Intermittent fasting over a long period of time reduces the risk of hospitalisation and death among patients infected with COVID-19
Long-term intermittent fasting significantly lowers the risk of both hospitalisation and mortality in those with COVID-19 but does not reduce the risk of becoming infected according to the findings of an analysis of registry data by US researchers.
Intermittent fasting (IF) describes a way of restricted eating and which can be undertaken in several different ways. For example, with the 16/8, food is only consumed over 8 hours or in the 5:2 approach, individuals eat normally for five days but then limit daily calorie intake the other two days, to only 500 –600 calories. There is now good evidence that IF may benefit cardiometabolic health by decreasing blood pressure, insulin resistance, and oxidative stress. One metabolic change seen with IF is increased linoleic acid-enriched triacylglycerol species in the liver and serum during fasting. Furthermore, recent in vivo data have revealed how the COVID-19 spike protein tightly binds linoleic acid in three composite pockets, resulting in reduced angiotensin-converting enzyme 2 interaction. Another advantage to IF is increased levels of galectin-3, a protein which has been shown to directly bind to pathogens and to have various effects on the functions of the cells of the innate immune system.
The available evidence thus tentatively suggests that those who practice IF could have a reduced disease severity if infected with COVID-19. To examine this in more details, the researchers undertook a prospective, observational study using data held in the INtermountain Healthcare Biological Samples Collection Project and Investigational REgistry (INSPIRE) which collects biological samples, clinical information and laboratory data from patients. For the purposes of the study, the team included registry patients who had undergone COVID-19 testing but also included demographic and clinical data from these patients. For the study, the primary endpoint was a composite of all-cause mortality and hospitalisation for COVID-19. The main secondary outcome was a positive test for COVID-19.
Intermittent fasting and adverse COVID-19 outcomes
A total of 205 individuals with a mean age of 63.5 years (37.1% female) were included, of whom 73, practiced IF and had done so for a mean of 40.4 years before their COVID-19 diagnosis.
From the whole cohort, 11% of IF individuals and 28.8% of non-fasters experienced the primary endpoint and this difference was significant (hazard ratio, HR = 0.61, 95% CI 0.42 – 0.90, p = 0.013) and in fully adjusted models, this difference remained significant (HR = 0.63, 95% CI 0.42 – 0.93, p = 0.021). Predictors of hospitalisation and mortality included age, coronary artery disease, hypertension, smoking and hyperlipidaemia.
Interestingly, for the secondary outcome, testing positive for COVID-19, there were no significant differences, with 14.3% of those practising IF and 13% of non-fasters becoming infected (p = 0.51).
The authors concluded that IF appeared to reduce the severity of COVID-19. In addition, they suggested that further work should examine the complementary role of IF with vaccination to reduce COVID-19 severity and how it might impact on long COVID.
Citation
Horne BD et al. Association of periodic fasting with lower severity of COVID-19 outcomes in the SARS-CoV-2 prevaccine era: an observational cohort from the INSPIRE registry BMJ nutr. prev. health 2022
