Mediterranean diet is linked to improved gut microbiome in elderly people

As the global population is predicted to live for longer than ever before, it is important that ways are found to help people live healthier for longer. There’s a lot of research focusing on the role of regular exercise and balanced diet in maintaining good health, but recent research has found our gut microbiome could have an important impact on the way we age.

Following a Mediterranean diet, based on eating mainly vegetables, legumes, fruits, nuts, olive oil and fish and moderating the intake of red meat and saturated fats improves gut microbiome health in the elderly according to new research from University College Cork.

The study, published in the journal Gut identified that by following a Mediterranean diet, this can lead to microbiome changes that can improve cognitive function and memory, along with strengthening the immune system and bone health.

The gut microbiome is a complex community of trillions of microbes, that live semi-permanently in the intestines. These microbes have co-evolved with humans and other animals to break down dietary ingredients such as inulin (natural dietary fibre), arabinoxylan and resistant starch - things that a person cannot digest. They also prevent bacteria from growing that causes diseases. 

The gut microbiome is very sensitive, many things including diet, medications, genetics, and conditions such as inflammatory bowel disease and irritable bowel syndrome (IBS), can all change the gut microbiota community.

The Mayo Clinic states: "It's not surprising that what you feed your microbiome can have the greatest impact on its health. The healthier it is, the healthier you are.”

University College Cork’s observational research involved 12 month study of 612 people aged 65-79 from France, Italy, the Netherlands, Poland and the UK. A total of 289 people were asked to continue allowed to continue with their usual diet and 323 participants  were required to follow a Mediterranean diet. The researchers collected stool samples at the beginning and end of the study, to make a comparative analysis of the gut microbiome. 

The results demonstrated that eating a Mediterranean diet promotes the production of good bacteria related to healthy ageing. It also contributes to a greater diversity of bacteria in the intestinal microbiome, a condition associated with health that many older people lack. 

To make more detailed analysis, the researchers also divided their cohort based on whether they were frail, nearly frail, or not frail at baseline. From this, they found that a Mediterranean diet was associated with decreased frailty and inflammation, by testing hand grip strength, memory, and markers of inflammation.

On further analysis, the scientists found that the microbial changes that occurred in the gut were associated with an increase in bacteria producing beneficial short-chain fatty acids and a decrease in bacteria producing certain bile acids. An overproduction of bile acids is often linked to an increased risk of insulin resistance, liver problems, cell damage and intestinal cancer. 

A link was also made between long-term continuation consuming a Mediterranean diet with improvements in overall cognitive capacity, episodic memory, immune function, blood pressure and stiffness as well as reduced bone mass loss in people with osteoporosis. The best way to improve the gut microbiome is to be consistent, the researchers explain.

Despite the findings, the researchers point out that the interaction between diet, microbiome and health is complex and is influenced by several different elements beyond diet - including genetics and environmental factors.

The researchers recognise that following a Mediterranean diet isn’t necessarily possible for everybody who starts thinking about ageing, which is usually around the age of 50. Future studies will need to focus on what key ingredients in a Mediterranean diet are responsible for the positive microbiome changes. 

The key advice from the scientists is to ensure that as you get older, you eat a nutritious balanced diet that is high in plant-based products and fibre.