What are the risks of too much choline?

January 12, 2026 •

4 min read

While most Americans consume less than the recommended amount of choline, a tolerable upper intake level (UL) for adults is set at 3,500 mg per day. Exceeding this amount, primarily through high-dose supplements, can lead to the risks of too much choline, including several unpleasant and potentially harmful side effects.

Quick Summary

Excessive choline intake, almost exclusively from high-dose supplements, can cause adverse side effects. These include a fishy body odor, gastrointestinal issues, low blood pressure, and excessive sweating. The adult upper limit is 3,500 mg daily.

Key Points

Tolerable Upper Limit: The safe upper intake level for adult choline consumption is 3,500 mg per day from all sources, including food and supplements.
Supplementation is the Main Risk: Overconsumption and toxicity from choline are almost exclusively linked to high-dose supplements, as it is very difficult to exceed the UL from food alone.
Fishy Body Odor: A distinctive side effect of too much choline is a strong, fishy body odor caused by excess trimethylamine.
Gastrointestinal and Cardiovascular Side Effects: Excess choline can lead to unpleasant digestive issues like nausea and diarrhea, as well as a drop in blood pressure (hypotension). Some studies also link high intake to an increased risk of heart disease via TMAO production.
Vulnerable Populations: Individuals with certain genetic conditions (like trimethylaminuria) or pre-existing health issues (liver/kidney disease) may be more susceptible to the adverse effects of high choline intake.
Moderation is Best: For most people, a balanced diet is enough to meet choline requirements, and supplementation should be used cautiously and under the guidance of a healthcare provider.

The Dangers of Excessive Choline Intake

Choline is an essential nutrient vital for several bodily functions, including liver health, brain development, and metabolism. While many people do not meet the recommended daily intake from diet alone, excessive supplementation can push levels into a toxic range, leading to various adverse health effects. Understanding the signs of choline toxicity and the safe upper limits is critical for anyone considering high-dose supplementation.

Common Side Effects of Choline Overconsumption

Consuming choline above the established Tolerable Upper Intake Level (UL) can trigger a range of uncomfortable symptoms. These are typically dose-dependent and become more pronounced with higher intakes.

Fishy Body Odor: This is one of the most distinctive and well-documented side effects of excessive choline. It occurs due to the body producing an excess of trimethylamine (TMA) during choline metabolism. Some individuals with a genetic disorder called trimethylaminuria are particularly susceptible to this side effect, as their bodies cannot properly break down TMA.
Gastrointestinal Distress: High doses of choline can disrupt the digestive system, leading to symptoms like nausea, vomiting, and diarrhea. For some, even normal doses may cause mild gastrointestinal upset.
Low Blood Pressure (Hypotension): Excess choline can have a hypotensive effect, causing blood pressure to drop. In severe cases, this can lead to dizziness, lightheadedness, and fainting. This risk is particularly relevant for individuals already on blood pressure medication.
Excessive Sweating and Salivation: Overstimulation of the parasympathetic nervous system, which is linked to acetylcholine production from choline, can result in increased sweating and salivation.
Other Potential Issues: Rare cases of heart rhythm problems, depression, and liver issues have also been reported, though causality is not always definitive and may be linked to specific pre-existing conditions or different choline compounds.

The Link Between Choline and Cardiovascular Disease

An area of ongoing research and concern regarding high choline intake is its potential impact on cardiovascular health. When intestinal bacteria metabolize choline, they can produce trimethylamine (TMA). The liver then converts this TMA into trimethylamine N-oxide (TMAO).

Some studies have suggested that elevated levels of TMAO in the blood may be associated with an increased risk of cardiovascular diseases, such as atherosclerosis (hardening of the arteries). However, the relationship is complex, and other studies have found mixed or no association between dietary choline and heart disease risk. The research is still developing, and not all findings are conclusive, but it remains a notable risk factor associated with excessively high choline levels.

Tolerable Upper Intake Levels (UL) for Choline

To minimize the risk of adverse effects, the Food and Nutrition Board (FNB) has established Tolerable Upper Intake Levels (UL) for choline. These are the maximum daily intakes from food and supplements combined that are unlikely to cause adverse health effects in most healthy individuals.

