What Are the Symptoms of High Choline Levels?

October 22, 2025 •

4 min read

The Tolerable Upper Intake Level (UL) for adults is 3,500 mg of choline daily, with intakes exceeding this threshold possibly causing symptoms of high choline levels, such as a distinct body odor. This is a rare occurrence caused primarily by high-dose supplements, as reaching this level through diet alone is nearly impossible.

Quick Summary

Excessive intake of choline, typically from high-dose supplements, can lead to several unpleasant side effects. These common reactions include a fishy body odor, excessive sweating, digestive upset, and low blood pressure.

Key Points

Fishy Body Odor: Excessive choline intake is notoriously associated with a strong, unpleasant fishy body odor, caused by the buildup of trimethylamine.
Gastrointestinal Distress: Common digestive symptoms of too much choline include nausea, vomiting, and persistent diarrhea.
Cardiovascular Effects: High choline levels can lead to hypotension, or low blood pressure, which may cause dizziness and is a key factor in establishing safety limits.
Excessive Sweating: Heavy sweating and increased salivation are also symptoms that can accompany high choline intake.
Supplement-Induced Toxicity: High choline levels are almost always the result of consuming excessive amounts via supplements, not through diet alone.
Liver Strain: Very high doses of choline can potentially cause liver toxicity, placing undue stress on this vital organ.

Common Side Effects of Excessive Choline Intake

High levels of choline can occur when an individual consumes an amount far greater than the recommended daily allowance, most often through dietary supplements. While choline is an essential nutrient vital for several bodily functions, excess amounts can overwhelm the body's metabolic pathways and lead to a variety of symptoms. The most well-known and often reported side effect is the development of a distinct, unpleasant body odor.

Gastrointestinal Distress

One of the most immediate and common signs of excessive choline intake is digestive upset. The gastrointestinal tract is often the first system to react to a high concentration of the nutrient, leading to several noticeable symptoms. These effects can range from mild discomfort to more severe issues that significantly impact daily life.

Key gastrointestinal symptoms include:

Nausea and Vomiting: A feeling of sickness and potential vomiting is a well-documented side effect of high choline doses.
Diarrhea: Excess choline can lead to a significant increase in bowel movements, resulting in diarrhea.
Increased Salivation: Some individuals may experience excessive drooling or salivation.

These symptoms typically appear in tandem and are a clear indicator that choline intake is too high for the body to process effectively.

The Characteristic 'Fishy' Body Odor

Perhaps the most unusual and socially challenging symptom of high choline levels is a fishy body odor. This occurs because choline is metabolized in the body, primarily in the liver, into a substance called trimethylamine (TMA). In healthy individuals, TMA is further metabolized into a non-odorous compound and excreted. However, when choline intake is excessive, the body's ability to process TMA is overloaded, leading to its accumulation. The excess TMA is then released through sweat, breath, and urine, causing the strong, fishy smell. A rare genetic condition called trimethylaminuria can also cause this symptom, but in cases of high choline, it's a direct result of over-supplementation.

Cardiovascular and Other Effects

Beyond the more obvious and immediate symptoms, high choline intake can also affect the cardiovascular system and potentially cause other health issues. It is important to monitor these less-obvious signs, especially when taking high-dose supplements.

Hypotension (Low Blood Pressure): Large doses of choline can lead to a drop in blood pressure, potentially causing symptoms like dizziness or lightheadedness. This effect is one of the primary reasons the Tolerable Upper Intake Level was established.
Excessive Sweating: In addition to contributing to body odor, excessive sweating is a direct side effect of high choline intake.
Liver Toxicity: In rare cases and at very high doses, liver toxicity has been observed. The liver is crucial for metabolizing choline, and excess levels can place a strain on its function.
Cardiovascular Disease Risk: Some research suggests a link between high choline intake and an increased risk of cardiovascular disease, potentially due to the production of TMAO (trimethylamine-N-oxide). However, the research on this is mixed and ongoing, and more studies are needed to understand the connection.

