Healthy eating factors in COVID-19 susceptibility, progression

The risk of COVID-19 and contracting a severe infection may also be attributed to what people eat, with a recent study showing that a diet rich in healthy plant-based foods is particularly protective.

In a cohort of 592,571 adults (mean age 56 years, 68.2 percent female) who participated in the smartphone-based COVID-19 Symptom Study, a higher diet quality defined as a pattern characterized by healthy plant-based foods conferred a 9-percent lower risk of COVID-19 (hazard ratio [HR], 0.91, 95 percent confidence interval [CI], 0.88–0.94) and 41-percent lower risk of severe COVID-19 (HR, 0.59, 95 percent CI, 0.47–0.74) compared with a low diet quality. [Gut 2021;doi:10.1136/gutjnl-2021-325353]

Notably, the association between diet quality and COVID-19 and severe disease was more pronounced among individuals living in areas with high vs low socioeconomic deprivation, according to the investigators.

“Our findings are aligned with preliminary evidence showing that improving nutrition could help reduce the burden of infectious diseases. Previous studies have shown that the administration of arachidonic or linoleic acid partially suppresses SARS-CoV-1 and coronavirus 229E viral replication, and that specific nutrients or dietary supplements associate with modest reductions in COVID-19 risk,” they pointed out. [N Engl J Med 2020;383:e69; BMJ Nutr Prev Health 2020;3:74-92; Viruses 2019;11:73; BMJ Nutr Prev Health 2021;4:149-57]

How eating healthy might protect against COVID-19, the investigators pointed out that it may be partially explained by trace elements, vitamins (A, B₆, B₁₂, C, D, and E, and folate), amino acids, long-chain omega-3 fatty acids (docosahexaenoic and eicosapentaenoic), and non-nutrient-bioactive compounds (ie, polyphenols) having a role in immune system function and cytokine release. [Altern Complement Med 2021;27:176-178]

In the study, the investigators assessed the dietary pattern of the participants using data drawn from a modified version of the Leeds Short Form Food Frequency Questionnaire that included 27 food items. They quantified diet quality with the healthful Plant-Based Diet Index, where the food items were combined into 14 food groups given positive (healthy plant food groups) or reverse scores (less healthy plant and animal food groups). All component scores were added to obtain a total score ranging from 14 (lowest diet quality) to 70 (highest) points.

Participants in the highest vs lowest quartile of the diet score tended to be older, female, healthcare workers, of lower body mass index, and engage in physical activities ≥5 days/week. They also were less likely to reside in areas with higher socioeconomic deprivation.

A total of 31,815 COVID-19 cases were recorded over 3,886,274 person-months of follow-up. The absolute excess rates of COVID-19 cases associated with the lowest vs highest quartile of the diet score were 40.8 per 10,000 person-months among individuals living in areas with high deprivation and 22.5 per 10,000 person-months among those residing in areas with low deprivation.

The proportion of contribution to excess COVID-19 risk was estimated to be 31.9 percent for diet quality, 38.4 percent for socioeconomic deprivation, and 29.7 percent for their interaction.

“While our study supports the beneficial association of diet quality with COVID-19 risk and severity, particularly among individuals with higher deprivation, we cannot completely rule out the potential for residual confounding. Individuals who eat healthier diets are likely to share other features that might be associated with lower risk of infection such as the adoption of other risk mitigation behaviours, better household conditions and hygiene, or access to care,” the investigators noted.

Nevertheless, they pointed out that the present data add to the evidence base highlighting the beneficial effect of healthy dietary patterns on severe COVID-19 and are in line with a comparative risk assessment study suggesting that a 10-percent reduction in the prevalence of diet-related conditions such as obesity and type 2 diabetes would have prevented ~11 percent of the COVID-19 hospitalizations that have occurred among US adults since November 2020. [J Am Heart Assoc 2021;10:e019259]

“These findings suggest that efforts to address disparities in COVID-19 risk and severity should consider specific attention to access to healthy foods as a social determinant of health,” according to the investigators.