Longevity Briefs: Does Eating More Fibre Slow Ageing?

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.

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The problem:

Dietary fibre is plant-based material that the body cannot digest or absorb. While it doesn’t provide sustenance, fibre benefits health by slowing the absorption of other nutrients like carbohydrates and fats (which avoids sharp peaks in blood sugar and lowers overall blood sugar and fats), and by aiding bowel movements. Some fibre can also be broken down by gut bacteria to produce short-chain fatty acids (SCFAs) that support gut health and the immune system.

Numerous studies suggest that people who eat more fibre are healthier and live longer. In this study, researchers looked at the relationship between fibre consumption and telomere length. Telomeres are the protective caps at the ends of our chromosomes that shorten each time a cell divides. Telomere shortening throughout life is widely considered to be one of the primary drivers of ageing. Faster telomere shortening theoretically means faster ageing, though there’s some disagreement about what telomere length can really tell us.

The discovery:

In this study, which was conducted back in 2018, researchers examined data from 5674 U.S. adults who participated in a nutrition and health survey called NHANES (National Health and Nutrition Examination Survey). NHANES is a popular dataset for studying the link between nutrition and telomere length, since participants gave blood samples from which telomere length can be measured.

The researchers found that, after controlling for confounding factors like age and gender, there was a linear association between fibre intake and telomere length. Specifically, for each 1 gram of additional fibre intake per 1000 kilocalories of total energy intake, participants’ telomeres were 6.7 base pairs (the ‘letters’ of the genetic code) longer on average. The researchers estimated, based on the known relationship between telomere length and biological ageing, that increasing fibre intake by 10g per 1000kcal would equate to a 4.3 years reduction in biological age.

The implications:

This study suggests that people who eat more fibre have longer telomeres, theoretically slowing biological ageing. However, it’s quite likely that fibre intake was not the only factor at play. People who eat more fibre tend to eat more fruits, vegetables and whole grains since these are the primary sources of fibre. These foods contain many other beneficial compounds that could also influence telomere length. People who eat a lot of these foods are also more likely to make other healthy decisions. Without performing a randomised trial in which participants are randomly assigned to a low or high fibre diet, it’s impossible to completely eliminate such confounders.

The survey did not contain any information about what type of fibre participants ate, so we do not know if these correlated with telomere length differently. It’s also worth pointing out that telomere length was only measured in white blood cells, so we have no idea how telomeres were affected in other tissues. With these caveats aside, eating foods rich in fibre is undoubtedly beneficial for healthy ageing – it’s just not yet clear exactly which components matter the most.