Plant-based and / or fish-based (pescatarian) diets may help reduce the chances of developing moderate to severe Covid-19, the results of a study in six countries suggest.
Several studies have suggested that diet may have an important role in the severity of symptoms and the duration of Covid-19 disease.
But, so far, there is little evidence to confirm or disprove this theory.
To explore this further, the researchers drew on survey responses from 2,884 primary care physicians and nurses highly exposed to the SARS-CoV-2 virus that causes Covid-19, working in France, Germany, Italy, Spain, United Kingdom and United States.
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 at high risk of Covid-19 because of their work.
The online survey, which took place between July and September 2020, was designed to obtain detailed information on the eating habits of respondents during the previous year, based on a food frequency questionnaire from 47 items, and the severity of any Covid-19 infections they had had. , using objective criteria.
The survey also gathered information on personal history, medical history, medication use and lifestyle.
The various diets were combined into plant-based (higher in vegetables, legumes and nuts, and lower in poultry and red and processed meats); pescatarian / herbal (same as above, but with fish / seafood added); and diets low in carbohydrates and high in protein.
Some 568 respondents (cases) reported having had symptoms consistent with Covid-19, or no symptoms, but a positive swab test, for the infection.
The remaining 2,316 said they had no symptoms or tested positive (comparison group).
Among the 568 cases, 138 clinicians reported having had moderate to severe Covid-19.
The other 430 said they had very mild to mild Covid-19.
After taking into account several potentially influencing variables, including age, ethnicity, medical specialty and lifestyle (smoking, physical activity), respondents who reported eating plant-based diets or Plant-based / pescatarian diets had 73% and 59% lower chances of moderate to severe Covid-19, respectively, compared to those who did not have these eating habits.
And compared to those who said they ate a plant-based diet, those who said they ate a low-carb, high-protein diet were almost four times more likely to have Covid- 19 moderate to severe.
These associations were true when body mass index (BMI) and coexisting medical conditions were also taken into account.
But no association has been observed between any type of diet and the risk of contracting Covid-19 or the duration of subsequent illness.
This is an observational study, and therefore cannot establish the cause, only the correlation.
It was also based on individual reminders rather than objective assessments, and the definition of certain diets may vary from country to country, the researchers point out.
Men outnumbered women in the study, so the results may not apply to women, they add.
But plant-based diets are high in nutrients, especially phytochemicals (polyphenols, carotenoids), vitamins and minerals, all of which are important for a healthy immune system, 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.
âOur results suggest that a healthy diet rich in nutrient-dense foods may be considered for protection against severe Covid-19,â they conclude.
âThe trends in this study are limited by study size (small numbers with a confirmed positive test) and design (self-reported diet and symptoms), so caution should be used in interpretation results, âcomments NNEdPro Nutrition and Covid- 19 Vice-president of the working group Shane McAuliffe.
“However, a high quality diet is important for developing an adequate immune response, which in turn can influence the susceptibility to infection and its severity.”
He adds, âThis study highlights the need for better-designed prospective studies on the association between diet, nutritional status and Covid-19 outcomes. “
NNedPro Global Center for Nutrition and Health is a UK-based think tank.
The study was published in the online journal BMJ Nutrition Prevention & Health.