Current research has found that older people who have adhered to a Mediterranean diet for one year had better microbiomas of the gut and enhanced frailty controls.
Mediterranean diets— rich in fruits, legumes, nuts and whole grains, and generally lacking red meat — were the subject of numerous health and nutrition studies.
A lot of people who adopt a Mediterranean diet may have improved cardiac and metabolic health, live longer, and may even have better mental health.
A new study conducted by institutional experts in eight countries— including Bologna University, Italy, and University College Cork, Ireland — is now adding to the list of potential benefits of a Mediterranean diet.
The researchers— who report their findings in Gut journal— worked in five countries with data from a cohort of over 600 older adults. Researchers found a Mediterranean diet across the spectrum apparently improving the health of the gut of aged individuals and reducing frailty.
The study paper’s first author is Tarini Shankar Ghosh, Ph.D., from research institute APC Microbiome Ireland.
Seeking to reduce frailty
The authors of the study point out that earlier research has suggested that a simple dietary intervention such as transitioning to a diet in the Mediterranean style will minimize frailty in older people.
This is critical because frailty entails the progressive breakdown of multiple systems at once, often involving widespread, low-grade inflammation that contributes further to poor health.
To check that switching to a Mediterranean diet could reduce frailty steps, 612 individuals aged 65–79 were recruited by the researchers engaged in the current study.
Medical examinations revealed that 28 participants in the study identified as “frail,” 151 were on the verge for frailty and 433 showed no signs of frailty.
The participants came from France, Italy, the Netherlands, Poland or the UK.
Of the total number, 323 individuals (141 men and 182 women) agreed to follow a one-year Mediterranean diet, while the rest continued with their normal diets and acted as a community of controls.
The included Mediterranean diet was rich in vegetables, legumes, fruits, nuts, olive oil, and fish. It featured very small red meat and few dairy or saturated fats.
Better bacterial diversity in the gut
To understand the effects of the diet on the health of the older people, the researchers started by analyzing the effects on the health of the stomach.
That was because previous studies have suggested this older people— particularly those living in residential care facilities — appear to have less safe intestinal microbiotas, likely because of more restrictive diets.
In addition, an unstable gut in older adults leads to poorer overall health and a more rapid emergence of frailties.
When the researchers compared the gut microbiome compositions of participants who had adopted a Mediterranean diet for a year to those of participants who had followed their normal diets, they found significant differences.
Stool samples showed that the participants had higher bacterial diversity in the stomach, compared to peers from the control group, after 12 months on the Mediterranean diet.
In addition, improved indicators of frailty were associated with improved gut bacterial diversity, including improved walking speed, improved handgrip ability and improved cognitive function.
Participants who had adhered to the Mediterranean diet also displayed fewer signs of low-grade chronic inflammation.
Why Mediterranean diets may be beneficial
Taking a closer look at what was happening in the guts of the participants, the researchers found that health gains were correlated with improved populations of bacteria producing beneficial short-chain fatty acids, on the one hand, and reduced bacteria producing bile acid populations, on the other.
The researchers show that it is associated with an increased risk of insulin resistance, fat accumulation in the liver, cell damage and even bowel cancer when bacteria release too much of those bile acids.
According to the researchers, the positive changes were likely due to the Mediterranean diet having provided a consistent source of key nutrients including dietary fiber and important vitamins and minerals, such as vitamins C, B-6, and B-9, as well as copper, potassium, iron, manganese, and magnesium.
Although their results were modified for possible confounding factors, such as the age and body mass index, the authors noticed that the correlations between Mediterranean diet and improved gut health remained in place.
The researchers also observed subtle differences in microbiome shifts for participants, based on the countries they lived in, which points to different effects from other environmental factors.
Because of these differences, the researchers stress that all of the people who followed the Mediterranean diet showed the same overall changes in gut and systemic health.
While they note that their work is observational, and therefore can not point to a direct causal association, the researchers write:
“By protecting the ‘core’ of the gut microbial community, adherence to the [Mediterranean] diet could facilitate the retention of a stable community state in the microbiome, providing resilience and protecting from changes to alternative states that are found in unhealthy [individuals].”
Although maintaining that the Mediterranean diet is beneficial overall, the researchers agree that it may be impractical for some older people— an challenge that healthcare professionals will have to deal with.
“The introduction of a[ Mediterranean diet] may not be a realistic option in some older[ people] with problems such as dentition, saliva development, dysphagia or irritable bowel syndrome,” the researchers cautioned in their report.