Theobromine, found in dark chocolate and coffee, associated with slower cellular ageing, study suggests

The researchers used data from participants in two groups: 509 women from the TwinsUK cohort; and 1160 men and women from the KORA group in Germany. Both groups had an average age of 60.They measured the amount of theobromine in the participants’ blood and analysed their DNA using models that estimate ageing based on molecular biomarkers.The researchers discovered that higher levels of theobromine in the blood was associated with a reduced pace of ageing, as seen by two of these “clocks”.When the team investigated whether other substances in dark chocolate had that effect, they found the link persisted only with theobromine.

Can dark chocolate really affect cellular ageing?

Much of how we age is determined by our genes. But epigenetic factors such as our behaviours, environments and diets can turn some genes on or shut others off through different processes.

One such mechanism is DNA methylation, the focus of the new study.

“What we were looking for here are the chemical ‘tags’ that can be added onto your DNA,” said Jordana Bell, a professor in epigenomics at King’s College London and the lead author of the study.

Consider it the “grammar” of your genome, said Jose Ordovas, a senior scientist and leader of the Precision Nutrition and Healthy Ageing directive at Tufts University who was not involved in the study.

These markers don’t alter the fixed sequence of your DNA, but the tags (like punctuation marks) affect how they are expressed, he said.

DNA methylation patterns also shift with age, allowing for the development of epigenetic clocks that estimate biological (rather than chronological) age.

Using these clocks to compare epigenetic markers of ageing among the study participants, the researchers found a link between higher levels of theobromine in the blood and reduced signs of cellular ageing.

After running further tests to see whether other cocoa components – including caffeine – showed similar patterns, Bell and her team discovered it occurred only with theobromine.

“What our results are suggesting is that [theobromine] might be affecting the activity of genes,” Bell said. “And then that contributes to ageing and health.”

It’s also possible that something synergistic is going on with the theobromine and other chocolate components they didn’t measure in the study, such as polyphenols, Bell said.

These anti-inflammatory compounds, which are also found in dark chocolate, are linked to better brain function, a more varied gut microbiome, and lower risks of conditions such as cancer, heart disease and diabetes.

What are the study limitations?

While the findings are interesting – and who doesn’t want to hope that their favourite treat might be a fountain of youth – there are a few limitations to recognise before you eat up.

The study didn’t dig into diet, so it’s not clear whether people had high levels of theobromine because of chocolate.

“They did not measure the intake of chocolate; they looked at a biomarker of something that is in chocolate,” Ordovas said.

One of the sample groups did complete a food questionnaire that asked how frequently the participants ate chocolate, but it didn’t delve into specifics such as what kind they were eating, the percentage of cocoa it had, or how much of it they ate.

The data also comes from one single point in time, so the study wasn’t able to see how theobromine levels over weeks, months or years might relate to ageing rates, Bell said.

“You need to see things moving one time after another,” Ordovas said. “That brings more confidence.”

And epigenetic clocks aren’t set in stone.

“These are dynamic estimates,” Bell said.

“It just means that at this point in time, looking at your DNA, we estimate that you seem to be ageing a little bit slower or faster than we would expect based on your chronological age.”

This is a good thing because you can use this knowledge to guide diet or other health interventions to change your biological age estimate, she said.

What does this mean for choosing chocolate?

The findings about theobromine add to what we know about the other health-promoting compounds in dark chocolate, such as polyphenols.

And here are some recommendations about dark chocolate from Alexis Supan, an outpatient dietitian at the Bariatric and Metabolic Institute with the Cleveland Clinic:

While anything above 50% cocoa solids can be considered “dark” chocolate, that range is a big one, and you’d probably be better served aiming for 70% or greater.The higher the percentage, the more bitter it will be, but it will also bring a higher concentration of the beneficial compounds and less of the “not-so-healthy things like the saturated fat and the sugar.”Make sure that cocoa is the first ingredient listed on the label. Ideally, you’d want just three ingredients: cocoa, sugar and cocoa butter.Choose chocolate that isn’t Dutch-processed which is sometimes listed on the label. This alkalisation process mellows its flavour but also strips away some of the polyphenols. “You’re not getting quite as much antioxidant power,” Supan said.For balance in your diet, keep the rest of your daily added sugar in check. A one-ounce serving of dark chocolate can provide about one-third of the daily upper limit for women and one-quarter for men.Dark chocolate can contain higher levels of harmful metals such as cadmium and lead, which are riskier for pregnant people or younger children, Supan said. Consumer Reports has a list of levels in many popular brands, so you can make an informed decision.

As long as the chocolate fits this criteria, what form you choose to consume it in, whether in a mug or bar, shouldn’t matter.

But when used in baking – say, that dark chocolate cake or rich, gooey biscuits – keep in mind that the cocoa is competing with ingredients such as butter, sugar and flour, so you’re probably taking in less of the good products, Supan said.

Her tip for the holidays? Try a dark chocolate bark. You can make it festive with some fruit and nuts, but you’ll still be getting a solid dose of the actual dark chocolate.

Finally, if you aren’t a fan of chocolate, don’t force yourself to eat it simply for some type of cellular benefits that theobromine might bring.

After all, “methylation is involved in ageing, but it is a tiny percentage compared with all the many other factors,” Ordovas said.

These include your diet as a whole, physical activity, sleep and stress levels.

“This is one tiny little sliver, and it’s a great reason to not feel bad about having an ounce of dark chocolate today,” Supan said.

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