Authored by: Venkat Rao
Is not that an interesting postulation—vegetarians or those following a plant-based diet are less likely to contract COVID-19 compared to those on omnivorous diet. A recent study published in the British Medical Journal by a Brazilian research team tested that hypothesis and concluded vegetarian diets were associated with a lower incidence of COVID-19 infection and that plant-based or vegetarian dietary life-style may have played a protective role in preventing COVID -19 infection.
Investigators used an observational study design involving 702 participants consisting of 278 participants on a plant-based and 424 omnivorous dietary habits, matched for sociodemographic characteristics and dietary information, were observed for COVID-19 outcomes between
March to July 2022. COVID-19 outcomes in these groups included disease incidence, infection severity and duration. These disease outcomes were analyzed after adjusting for body mass index, self-reported physical activity, and pre-existing medical conditions. Participant group on plant-based and vegetarian diet group had 39% lower odds of incidence of COVID-19 infection, compared to the omnivorous group. However, dietary habits were not associated with the severity or duration of the disease. In other words, plant-based, vegetarian dietary lifestyle seemed to confer a protective effect towards contracting COVID-19.
The observational study design used by the Brazilian investigators is a self-reported survey, which are considered less reliable compared to other investigative methods used by public health researchers. Moreover, the study did not take into account other confounding factors such as health and wellness links to dietary habits rendering these conclusions less reliable. At the outset, association of infectious disease incidence with dietary patterns may seem like a long stretch, although evidence from the published literature documents a much more complex set of factors linking numerous cultural, type of food combinations and dietary patterns linked to incidence of infectious diseases. The type of food consumed in various counties as a mark of history, culture and heritage may be a key factor in either inducing or preventing infectious disease outbreaks.
For example, human infectious diseases of animal origin, known as zoonotic disease, spread to human population living in close proximity to infected animals, their infected residues, contaminated water, air, or other forms of exposures creating ideal conditions for transmission of pathogens from animals to humans. Disease transmission through exposure to contaminated water, soil and consumption of infected food happen variously and specially in the rural areas where small scale animal breeding and farming in close quarters create an ecosystem sharing water, air and other resources among humans and domestic animals increasing the risk of animal-borne diseases entering human population. From a risk assessment standpoint, omnivorous diet introduces yet another exposure pathway for viral pathogens such as SARS-CoV-2 through consumption of contaminated meat products.
Nevertheless, consumption of contaminated meat products is different from omnivorous dietary habits in the population as a factor introducing an added risk for infectious disease such as COVID-19. Does omnivorous dietary lifestyle by itself, no matter the quality of the meat products consumed, increase the risk of contracting an infectious disease? The Brazilian study merely points to an association between the self-reported dietary habits of two population groups, without additional information on the quality of food products consumed and establishing a cause-effect relationship between dietary lifestyle practices and risk of contracting infectious diseases. Moreover, the study did not consider the overall health and wellness of the participants in both groups, which is a key factor to the severity and duration of COVID-19. The study did not find any significant difference between the vegetarian and omnivorous dietary habit groups when it came to the severity and duration of COVID-19 disease. The only notable difference was the lower incidence of COVID-19 among the vegetarian and plant-based dietary population compared to the omnivorous group.
Reliable Evidence from published literature bolters tying dietary habits to chronic infectious diseases. Research studies indicate increased vegetable intake can decrease the risk of acquiring chronic infectious diseases caused by viruses, such as hepatitis, and SARS. However, poor eating habits such as consuming raw/uncooked food or meat and animal products from wild animals are historically linked to infectious disease outbreaks, it is unclear how the risk of contracting an infectious disease such as COVID-19 differs among population groups merely by their plant-based or omnivorous eating habits. There was no reference to the type of food consumed, source and quality of the food consumed by the two study groups in the Brazilian study, nor does the authors infer contaminated food sources, among the omnivorous participants, may have contributed to additional COVID-19 incidence. Authors concluded without any qualifications that plant-based and vegetarian diet was associated with a lower incidence of COVID-19 infection and these dietary patterns may have a protective effect against COVID-19 infection.
A comprehensive analysis of protective effects attributed micro-nutrients of plant origin such as beta-carotene, vitamin C, vitamin E and polyphenolic compounds in vegetarian diet. These Phyto-nutrients are metabolically active antioxidant and anti-inflammatory compounds modulating immune function and enhancing the built-in disease fighting resilience to prevent acquiring infectious diseases and other chronic health conditions.
During the early phase of the COVID-19 pandemic, an online search of all coronavirus treatment options recommended review of nutritional status of all SARS-CoV-2 infected patients and consider dietary options together with medical intervention to contain the rapidly expanding pandemic. Other similar studies linking dietary factors indicated supplementation of Omega-3-Fatty Acids in the diet showing positive therapeutic effects on COVID-19 patients by limiting inflammation and regulating metabolism. Nutritional factors are known to modulate cytokines, which are small protein molecules modulating growth, immune and inflammatory response, play a crucial role in late phase of COVID-19 disease. Anti-inflammatory properties of Omega-3-Fatty Acid are shown to reduce morbidity and mortality from COVID-19 infection.
A famous mantra often quoted by dietitians on diet and health goes like this, “A health journey is the sum of small efforts repeated day in and day out.” Nutrition is the core to sustenance, health, and survival of life, but our present-day eating habits have evolved beyond biological necessity. Eating habits, food selection and intake are driven by culture, religious beliefs, and the extremely diverse culinary practices making food consumption as a pleasure and a fashion signature.
Be that as it may, consumption of contaminated food products, both vegetarian and meat-based products, leading to outbreak of infectious diseases is a well-established public health fact. Modern dietary practices are not mere fashion signatures, but one of the crucial factors in the disease burden carried by a society at-large and linked to outbreak of infectious diseases. But dietary practices, per se, no matter the quality and safety of the food consumed playing a determinative role in the outbreak of infectious diseases as the Brazilian study concludes appears weak and suspicious requiring further investigations.