Can Chocolate Cause Atrial Fibrillation? Separating Fact from Fiction

October 27, 2025 •

4 min read

According to a large 2017 study published in the journal Heart, moderate chocolate consumption was associated with a lower risk of atrial fibrillation (AFib). While this may seem counterintuitive given chocolate contains stimulants, the link between chocolate and AFib is complex and largely dependent on consumption amount, type of chocolate, and individual sensitivity.

Quick Summary

Investigating whether chocolate can cause atrial fibrillation, this article explores the scientific evidence behind the claim, focusing on the effects of caffeine and other compounds in chocolate on heart rhythm. It distinguishes between moderate intake and overconsumption, examining factors that influence individual risk.

Key Points

Moderate Intake: A large Danish study found that moderate chocolate consumption (1-6 servings/week) was associated with a lower risk of clinically apparent atrial fibrillation.
Caffeine Content: The caffeine levels in chocolate are significantly lower than in coffee, with dark chocolate containing more than milk chocolate. White chocolate has none.
Overconsumption Risk: Excessive chocolate intake, particularly high-cocoa varieties, could potentially trigger arrhythmias in susceptible individuals due to stimulant overload from methylxanthines like caffeine and theobromine.
Beneficial Compounds: The cardiovascular benefits of chocolate are often attributed to its high concentration of flavonoids and antioxidants, especially in dark chocolate, which can improve endothelial function and reduce inflammation.
Key Triggers: Other major and more common AFib triggers include excessive alcohol, high-sodium diets, processed foods, stress, and stimulant abuse, all of which are generally more impactful than moderate chocolate consumption.
Individual Sensitivity: A person's unique sensitivity to stimulants is a critical factor. For those prone to palpitations, any amount of a trigger, including caffeine, might be problematic.

Unpacking the Science: How Chocolate’s Components Affect the Heart

Chocolate, derived from cocoa beans, contains several compounds that can impact the cardiovascular system. The most relevant of these are methylxanthines, which include caffeine and theobromine. While often grouped, they have different effects and potencies.

Caffeine: The Stimulant Factor

Caffeine is a well-known stimulant that can increase heart rate and blood pressure, particularly in individuals sensitive to it or when consumed in large amounts. For many years, doctors advised patients with AFib to avoid caffeine, though recent research suggests that moderate intake may not directly cause or worsen AFib in most individuals. However, excessive consumption, such as from high-caffeine energy drinks, is a known risk factor. While chocolate contains caffeine, the amount is significantly lower than in coffee.

Theobromine: The Heart-Healthy Component?

Theobromine is the other major methylxanthine in chocolate and acts as a milder stimulant than caffeine. It is also known to be a vasodilator, meaning it widens blood vessels, and has diuretic properties. Some research has even linked theobromine to improved cardiovascular health, although excessive doses can be stimulating. The concentration of theobromine is much higher in dark chocolate, which also contains beneficial flavonoids.

Flavanols and Antioxidants: The Protective Elements

Dark chocolate, in particular, is rich in flavonoids, which are powerful antioxidants. These compounds are believed to have anti-inflammatory and blood vessel-relaxing properties. Many studies highlighting the health benefits of chocolate, including potential cardioprotective effects, attribute them to these flavanols. The observational Danish study showing a lower AFib risk with moderate chocolate consumption theorized that these flavonoids might be the responsible factor.

The Verdict: Context is Everything

So, can chocolate cause atrial fibrillation? The short answer is: probably not in moderation, and in some cases, it might even be beneficial. The risk, if any, is tied to overconsumption of chocolate, particularly high-caffeine varieties, and individual sensitivity to stimulants. The vast majority of studies, including a 2017 Danish study, suggest that moderate intake is not associated with an increased risk and may even be linked to a lower rate of AFib. However, for someone with known AFib triggers, it's wise to monitor personal reactions.

