Researchers wanted to know if eating cocoa extract supplements could change two important chemicals in your blood called TMAO and choline. These chemicals are connected to heart health. They gave some older adults cocoa supplements and others a fake pill for one year, then checked their blood. The cocoa group showed small trends toward better levels of these chemicals, but the changes weren’t big enough to be sure they were real. This was a small test run to plan a bigger study that might give clearer answers about whether cocoa really helps your heart.

The Quick Take

  • What they studied: Whether taking a cocoa extract supplement every day could lower a heart-damaging chemical called TMAO and change levels of an important nutrient called choline in the blood.
  • Who participated: 37 older adults (average age 77 years old) from a larger health study. About half were women. They were randomly chosen to either take cocoa supplements or a fake pill for one year.
  • Key finding: People taking cocoa showed small trends toward lower TMAO and higher choline after one year compared to the placebo group, but these differences were too small to be confident they were real (not just random chance).
  • What it means for you: This early test suggests cocoa might help heart health through these chemicals, but we can’t be sure yet. The researchers need to study many more people to get a clear answer. If you’re interested in heart health, talk to your doctor before starting supplements.

The Research Details

This was a pilot study, which means it was a small test run before doing a bigger experiment. The researchers took 40 older adults from a huge health study called COSMOS and randomly split them into two groups. One group took cocoa extract supplements (containing 500 mg of special plant compounds called flavanols) every day, while the other group took a fake pill that looked the same. They measured two chemicals in the participants’ blood at the start and after one year to see if the cocoa made a difference.

The researchers used a special lab technique called liquid chromatography to measure TMAO and choline in blood samples. This is like using a very precise filter to separate and count the chemicals. They also looked at whether age, sex, and other factors affected the results.

This study design is important because it’s the first step in understanding whether cocoa supplements really affect these heart-related chemicals. By testing a small group first, researchers can figure out how many people they’d need to study to get a reliable answer. This saves time and money before doing a massive study.

This was a well-designed study because it randomly assigned people to groups, which helps make sure the groups were similar at the start. The researchers measured chemicals in stored blood samples using precise lab methods. However, the sample size was very small (only 37 people), which is why the results weren’t definitive. The researchers excluded 3 people with unusual blood values, which is a reasonable quality control step.

What the Results Show

The cocoa group started with similar TMAO and choline levels as the placebo group. After one year, the cocoa group showed a small decrease in TMAO (a heart-damaging chemical) of about 0.60 units, while the placebo group’s TMAO stayed about the same. However, this difference between groups was very small and could easily have happened by chance (the researchers weren’t confident it was real).

For choline (an important nutrient), the cocoa group showed a small increase of about 0.84 units after one year, while the placebo group’s choline stayed similar. Again, this difference was too small to be confident it was real. The researchers used a statistical measure called a P-value to check if results were real—both results had P-values above 0.05, meaning they could have happened by random chance.

The study successfully created two similar groups at the start, with matching ages, genders, health conditions, and eating habits. This is important because it means any differences after one year were more likely due to the cocoa supplement rather than the groups being different to begin with. The researchers also noted that a larger study of 1,500 people would have an 84% chance of finding a real difference if one actually exists.

Previous research has shown that TMAO is linked to heart disease and that cocoa contains healthy plant compounds. However, very few studies have actually tested whether cocoa supplements change TMAO levels in real people. This pilot study is one of the first to measure this in a controlled way. The results fit with the idea that cocoa might help, but don’t prove it yet.

The biggest limitation is the small sample size—only 37 people is too small to see real effects clearly. It’s like trying to predict election results by asking only 37 people. The study only lasted one year, so we don’t know if effects would be bigger or smaller over longer time periods. The researchers also had to exclude 3 people with unusual blood values, which slightly changed the final group. Finally, all participants were older adults (average age 77), so results might not apply to younger people.

The Bottom Line

Based on this small pilot study, we cannot yet recommend cocoa supplements specifically for changing TMAO or choline levels. The evidence is too early and too limited. If you’re interested in heart health, focus on proven strategies: eat a healthy diet with lots of fruits and vegetables, exercise regularly, maintain a healthy weight, and don’t smoke. Talk to your doctor before starting any supplements, especially if you take medications.

This research is most relevant to older adults interested in heart disease prevention and researchers studying cocoa’s health effects. If you have heart disease or high cholesterol, this is interesting but not yet actionable—wait for larger studies. If you’re generally healthy, standard heart-healthy habits are still your best bet.

This is a pilot study, so don’t expect immediate changes. The researchers are planning a much larger study with 1,500 people that will take several years. Real answers about whether cocoa supplements help your heart probably won’t be available for 3-5 years.

Want to Apply This Research?

  • If using a health app, track daily cocoa or flavanol supplement intake (yes/no) and note any heart-related symptoms or energy levels weekly. This creates a personal record you can discuss with your doctor, even though this small study didn’t show definitive effects.
  • Rather than waiting for cocoa supplement proof, use your app to track proven heart-healthy behaviors: daily steps (aim for 7,000+), servings of fruits and vegetables (aim for 5+), and water intake (aim for 8 glasses). These have strong evidence for heart health.
  • Set monthly reminders to log overall energy, mood, and any heart-related symptoms. This helps you notice patterns over time. If you do take cocoa supplements, keep a simple log of when you take them and any changes you notice, then share this with your doctor at your next visit.

This research is a small pilot study and does not yet provide definitive evidence that cocoa supplements change TMAO or choline levels or prevent heart disease. The findings are preliminary and based on only 37 people. Do not start, stop, or change any supplements or medications without talking to your doctor first. This information is for educational purposes only and should not replace professional medical advice. If you have heart disease, high cholesterol, or take blood-thinning medications, consult your healthcare provider before using cocoa supplements, as they may interact with medications.