symptoms like headaches and memory impairment. If your body lacks the building blocks for sufficient acetylcholine production, gut motility can slow down, potentially contributing to infrequent bowel movements.

Symptoms of Choline Excess

High doses of supplemental choline, far exceeding dietary intake, are known to cause a different set of digestive issues. Rather than constipation, excessive choline can lead to:

Diarrhea
Nausea and vomiting
Stomach cramps
Fishy body odor due to its metabolism into trimethylamine (TMA)

These side effects most often occur when intake exceeds the Tolerable Upper Intake Level (UL) of 3.5 grams per day for adults. It is nearly impossible to reach this level from food alone; it is almost always linked to high-dose supplementation.

Managing Digestive Issues Related to Choline

If you are experiencing digestive problems while taking choline, consider the following points:

Check Your Dosage: Evaluate your supplement dosage. If it's on the higher end, particularly over 3.5 grams, it could be the cause of diarrhea. Reducing the dose may resolve the issue.
Switch Forms: Some forms of choline, like citicoline, are often reported to be more easily tolerated and less likely to cause significant gastrointestinal side effects than bulk choline salts.
Assess Total Intake: Consider your overall choline intake from both food and supplements. Foods like egg yolks, beef liver, fish, and soybeans are rich sources.
Pair with Fiber: When increasing choline, especially from foods, ensure a balanced diet with adequate fiber. Studies have shown that combining choline with prebiotics like inulin can have beneficial effects on bowel movements and other digestive symptoms in patients with constipation.

Choline Deficiency vs. Overdose: A Comparison

To summarize the different outcomes, here is a comparison table:


Symptom	Choline Deficiency	Choline Overdose
Bowel Movements	Can be linked to constipation and slow gut motility	Often results in diarrhea or loose stools
Other Digestive Issues	Impaired liver function, disrupted gut lining	Nausea, vomiting, stomach cramps
Other Symptoms	Headaches, memory issues, mood disturbances	Fishy body odor, low blood pressure, sweating
Primary Cause	Inadequate dietary intake	High-dose supplementation beyond Tolerable Upper Intake Level

Conclusion: The Answer is Not Constipation

Contrary to the common misconception, choline does not cause constipation when consumed in normal dietary amounts or sensible supplement dosages. The digestive side effect associated with high, excessive intake is actually diarrhea, a result of its cholinergic properties and metabolism. Conversely, a lack of choline has been identified as a possible contributing factor to constipation by hindering proper gut motility. If you are experiencing constipation and believe it may be related to your choline intake, a deficiency is a far more likely culprit than an excess.

For optimal gut health, it is important to maintain a balanced intake of all essential nutrients, including choline, and to consult a healthcare provider before beginning any high-dose supplementation. The National Institutes of Health provides comprehensive dietary recommendations and information on choline.

Frequently Asked Questions

Taking too much choline can cause side effects such as diarrhea, nausea, vomiting, a fishy body odor, excessive sweating, and low blood pressure. These symptoms are typically associated with high supplemental doses, not dietary intake.

Choline is generally good for digestion when consumed within recommended limits. It is a precursor to acetylcholine, a neurotransmitter that helps regulate gut motility. However, excessive intake can lead to digestive upset like diarrhea.

Yes, a choline deficiency can be a contributing factor to constipation. Choline is needed to produce acetylcholine, which promotes muscle contractions in the gut, and insufficient levels can lead to slow motility.

The Tolerable Upper Intake Level (UL) for choline for most adults is 3.5 grams (3,500 mg) per day. Side effects, including digestive issues, are more likely to occur at doses exceeding this limit.

The most common side effects from high doses of choline supplements include gastrointestinal distress such as diarrhea, nausea, and vomiting, along with a distinct fishy body odor and increased sweating.

It is highly unlikely to consume an excessive amount of choline from food sources alone. The upper intake level is very difficult to reach without high-dose supplementation.

Some studies suggest that combining choline with fiber-rich prebiotics, such as inulin, can help mitigate digestive symptoms and promote healthy bowel function. Always consult a healthcare provider for personalized advice.

Some people find that forms like citicoline are better tolerated than bulk choline salts, which are more commonly associated with gastrointestinal problems. Individual tolerance can vary.