Comparison: Recommended Intake vs. Excessive Intake

This table outlines the key differences between consuming a healthy amount of choline and an excessive amount.


Feature	Healthy Choline Intake (e.g., AI for adults is 425–550 mg/day)	Excessive Choline Intake (e.g., >3,500 mg/day for adults)
Source	Primarily from dietary sources like eggs, meat, fish, and vegetables.	Typically from high-dose dietary supplements.
Effect on Body	Supports essential functions like cell structure, brain development, and fat transport.	Overwhelms metabolic pathways, leading to side effects.
Body Odor	Normal body odor.	Distinct and unpleasant fishy body odor due to TMA production.
Digestive System	Regular, healthy digestion.	Nausea, vomiting, diarrhea, and upset stomach.
Blood Pressure	Maintains normal, healthy blood pressure.	Can cause a drop in blood pressure (hypotension).
Overall Risk	Very low health risk.	Increased risk of unpleasant side effects and potential long-term issues.

When to See a Doctor

While most cases of high choline intake are temporary and resolve by reducing supplement dosage, it is crucial to consult a healthcare provider in certain situations. Immediate medical attention is recommended if you experience severe symptoms, such as significant drops in blood pressure (hypotension) leading to dizziness or fainting. You should also talk to a doctor if you experience persistent nausea, vomiting, or diarrhea after starting a choline supplement. Individuals with pre-existing conditions like liver disease or a known genetic predisposition for trimethylaminuria should be especially careful and always consult a doctor before starting new supplements.

Preventing High Choline Levels

The best way to prevent excessive choline intake is to be mindful of your supplement dosage. As established, it is extremely difficult to consume toxic levels of choline through food alone, making supplements the primary culprit. Most individuals can meet their daily choline needs through a balanced diet, so supplementation is often unnecessary unless advised by a healthcare professional. Always read supplement labels carefully and adhere to the recommended dosages. If you suspect your symptoms are related to high choline, the simplest and most effective solution is to reduce your dosage or stop taking the supplement entirely, which should lead to the resolution of symptoms.

Conclusion

Understanding what are the symptoms of high choline levels is crucial for anyone taking high-dose supplements. The most telling signs are a fishy body odor and various forms of gastrointestinal upset, while more serious issues like low blood pressure and liver concerns can also arise. Excessive intake is almost exclusively a result of over-supplementation, not diet. By adhering to recommended dosage guidelines and consulting a healthcare professional when symptoms appear, you can mitigate the risks associated with high choline levels and maintain a healthy balance of this essential nutrient.

For more detailed information on nutrient intake and health guidelines, refer to the NIH Office of Dietary Supplements.

Frequently Asked Questions

Yes, very high intakes of choline can be dangerous. While mild symptoms like a fishy body odor and digestive upset are more common, excessive levels can lead to more serious issues such as low blood pressure (hypotension) and liver toxicity.

The Tolerable Upper Intake Level (UL) for adults is 3,500 mg per day. Consuming more than this amount increases the risk of side effects like fishy body odor, digestive upset, and low blood pressure.

It is highly unlikely to get dangerously high levels of choline from food alone, even from rich sources like eggs and beef liver. Excessive choline intake almost always comes from taking high-dose dietary supplements.

The most effective treatment is to reduce or stop the intake of the choline supplement causing the issue. Once the body's choline levels return to a normal range, the production of the odor-causing trimethylamine will decrease, and the smell will dissipate.

Some studies suggest a potential link between high choline intake and an increased risk of cardiovascular disease, partly due to the production of TMAO. Research on this topic is still mixed, and more evidence is needed.

No, high choline levels and choline deficiency are opposite conditions. Deficiency can lead to fatty liver disease and muscle damage, while high levels cause symptoms like a fishy body odor, digestive issues, and hypotension.

The first step is to reduce or stop your choline supplement intake. If symptoms are severe or persistent, or if you have pre-existing health conditions, consult a healthcare provider to determine the appropriate course of action.

While generally not known to interact with many medications, it's wise to discuss all supplements with your doctor. High-dose choline could potentially decrease the effect of some medications, such as atropine.