Polyphenol-Rich Diet Reduces Inflammation, Boosts Gut Health for Older Adults: Study

Green tea leaves in a pot and dried (KMNPhoto/Shutterstock)

A Spanish study on older adults aged 60 or older has confirmed that a rich polyphenol diet can reduce inflammation and improve gut health by encouraging the production of indole-3-propionic acid (IPA); an antioxidant and anti-inflammatory molecule linked with healthy aging.

“If we consider the beneficial effects of IPA on the gut microbiota and health in general, it is important to find reliable strategies to promote the production of this metabolite,” said the co-first signatory of the study, Tomás Meroño.

Participants that consumed 750 mg of polyphenols daily for 8 weeks increased gut bacterial production of IPA by one-third greater than the control group. Polyphenols are naturally occurring plant-based compounds and can be obtained through food such as fruits and vegetables.

Whilst researchers did not specify what polyphenols were consumed, they found that polyphenols interacted with the gut bacteria, therefore inducing an increase in bacterial production of IPA.

The antioxidant and anti-inflammatory metabolite is produced by some bacteria in the gut through the conversion of tryptophan, an amino acid commonly obtained through dairy products and fish.

IPA is linked to healthy aging, as its antioxidating and anti-inflammatory properties reduce the risk of chronic diseases that may be present in old age.

The authors noted that participants that ate polyphenols not only saw increases in IPA in the bloodstream, but also promoted the growth of beneficial bacteria such as Faecalibacterium prausnitzii and bacteria of the Butyricicoccus genus.

These bacteria produce butyrate, a short-chain fatty acid (SCFA) produced through dietary fiber. The SCFA is beneficial for gut health as gut cells consume these fatty acids for energy rather than turning to the layer of carbohydrates that acts as a barrier between gut cells and gut bacteria; thereby maintaining the gut stability.

However, the same increase in biodiversity of the gut was not observed in participants who had renal diseases, particularly seniors with chronic kidney diseases, where researchers observed greater prevalence of inflammatory bacteria in the gut.

“Low IPA levels have been associated with a rapid decline of kidney function and a chronic kidney disease,“ notes Prof. Cristina Andrés-Lacueva. ”These results could be clinically relevant.”

Further, IPA increases were linked with decreases in markers for inflammation such as IL-6 and C-reactive proteins, both of which are involved and become prevalent during inflammation.

IPA can promote healthy aging as its antioxidizing properties can neutralize free radicals; reactive derivatives of oxygen that cause harm to our cells and promote aging. Further, its anti-inflammatory effects prompt immune balance and reduce risks of inflammatory diseases such as obesity, heart diseases, diabetes, cancer, and other autoimmune disorders such as arthritis.

Though researchers did not outline what polyphenol-rich foods were consumed, the recruitment announcement for the trial suggested consideration of berries and blood oranges and their derived products, pomegranate juice, Renetta apples and puree, green tea, and dark chocolate products as potential food for the diet.

Currently, daily recommendations for polyphenol are recommended at 500 mg to 1000 mg a day. The authors advised against supplements due to concerns of supplement intake being linked with reduced iron absorption.

The study was published in Wiley Online Library, a peer-reviewed scientific journal.