First study on polyphenol rich Mediterranean diet shows reduced brain aging by 9 months

A study funded by the German Research Foundation, the Health & Science ministries of Israel and the California Walnuts Commission had many leading epidemiologists and scientists working on the effect of a green Mediterranean diet on the brain. The result of this intervention diet was published on April 6, 2023, and showed how a green diet from the Mediterranean slows down ageing.

The editors who reviewed the article before publishing it in eLife hailed it as pathbreaking as this is the first time such a study has been done.

Why is it important?

In a study conducted for 18 months by Professor Galia Avidan from the Psychology Department and Dr Gidob Levakov from the Cognitive and Brain Sciences, it was found that the brain became nine months younger when a greener Mediterranean diet was taken.

This was proportional to one per cent body weight loss. This means that for every one per cent of weight reduction, the brain grew nine months younger in the people who indulged in a green Mediterranean diet for these 18 months.

Professor Iris Shai from the Ben-Gurion University of the Negev and Dr Alon Kaplan from Leipzig Universities supported the large-scale study, the result of which is the above conclusion.

The findings highlight how crucial diet is in regulating brain health and how it can help in keeping the brain healthier and younger.

With more investigative research, this might be crucial in tackling neurodegenerative diseases.

How was it done?

For the sub-study trial, the researchers selected 102 people who fulfilled all the criteria for obesity and other related parameters. In the initial 102-people trial other obesity-related changes like liver health were also checked.

For the next 18 months, the participants of the trial were given a Mediterranean diet which contained green healthy plant-based food items. The objective was to check the effect of the diet on the brain and on weight loss.

When the preliminary trial showed affirmative results of nine-year anti-ageing activity of the brain for every one per cent weight loss, the researchers turned towards a larger trial with 300 people.

The initial trial showed that a Mediterranean diet rich in polyphenols holds the key. This along with a little to no processed meat or red meat plan worked the best.

Foods like tomatoes and olive oil in the Mediterranean diet seem to play a crucial role in this. Both of these were proved right in the enhanced larger direct-plus trial

This was done by studying the changes in the brain structure in brain scan images for 18 months and comparing the different changes that happened. By this method, any lifestyle intervention method's (like exercise or diet) effect on the brain could be tested. They determined the changes in the brain by comparing the brain scans at the start and the end of the trial which showed that the brain grew younger by nine months for every one per cent of body weight reduction along with the lowering of other obesity parameters like liver enzymes and liver fat.

Why did the enhanced Mediterranean diet work?

The direct plus trial is significantly different from any intervention Mediterranean diet trial done before as it is the first time a more healthy diet has been used.

Here the larger study in 300 participants used a polyphenols-rich green diet from the Mediterranean which marked differed from the regular Mediterranean diet. Polyphenols are known to aid in weight loss and have other health benefits.

This study also coupled this diet with low processed meat or red meat intake.

People on this diet had three to four cups of green tea, 28 grams of walnuts along with a cup of Wolffia globosa–Mankai duckweed shake every day for 18 months. Mankai is rich in Vitamin B12, iron, protein, and polyphenols. This compensated for the meat intake in the regular diet.

What do the results mean?

The findings highlighted how weight loss intervention diets could affect the brain positively by reducing obesity-induced brain ageing. Obesity has a link with brain ageing and it is known to age the brain faster than it normally ages. Research shows that obesity causes hypertension which restricts blood flow into the brain, resulting in damaging the vascular tissues of the brain. This prompts the brain to age faster and increases the risk of cognitive problems as we enter mid-life. It's particularly important to regulate this in midlife as obesity in midlife accelerates the problem.

The decrease in the liver fat and liver enzymes seen in the trial is a critical takehome from the experiment as the increase in liver enzymes is associated with neurodegenerative diseases like Alzheimer's.

What's next?

As such, the researchers are planning to expand their work by investigating how this slowed-down brain ageing works in neurodegenerative patients. The study could also be used to investigate obesity-related brain health strategies like this diet intervention.

Such trials are the need of the hour as obesity increases all over the world and has become a lifestyle disorder.