If you enjoy dark chocolate or coffee, or both, you may be benefiting from a substance found in these products that is linked to a reduction in cellular aging
A study published this month in the journal Aging found that people with higher blood levels of an alkaloid called theobromine seemed to have slower cellular aging as measured by “epigenetic clocks,” models that estimate aging based on molecular biomarkers. Most abundant in cocoa, theobromine is also found in smaller amounts in coffee and tea.
But before you start eating more dark chocolate and drinking more cups of coffee, know that the study found an association, not a causal link, and that it didn’t suggest how much you would have to eat or drink to potentially derive an aging-related benefit.
The facts:
- The researchers used data from participants in two groups: 509 women from the TwinsUK cohort; and 1,160 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 analyzed their DNA using models that estimate aging based on molecular biomarkers.
- The researchers discovered that higher levels of theobromine in the blood was associated with a reduced pace of aging, 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 aging?
Much of how we age is determined by our genes. But epigenetic factors such as our behaviors, 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 José M. Ordovás, a senior scientist and leader of the Precision Nutrition & Healthy Aging 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 aging among the study participants, the researchers found a link between higher levels of theobromine in the blood and reduced signs of cellular aging.
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 aging 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 favorite treat might be a fountain of youth — there are a few limitations to recognize 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,” Ordovás 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 aging rates, Bell said. “You need to see things moving one time after another,” Ordovás 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 aging 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 & Metabolic Institute with the Cleveland Clinic:
- While anything above 50 percent cocoa solids can be considered “dark” chocolate, that range is a big one, and you’d probably be better served aiming for 70 percent 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 alkalization process mellows its flavor, 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 cookies — 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 aging, but it is a tiny percentage compared with all the many other factors,” Ordovás 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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