Longevity Briefs: Coffee And Fruit Consumption Might Slow The Biology Of Ageing

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Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

Polyphenols are a collection of natural plant compounds that have drawn interest for their anti-inflammatory and antioxidant properties. Antioxidants are molecules that neutralise harmful metabolic byproducts called reactive oxygen species (ROS) that are capable of damaging proteins and DNA in a process known as oxidative stress. Inflammation and oxidative stress are interlinked, and both thought to contribute to the ageing process, so there is some interest in whether polyphenol intake might be able to slow down some of the fundamental biology of ageing.

One element of this fundamental biology is telomere shortening. Telomeres are regions of DNA on the ends of the chromosomes that do not encode any genetic information. Instead, they serve a sacrificial role – when cells divide and chromosomes must be duplicated, the DNA replication machinery is incapable of copying the very ends of each DNA strand. This means that chromosomes become a little shorter each time a cell divides. Telomeres serve as a kind of buffer zone to ensure that more important, coding DNA isn’t lost. The downside is that once telomeres become too short, cells can no longer divide, which poses its own set of problems.

In a recent study, researchers investigated whether there was a relationship between greater polyphenol consumption and longer telomeres. The study was presented at the European Congress on Obesity, but has not yet been published, so there is a limit to how much detail can be provided. However, what was shown appears to be promising.

The discovery:

Researchers looked at data from the SUN project, a study that began in December 1999 in which Spanish university graduates were followed up with questionnaires every 2 years, resulting in over 25 years of follow-up health data. Researchers derived telomere length from saliva samples from participants and compared this against polyphenol intake and other dietary habits based on self reported data.

‘Short telomeres’ were defined as telomere length in the 20th percentile – that is to say, participants were considered to have short telomeres if they were among the fifth of participants with the shortest telomeres. Researchers found that those with the highest polyphenol consumption were around half as likely to have short telomeres compared those with the lowest consumption. Consumption of coffee and fruits, which are both rich in polyphenols, was also associated with longer telomere length. One cup of coffee per day was associated with a 26% reduced risk of short telomeres compared to not drinking coffee, while high fruit consumption was associated with a 29% reduced risk compared to low consumption.

Significant associations weren’t observed for other polyphenol-rich foods like olive oil, red wine and vegetables. This doesn’t necessarily mean they didn’t contribute to the beneficial effects of polyphenol intake, just that they weren’t impactful enough by themselves to produce as a statistically significant association.

The implications:

This study suggests that there is an association between higher polyphenol intake and reduced risk of telomere shortening. This relationship is plausible, because polyphenols protect the DNA against damage, which accelerates telomere shortening. Animal studies suggest that telomere shortening causes accelerated ageing (rather than the other way around) since interventions to accelerate telomere shortening have been found to shorten lifespan, while telomere-lengthening treatments have the opposite effect. There is still no definitive proof that this is the case in humans, however.

Since this study was observational in nature, it cannot prove that polyphenol intake caused longer telomeres. People who consume more polyphenols mostly represent people who consume healthier diets overall, so other dietary components could be responsible for the effects on telomere length. People who consume healthier foods are also more likely to engage in other healthy behaviours such as exercise. Without seeing the full study, we don’t known how well the researchers controlled for these confounders, but it is very hard to control for them completely.

It is also worth considering that polyphenol intake was estimated based on self-reported dietary habits, which can introduce reporting bias. This is further complicated by the fact that different foods may have wildly different polyphenol content, so these estimates could be quite inaccurate compared to measuring polyphenol content in blood or urine. All that said, you have little to lose from consuming more polyphenol-rich foods, as they are generally healthy in many other ways.