Plant-Based and Fish Diets May Help Lessen Severity of COVID-19 Infection

A plant-based diet is associated with a 73% lower risk of moderate to severe COVID-19.

Associated with 73% and 59% lower risk of moderate to severe disease, respectively.

Plant-based and/or fish (pescatarian) diets may help reduce the chance of developing moderate to severe COVID-19 infection, the findings of a study in six countries suggest, published in the online journal BMJ Nutrition Prevention & Health.

They were associated with 73% and 59% lower odds of serious illness, respectively, the findings show.

Several studies have suggested that diet may play an important role in the symptom severity and duration of a COVID-19 infection. But so far there is little evidence to confirm or disprove this theory.

To explore this further, the researchers used the survey responses of 2,884 primary care physicians and nurses with extensive exposure to SARS-CO-v2, the virus responsible for COVID-19 infection, working in France, Germany, Italy, Spain, the UK, and the US.

The participants were all part of a global network of healthcare professionals registered with the Survey Healthcare Globus network for healthcare market research. The researchers used this network to identify clinicians who are at high risk for COVID-19 infection because of their work.

A pescatarian (fish) diet is associated with a 59% lower risk of moderate to severe COVID-19.

The online survey, which ran between July and September 2020, was designed to obtain detailed information about respondents’ dietary patterns, based on a 47-item food frequency questionnaire, over the previous year, and the severity of any COVID-19 infections. infections she had had, using objective criteria.

The survey also collected information about personal background, medical history, medication use and lifestyle.

The different diets were combined to vegetable (higher in vegetables, legumes and nuts, and lower in poultry and red and processed meats); pescatarian/vegetable (as above, but with added fish/seafood); and low-carb, high-protein diets.

About 568 respondents (cases) said they had had symptoms consistent with a COVID-19 infection or had no symptoms but a positive swab test for the infection; 2316 said they had no symptoms/tested positive (comparison group).

Of the 568 cases, 138 clinicians said they had moderate to severe COVID-19 infection; the remaining 430 said they had had a very mild to mild COVID-19 infection.

After taking into account several potentially influential variables, including age, ethnicity, medical specialty, and lifestyle (smoking, physical activity), respondents who said they eat plant-based or plant-based/pescatarian had a 73% and 59% lower risk of moderate to severe COVID-19 infection, compared to those who did not have these diets.

And compared to those who said they ate a plant-based diet, those who said they ate a low-carb, high-protein diet were nearly 4 times more likely to have a moderate to severe COVID-19 infection.

These associations were true when weight (BMI) and coexisting medical conditions were also taken into account.

But no association was observed between any type of diet and the risk of contracting a COVID-19 infection or the duration of subsequent illness.

This is an observational study, so cannot establish a cause, only correlation. It also relied on individual recalls rather than objective assessments, and the definition of certain dietary patterns may vary by country, the researchers point out.

There were more men than women in the study, so the findings may not apply to women, they add.

But plant-based diets are rich in nutrients, especially phytochemicals (polyphenols, carotenoids), vitamins and minerals, all of which are important for a healthy immune system, the researchers say.

And fish is an important source of vitamin D and omega-3 fatty acids, both of which have anti-inflammatory properties, they add.

“Our results suggest that a healthy diet rich in nutritious foods can be considered for protection against severe COVID-19,” they conclude.

“The trends in this study are limited by study size (small numbers with a confirmed positive test) and design (self-reporting of nutrition and symptoms), so caution should be exercised in interpreting the findings,” said Vice President of the NNEdPro Nutrition and COVID-19 task force, Shane McAuliffe.

“However, a high-quality diet is important for building an adequate immune response, which in turn can influence susceptibility to infection and its severity.”

He adds, “This study highlights the need for better-designed prospective studies on the association between diet, nutritional status, and COVID-19 outcomes.”

Reference: “Plant-based diets, pescatarian diets, and the severity of COVID-19: a population-based case-control study in six countries” June 7, 2021, BMJ Nutrition Prevention & Health.
DOI: 10.1136/bmjnph-2021-00272

Funding: Survey Healthcare Globus, National Institutes of Health