The rapid transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of the coronavirus disease 2019 (COVID-19) pandemic, has immensely affected the global healthcare sector and economy. Additionally, the incidence of long COVID, which involves the persistence of symptoms for more than three months, has significantly affected millions of individuals.
Study: Impact of ultra-processed food intake on the risk of COVID-19: a prospective cohort study. Image Credit: Daisy Daisy / Shutterstock.com
Several COVID-19 vaccines, therapeutics, and non-pharmaceutical strategies have been designed to manage the ongoing pandemic. Nevertheless, a better understanding of the risk factors associated with SARS-CoV-2 infection would help protect individuals from contracting the infection in the future.
Nutrition is the key source of energy and is considered to be a major determinant of human health. A balanced diet is associated with maintaining a healthy gut microbiome, which is an important factor that regulates the immune system.
According to a recent study, individuals who consume greater amounts of fruits and vegetables, as well as a healthy plant-based diet, are at a lower risk of COVID-19. This observation indicates a potential link between diet and COVID-19.
Based on the extent and purpose of industrial processing, food-based products have been categorized into four groups by the NOVA classification system. Of these four groups, ultra-processed foods (UPFs) consist of industrial formulations of processed food substances, such as fats, oils, starch, sugar, and protein isolates. These food products are subjected to hydrogenation, hydrolysis, or other chemical modifications by the addition of colorings, flavorings, and emulsions.
Typically, UPFs contain high levels of saturated fats, sugars, trans fats, and salt. Additionally, these products contain a low amount of protein, dietary fiber, vitamins, and minerals.
Several studies have indicated that UPFs are a primary dietary source of food adulterants and neo-formed compounds, which may alter the composition of the gut microbiota and increase the risk of inflammation.
About the study
Individuals heavily dependent on a UPF-rich diet often suffer from mineral and vitamin deficiencies, experience damage to the immune system, and are highly susceptible to infections. UPFs are associated with an increased risk of inflammatory bowel disease, cardiovascular disease, and cancer.
Scientists have noted a scarcity of evidence related to the relationship between UPF consumption and the risk of COVID-19. Considering this gap in research, a recent European Journal of Nutrition study explored the association between UPF consumption and the risk of SARS-CoV-2 infection.
The current study used data from the United Kingdom Biobank, which is a prospective cohort containing about half a million participants from twenty-two assessment centers across Scotland, Wales, and England. All study participants were between 40 and 69 years of age. A total of 41,012 participants from the U.K. Biobank were considered in this study.
To assess the dietary intake of the participants in the previous 24 hours, scientists used the Oxford WebQ dietary questionnaire. This questionnaire included 206 types of food, along with their quantities and 32 types of drinks.
For the 24 hours dietary assessment, the online dietary questionnaire was recalled a minimum of two times and a maximum of five times. The current study measured the association between UPF consumption, as indicated by the percent daily gram intake, and SARS-CoV-2 infection using a multivariable logistic regression that was adjusted for potential confounders.
A strong relationship between UPF consumption and increased risk of COVID-19 was observed. This association was consistent in varied sub-groups based on age, comorbidity status, and educational level.
Although the association between UPF consumption and COVID-19 was partially mediated by body mass index (BMI), a direct effect of UPF weight ratio on the risk of COVID-19 was established.
Some of the mechanisms that link UPF intake and increased risk of COVID-19 include enhanced levels of sugars and trans-fat, which stimulates pro-inflammatory effects. This condition could adversely affect the synthesis and function of immune cells.
Additionally, UPFs contain high saturated fats and reduced fibers, which might lead to chronic activation of the innate immune system and suppression of the adaptive immune system. The chemical additives of UPFs also adversely affect human health. Furthermore, a UPF-rich diet may cause vitamin and mineral deficiencies that could significantly affect the human immune system.
BMI was found to be a partial mediator that influenced the association between UPF and COVID-19. A significant increase in UPF consumption occurred during the COVID-19 lockdown, which might have affected people’s immunity, thus making them more susceptible to the infection.
The current study is the first to explore the relationship between UPF consumption and the risk of SARS-CoV-2 infection. This large prospective cohort study revealed that a UPF-rich diet was associated with a significantly increased risk of COVID-19. Therefore, a healthy diet with reduced UPF intake has been recommended to protect individuals from severe clinical outcomes.
- Zhou, L., Li, H., Zhang, S. et al. (2022) Impact of ultra-processed food intake on the risk of COVID-19: a prospective cohort study. European Journal of Nutrition. doi:10.1007/s00394-022-02982-0