Choline Upper Intake Levels


Life Stage	Upper Limit (UL)
Children 1–3 years	1,000 mg/day
Children 4–8 years	1,000 mg/day
Children 9–13 years	2,000 mg/day
Teens 14–18 years	3,000 mg/day
Adults 19+ years	3,500 mg/day
Pregnant Teens	3,000 mg/day
Pregnant Adults	3,500 mg/day

It is important to note that it is extremely difficult to exceed the UL from diet alone. The majority of choline overconsumption occurs in individuals taking high-dose supplements. Therefore, supplementation should be approached with caution and ideally under medical supervision.

Choline from Diet vs. Supplements

Most people do not get enough choline from their diet, but the risk of toxicity from food sources is minimal. High-dose supplements, on the other hand, pose a significant risk of exceeding the UL.


Aspect	Choline from Diet	Choline from Supplements
Source	Naturally occurring in foods like eggs, liver, meat, poultry, fish, dairy, and cruciferous vegetables.	Isolated and concentrated forms, such as choline bitartrate, phosphatidylcholine, or alpha-GPC.
Toxicity Risk	Very low to negligible, as the body’s intake is regulated and distributed through food.	High, especially with large, unregulated doses, as the intake is concentrated and often exceeds normal physiological needs.
Body Odor	Not a concern at normal intake levels.	A common side effect of excess intake due to TMA production.
GI Symptoms	Unlikely to cause issues.	Can cause nausea, vomiting, and diarrhea.
Cardiovascular Risk (TMAO)	Potential link at very high intake, but often balanced by other dietary factors.	More pronounced risk due to rapid and high concentration of choline, increasing TMAO levels.

The Role of Genetics and Pre-existing Conditions

Certain individuals may be more susceptible to the adverse effects of excessive choline due to genetic predispositions or underlying health conditions. For example, individuals with inherited metabolic disorders, such as trimethylaminuria, lack the enzyme to properly process TMA and can experience an intensified fishy odor even at moderate doses. People with pre-existing liver or kidney disease may also be at increased risk because these conditions can affect the metabolism and elimination of choline. In rare cases, high choline intake has been linked to depression, and it is advised against for those with bipolar disorder.

Conclusion: Balance is Key

While choline is an essential nutrient for overall health, the risks of too much choline cannot be overlooked. The side effects, ranging from the socially disruptive fishy body odor to more serious cardiovascular concerns, are overwhelmingly linked to the excessive use of high-dose supplements rather than dietary intake. The established upper intake levels provide a critical guideline for safe consumption. For most healthy individuals, a balanced diet rich in choline-containing foods is sufficient to meet their needs without risking toxicity. For those who choose to supplement, adhering to recommended dosages and consulting a healthcare professional, especially if you have pre-existing conditions, is the safest path forward. As always, informed moderation is the best policy for maintaining your health.

For more information on the various functions of choline, refer to the NIH Office of Dietary Supplements Fact Sheet on Choline.

Frequently Asked Questions

For adults aged 19 years and older, the Tolerable Upper Intake Level (UL) for choline is 3,500 mg per day. This limit applies to total intake from both food and supplements.

It is extremely unlikely to get too much choline from your diet alone. Overconsumption and the associated side effects are typically only seen in individuals taking high-dose choline supplements.

A fishy body odor is a sign of excessive choline intake. It happens when the body produces excess trimethylamine (TMA) during metabolism, which some people with a specific genetic condition cannot break down properly.

Yes, high intake of choline has been associated with a decrease in blood pressure, a condition known as hypotension. This can lead to symptoms like dizziness.

Some research indicates that high levels of choline can increase the production of TMAO, a substance linked to a higher risk of cardiovascular disease. However, research on this link is still ongoing, and findings are mixed.

Individuals with pre-existing liver or kidney disease, those with the genetic disorder trimethylaminuria, and people with a history of depression or bipolar disorder should be cautious with choline intake. High doses are not recommended without medical supervision for these groups.

Common signs of choline toxicity include a fishy body odor, gastrointestinal issues such as diarrhea and vomiting, excessive sweating, increased salivation, and low blood pressure.