Back in 2020, as the world was trying to come to grips with the Covid-19 pandemic, researchers speculated on whether diet might play a role in resisting infection and recovery.

Irish and US researchers wrote then that, “as a mitigation strategy” it may have been to identify “food groups and key nutrients of importance that may affect the outcomes of respiratory infections”.

More than a year later, Italian researchers found that the Mediterranean diet might be protective against the coronavirus.

They gave two reasons for this.

Firstly, the Mediterranean diet is associated with a lower risk of overall mortality, cancer incidence and cardiovascular diseases.

Secondly, the diet was an anti-inflammatory, and thus could be effective against the Covid-related inflammation that was killing many people. 

A paper from 2016, found that adopting the Mediterranean diet “could be a major contribution to the improvement of patients with recurring colds and frequent inflammatory complications”.

The common cold virus is a coronavirus.

New systematic review

More recently, a new study has found the Mediterranean diet could potentially protect against Covid-19 infection.

This was the main finding of a systematic review of six observational studies from five countries published from 2020 to 2023. 

The studies were based on food-frequency questionnaires, which isn’t the most rigorous evidence. But the total sample size was large, involving 55,489 patients.

The review comes from the Universitas Sumatera Utara in Indonesia and has been widely reported.

The results are encouraging – and significant – but a little frustrating. The review relied on qualitative evidence – a softer form of evidence where patients shared what they ate and how they felt.

What’s lacking is a quantitative analysis. Often these sorts of studies will conclude that the risk of infection is cut by such-and-such percentage. That didn’t happen here.

Dr Andre Marolop Pangihutan Siahaan, leader of the review, said this wasn’t possible with the material at hand. The review did suffer from mixed results. That might well be because of the difficulty of field research during the pandemic.

However, overall, the trend that close adherence to the diet afforded protection was consistent. Any benefit against symptoms and their severity remained unclear.

We need to see hard clinical evidence of the diet’s protective effects against Covid-19 and its symptoms. It would serve as a test of the diet’s anti-inflammatory benefits.

Is this helpful?

In an interview with Medical News Today, Siahaan was asked why it’s important for researchers to continue to find new ways in which people can lower their Covid-19 infection risk.

He answered: “Despite global vaccination, advanced medication, and preventive measures, multiple waves of Covid-19 infection continue to be reported worldwide.

“The recent Olympic Games saw over 40 athletes testing positive for the virus, underscoring the ongoing threat.”

He noted that “the growing evidence of reinfection, and even multiple reinfections in one individual, is a cause for concern”.

He said the latest study suggested that reinfection severity correlates more with the initial infection.

That is, it could be important to contain the severity of infection in your first bout of Covid-19. It may be that any subsequent reinfection is less likely to be severe.

“It’s crucial to emphasise further research to fully understand the long-term impact, as we cannot yet consider it harmless,” he said.