What are the dangers of taking choline? A guide to risks and side effects

October 6, 2025 •

3 min read

While choline is an essential nutrient vital for healthy brain function, cell structure, and metabolism, excessive intake from supplements can pose significant risks. High doses, well above recommended levels, can cause unpleasant side effects and potentially serious health complications. Understanding what are the dangers of taking choline is crucial for anyone considering supplementation, as the risks far outweigh the benefits at toxic levels.

Quick Summary

Excessive choline intake, almost exclusively from high-dose supplements, can cause a fishy body odor, excessive sweating, gastrointestinal distress, and low blood pressure. Some research also suggests a link between high choline levels and an increased risk of cardiovascular issues. The tolerable upper intake level for adults is 3,500 mg per day.

Key Points

Tolerable Upper Intake Level: For healthy adults, the maximum daily intake unlikely to cause harm is 3,500 mg, primarily from high-dose supplements.
Fishy Body Odor: High choline consumption can lead to the production of trimethylamine (TMA) by gut bacteria, causing a distinct fishy smell.
Gastrointestinal Problems: Nausea, vomiting, and diarrhea are common side effects when exceeding the recommended intake via supplements.
Blood Pressure Drop: Very high doses of choline can induce hypotension, or low blood pressure, in some individuals.
Potential Cardiovascular Risk: The metabolism of choline can produce TMAO, a compound controversially linked to an increased risk of heart disease.
Susceptible Groups: Individuals with liver or kidney disease, or the genetic condition trimethylaminuria, are more vulnerable to adverse effects.
Consult a Doctor: It is critical to consult a healthcare provider before taking high-dose choline supplements, especially if you have existing health concerns.

Choline is a water-soluble compound essential for vital bodily functions, including nerve signaling and metabolism. While the body produces some choline, most comes from foods like eggs and meat. Deficiency can lead to liver or muscle damage, but risks are primarily associated with excessive intake, nearly always from high-dose supplements.

The side effects of excessive choline intake

Exceeding the Tolerable Upper Intake Level (UL) of 3,500 mg per day for adults, usually through supplements, can cause various adverse effects.

Fishy body odor: High choline can lead to a fishy odor in sweat, breath, and urine as gut bacteria convert it to trimethylamine (TMA). Normally, the liver converts TMA to odorless TMA N-oxide (TMAO), but excess choline or the condition trimethylaminuria can overwhelm this process.
Gastrointestinal distress: High doses can cause nausea, vomiting, and diarrhea.
Hypotension: Excessive intake may lower blood pressure, causing dizziness.
Excessive sweating and salivation: High choline levels can overstimulate the nervous system, increasing sweating and salivation.

The link between choline, TMAO, and cardiovascular risk

Choline is converted to TMA and then TMAO, which some research links to increased cardiovascular risk. However, this link is still debated and under investigation, potentially being more relevant for those with specific gut bacteria or high intakes of both choline and carnitine. Risks are less associated with dietary choline than with high-dose supplements.

Who is most at risk of choline dangers?

Some individuals are more sensitive to excess choline. These include:

Genetic conditions: Those with trimethylaminuria have difficulty processing TMA, increasing the risk of fishy odor.
Liver or kidney disease: These conditions can impair the body's ability to process and excrete excess choline.
Specific neurological conditions: High doses have been rarely linked to depression and worsening Parkinson's symptoms.

Dietary intake vs. supplement-driven risks

It's difficult to reach toxic levels of choline through diet alone. High-choline foods include eggs, liver, fish, and certain vegetables. Supplements, however, can easily exceed the UL. Common forms in supplements are choline bitartrate and phosphatidylcholine. Always check labels and consult a doctor before exceeding recommended doses.

Choline Intake Comparison: Food vs. Supplements


Aspect	Dietary Intake	Supplement Intake	Recommended for Adults	Tolerable Upper Limit (UL) for Adults	Associated Risks	Source of Risk	How to stay safe?
Typical Level	Generally below AI (425-550mg)	Highly variable, often high doses	425-550 mg/day	3,500 mg/day	Mild side effects	Not a significant risk	Maintain balanced diet
Risk of Toxicity	Extremely low	High with large doses	-	-	Fishy odor, GI issues, hypotension	Excessive supplementation	Follow UL guidelines
Cardiovascular Risk	Mixed evidence, low risk	Higher TMAO production	-	-	Potential heart disease link (controversial)	Gut bacteria + high doses	Moderation, consult doctor
Liver Impact	Prevents fatty liver disease	Can cause toxicity at very high levels	-	-	Liver toxicity	Massive doses	Don't exceed UL

Conclusion

Choline is essential, and a balanced diet is usually sufficient. Supplements should be used cautiously due to potential side effects at high doses. The UL of 3,500 mg per day for adults is a safety guideline. Consult a healthcare professional before taking high-dose supplements, especially with existing health conditions.

For details on choline intake levels, refer to the NIH Office of Dietary Supplements.

Symptoms of Excessive Choline Intake

Unpleasant odors: Fishy smell from body, sweat, and breath.
Digestive issues: Nausea, vomiting, and diarrhea.
Cardiovascular effects: Low blood pressure (hypotension).
Increased sweating: Excessive sweating and salivation.
Neurological effects: Possible link to depression in some individuals at very high doses.

Frequently Asked Questions

The most common side effects of too much choline include a fishy body odor, excessive sweating, gastrointestinal issues such as diarrhea and vomiting, and low blood pressure (hypotension).

Yes, high-dose choline supplements can cause a fishy body odor. This is due to the breakdown of choline into trimethylamine (TMA) by gut bacteria. When the liver cannot process the TMA fast enough, it is released through sweat and other bodily fluids, causing the odor.

The Tolerable Upper Intake Level (UL) for choline for adults is 3,500 mg per day. Exceeding this amount, typically through high-dose supplementation, increases the risk of experiencing adverse side effects.

It is highly unlikely for a healthy individual to consume a toxic level of choline from food alone. The risk of toxicity is almost exclusively associated with high-dose dietary supplements.

Some studies suggest a link between high choline intake and increased production of TMAO, a substance potentially associated with a higher risk of cardiovascular disease. However, research on this topic is mixed, and more evidence is needed to confirm a causal relationship.

Individuals with pre-existing liver or kidney disease may be more susceptible to the adverse effects of high choline intake because their bodies may have difficulty processing and eliminating excess amounts of the nutrient.

Very high doses of choline can cause a significant drop in blood pressure, a condition known as hypotension. This can result in symptoms such as dizziness and lightheadedness.