Longevity Briefs: Can Regular Fasting Protect Against COVID-19?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: We know that fasting is associated with a wide range of health benefits including reduced risk of chronic diseases such as heart failure and cancer. One of the many ways fasting exerts these effects is by reducing levels of inflammation throughout the body. Since many COVID-19 deaths are caused by a runaway inflammatory response, some scientists wonder whether fasting and other forms of dietary restriction might be protective against the disease.

What did the researchers do: In this study conducted in the Utah in the United States, researchers looked at data from individuals who participated in a health registry called INSPIRE. This included a survey about health practices including whether participants routinely fasted and for how many years. They then identified 1526 of these individuals who were tested for COVID-19 between March 2020 and February 2021. Of these, 205 had a positive test.

The researchers wanted to see if those who regularly engaged in fasting were either:

• Less likely to be hospitalised or to die after contracting COVID when compared to non-fasters
• Less likely to contract COVID in the first place when compared to non-fasters

Key takeaway(s) from this research: Of the 205 patients with COVID-19, just over a third reported engaging in regular fasting (this high number is mostly due to Utah’s high Mormon population), and had been doing this for an average of 40 years. By February 2021, 11.0% of fasters had either died, been hospitalised, or both, compared with 28.8% of non-fasters. This was a statistically significant difference and fasting appeared associated with similar benefits in both those over 65 and under 65 years old. However, there was no significant difference in the frequency of positive COVID tests between fasters and non-fasters.

As already mentioned, fasting can reduce inflammatory signalling, which may be protective against the more dangerous effects COVID-19. Another interesting possibility is that the proposed protective effects of fasting are due to a fatty acid called linoleic acid. Levels of linoleic acid rise in the blood after a sufficiently long period of fasting, and previous research shows that this fatty acid binds to the coronavirus spike protein in a way that makes it harder for the virus to infect human cells.

Since this study didn’t randomise participants to either fast or eat normally, we can’t be sure that the effects of fasting aren’t due to some other variable. People who choose to fast are more likely to engage in other healthy practices, and these are very difficult to account for, though the researchers did try to control for many of them. In this case, Utah has a large population of Mormons, who typically fast on the first Sunday of each month. This means that the lifestyles of fasters and non-fasters in this study were likely to have been different in other ways. For example, the fasters may have engaged in more religious gatherings, which may have made them more likely to contract COVID, which would confound the finding that fasting doesn’t prevent infection.