Here’s a breakdown of the differences between chocolate types and their potential effects on AFib:


Chocolate Type	Caffeine Content (per ounce)	Key Ingredients	Potential AFib Impact
Dark Chocolate (70-85% cacao)	~23 mg	High in cocoa solids, flavonoids, theobromine; some caffeine.	Moderate intake linked to lower AFib risk in some studies due to flavanols. Overconsumption may pose a risk due to stimulants.
Milk Chocolate	~6 mg	Lower in cocoa solids and flavanols; added milk and sugar.	Very low stimulant content, but high sugar and fat can negatively impact heart health overall.
White Chocolate	0 mg	Contains cocoa butter, milk, and sugar; no cocoa solids.	No caffeine, but provides no cardioprotective benefits and is high in sugar and calories, which can contribute to other AFib risk factors like weight gain.

Other Dietary and Lifestyle Triggers for Atrial Fibrillation

While chocolate is generally not a major concern, other factors in a person's diet and lifestyle are known AFib triggers. Managing these is often more impactful for heart rhythm control.

Excessive alcohol: Binge drinking is a well-known trigger, and some individuals are sensitive to even modest amounts.
High-sodium foods: Excessive salt intake can contribute to high blood pressure, a significant risk factor for AFib.
Processed and sugary foods: High intake of ultra-processed foods, high sugar, and saturated fats can contribute to obesity and other heart-related issues that increase AFib risk.
Stimulant abuse: Use of illegal drugs like cocaine or amphetamines, as well as high-caffeine energy drinks, can trigger or worsen AFib.
Dehydration: Lack of adequate fluid intake can affect electrolyte balance and potentially trigger palpitations.
Stress: High levels of emotional or physical stress are linked to a higher risk of AFib.

Conclusion: Moderation is Key for Chocolate Lovers

For most people, a moderate amount of chocolate, particularly dark chocolate with its higher cocoa content and beneficial flavonoids, is a healthy part of a balanced diet and is not considered a cause of atrial fibrillation. Overconsumption, however, can introduce stimulants like caffeine and theobromine in higher doses, which may affect susceptible individuals. The overall picture of heart health, including factors like weight, diet, exercise, and alcohol intake, is far more significant than moderate chocolate consumption. If you have been diagnosed with AFib, it's always best to consult with a healthcare professional to identify your specific triggers and manage your diet accordingly. The key is to enjoy chocolate in moderation and opt for darker varieties for maximum health benefits with minimal stimulant impact.

For more information on AFib and heart-healthy lifestyle choices, visit the American Heart Association website: https://www.heart.org/en/health-topics/atrial-fibrillation/treatment-and-prevention-of-atrial-fibrillation/lifestyle-strategies-for-afib.

Frequently Asked Questions

For most people with AFib, moderate chocolate consumption is safe and unlikely to cause issues. However, if you are particularly sensitive to stimulants like caffeine or have other known triggers, it is best to monitor your personal reaction and consult a healthcare provider.

While some observational studies, such as one in Denmark, have shown an association between moderate dark chocolate intake and a lower risk of AFib, the evidence is not conclusive. It is not proven that chocolate directly prevents AFib, but its flavonoid content offers other heart-healthy benefits.

The caffeine content in chocolate is much lower than in a typical cup of coffee. An average 1-ounce serving of dark chocolate has about 23mg of caffeine, while a cup of coffee has around 80-155mg. The risk from caffeine in chocolate is therefore much smaller.

Theobromine is a natural stimulant found in cocoa. It is a milder stimulant than caffeine and can act as a vasodilator (widening blood vessels). At very high doses, it can be stimulating, but in the quantities found in moderate chocolate intake, it is generally not a concern.

No, a complete avoidance of chocolate is typically not necessary. For individuals concerned about stimulants, white chocolate is a caffeine-free option. However, the overall diet and moderation are more important factors than small amounts of chocolate.

Yes, regardless of caffeine content, chocolates high in sugar and saturated fats (like milk and white chocolate) can negatively impact overall cardiovascular health by contributing to weight gain and metabolic problems, which are risk factors for AFib.

Rather than focusing solely on chocolate, it is more beneficial to manage other known dietary triggers such as excessive alcohol, high-sodium foods, and large amounts of processed or sugary items. A heart-healthy diet, like the Mediterranean diet, is often recommended.