Plant based diets appear to protect against COVID19

Research from a team at Johns Hopkins Bloomberg School of Public Health in Baltimore reported in the BMJ Journals  suggests that plant based or pescaterian diets protect against severe COVID19. And not just protect slightly. ‘After adjusting for important confounders, participants who reported following ‘plant-based diets’ and ‘plant-based diets or pescatarian diets’ had 73%  and 59% lower odds of moderate-to-severe COVID-19 severity, respectively, compared with participants who did not follow these diets’.

This was such a startling headline that I read the report rather more closely. (It is open source so you can read the whole thing yourself.)

The researchers devised a ‘control study of frontline physicians and nurses in six countries (France, Germany, Italy, Spain, UK, USA) evaluating nutritional factors with the risk of COVID-19 infection, severity, and duration…… We aimed to recruit participants with a high frequency of exposure to patients with COVID-19…….  Participants could not enter into the study if they had infrequent exposure to patients with COVID-19…. unless they had COVID-19 symptoms or a positive COVID-19 test result which suggests substantial exposure….. Participants whose medical specialty or practice setting was not considered to be high-risk could not enter the study…….We screened 7344 participants for eligibility of whom…. 2884 health care workers with high frequency of exposure to patients with COVID-19 were considered eligible…..

Participants completed a detailed web-based questionnaire of approximately 100 items between 17 July and 25 September 2020. Information was collected on ‘basic demographic characteristics, past medical history, medications, lifestyle, and COVID-19 symptoms, and a 47-item food frequency questionnaire allowed us to capture food groups of the respondent’s diet.’

Their conclusion was that ‘in health care workers from six countries with a high frequency of exposure to COVID-19 patients, following plant-based diets or a spectrum of plant-based diets (plant-based diets or pescatarian diets) was associated with 73% and 59% lower odds of moderate-to-severe COVID-19-like illness, respectively, compared with individuals who did not follow these diets’.

The following discussion made a  number of interesting points briefly summarised below:

• Plant-based diets are rich in nutrients, especially phytochemicals…. higher fibre, vitamins A, C, and E, folate, and mineral (iron, potassium, magnesium).
• Studies have reported that supplementation of some of these nutrients, specifically vitamins A, C, D, and E, decreased the risk of respiratory infections, such as the common cold and pneumonia, and shortened the duration of these illnesses. These nutrients are hypothesised to support the immune system…
• Both specific micronutrient deficiencies and generalised malnutrition have been associated with immune dysfunction in the host…. multiple viruses, such as coxsackievirus and influenza, have been shown to develop increased virulence… when replicating in a host deficient in selenium. Selenium may be an important nutrient to consider, considering its role in immunity.
• Along with plant-based diets, individuals who reported following pescatarian diets had lower odds of severe COVID-19… Fish intake is an important source of vitamin D and omega-3 fatty acids EPA and DHA. Randomised controlled trials in patients with acute respiratory distress syndrome (ARDS) found that those who received formulas high in omega-3 fatty acid had shorter duration of mechanical ventilation and shorter length of stay at intensive care units.

And finally they concluded that the study had specific strengths and limitations.

• Its large sample size including diverse health care workers from multiple countries was definitely a strength, as was the researchers’ careful adjustment of potential confounding factors.
• They were able to capture the early phase of the global pandemic, before the detection of known SARS-CoV2 variants which could complicate a multinational epidemiological analysis.
• In terms of limitations, they relied on participants’ self-report to define exposures and outcomes although health care workers are unique in that they are a source of high-quality data.
• The definition of certain dietary patterns (eg, plant-based diets, pescatarian diets, low carbohydrate, high protein diet) may vary by countries although the responses on the food frequency questionnaire reflected intake of food groups that were consistent with these dietary patterns.
• The study may not have included individuals with more severe COVID-19 illness, given that severe cases (mechanical ventilation, admission to intensive care units) may not have been able to complete our questionnaire.
• The study population comprised predominantly male physicians; thus, the findings of the study may need to be replicated in women and non-health care workers.

Maybe the Vegan Society should be funding more research in this area?