According to research and survey, it has been noted that vegetarian and fish-based diets may be associated with a lower chance of developing moderate to severe COVID-19 infection. This has been suggested by the findings of a six-country survey based on self-reported symptoms.
But this does not establish a causative relation between diet and COVID-19 severity, and caution is needed in the interpretation of the findings.
The survey results have been published in the journal BMJ Nutrition Prevention & Health on Tuesday which indicates that plant and fish-based diets were associated with 73 per cent and 59 percent lower odds, respectively, of severe disease.
But several studies have suggested that the diet might have an important role to play in the symptom severity and illness duration of the coronavirus infection. However, there’s little evidence to confirm or refute this theory.
The researchers, including those from Johns Hopkins Bloomberg School of Public Health, US, drew on the survey responses of 2,884 frontline doctors and nurses with extensive exposure to SARS-CoV-2, the virus behind novel coronavirus, working in France, Germany, Italy, Spain, the UK, and the US.
The survey was conducted online between the month of July and September 2020, was designed to cause detailed information about respondents’ dietary patterns over the last year.
It was based on a 47-item food frequency questionnaire and the severity of any COVID-19 infections the respondents had. On the basis of personal background, medical history, medication use, and lifestyle the survey gathered the information.
The various diets were combined into plant-based like higher in vegetables, legumes, and nuts, and lower in poultry and red and processed meats -– pescatarian/plant-based with added fish or seafood, and low carb high protein diets.
Around 568 respondents said they had symptoms consistent with coronavirus infection or had no symptoms but a positive swab test for the infection.
As many as, 2,316 said they had no symptoms or had not tested positive. Among the 568 cases, 138 clinicians said they had moderate to severe COVID-19 infection, while the remaining 430 said they had had very mild to mild COVID-19 infection.
The respondents who said they ate plant-based diets’ or plant-based/fish diets had, respectively, 73 percent and 59 percent lower odds of moderate to severe COVID-19 infection.
Compared to people who said they ate a plant-based diet, those who said they ate a low carb-high protein diet had nearly four times the odds of moderate to severe COVID-19 infection, according to the researchers. These associations held true when weight (BMI) and co-existing medical conditions were also factored in, they said.
However, no association between any type of diet and the risk of contracting COVID-19 infection or length of the subsequent illness was found by the researchers. The survey relied on individual recall rather than on objective valuations, and the definition of certain dietary patterns may vary by country, the researchers noted.
They said the findings may not be applicable to women as men outnumbered women in the study.
However, plant-based diets are rich in nutrients, especially phytochemicals, vitamins and minerals, all of which are important for a healthy immune system, the researchers said. Also, fish is an important source of vitamin D and omega-3 fatty acids, both of which have anti-inflammatory properties, they said.
“Our results suggest that a healthy diet rich in nutrient-dense foods may be considered for protection against severe COVID-19,” the researchers noted.
“The trends in this study are limited by study size and design (self-reporting on diet and symptoms) so caution is needed in the interpretation of the findings,” said Shane McAuliffe, Deputy Chair of the NNEdPro Nutrition and COVID-19 Taskforce, a UK based think-tank that works on nutrition education, research, and innovation.
“However, a high-quality diet is important for mounting an adequate immune response, which in turn can influence susceptibility to infection and its severity,” McAuliffe, who was not involved in the study, said.